Search

The haemolymph plasma of adult desert locust, Schistocerca gregaria was analyzed in order to detect the induction of antibacterial activity following injection with a sublethal dose of Bacillus thuringiensis israelensis (Bti). A slight activity was demonstrated in the normal locust plasma, while a significant increase of this activity was appeared in both control and immune plasma, when tested by the agar-disk diffusion method. The maximum activity was attained after 24 h post-injection. Analysis of proteins by SDS polyacrylamide gel electrophoresis showed disappearance of some protein bands and appearance of other new ones in the injected adult locusts. Some of these new proteins may affect adult immunity. The phenoloxidase (PO) activity was significantly higher at 6 and 12 h after injection with Bti, but at 24 and 48 h, the activity was significantly lower than that of the controls. However, no significant changes in lysozyme activity were detected at all time intervals post-injection compared with the control insects.

Two indigenous entomofungal strains each of Beauveria bassiana and Metarhizium anisopliae were tested for their pathogenic effect on Aak grasshopper, Poekilocerus pictus, Fabricus, 1775 (Orthoptera: Acrididea) under laboratory conditions. Among the four isolates tested, M. anisopliae ICAR-NBAIR Ma-4 and ICAR-NBAIR Ma-35 caused 100 and 90% mortality, respectively, whereas B. bassiana ICAR-NBAIR Bb-78 and ICAR-NBAIR Bb-45 showed 40 and 14% mortality, respectively. ICAR-NBAIR Ma-4 and ICAR-NBAIR Ma-35 isolates were further tested on eggs of grasshoppers which showed 72.7 and 59.8% mortality respectively. Dose and time mortality studies with ICAR-NBAIR Ma-4 showed LC50 value of 1.52 × 103 spores/ml and LT50 of 68.17 h at dose of 1 × 108 spores/ml. ICAR-NBAIR Ma-35 showed LC50 value of 2.09 × 103 spores/ml and LT50 of 87.10 h at dose of 1 × 108 spores/ml. The use of isolate ICAR-NBAIR Ma-4 as a potential control agent of Poekilocerus pictus with a lower LC50 which killed faster half of Poekilocerus pictus individuals. This isolate can be further tested against the devastating invasive desert locust, Schistocerca gregaria for its management on the eggs and early hopper stages.

The recent upsurge of the desert locust Schistocerca gregaria (Forskål, 1775) has had an impact on East Africa and the Middle East as far as India. It has affected and slowed down many aspects of the Pakistani economy. Swarms of locusts have infested many areas and caused immense damage to all types of crops. Both farmers and economists are concerned and are trying to get the most up-to-date information on the best strategy to manage this pest. This paper is an attempt to (i) provide insight into the dynamics of this upsurge internationally as well as in the various regions of Pakistan, (ii) briefly assess its local impact and locust control measures, and (iii) clarify the role of the various stakeholders in the management, both nationally and internationally, suggesting various improvements for the future.

Climate changes indulge the spread of pests outside their active range by increasing, decreasing, or shifting appropriate climatic conditions and niche of a particular species. Modeling the future potential distribution of pests using MaxEnt under different climate change scenarios is an effective method for prevention and management protocol. This study was conducted to predict the potential distribution of Schistocerca gregaria in future for better management plans based on two socio-economic pathways (SSPs) for 2050 and 2070. To evaluate the predictive performance of the model, the area under the receiver operating characteristic curve (AUC) was used. We used 226 occurrence records and 9 bioclimatic variables to simulate the current and future distributions of S. gregaria. The precision of the MaxEnt model was highly significant, with mean AUC value ranging from 0.929 to 0.940 for all of the evaluated models. The jackknife test showed that Bio 11 and Bio18 contributed 51.4% and 17.3% to the MaxEnt model. A total of 2,557,856 km2 (1.69%) area were recognized as high potential habitats of S. gregaria. However, in 2050 and 2070 high-potential areas would decrease for both of the SSP scenarios.

