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In this work, chitin was extracted using a single step of deproteinization from the whole locust and its different morphological parts (thorax, legs, abdomen, head and wings). All chitins present an α structure with contents of 10 to 12% and high degrees of acetylation (DA) (92–96%). Physicochemical differences are observed among the chitins from the different parts, particularly in terms of crystallinity indexes (54–72%), molar masses Mv (537,000–672,000 g·mol−1) and surface morphology (fibrous or porous). The N-deacetylation of chitins from the different parts was carried out using KOH in an anhydrous medium (Broussignac process). Other tests using NaOH in an aqueous solution (Kurita process) were also applied to the chitin from the legs. The results show that it is possible to valorize the desert locust by preparing highly deacetylated chitosan (4–14%) with remarkably low to relatively high Mv (11,000–123,000 g·mol−1), depending on the process used. [ABSTRACT FROM AUTHOR]

The outbreak of the desert locust Schistocerca gregaria Forskål, 1775, which originated from the Horn of Africa in 2019–2020 created an episodic plague under bio-geographical settings in the arid and semi-arid areas of South and Southwest Asia. In India, it happened after twenty-seven years due to the persistence of a few favourable conditions caused by its plague, resulting in hundreds of crores in crop damage. Keeping this in mind, the study aims to assess the suitability and likelihood of the desert locust epidemic occurring in India, utilizing two widely recognized statistical models: Weight-of-Evidence (WoE) and Frequency Ratio (FR). This work evaluated nine critical climatic factors for the study considering western and central parts of India. The 'Projected Locust Suitability' (PLS) was calculated by analyzing the correlation of the considered variables and the occurrence of locust swarms and bands. The significance (importance) of each variable on PLS was determined using Principal Component Analysis (PCA) and Random Forest (RF) algorithms. The PLS maps clearly show that 42.7–52.8% of the areas fall under high and very high locust suitability zones. The result suggests that the Ajmer-Gwalior-Allahabad tract is highly prone to future locust occurrences, while the Aligarh-Bareilly-Lakhimpur tract is moderately susceptible. The effectiveness of both modelled PLS maps was determined with the help of the ROC curve. The AUC results indicate that both the WoE (0.92) and the RF (0.90) models worked remarkably well in precisely predicting PLS. The RF-based IncNodePurity analysis indicates that low to moderate temperatures in the presence of cloud cover significantly impact locust occurrence and migration. The present findings are projected to direct the development of sustainable locust management strategies utilizing proper land use policies in the tropical climate. [ABSTRACT FROM AUTHOR]

World's Best Practice management of locusts and grasshoppers requires accurate forecasting that helps determine where and when surveys are preferentially conducted so that infestations can be found quickly as part of ensuring early intervention treatments. Using survey data downloaded directly into a Geographic Information System (GIS), as well as rainfall and other factors important in the population dynamics of the species concerned, models within the GIS provide forecasts of future developments. The GIS provides forecasts of likely events and is used by locust and grasshopper experts to make decisions; that is, the forecasting is part of a Decision Support System for improved locust and grasshopper management. Surveys are generally conducted by ground vehicles, but for locusts, surveys by aircraft can be an important way to rapidly find bands. In Australia, dense bands can often be seen from an aircraft flying overhead at a height of 300 m, and similar detection of bands of the desert locust by aircraft has been conducted in Somalia. Swarms can be detected by ground vehicles, but because swarms move, surveying by aircraft is also an important way of locating swarms for treatment. When locust infestations are found, they are rapidly treated as part of early intervention preventive management. However, it is generally recognized that it is extremely difficult for landholders alone to protect crops against locusts and grasshoppers, so government intervention is often necessary. These organizations use a variety of treatment techniques to reduce the amount of chemical pesticide applied either by strip spraying or treating very dense infestations, such as roosting swarms, or using biopesticides. These techniques, as used in a number of countries, have proven to be very effective in managing locust populations while reducing the risk to the natural environment and human health. [ABSTRACT FROM AUTHOR]

The fact that the monarch butterfly (Danaus plexippus L.) migrates from Canada to central Mexico is a well-known fact. Here, the migration of the Eastern and Western populations of monarchs is described. This article will not be a field study but an attempt to synthesize a theory of how this migration could originate in a young-Earth context, given that butterflies were created essentially as seen today or will be assumed to have originated this way. The Uvarov Phase Theory is discussed as it applies to desert locusts and its possible relation to the unique migratory generation of monarchs, that is, the larger size of the Fall migratory individuals, and the importance of diapause. The establishment of this interesting migratory pattern is discussed in terms of geography and topography and related to the unique flight abilities of these butterflies. [ABSTRACT FROM AUTHOR]

Adult female desert locusts (Schistocerca gregaria) dig underground to lay their eggs, ensuring optimal conditions for successful hatching. Digging is performed using the two pairs of oviposition valves at the tip of the female's abdomen. These valves are subjected to considerable shear forces during the repeated digging cycles, potentially leading to wear over time. The resilience of the valves is investigated by analyzing the relationship between digging experience and valve damage and wear throughout the female locust's life. The findings reveal the ability of the valves to withstand the significant shear forces encountered during digging. Despite this resilience, however, perceptible limitations in the valves’ mechanical durability against wear are observed. Toward the end of the female locust's life, the valves show substantial signs of wear, indicating effective performance but with limited longevity, i.e., a designated life span that enables successful oviposition for ca. four oviposition cycles. A comparison of the valve material with that of the animals’ mandibles, which are used continuously throughout their life and show remarkable wear‐resistance, further highlights the evolutionary adaptation of the valve materials to their specific function, suggesting a trade‐off between energetic investment and the sufficient, or “good‐enough”, performance that is required for survival. [ABSTRACT FROM AUTHOR]

Desert locusts (Schistocerca gregaria) pose a significant threat to food security. However, they also serve as a nutrient‐rich delicacy in many African and Arabic communities where they are traditionally harvested for food and feed. Traditional harvesting methods are inefficient, laborious, and time‐consuming; hence, there is a need to explore more convenient and efficient techniques. This study assessed preferential selection and feeding behavior of desert locusts to identify trap plants that could attract and aggregate them for easy harvesting. Four trap plants (cowpea, finger millet, sorghum, and amaranth) and four repellent plants (neem, pencil cactus, garlic, and cayenne red pepper) were evaluated through multiple‐choice experiments. A randomized complete block design involving mature adult, immature adult, and hopper stages of desert locusts was used. Analysis of variance was used to determine the effects of repellent and trap plants on feeding preferences of desert locusts. Mean differences between treatments at p < 0.05 were separated using post hoc Tukey's honestly significant difference. Cowpea as the most preferred trap plant attracted 62.7%, 70.7%, and 76.9% of mature adult, immature adult, and hopper locust stages, respectively. Neem exhibited the most potent repellent effect and attracted no desert locusts for feeding. Neem repelled locusts, thereby reducing infestation and damage of cowpea as a pull plant when both plants were grown in the same pot in a "push–pull" system. The push–pull attracted 3.7%, 24.3%, and 7.8% of mature adult, immature adult, and hopper locust stages, respectively. However, cowpea attracted large numbers of locusts (96.3% mature adults, 75.7% immature adults, and 92.2% hoppers) when grown separately from neem. These findings provide valuable insights on the potential of exploiting traps and repellents to enhance aggregation and harvesting of desert locusts as food and feed. [ABSTRACT FROM AUTHOR]

Background: Accurate detection of pheromones is crucial for chemical communication and reproduction in insects. In holometabolous flies and moths, the sensory neuron membrane protein 1 (SNMP1) is essential for detecting long-chain aliphatic pheromones by olfactory neurons. However, its function in hemimetabolous insects and its role for detecting pheromones of a different chemical nature remain elusive. Therefore, we investigated the relevance of SNMP1 for pheromone detection in a hemimetabolous insect pest of considerable economic importance, the desert locust Schistocerca gregaria, which moreover employs the aromatic pheromone phenylacetonitrile (PAN) to govern reproductive behaviors. Results: Employing CRISPR/Cas-mediated gene editing, a mutant locust line lacking functional SNMP1 was established. In electroantennography experiments and single sensillum recordings, we found significantly decreased electrical responses to PAN in SNMP1-deficient (SNMP1−/−) locusts. Moreover, calcium imaging in the antennal lobe of the brain revealed a substantially reduced activation of projection neurons in SNMP1−/− individuals upon exposure to PAN, indicating that the diminished antennal responsiveness to PAN in mutants affects pheromone-evoked neuronal activity in the brain. Furthermore, in behavioral experiments, PAN-induced effects on pairing and mate choice were altered in SNMP1−/− locusts. Conclusions: Our findings emphasize the importance of SNMP1 for chemical communication in a hemimetabolous insect pest. Moreover, they show that SNMP1 plays a crucial role in pheromone detection that goes beyond long-chain aliphatic substances and includes aromatic compounds controlling reproductive behaviors. [ABSTRACT FROM AUTHOR]