This Special Issue presents the outcomes from the 23rd African Association of Insect Scientists' Conference held in Cote D’Ivoire, in connection with similar initiatives within and outside Africa. Over 65 scientific papers from several countries, worldwide, were submitted, of which about 40 were accepted and published. The issue focused on new advances in the value chain of edible insects in Africa and beyond. An innovative light-emitting diode technology for mass harvesting of edible grasshopper has been developed. The nutrient composition of insects such as the desert locust has been evaluated. Organic waste streams have been found to affect insect productivity and nutritional value. Insect-based feed increases the nutritional quality of poultry meat. Conventional processing methods reduce microbiological hazards in edible insects. Bioaccumulation of heavy metals, excessive microbial loads and pesticides residues threaten safety of some edible insects, if quality control measures are not developed. Climate change will impede availability of edible insects; hence, necessitating upscaling of mass production technologies and sound conservation practices. Safety and hygiene, on the other hand, hamper the acceptability of insects as food and/or feed, particularly in developed countries. Food fortification with insects and isolation of bioactive compounds from them are new highlights in the Special Issue, which were previously under-explored in Africa. The application of modern food processing technology in the development of new products and the medicinal or commercial value derivable from edible insects and their therapeutic functions are excellent opportunities for expanding the sector. Since disgust factors exist, mass sensitisation on the benefits of consuming insects and insect-based products is a must. We believe that the new frontiers on insects for food, feed and other uses that have been presented in this special issue will undoubtedly stimulate more debates and collaborations in the sector within Africa and beyond.

To preserve crop production losses, monitoring of desert locust attacks is a significant feature of agriculture. In this paper, a mathematical model was formulated and analyzed to protect crops against desert locust attack via early intervention tactics. We consider a triple intervention approach, namely, proaction, reaction, and outbreak prevention. The model integrates a stage-structured locust population, logistics-based crop biomass, and blended early intervention via pesticide spray. We assume that the amount of pesticide spray is proportional to the density of the locust population in the infested area. Conventional short residual pesticides within ultralow volume formulation and equipment control operations are considered. The trivial and locust-free equilibrium of the model is unstable, whereas the interior equilibrium is asymptotically stable. Numerical simulations validate the theoretical results of the model. In the absence of intervention measures, desert locust losses are approximately 71% of expected crop production. The model projection shows that effective proactive early intervention on hopper stage locust contained locust infestation and subdued public health and environmental hazards. Relevant and up-to-date combined early interventions control desert locust aggression and crop production losses.

The lateral complexes (LXs) are bilaterally paired neuropils in the insect brain that mediate communication between the central complex (CX), a brain center controlling spatial orientation, various sensory processing areas, and thoracic motor centers that execute locomotion. The LX of the desert locust consists of the lateral accessory lobe (LAL), and the medial and lateral bulb. We have analyzed the anatomical organization and the neuronal connections of the LX in the locust, to provide a basis for future functional studies. Reanalyzing the morphology of neurons connecting the CX and the LX revealed likely feedback loops in the sky compass network of the CX via connections in the gall of the LAL and a newly identified neuropil termed ovoid body. In addition, we characterized 16 different types of neuron that connect the LAL with other areas in the brain. Eight types of neuron provide information flow between both LALs, five types are LAL input neurons, and three types are LAL output neurons. Among these are neurons providing input from sensory brain areas such as the lobula and antennal neuropils. Brain regions most often targeted by LAL neurons are the posterior slope, the wedge, and the crepine. Two descending neurons with dendrites in the LAL were identified. Our data support and complement existing knowledge about how the LAL is embedded in the neuronal network involved in processing of sensory information and generation of appropriate behavioral output for goal-directed locomotion.

The desert locust, Schistocerca gregaria (Forskal) (Orthoptera: Acrididae), is the world’s most dangerous and destructive migratory pest. It is a highly voracious and polyphagous insect. Its swarms can migrate hundreds of kilometers per day and invade areas covering millions of square kilometers, causing significant and widespread crop losses. In this review, we synthesize published research and reports on the life cycle, behavior, phases of desert locust along with its damage and management. Elements of locust management include population monitoring and population prediction. However, there are difficulties involved with estimating locust populations because locust swarms are highly mobile. Control techniques for managing locust swarms include cultural control (digging, burning), baiting (scattering locust food impregnated with insecticides), dusting with insecticide, and spraying liquid insecticides (chemical or biological) using ultra-low volume (ULV) application. Effective management strategy relies on improved knowledge of pest biology, more efficient monitoring and control techniques.

Desert locusts Schistocerca gregaria are threatening the food security of millions of people and devastating economies in eastern Africa and northern India. The ongoing outbreak is the largest in seven decades. These events give us cause to reflect on the natural history of locusts, our fraught relationship with them, and how they are represented in American popular culture and others. Symbolic representations span millennia and most have roots in the natural life cycle of locusts—they transform, they swarm, they devastate specific food crops. There is strong tendency to exaggerate the body size of locusts and the effectiveness of control efforts. Expressions of human futility are rare except in the form of ironic humour. We conclude by suggesting that we humans indulge in hyperbole and humour to normalize and inure ourselves to the psychologically unbearable, and that this tendency is a precondition for the techno‐optimism that drives anti‐locust technologies. There is no substitute for effective monitoring and management programs, but the importance of new and emerging anti‐locust technologies is expected to increase with projections of increased cyclone activity in the northern Indian Ocean. A free Plain Language Summary can be found within the Supporting Information of this article.

The desert locust is the most destructive locust species in the world. Locusts differ from grasshoppers in behaviour as they can form hopper bands and swarms. During plagues in the past, locusts have been collected or destroyed by mechanical means. One of the control methods that are being suggested is to collect the locusts for consumption instead of using pesticides. Upsurges and plagues are an ideal opportunity to harvest these insects for food and feed. However, this is unlikely to significantly reduce the population.

The efficacy of Neem, Metarhizium acridum,and their mixture on immature adults of Schistocerca gregaria were tested. Neem when applied at a tenth of recommended dose mixed with M. acridum, caused a significant increase to M. acridum efficacy where the mortality reached 96.6 % while mortality of M. acridum alone reached 76.6 %, after 14 days post-treatment, mortality of due to Neem alone reached to 26.6%. M. acridum, and Neem mixture caused significant reduction of trehalse activity at 2, 4, 6 days post-treatment, while same treatment caused a significant increase in lactate dehydrogenase activity at day 2 post-treatment then this activity was reduced significantly at days 4, and 6 post-treatment.

The desert locust Schistocerca gregaria is a destructive pest for several crops, particularly which are considered as the main food sources for human and animals. Much attention has been paid to use the plant extracts or plant products for controlling this pest. The present study aimed to investigate the disturbing effect of Nimbecidine on the phosphatase activity in S. gregaria. The penultimate instar nymphs were treated, through the fresh food, with 1.0 and 0.3% Nimbecidine and the activities of acid phosphatase (ACP) and alkaline phosphatase (ALP) were estimated in the last instar nymphs and adults. The most important results could be summarized as follows. Nimbecidine significantly promoted the ACP activity in haemolymph, irrespective of the stage, age, or concentration. In addition, Nimbecidine exhibited a remarkable inducing effect on the enzyme activity in fat bodies, regardless the stage and age, with an exception of the late-aged nymphs in which the enzyme activity was suppressed. Regarding the effect of Nimbecidine on ALP activity in haemolymph of the nymphs and adults, results clearly displayed a general reducing effect of Nimbecidine on the enzyme activity in haemolymph of the last nymphal instar. An exceptional case of promoting action was detected in the newly emerged adults, at the higher concentration. In respect of the effect on ALP activity in fat bodies, results indicated that the enzyme activity was significantly induced in nymphs but reduced in adults.