The desert locust, Schistocerca gregaria (Forsk., 1775), stands as one of the most pervasive pests globally, inflicting extensive damage across Asia and Africa. Facilitated by intercontinental migration, the desert locust engages in population exchange between different source areas, perpetuating its widespread proliferation. Despite the wind being recognized as a key factor during migration events, elucidating its precise influence on intercontinental migration has remained elusive. In this study, we scrutinized monitoring data sourced from the FAO monitoring system, pinpointing 13 desert locust events featuring intercontinental migrations since 1967. From these events, four migration routes were summarized, traversing the Red Sea (RS-WE and RS-EW) and the northern Indian Ocean (IO-WE and IO-EW). Typically, RS-WE and IO-EW migrations occurred between December and March, whereas RS-EW and IO-WE migrations were observed from May to June and April to July, respectively. Our examination of wind field data spanning the past 15 years revealed that wind direction and speed facilitated intercontinental migrations. Furthermore, migration trajectory modeling indicated that desert locusts might exhibit migratory behavior both during the day and at night in the cases of RS-WE and RS-EW, with cross-oceanic migration potentially lasting for a week for IO-WE and IO-EW. In summary, our study identifies four migration routes for the intercontinental migration of the desert locust, providing crucial support for the scientific prediction of its occurrence and contributing to international food security efforts. [ABSTRACT FROM AUTHOR]

Schistocerca gregaria is a notorious pest amongst insects populating around the globe. S.gregaria form swarms that can spread across millions of square kilometers daily, significantly impacting international economies, societies, and ecosystems. The invasions can devastate the rural communities in the affected areas, threatening their ability to provide for themselves and their families with food. Many millions of dollars are often spent on control measures, and the widespread use of chemical insecticides has negative consequences for the ecosystem. During the present study 597 specimen of Schistocerca gregaria collected from different localities of Taluka Dadu. These specimens were identified according to the four different coloration; Pink, Light Brown, Yellow, and White. Solitarious phase specimens 104 and 493 Gregarious phase collected from various localities. Besides this, the distribution, morphology, and diversity of S.gregaria have been presented in this study. [ABSTRACT FROM AUTHOR]

The antennal flagellum of the locust S. gregaria is an articulated structure bearing a spectrum of sensilla that responds to sensory stimuli. In this study, we focus on the basiconic-type bristles as a model for sensory system development in the antenna. At the end of embryogenesis, these bristles are found at fixed locations and then on only the most distal six articulations of the antenna. They are innervated by a dendrite from a sensory cell cluster in the underlying epithelium, with each cluster directing fused axons topographically to an antennal tract running to the brain. We employ confocal imaging and immunolabeling to (a) identify mitotically active sense organ precursors for sensory cell clusters in the most distal annuli of the early embryonic antenna; (b) observe the subsequent spatial appearance of their neuronal progeny; and (c) map the spatial and temporal organization of axon projections from such clusters into the antennal tracts. We show that early in embryogenesis, proliferative precursors are localized circumferentially within discrete epithelial domains of the flagellum. Progeny first appear distally at the antennal tip and then sequentially in a proximal direction so that sensory neuron populations are distributed in an age-dependent manner along the antenna. Autotracing reveals that axon fasciculation with a tract is also sequential and reflects the location and age of the cell cluster along the most distal annuli. Cell cluster location and bristle location are therefore represented topographically and temporally within the axon profile of the tract and its projection to the brain. [ABSTRACT FROM AUTHOR]

Insects like Schistocerca gregaria, the desert locust, are becoming recognized as possible poultry feed. More and more scientists are becoming interested in using insects for poultry feed, especially as a novel and sustainable source of high-grade protein. This study investigated the effects of desert locust dietary supplementation on the growth performance, carcass quality, and blood biochemistry of broiler chickens. A total of 320 1-day old broiler chicks (Cobb 500) were randomly divided into 4 treatment groups (3 levels of locusts' supplementation and 1 control group) and fed diets with varying levels of desert locust inclusion (control, 1, 2 & 3%). There were four replicates of each dietary treatment resulting in 80 birds per treatment group (20 birds/ replication). Birds were arranged in a completely randomized design. The trial lasted six weeks, growth performance parameters were evaluated. Ten birds from each treatment were slaughtered for the carcass analysis at the end of the experiment. Additionally, 10 blood samples from each dietary treatment (from the slaughtered birds) were collected for biochemical parameters to assess the physiological parameters (plasma total protein, albumin, total cholesterol, triglycerides, creatinine, and uric acid) responses to the dietary treatments. Significant variation had been observed in the growth performance at 5th week of age (P< 0.01). Broiler diets supplemented with 2% locusts were found to improve body weight and kidney function while having no negative impact on carcass and organ weights. The results indicated a substantial increase (P< 0.03) in the antibody titer against the Newcastle disease virus in the chickens fed 3% locust meal. The findings provide insights into the potential utilization of desert locusts as a sustainable protein source in broiler chicken diets. In conclusion, the use of desert locust meal in broiler chicken diets presents opportunities for the poultry industry to enhance sustainability, reduce costs, and improve feed efficiency. [ABSTRACT FROM AUTHOR]

The desert locust is one of the most destructive locusts recorded in human history, and it has caused significant food shortages, monetary losses, and environmental calamities. Prediction of locust attacks is complicated as it depends on various environmental and geographical factors. This research aims to develop a machine-learning model for predicting desert locust attacks in 42 countries that considers three predictors: soil moisture, maximum temperature, and precipitation. We developed the Global Locust Attack Database for 42 countries (GLAD42) by integrating TerraClimate’s environmental data with locust swarm attack data from the Food and Agriculture Organization (FAO). To improve the usability of spatial data, reverse geocoding which is the process of converting geographic coordinates (longitude and latitude) into human-readable location names (such as countries and regions) was employed. This step enhances the clarity and interpretability of the data by providing meaningful geographic context. This study’s initial dataset focused on instances where locust attacks were recorded (positive class). To ensure a comprehensive analysis, we also incorporated negative class instances, representing periods (specific years and months) in the same countries and regions where locust attacks did not occur. This research utilizes the benefits of lazy learners by employing the K-nearest neighbor algorithm (K-NN), which provides high accuracy and the benefit of no time-consuming retraining even if real-time updated data is periodically added to the system. This research also focuses on building an eco-friendly machine learning model by evaluating carbon emissions from ML models. The results obtained from LocustLens are compared with other machine learning models, including baseline–K-NN, decision trees (DT), Logistic regression (LR), AdaBoost Classifier, BaggingClassifier, and support vector classifier (SVC). LocustLens outperformed all competitors with an accuracy of 98%, while baseline-K-NN achieved 96%, SVC gave 91%, DT gave 97%, AdaBoost has accuracy of 91%, BaggingClassifier gave 94% and LR gave 83%, respectively. Carbon emissions from RAM and CPU electricity consumption are measured in kg gCO2. They are a minimum for AdaBoost Classifier equal to 0.02 and 0.07 for DT and a maximum of 9.03 for SVC. The carbon footprint of LocustLens is 4.87 kg gCO2.

ABSTRACTDesert locust outbreaks pose severe threats to agricultural production and ecological environments. Hence, understanding the distribution of habitat suitability is crucial for establishing effective prevention and control measures. We introduce an innovative method for analyzing the temporal and spatial variations of desert locust habitat suitability in Yemen. This method integrates ecological niche models with space–time cube analysis. First, we gathered key environmental variables that affect desert locust distribution, including vegetation and soil types, precipitation, and temperature. Subsequently, we employed the MaxEnt model to assess habitat suitability for desert locusts in Yemen for 2010 and 2013–2021. Finally, we applied the space–time cube method for spatiotemporal analysis to reveal the spatiotemporal dynamics of habitat suitability distribution. The MaxEnt model results showed that the kappa coefficients exceeded 0.46 and the area under the curve exceeded 0.75. The spatiotemporal analysis results showed that from 2010 to 2021, the Red Sea coastal plains in western Yemen exhibited the highest habitat suitability levels, with significant increases in habitat suitability in the western and central regions. This study offers a new perspective on studying the spatial and temporal characteristics of desert locust habitat suitability distribution and can provides a scientific basis for the management of desert locusts.

Desert locust (Schistocerca gregaria) infestations cause significant damage to crops and pastureland, impeding food security and livelihoods globally. In recent years, some East African countries have suffered severe desert locust outbreaks, causing significant harm to agriculture and local communities. To comprehensively understand and mitigate the socio‐economic impacts of this pest, an integrated assessment approach is crucial. This study proposes an integrated assessment model that combines ecological, economic, and social dimensions to analyze the multifaceted impacts of the desert locust on the rate of urbanization changes, farming expansion, and food production and how they lead to food unavailability (demand, supply, and price) and food and nutrition insecurity in Eastern Africa. A system dynamics‐based assessment model was first developed for Sudan using the dynamic relations among the factors and their variations over time and how they affect the socio‐economic variables. The developed model was used to spatially simulate the impacts over the entire Eastern Africa. Various scenarios were further simulated and analyzed, incorporating different policy options to effectively mitigate the impacts. Results demonstrated that in all the countries, desert locusts extensively contribute to the slowing down of farming expansion and food production and supply. Consequently, these factors lead to increased urbanization rates through people rural‐urban migration and food demand at different magnitudes across different countries. By considering both short‐term and long‐term effects, this approach aims to provide policymakers, researchers, and practitioners with a holistic understanding of the complex dynamics involved and inform effective management strategies. For example, communities equipped with accurate breeding detection tools and employing an integrated pest management strategy combining chemical pesticides and biopesticides had the highest potential for effectively mitigating the future impacts of desert locusts for enhancing community livelihood. Plain Language Summary: Desert locusts are a major problem for agriculture and communities in East Africa. They eat crops and grasslands, which can lead to food shortages and higher prices. To better understand and deal with this issue, we have created a model that looks at how locusts affect things like farming, urbanization, and food supply. We studied this in Sudan and then applied it to the whole of East Africa. The results showed that locusts make farming harder and push more people to move from rural areas to cities. This causes more demand for food in cities. The study tested different ways to deal with locusts and found that communities with good tools for detecting locusts and using both chemical and biopesticide control methods were the best at reducing the impact of locusts on their lives. This study gives policymakers and others a better understanding of how locusts affect communities and how to manage them effectively in the future. Key Points: In Eastern Africa, desert locusts swarm in vast numbers, devouring crops, and vegetation, causing crop production losses ranging from 42% to 69%The system dynamics model was employed for a comprehensive analysis of the impacts, scenarios, and policy options for mitigating desert locust effectsDesert locusts hinder farming, reduce food production, spur urbanization, and heighten food insecurity across affected Eastern African countries [ABSTRACT FROM AUTHOR]

Desert locusts threaten crop production and food security. Spatially synchronized locust outbreaks further exacerbate these crises. Continental-scale understanding of such compound locust risks and underlying climatic drivers is crucial to designing coordinated and predictive control strategies but remains elusive. Here, we develop a data-driven framework to assess the compound risk of locust outbreaks in the Middle East and North Africa (MENA) and elucidate the role of climate in locust dynamics. We find that more than one-fifth of high-risk country pairs faced spatially synchronized locust risks from 1985 to 2020, dominated by concurrent winds or inundations. Individual locusts are more prone to infest arid areas punched by extreme rainfall. The spatial prevalence of locusts is strongly modulated by climate variability such as El Niño-Southern Oscillation. A warming climate will lead to widespread increases in locust outbreaks with emerging hotspots in west central Asia, posing additional challenges to the global coordination of locust control. [ABSTRACT FROM AUTHOR]

Simple Summary: Locusts can be at a state called the solitarious phase, associated with harmless populations, or at the gregarious phase, associated with outbreaks. Given the importance of the phenomenon, researchers are trying to reveal its molecular basis and find ways to tackle it. For this, assessing the phase state and comparing locusts is essential, and researchers have thus far used different formulae. To address the problem presented by the lack of standardised tools for such an essential task, we previously suggested two models as tools for standardising the method for assessing the main pest locust, Schistocerca gregaria. However, a theoretical work later cast doubts on the validity of such models and predicted that they would not work as well on future samples as in their initial application. Here, we use additional, different S. gregaria samples to test and assess the performance of these models. The results reaffirm the validity of the results of our previous work, since the models performed just as well on the present samples as they did in the previous ones. The models are thus reinstated as potential tools for standardising the way solitarious and gregarious S. gregaria samples are assessed and compared. Outbreaks of the desert locust Schistocerca gregaria affect some of the poorest parts of Africa, with devastating outcomes. The key to understanding and dealing with this problematic adaptation to environmental changes is comparing gregarious and solitarious locusts, either in nature or in laboratories. Categorising locusts and detecting changes in their phase status is key to such comparisons, which have been hitherto based on applying mathematical models that use behavioural parameters and that each laboratory has to build anew for each experiment. All the models used thus far are different from one another. This implies differences in the tools used for the different experiments and by the different laboratories and, thus, potential noise in the results and interpretations. Standardising the way locusts are categorised is necessary if we want to reduce noise and errors. It is crucial if we seek to make the results and interpretations transferable and comparable between experiments and laboratories for such an important research area. To tackle this problem, we suggested two models as possible standardising tools. However, the problem of a lack of standardised tools re-emerged due to the doubts cast on the validity of those models. Here, we use samples from independent S. gregaria populations in order to test and validate those models. We discuss how successful the two models were at categorising solitarious, intermediate (transient), and gregarious nymph and adult S. gregaria samples. We highlight shortcomings and make more specific recommendations on the use of those models based on the precision differences they show when categorising solitarious and gregarious S. gregaria nymph and adult samples. Overall, both models have proven to be valid since their results were largely replicated and seem reproducible. [ABSTRACT FROM AUTHOR]

Background: The main objective of this study is to evaluate the effect of magnesium oxide nanoparticles on desert locust adults and thus recommend its use in integrated pest management programs. Methods: This study investigated the impact of magnesium oxide nanoparticles (MgO) on adult Schistocerca gregaria. The insects were treated with Nano and Lambda-cyhalothrin 4% at three different concentrations, in addition to a control group with a concentration of 0.00, 0.150, 0.300, and 0.600 mL/L. Results: The study revealed a positive correlation between the concentration of nanomaterial mixed with the insecticide and the fatality rate. The study revealed that the half-lethal concentration (LC50) value is 0.050. Furthermore, the results indicated a significant disparity between the impact of nanoparticles and the pesticide, with respective p-values of 0.008 and 0.15 at concentrations of 0.150 and 0.600. However, both substances exhibited an equal effect at a concentration of 0.300. The impact of MgO nanoparticles and the pesticide on insect fertility was evident across all three concentrations of the nanomaterial mixed with the pesticide. The observed fertility rates were 35.4%, 35.4%, and 78.2%, respectively. In contrast, the control group consisting solely of the pesticide showed no difference in fertility, with a rate of 0%. Conclusion: When magnesium oxide (MgO) nanoparticles and Lambda-cyhalothrin 4% insecticide are mixed, they have a big effect on adult desert locusts (Schistocerca gregaria). This is due to the high toxicity of the nanoparticles and their ability to penetrate the insect's cuticle layer, as well as their effect on the respiratory system and the gastrointestinal system of insects. It was shown that increasing the concentration of nanoparticles mixed with this pesticide results in higher mortality rates for both male and female individuals of the species. Additionally, it causes a decrease in the fertility rate, specifically for female insects, when exposed to the pesticide. [ABSTRACT FROM AUTHOR]

This article aimed to investigate the challenges that Ethiopia faces during COVID-19. The article looks highly at COVID-19, political instability, desert locust and the ideal conflict between Ethiopia and Egypt on the great Ethiopian renaissance dam. Economic rescission, food insecurity and internal war are also the main topics clearly discussed. The results revealed that unemployment, inflation and income inequality are aggravated as pandemics arise. Thousands were killed and others were displaced due to internal political instability. Output reduction and famine resulted due to desert locust infestation. Bad political spirit is also one fact in Ethiopia due to ideal conflict with Egypt. Consequently, thousands have been arrested; killing innocent people, food insecurity, economic depression and displacement were highly aggravated. While other countries have been moving to prosperity, the Ethiopian economy has been challenged with stagnation. Therefore, the authors suggest that there should be strong intervention from both non-governmental organisation and the government of Ethiopia. Let Ethiopia's recovery come to tell new development. [ABSTRACT FROM AUTHOR]

Naturally occurring collective motion is a fascinating phenomenon in which swarming individuals aggregate and coordinate their motion. Many theoretical models of swarming assume idealized, perfect perceptual capabilities, and ignore the underlying perception processes, particularly for agents relying on visual perception. Specifically, biological vision in many swarming animals, such as locusts, utilizes monocular non-stereoscopic vision, which prevents perfect acquisition of distances and velocities. Moreover, swarming peers can visually occlude each other, further introducing estimation errors. In this study, we explore necessary conditions for the emergence of ordered collective motion under restricted conditions, using non-stereoscopic, monocular vision. We present a model of vision-based collective motion for locust-like agents: elongated shape, omni-directional visual sensor parallel to the horizontal plane, and lacking stereoscopic depth perception. The model addresses (i) the non-stereoscopic estimation of distance and velocity, (ii) the presence of occlusions in the visual field. We consider and compare three strategies that an agent may use to interpret partially-occluded visual information at the cost of the computational complexity required for the visual perception processes. Computer-simulated experiments conducted in various geometrical environments (toroidal, corridor, and ring-shaped arenas) demonstrate that the models can result in an ordered or near-ordered state. At the same time, they differ in the rate at which order is achieved. Moreover, the results are sensitive to the elongation of the agents. Experiments in geometrically constrained environments reveal differences between the models and elucidate possible tradeoffs in using them to control swarming agents. These suggest avenues for further study in biology and robotics. Author summary: Swarm collective motion is a wide-ranging phenomenon in nature, with applications in multi-agent, multi-robot systems. In most natural swarming species, individuals rely on monocular, non-stereoscopic vision as the key sensory modality for their interactions. For example, the desert locust (Schistocerca gregaria) displays large swarms of individuals, moving in alignment and relying solely on non-stereoscopic visual perception. Inspired by these locust swarms, we have developed a monocular, non-stereoscopic vision-based model that achieves synchronized motion in a swarm of two-dimensional agents, even with inaccurate estimates of distances and velocities, particularly in the presence of occlusions. We explore three general strategies for handling occlusions, which differ in the requirements they place on the complexity of the visual perception process. We show that strategies may reach a highly ordered motion state but differ in their rate of convergence to this ordered state. [ABSTRACT FROM AUTHOR]

After overexposure to loud music, we experience a decrease in our ability to hear (robustness), which usually recovers (resilience). Here, we exploited the amenable auditory system of the desert locust, Schistocerca gregaria , to measure how robustness and resilience depend on age. We found that gene expression changes are dominated by age as opposed to noise exposure. We measured sound-evoked nerve activity for young and aged locusts directly, after 24 hours and 48 hours after noise exposure. We found that both young and aged locusts recovered their auditory nerve function over 48 hours. We also measured the sound-evoked transduction current in individual auditory neurons, and although the transduction current magnitude recovered in the young locusts after noise exposure, it failed to recover in the aged locusts. A plastic mechanism compensates for the decreased transduction current in aged locusts. We suggest key genes upregulated in young noise-exposed locusts that mediate robustness to noise exposure and find potential candidates responsible for compensatory mechanisms in the auditory neurons of aged noise-exposed locusts. [ABSTRACT FROM AUTHOR]

Locust swarm control is still a main topic in agriculture and is often based on the extensive use of chemical agents that can be problematic for the environment and human health. Currently, only a few alternative control agents are available on the market, such as neem oil, the fungus Metarhizium sp., and the microsporidian Paranosema locustae. In this study, we improved the formulation of a botanical insecticide that is based on linseed oil and was found to be effective against the desert locust, Schistocerca gregaria. To make sure that linseed oil is most effective, we first tested several natural plant oils in a comparative laboratory study. Linseed oil performed best and resulted in 100% mortality within only 2 days after a single spray treatment. However, this linseed oil formulation contains three expensive essential oils, thus we further improved it to avoid costly essential oils. A much lower concentration of linseed oil was also found to be highly effective and killed adult S. gregaria within 3 days in an experiment performed under semifield conditions. Furthermore, a concentrated stock solution of this botanical insecticide was developed to increase stability and reduce shipping costs in areas where water for dilution is available. Mechanical treatment, applied during the preparation of this linseed oil emulsion, resulted in the formation of micro‐colloids, which prevent the separation of phases and enable 1:16 dilution with water containing bicarbonate. Interestingly, only 24 h after single spray treatment, locusts became immobile and most of them were unable to jump, which would make them easy prey for natural enemies. Later, insects died due to the hardening of the linseed oil emulsion. This novel linseed oil emulsion is harmless for humans, rather easy to produce, and remains stable over weeks in its concentrated form, which suggests that it is promising alternative agent for locust control. [ABSTRACT FROM AUTHOR]

The Orthoptera are a diverse insect order well known for their locomotive capabilities. To jump, the bush-cricket uses a muscle actuated (MA) system in which leg extension is actuated by contraction of the femoral muscles of the hind legs. In comparison, the locust uses a latch mediated spring actuated (LaMSA) system, in which leg extension is actuated by the recoil of spring-like structure in the femur. The aim of this study was to describe the jumping kinematics of Mecopoda elongata (Tettigoniidae) and compare this to existing data in Schistocerca gregaria (Acrididae), to determine differences in control of rotation during take-off between similarly sized MA and LaMSA jumpers. 269 jumps from 67 individuals of M. elongata with masses from 0.014 g to 3.01 g were recorded with a high-speed camera setup. In M. elongata, linear velocity increased with mass0.18 and the angular velocity (pitch) decreased with mass−0.13. In S. gregaria, linear velocity is constant and angular velocity decreases with mass−0.24. Despite these differences in velocity scaling, the ratio of translational kinetic energy to rotational kinetic energy was similar for both species. On average, the energy distribution of M. elongata was distributed 98.8% to translational kinetic energy and 1.2% to rotational kinetic energy, whilst in S. gregaria it is 98.7% and 1.3%, respectively. This energy distribution was independent of size for both species. Despite having two different jump actuation mechanisms, the ratio of translational and rotational kinetic energy formed during take-off is fixed across these distantly related orthopterans. [ABSTRACT FROM AUTHOR]

The desert locust, Schistocerca gregaria (Forsk., 1775), stands as one of the most pervasive pests globally, inflicting extensive damage across Asia and Africa. Facilitated by intercontinental migration, the desert locust engages in population exchange between different source areas, perpetuating its widespread proliferation. Despite the wind being recognized as a key factor during migration events, elucidating its precise influence on intercontinental migration has remained elusive. In this study, we scrutinized monitoring data sourced from the FAO monitoring system, pinpointing 13 desert locust events featuring intercontinental migrations since 1967. From these events, four migration routes were summarized, traversing the Red Sea (RS-WE and RS-EW) and the northern Indian Ocean (IO-WE and IO-EW). Typically, RS-WE and IO-EW migrations occurred between December and March, whereas RS-EW and IO-WE migrations were observed from May to June and April to July, respectively. Our examination of wind field data spanning the past 15 years revealed that wind direction and speed facilitated intercontinental migrations. Furthermore, migration trajectory modeling indicated that desert locusts might exhibit migratory behavior both during the day and at night in the cases of RS-WE and RS-EW, with cross-oceanic migration potentially lasting for a week for IO-WE and IO-EW. In summary, our study identifies four migration routes for the intercontinental migration of the desert locust, providing crucial support for the scientific prediction of its occurrence and contributing to international food security efforts.

Owing to alignment of rhodopsin in microvillar photoreceptors, insects are sensitive to the oscillation plane of polarized light. This property is used by many species to navigate with respect to the polarization pattern of light from the blue sky. In addition, the polarization angle of light reflected from shiny surfaces such as bodies of water, animal skin, leaves, or other objects can enhance contrast and visibility. Whereas photoreceptors and central mechanisms involved in celestial polarization vision have been investigated in great detail, little is known about peripheral and central mechanisms of sensing the polarization angle of light reflected from objects and surfaces. Desert locusts, like other insects, use a polarization-dependent sky compass for navigation but are also sensitive to polarization angles from horizontal directions. In order to further analyze the processing of polarized light reflected from objects or water surfaces, we tested the sensitivity of brain interneurons to the angle of polarized blue light presented from ventral direction in locusts that had their dorsal eye regions painted black. Neurons encountered interconnect the optic lobes, invade the central body, or send descending axons to the ventral nerve cord but are not part of the polarization vision pathway involved in sky-compass coding. [ABSTRACT FROM AUTHOR]

Simple Summary: Four species of plague locust, namely the brown locust, the African migratory locust, the red locust, and the southern African desert locust, have threatened agricultural production in South Africa for centuries. The history of the plague invasions of the red locust and African migratory locust into South Africa are described, as well as the rare local outbreaks of the southern African desert locust in the Kalahari Desert region. The dynamics of the locally produced outbreaks of the African migratory locust in the cereal crop environment on the Highveld are discussed in detail. However, the brown locust is by far the most economically important locust species in South Africa, with a very high frequency of outbreaks occurring in the semi-arid Karoo region. After synthetic insecticides became available in 1945, most of the outbreaks were contained within the Karoo following vigorous control campaigns with only short-lived escapes of swarms into grain production areas outside the Karoo and into surrounding countries. However, the large-scale plague eruptions of the brown locust are almost impossible to stop with the resources currently available to the South African locust control organization, and the threat that the brown locust poses to food security in southern Africa is very real. The current paper provides a detailed review of the historical outbreaks of each of the four plague locust species found in South Africa, namely the brown locust, the African migratory locust, the red locust, and the southern African desert locust. The history and dynamics of the plague infestations and the major local outbreaks are summarized. The typical patterns of the outbreaks of the different species are described, and the threat of these locusts to agriculture in South Africa is defined. The brown locust produces regular outbreaks in the semi-arid Karoo, with large-scale eruptions of plague proportions occurring about once per decade. Patterns of outbreaks often repeat themselves, but the sheer size of the plague outbreaks is almost impossible to stop, and the brown locust has the potential to threaten food security throughout southern Africa. The African migratory locust produces outbreaks in some of the main maize and wheat cropping areas where it is difficult to control. This locust has taken advantage of the man-made crop environment to produce an extra generation per year that was not previously possible in the original grasslands. The coastal area of KwaZulu Natal Province in South Africa was a prime reception and breeding area for plague invasions of the red locust in the past, and the country, therefore, relies on the successful control of outbreaks in east and central Africa to prevent the recurrence of the plague invasions. The southern African desert locust occurs in the Kalahari Desert area, and outbreaks requiring chemical control are rare. [ABSTRACT FROM AUTHOR]

Maize (Zea mays L.) is a staple food for many households in sub-Saharan Africa (SSA) and also contributes to the gross domestic product (GDP). However, the maize yields reported in most SSA countries are very low and this is mainly attributed to biotic and abiotic stresses. These stresses have been exacerbated by climate change which has led to long periods of drought or heavy flooding and the emergence of new biotic stresses. Few reports exist which compile the biotic stresses affecting maize production in SSA. Here, five major biotic stresses of maize in Kenya are presented which are attributed to high yield losses. They include Maize lethal necrosis, fall armyworm, gray leaf spot, turcicum leaf blight and desert locusts. Maize lethal necrosis and fall armyworm are new biotic stresses to the Kenyan maize farmer while gray leaf spot, and turcicum leaf blight are endemic to the region. The invasion by the desert locusts is speculated to be caused by climate change. The biotic stresses cause a reduction in maize yield of 30-100% threatening food security. Therefore, this review focuses on the cause, control measures employed to control these diseases and future prospective. There should be deliberate efforts from the government and researchers to control biotic stresses affecting maize yields as the effect of these stresses is being exacerbated by the changing climate. [ABSTRACT FROM AUTHOR]

Edible insects play an important role as a protein source of high-nutritional value in the western region of Kenya. However, current knowledge on edible grasshopper/locust species consumed in western Kenya and the perception towards these insects as an alternative protein source are not well documented. A questionnaire was issued to 901 respondents in four counties of western Kenya. The results showed that 91.6% of the respondents had heard that grasshoppers/locusts are edible insects and that 51.2% of the respondents had consumed them. The most frequently identified edible species was Cyrtacanthacris tatarica, with 58.6% cases followed by Schistocerca gregaria (25.7%), while Ruspolia differens was the least identified (1.2%). The majority of the consumers (60.0%) were introduced to entomophagy by their relatives, fewer by their friends (34.0%), and 5.7% by themselves. For those who had never eaten them, 53.8% were unwilling to try, while 11.9% were willing. On availability in the market, 97.9% indicated having never bought, while only 2.1% had bought the insect. The highly preferred method of cooking was smoking/roasting at 53.3%. The majority at 50.1% indicated the willingness to rear, while 21.0% were undecided. The frequency of the respondents who highly preferred to rear the insect for food and feed was 50.4%. The results suggest that the study population has knowledge of edible grasshopper/locust species and is willing to rear edible insects as an alternative protein food source. [ABSTRACT FROM AUTHOR]

The desert locust Schistocerca gregagia (Forskål, 1775) is one of the most harmful migratory pests in the world, posing a major threat to agricultural production, livelihoods, and food security. Climate, land use, and topography influence the distribution of desert locusts, but few studies have integrated all the factors on a global scale to explore the suitable areas for desert locusts and the paths through which this species could potentially spread. In this study, we established ensemble distribution models to investigate the distribution patterns and driving factors of desert locusts under baseline and future scenarios; we used ensembled niche dynamic models to evaluate their niche conservation during outbreaks. The results showed that the most important factor influencing desert locust distribution is climate, especially the minimum temperature of the coldest month, the annual precipitation, and the mean temperature of the driest quarter. Some areas with little or no desert locust distribution at present will be suitable for desert locusts in the future, and highly suitable contiguous areas may become the dispersal paths. The results also showed that the climatic niche of the desert locust is still conservative, which might explain why desert locusts tend to retreat after intermittent outbreaks rather than settle at the site of invasion. Therefore, more attention should be paid to the areas that are highly suitable for desert locusts, the key factors driving their outbreaks, and the shifting of their climatic niche in order to prevent desert locusts from settling in invasion areas and affecting local ecosystems and food security. [ABSTRACT FROM AUTHOR]

In most animals, multiple external and internal signals are integrated by the brain, transformed and, finally, transmitted as commands to motor centers. In insects, the central complex is a motor control center in the brain, involved in decision‐making and goal‐directed navigation. In desert locusts, it encodes celestial cues in a compass‐like fashion indicating a role in sky‐compass navigation. While several descending brain neurons (DBNs) including two neurons transmitting sky compass signals have been identified in the locust, a complete analysis of DBNs and their relationship to the central complex is still lacking. As a basis for further studies, we used Neurobiotin tracer injections into a neck connective to map the organization of DBNs in the brain. Cell counts revealed a maximum of 324 bilateral pairs of DBNs with somata distributed in 14 ipsilateral and nine contralateral groups. These neurons invaded most brain neuropils, especially the posterior slope, posterior and ventro‐lateral protocerebrum, the antennal mechanosensory and motor center, but less densely the lateral accessory lobes that are targeted by central‐complex outputs. No arborizations were found in the central complex and only few processes in the mushroom body, antennal lobe, lobula, medulla, and superior protocerebrum. Double label experiments provide evidence for the presence of GABA, dopamine, tyramine, but not serotonin, in small sets of DBNs. The data show that some DBNs may be targeted directly by central‐complex outputs, but many others are likely only indirectly influenced by central‐complex networks, in addition to input from multiple other brain areas. [ABSTRACT FROM AUTHOR]

The current study prepared and characterized chitosan from Schistocerca gregaria (Desert Locust) by a chemical method. The Schistocerca gregaria (Desert Locust) chitin and chitosan have yield of 42% and 43% with acceptable physicochemical properties such as Moisture content: 6.0±0.014 and 5.0±0.007 %, Ash content: 2.20 and 2.0%, Protein content 12.0±0.028 and 9.01 ±0.021, Crude fibre8.95±0.041 and 8.95 ± 0.014%, Lipid content, 10.0 ±0.014 and10.0 ±0.014%, however, high carbohydrate, 60.5±0.01 and 65.0±0.01% are quantified in the obtained chitin and chitosan. properties of chitosan prepared were compared with that of the other sources chitosan extracted, the study revealed that (FTIR) analysis confirmed the structure of chitosan by the presence of their characteristic IR bands such as the N-H and O-H stretching bands around 3630 cm-1, oxygen stretching (C-O-C) glycosidic linkage bands around 1125 cm-1, (C-O) in primary OH group bands around 976 cm-1, and 1634 cm-1 corresponding to the free amino group (-NH2) at C2 of glucosamine with 69% degree of deacetylation. Also, the obtained XRD peaks were around 19.01, and 20.48° which indicated the amophores structure. This indicates the successive formation of chitosan biopolymer. Therefore, the Schistocerca gregaria chitosan can be said to be of better quality and hence can replace commercial chitin and chitosan in terms of utilization and applications. [ABSTRACT FROM AUTHOR]

The digestive tract constitutes an important interface between an animal’s internal and external environment. In insects, available gut transcriptome studies are mostly exploratory or look at changes upon infection or upon exposure to xenobiotics, mainly performed in species belonging to holometabolan orders, such as Diptera, Lepidoptera or Coleoptera. By contrast, studies focusing on gene expression changes after food uptake and during digestion are underrepresented. We have therefore compared the gene expression profiles in the midgut of the desert locust, Schistocerca gregaria, between three different time points after feeding, i.e., 24 h (no active digestion), 10 min (the initial stage of feeding), and 2 h (active food digestion). The observed gene expression profiles were consistent with the polyphagous herbivorous lifestyle of this hemimetabolan (orthopteran) species. Our study reveals the upregulation of 576 genes 2 h post-feeding. These are mostly predicted to be associated with digestive physiology, such as genes encoding putative digestive enzymes or nutrient transporters, as well as genes putatively involved in immunity or in xenobiotic metabolism. The 10 min time point represented an intermediate condition, suggesting that the S. gregaria midgut can react rapidly at the transcriptional level to the presence of food. Additionally, our study demonstrated the critical importance of two transcripts that exhibited a significant upregulation 2 h post-feeding: the vacuolar-type H(+)-ATPase and the sterol transporter Niemann-Pick 1b protein, which upon RNAi-induced knockdown resulted in a marked increase in mortality. Their vital role and accessibility via the midgut lumen may make the encoded proteins promising insecticidal target candidates, considering that the desert locust is infamous for its huge migrating swarms that can devastate the agricultural production in large areas of Northern Africa, the Middle East, and South Asia. In conclusion, the transcriptome datasets presented here will provide a useful and promising resource for studying the midgut physiology of S. gregaria, a socio-economically important pest species. [ABSTRACT FROM AUTHOR]

Early 2020 witnessed the emergence of global agrarian crisis with the widespread burgeoning of the destructive migratory pest, Desert Locust (Schistocerca gregaria) in East Africa, South-west Asia, Pakistan and India. Characterized by the ability to eat ravenously, breed exponentially and migrate rapidly; locust swarms has led to substantial agrarian disaster. The current official strategy is to control the upsurges to evade plague. Though the strategy may seem attractive and efficient, it is sensible only if the numbers are relatively low. The socio-economic and environmental challenges posed by the unprecedented locust outbreak has prompted the scientists worldwide to emanate an effective preventive management strategy based on updated knowledge of pest biology, ecology and behaviour along with efficient monitoring, data management, analysis, forecasting, resource deployment and control techniques. Additionally, the integrated network of field teams, decision makers, analysts, rural governing bodies and farmers could potentially offer better compliance to the pest management strategies. [ABSTRACT FROM AUTHOR]

Understanding the thresholds of influencing parameters that favor the habitability of dangerous pests like desert locusts (Schistocerca gregaria) can aid in early detection and eradication using control operations. The life cycle of the desert locust and its behavioral changes are associated with the weather patterns and the region’s ecosystem settings. This study attempts to retrieve the preferential soil conditions like texture and moisture at the surface and subsurface levels for egg-laying by desert locusts. Towards this, Locust Hub, a comprehensive database of desert locusts maintained and disseminated by the Food and Agriculture Organisation under the Locust Watch program, was used to identify breeding site locations for 2017-2021. In this research, we extracted sand-silt-clay percentage at these breeding sites using SoilGrids ver. 2.0 from the World Soil Information Service database facilitated by International Soil Reference and Information Centre. Similarly, soil moisture conditions extracted from Level-4 data products of the Soil Moisture Active Passive mission for all these breeding sites aided in essaying the optimal soil conditions for the desert locust’s oviposition. This study’s results confirm the sand percentage in a broad range of 55-70% (for 90% of samples), followed by a narrow range of silt and clay with 19-24% and ~14-20%, respectively. Our study reveals that female desert locusts prefer sandy loam-textured soils for oviposition. The preferred range of soil moisture at the surface and subsurface resulted in 5-10% and 10-20%, respectively. These results confirm that dampness is required at the surface soil for initiating the oviposition by female desert locusts. Results from this research can aid in the early identification of breeding grounds during desert locusts’ invasion period.

For decades, humans have been confronted with numerous pest species, with the desert locust being one of the most damaging and having the greatest socio-economic impact. Trying to predict the occurrence of such pests is often complicated by the small number of records and observations in databases. This paper proposes a methodology based on a combination of classification and regression techniques to address not only the problem of locust sightings prediction, but also the number of locust individuals that may be expected. For this purpose, we apply different machine learning (ML) and related techniques, such as linear regression, Support Vector Machines, decision trees, random forests and neural networks. The considered ML algorithms are evaluated in three different scenarios in Western Africa, mainly Mauritania, and for the elaboration of the forecasting process, a number of meteorological variables obtained from the ERA5 reanalysis data are used as input variables for the classification–regression machines. The results obtained show good performance in terms of classification (appearance or not of desert locust), and acceptable regression results in terms of predicting the number of locusts, a harder problem due to the small number of samples available. We observed that the RF algorithm exhibited exceptional performance in the classification task (presence/absence) and achieved noteworthy results in regression (number of sightings), being the most effective machine learning algorithm among those used. It achieved classification results, in terms of F-score, around the value of 0.9 for the proposed Scenario 1. [ABSTRACT FROM AUTHOR]

Many arthropods and vertebrates use celestial signals such as the position of the sun during the day or stars at night as compass cues for spatial orientation. The neural network underlying sky compass coding in the brain has been studied in great detail in the desert locust Schistocerca gregaria. These insects perform long-range migrations in Northern Africa and the Middle East following seasonal changes in rainfall. Highly specialized photoreceptors in a dorsal rim area of their compound eyes are sensitive to the polarization of the sky, generated by scattered sunlight. These signals are combined with direct information on the sun position in the optic lobe and anterior optic tubercle and converge from both eyes in a midline crossing brain structure, the central complex. Here, head direction coding is achieved by a compass-like arrangement of columns signaling solar azimuth through a 360° range of space by combining direct brightness cues from the sun with polarization cues matching the polarization pattern of the sky. Other directional cues derived from wind direction and internal self-rotation input are likely integrated. Signals are transmitted as coherent steering commands to descending neurons for directional control of locomotion and flight. [ABSTRACT FROM AUTHOR]

Simple Summary: This study focuses on the desert locust, a critical insect pest species for agriculture. We aimed at investigating how to induce RNA interference by feeding in this species. RNA interference is a gene-silencing mechanism that promises to contribute to pest control strategies. We studied cell-penetrating peptides (CPPs) as potential dsRNA/siRNA delivery systems. We found CPPs that can complex with dsRNA and siRNAs, as well as protect them from the degradation of midgut enzymes. In addition, we report that intra-hemocoelic injection of naked siRNAs does not trigger a gene-silencing response in the desert locust but, for siRNAs complexed with one of the investigated CPPs, it does. Although we could not find a suitable CPP to induce RNAi by feeding in the locust, our results stimulate future research on this topic. In addition, our findings contribute to the understanding of the RNA interference response and its complexity in insects as well as emphasizing the importance of research in living insects when it comes to dsRNA/siRNA oral delivery systems. RNA(i) interference is a gene silencing mechanism triggered by double-stranded (ds)RNA, which promises to contribute to species-specific insect pest control strategies. The first step toward the application of RNAi as an insecticide is to enable efficient gene silencing upon dsRNA oral delivery. The desert locust, Schistocerca gregaria is a devastating agricultural pest. While this species is responsive to dsRNA delivered by intra-hemocoelic injection, it is refractory to orally delivered dsRNA. In this study, we evaluated the capacity of five cell-penetrating peptides (CPPs) to bind long dsRNA and protect it from the locust midgut environment. We then selected the CPP EB1 for further in vivo studies. EB1:dsRNA complexes failed to induce RNAi by feeding. Interestingly, we observed that intra-hemocoelic injection of small-interfering (si)RNAs does not result in a silencing response, but that this response can be obtained by injecting EB1:siRNA complexes. EB1 also protected siRNAs from midgut degradation activity. However, EB1:siRNA complexes failed as well in triggering RNAi when fed. Our findings highlight the complexity of the dsRNA/siRNA-triggered RNAi in this species and emphasize the multifactorial nature of the RNAi response in insects. Our study also stresses the importance of in vivo studies when it comes to dsRNA/siRNA delivery systems. [ABSTRACT FROM AUTHOR]

Group living has various benefits, but it also carries costs, such as risk of cannibalism. Molting is a vulnerable period of being cannibalized in juvenile arthropods, but how gregarious arthropods avoid this threat is poorly understood. Here, we examined how actively migrating gregarious nymphs of desert locust, Schistocerca gregaria , avoid cannibalism during molting, in the Sahara Desert of Mauritania. In the field, gregarious nymphs cyclically march and feed on grass during the day. Our field observations found that marching behavior helped separating pre-molting and cannibalistic non-molting nymphs. Cannibalistic non-molting nymphs marched away from roost plants, leaving sedentary pre-molting nymphs behind, creating cannibal-free spaces. Some non-molting nymphs reached a pre-molting state after daytime marching, thus both pre- and non-molting nymphs roosted on same plants at night. However, pre-molting nymphs moved away from conspecifics prior to molting. Starvation experiments confirmed that food-satiation decreased cannibalistic necrophagy. Physiological surveys of diel feeding and molting patterns revealed that nymphs molted at times when conspecifics were food-satiated rather than hungry. Hence, our results indicate that behavioral and physiological traits of gregarious locusts could function to spatiotemporally separate molting locusts from cannibalistic conspecifics, thus reducing molting-associated cannibalism. This is the first report of migration-dependent molting synchrony as a mechanism reducing costs of aggregation in gregarious arthropods. [ABSTRACT FROM AUTHOR]

Laboratory experiments evaluated the latent effects of lufenuron and rice bran extract on the newly hatched nymphs of Schistocerca gregaria produced from females who were treated as fifth nymphal instar with LC50 of each lufenuron and rice bran extract. Semithin sections of the newly hatchling showed great histological malformations in the structure of the brain, compound eyes, midgut, and hind leg muscles compared with control, these organs lost their normal structures, shapes, and functions. The tested compounds had serious extended histopathological effects, so they can be used to control S. gregaria as safe alternative agents to toxic synthetic pesticides. [ABSTRACT FROM AUTHOR]

In the recent past, the Horn of Africa witnessed an upsurge in the desert locust (Schistocerca gregaria) invasion. This has raised major concerns over the massive food insecurity, socioeconomic impacts, and livelihood losses caused by these recurring invasions. This study determined the potential vegetation damage due to desert locusts (DLs) and predicted the suitable habitat at high risk of invasion by the DLs using current and future climate change scenarios in Kenya. The normalized difference vegetation index (NDVI) for the period 2018–2020 was computed using multi-date Sentinel-2 imagery in the Google Earth Engine platform. This was performed to assess the vegetation changes that occurred between May and July of the year 2020 when northern Kenya was the hotspot of the DL upsurge. The maximum entropy (MaxEnt) algorithm was used together with 646 DL occurrence records and six bioclimatic variables to predict DL habitat suitability. The current (2020) and two future climatic scenarios for the shared socioeconomic pathways SSP2-4.5 and SSP5-8.5 from the model for interdisciplinary research on climate (MIROC6) were utilized to predict the future potential distribution of DLs for the year 2030 (average for 2021–2040). Using Turkana County as a case, the NDVI analysis indicated the highest vegetation damage between May and July 2020. The MaxEnt model produced an area under the curve (AUC) value of 0.87 and a true skill statistic (TSS) of 0.61, while temperature seasonality (Bio4), mean diurnal range (Bio2), and precipitation of the warmest quarter (Bio18) were the most important bioclimatic variables in predicting the DL invasion suitability. Further analysis demonstrated that currently 27% of the total area in Turkana County is highly suitable for DL invasion, and the habitat coverage is predicted to potentially decrease to 20% in the future using the worst-case climate change scenario (SSP5-8.5). These results have demonstrated the potential of remotely sensed data to pinpoint the magnitude and location of vegetation damage caused by the DLs and the potential future risk of invasion in the region due to the available favorable vegetational and climatic conditions. This study provides a scalable approach as well as baseline information useful for surveillance, development of control programs, and monitoring of DL invasions at local and regional scales. [ABSTRACT FROM AUTHOR]

Desert locusts' upsurges can cost heavy economic and agricultural losses and threaten the food security of millions of people over dozens of countries. Therefore, monitoring and spatial delimitation of their habitats are necessary for biological control studies and sampling, especially on large surfaces. This study aimed to assess and map desert locust suitable biotopes in southern Algeria, through a GIS tool, by integrating multicriteria analysis (Analytical hierarchy process) as a decision-making tool for preventive methods, biological control and research. The result is a resolution map, classified into four different zones according to pixel values. The results revealed that 28.51% of the study area is an unsuitable biotope for desert locusts. 35.92 % is a survival biotope, 19.51 % is a suitable biotope mainly for breeding and eggs lying and 16.05% is very suitable for desert locust gregarization and concentration. This study offers a simplified mapping procedure to assess locusts’ habitats for decision-making and studies in large areas.

Flexible orientation through any environment requires a sense of current relative heading that is updated based on self-motion. Global external cues originating from the sky or the earth‘s magnetic field and local cues provide a reference frame for the sense of direction. Locally, optic flow may inform about turning maneuvers, travel speed and covered distance. The central complex in the insect brain is associated with orientation behavior and largely acts as a navigation center. Visual information from global celestial cues and local landmarks are integrated in the central complex to form an internal representation of current heading. However, it is less clear how optic flow is integrated into the central-complex network. We recorded intracellularly from neurons in the locust central complex while presenting lateral grating patterns that simulated translational and rotational motion to identify these sites of integration. Certain types of central-complex neurons were sensitive to optic-flow stimulation independent of the type and direction of simulated motion. Columnar neurons innervating the noduli, paired central-complex substructures, were tuned to the direction of simulated horizontal turns. Modeling the connectivity of these neurons with a system of proposed compass neurons can account for rotation-direction specific shifts in the activity profile in the central complex corresponding to turn direction. Our model is similar but not identical to the mechanisms proposed for angular velocity integration in the navigation compass of the fly Drosophila. [ABSTRACT FROM AUTHOR]

Malnutrition is the major cause of mortality and morbidity globally with undernutrition contributing about 45% of all deaths of under five children. Besides the direct effects of protracted conflicts, the macroeconomic crisis that has greatly increased the national inflation rate hence devastating the purchasing power, the COVID-19 outbreak, flooding, and the Desert Locusts have contributed to a food security emergency. Besides being among the most under resourced states, South Kordofan has experienced years of conflict resulting in displacement of people and extensive infrastructure destruction with high rates of malnutrition. The state currently has 230 health facilities and out of these, only 140 are providing outpatient therapeutic programme centres with 28.6% (40) of these being operated by the state ministry of health and the rest by the international non-governmental organizations. Limited resources leading to donor dependence, limited accessibility due to insecurity and floods, poor referral system and gaps in continuity of care, lack of operational and implementation research data and limited integration of management of malnutrition in other health services have negatively affected effective implementation. Ensuring effective and efficient community based management of acute malnutrition, implementation needs action beyond the health sector with a multi-sectoral and integration approach. Federal and state development frameworks should ensure a comprehensive multi-sectoral nutrition policy with strong political commitment and allocation of adequate resources to ensure integrated and quality implementation. [ABSTRACT FROM AUTHOR]

Insect exposure to their predators can affect individuals and community processes, through direct consumption or nonlethal effects. However, the links between behavioral and physiological responses and stimuli needed for the development of predator avoidance are not clear. We subjected desert locusts (Schistocerca gregaria) to three nonlethal treatments, using great tits (Parus major) as a predator. The treatments included: (1) bird—presence of a great tit and its calls, (2) call—great tit calls only, (3) control—absence of a great tit and its calls. In the first behavioral laboratory experiment, locusts were offered food and shelter in an open space. The duration of hiding versus feeding indicated predator responses. In the second laboratory experiment, locusts were subjected to the same three treatments, and adipokinetic hormone (AKH) levels were measured in the central nervous system (CNS) and hemolymph. In the third experiment in an outdoor aviary, birds were allowed to fly freely over locusts before we measured physiological response. During the first experiment, locusts hid for a significantly longer amount of time and fed for a significantly shorter amount of time when the bird was present and calls were played, compared to when only calls were played or compared to the control treatment. The proximity of birds to locusts in the laboratory experiment elicited a significant increase in AKH levels in the CNS and hemolymph compared to the call/control treatment. The physical proximity of the great tits affected both the behavioral and physiological responses of the locusts. [ABSTRACT FROM AUTHOR]

The desert locust upsurge in the Horn of Africa over 2019–2021 led to a total of 1.6 million ha being treated with broad-spectrum organophosphate and pyrethroid insecticides in Ethiopia and Kenya, while insect growth regulators and the entomopathogenic fungus Metarhizium acridum were applied in Somalia. Environmental monitoring was largely absent, with limited surveys conducted in Kenya and Ethiopia. Overdosing of fenitrothion of a 960 g/L formulation in Kenya led to non-target mortality, including birds and honeybees. In Ethiopia, chlorpyrifos and malathion applications coincided with a honey production decline of 78% in 2020 compared to pre-upsurge levels. The use of M. acridum on nearly 253,000 ha was a breakaway from previous campaigns, in which its successful application in Somalia against both hopper bands and swarms shows that the persistent and pervasive use of organophosphate insecticides can no longer be justified. Furthermore, future procurement of organophosphate insecticides and possibly insect growth regulators could become increasingly problematic due to measures enacted by the European Union. It is recommended that the complementary impact of M. acridum and bird predation on locusts should be considered in an integrated management approach for both swarm and hopper control. [ABSTRACT FROM AUTHOR]

Locusts (Schistocerca gregaria) jump using a latch mediated spring actuated system in the femur-tibia joint of their metathoracic legs. These jumps are exceptionally fast and display angular rotation immediately after take-off. In this study, we focus on the angular velocity, at take-off, of locusts ranging between 0.049 and 1.50 g to determine if and how rotation-rate scales with size. From 263 jumps recorded from 44 individuals, we found that angular velocity scales with mass−0.33, consistent with a hypothesis of locusts having a constant rotational kinetic energy density. Within the data from each locust, angular velocity increased proportionally with linear velocity, suggesting the two cannot be independently controlled and thus a fixed energy budget is formed at take-off. On average, the energy budget of a jump is distributed 98.7% to translational kinetic energy and gravitational potential energy, and 1.3% to rotational kinetic energy. The percentage of energy devoted to rotation was constant across all sizes of locusts and represents a very small proportion of the energy budget. This analysis suggests that smaller locusts find it harder to jump without body rotation. [ABSTRACT FROM AUTHOR]

The digestive tract constitutes an important interface between an animal’s internal and external environment. In insects, available gut transcriptome studies are mostly exploratory or look at changes upon infection or upon exposure to xenobiotics, mainly performed in species belonging to holometabolan orders, such as Diptera, Lepidoptera or Coleoptera. By contrast, studies focusing on gene expression changes after food uptake and during digestion are underrepresented. We have therefore compared the gene expression profiles in the midgut of the desert locust, Schistocerca gregaria, between three different time points after feeding, i.e., 24 h (no active digestion), 10 min (the initial stage of feeding), and 2 h (active food digestion). The observed gene expression profiles were consistent with the polyphagous herbivorous lifestyle of this hemimetabolan (orthopteran) species. Our study reveals the upregulation of 576 genes 2 h post-feeding. These are mostly predicted to be associated with digestive physiology, such as genes encoding putative digestive enzymes or nutrient transporters, as well as genes putatively involved in immunity or in xenobiotic metabolism. The 10 min time point represented an intermediate condition, suggesting that the S. gregaria midgut can react rapidly at the transcriptional level to the presence of food. Additionally, our study demonstrated the critical importance of two transcripts that exhibited a significant upregulation 2 h post-feeding: the vacuolar-type H(+)-ATPase and the sterol transporter Niemann-Pick 1b protein, which upon RNAi-induced knockdown resulted in a marked increase in mortality. Their vital role and accessibility via the midgut lumen may make the encoded proteins promising insecticidal target candidates, considering that the desert locust is infamous for its huge migrating swarms that can devastate the agricultural production in large areas of Northern Africa, the Middle East, and South Asia. In conclusion, the transcriptome datasets presented here will provide a useful and promising resource for studying the midgut physiology of S. gregaria, a socio-economically important pest species.

Flexible orientation through any environment requires a sense of current relative heading that is updated based on self-motion. Global external cues originating from the sky or the earth‘s magnetic field and local cues provide a reference frame for the sense of direction. Locally, optic flow may inform about turning maneuvers, travel speed and covered distance. The central complex in the insect brain is associated with orientation behavior and largely acts as a navigation center. Visual information from global celestial cues and local landmarks are integrated in the central complex to form an internal representation of current heading. However, it is less clear how optic flow is integrated into the central-complex network. We recorded intracellularly from neurons in the locust central complex while presenting lateral grating patterns that simulated translational and rotational motion to identify these sites of integration. Certain types of central-complex neurons were sensitive to optic-flow stimulation independent of the type and direction of simulated motion. Columnar neurons innervating the noduli, paired central-complex substructures, were tuned to the direction of simulated horizontal turns. Modeling the connectivity of these neurons with a system of proposed compass neurons can account for rotation-direction specific shifts in the activity profile in the central complex corresponding to turn direction. Our model is similar but not identical to the mechanisms proposed for angular velocity integration in the navigation compass of the fly Drosophila.

The apparent failure of global health security to prevent or prepare for the COVID-19 pandemic has highlighted the need for closer cooperation between human, animal (domestic and wildlife), and environmental health sectors. However, the many institutions, processes, regulatory frameworks, and legal instruments with direct and indirect roles in the global governance of One Health have led to a fragmented, global, multilateral health security architecture. We explore four challenges: first, the sectoral, professional, and institutional silos and tensions existing between human, animal, and environmental health; second, the challenge that the international legal system, state sovereignty, and existing legal instruments pose for the governance of One Health; third, the power dynamics and asymmetry in power between countries represented in multilateral institutions and their impact on priority setting; and finally, the current financing mechanisms that predominantly focus on response to crises, and the chronic underinvestment for epidemic and emergency prevention, mitigation, and preparedness activities. We illustrate the global and regional dimensions to these four challenges and how they relate to national needs and priorities through three case studies on compulsory licensing, the governance of water resources in the Lake Chad Basin, and the desert locust infestation in east Africa. Finally, we propose 12 recommendations for the global community to address these challenges. Despite its broad and holistic agenda, One Health continues to be dominated by human and domestic animal health experts. Substantial efforts should be made to address the social–ecological drivers of health emergencies including outbreaks of emerging, re-emerging, and endemic infectious diseases. These drivers include climate change, biodiversity loss, and land-use change, and therefore require effective and enforceable legislation, investment, capacity building, and integration of other sectors and professionals beyond health. [ABSTRACT FROM AUTHOR]

The present work aims to investigate the ultrastructural changes in the fat body of fifth instar nymphs Schistocerca gregaria (Orthoptera: Acrididae) treated with zinc chromium oxide (ZnCrO). The nanoparticles (NPs) were prepared by co-precipitation route and characterized using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The ZnCrO NPs exhibited polycrystalline hexagonal structure, composed of spherical–hexagonal shapes with an average size ~ 25 nm. Besides, the UV–Vis spectrophotometer (Jasco-V-570) was utilized for optical measurements. The energy gap E g was estimated from the transmittance (T%) and reflectance (R%) spectra through the range of 3.307–3.840 eV. In biological sections, S. gregaria 5th instar nymphs, TEM images demonstrated that the fat body was strongly impacted with the concentration 2 mg NPs result in great agglomeration of chromatin in the nucleus as well as haemoglobin cells (HGCs) pierced with malformed trachea (Tr) at 5th and 7th days post treatment. The obtained results indicated a positive action of the prepared nanomaterial on Schistocerca gregaria fat body organelles. [ABSTRACT FROM AUTHOR]