Effects of n-hexane, acetone and methanol extracts of Zygophyllum simplex L. and Trigonella foenum-graecum L. on Schistocerca gregaria (Forskal) 5th nymphal instar were tested. Only n-hexane extracts of both plants showed that, biological toxic effects to S. gregaria nymphs. Mortalities percentages of 1000 ppm of Z. simplex and T. foenum-graecum n-hexane extracts to desert locust nymphs were 76.67 and 70.00 % after 8 days post treatment. Toxicity results indicated that, LD50s of Z. simplex and T. foenum-graecum extracts were 2.04 and 3.16 µg/nymph, respectively. Also total carbohydrates, lipids, and proteinsin haemolymph of treated nymphs with 250 ppm, were reduced at days 2, 4, and 6 days post treatment. Thirty four and thirty eight phytochemical compounds were detected in n-hexane extracts of Z. simplex and T. foenum-graecum, respectively. Seventeen compounds were present in both plant extract.

The objective of the current investigation was to assess the food deterrence property of chromafenozide and its impact on different food metabolic parameters of the 5th instar nymphs of the desert locust Schistocerca gregaria. For this purpose, three doses (10, 100 and 150 µg/nymph) were topically applied (once) onto the newly molted last (5th) instar nymphs. chromafenozide exhibited contradictory effects on the feeding since it acted as a weak antifeedant against female nymphs only at the lowest dose but acted as phagostimulant against their congeners at the higher two doses. Furthermore, the compound exerted a general phagostimulant action on the male nymphs, regardless the dose. The food intake by the last nymphal instar females was slightly reduced only at only the lowest dose but remarkably increased at the higher doses. The male nymphs had been promoted to consume more food amount. Treated nymphs of both sexes attained slightly or significantly increasing relative weight gain and discharged more frass pellets. The treated nymphs of both sexes achieved slightly increasing approximate digestibility (AD), with two exceptions for the male nymphs which had a slightly decreased AD at the medium dose and un-affected AD at the highest dose. Both the efficiency of conversion of ingested food into biomass (ECI) and efficiency of conversion of digested food into biomass (ECD) of the female nymphs slightly increased. ECI of male nymphs was enhanced but ECD was slightly inhibited. Depending on the present results, Chromafenozide cannot be recommended as a promising agent for controlling S. gregaria.

To understand brain function it is necessary to characterize both the underlying structural connectivity between neurons and the physiological integrity of these connections. Previous research exploring insect brain connectivity has typically used electron microscopy techniques, but this methodology cannot be applied to living animals and so cannot be used to understand dynamic physiological processes. The relatively large brain of the desert locust, Schistercera gregaria (Forksȧl) is ideal for exploring a novel methodology; micro diffusion magnetic resonance imaging (micro-dMRI) for the characterization of neuronal connectivity in an insect brain. The diffusion-weighted imaging (DWI) data were acquired on a preclinical system using a customised multi-shell diffusion MRI scheme optimized to image the locust brain. Endogenous imaging contrasts from the averaged DWIs and Diffusion Kurtosis Imaging (DKI) scheme were applied to classify various anatomical features and diffusion patterns in neuropils, respectively. The application of micro-dMRI modelling to the locust brain provides a novel means of identifying anatomical regions and inferring connectivity of large tracts in an insect brain. Furthermore, quantitative imaging indices derived from the kurtosis model that include fractional anisotropy (FA), mean diffusivity (MD) and kurtosis anisotropy (KA) can be extracted. These metrics could, in future, be used to quantify longitudinal structural changes in the nervous system of the locust brain that occur due to environmental stressors or ageing.

The desert locust, Schistocerca gregaria (Forsk.) (Orthoptera: Acrididae), avoids laying egg pods in sand containing locust fecal extracts. In this study, the oviposition inhibitory (OI) effect was investigated for a different locust species, the migratory locust Locusta migratoria (L.) (Orthoptera: Acrididae). Females of L. migratoria laid more egg pods in control sand than in sand containing fecal extracts obtained from L. migratoria and S. gregaria. However, L. migratoria oviposition was less sensitive to fecal extracts than was S. gregaria oviposition. The OI effect was observed in L. migratoria irrespective of whether the fecal extracts were prepared from gregarious or solitarious locusts, suggesting that phase-specific metabolism is not involved in OI activity. Heating and bleaching of the fecal extracts reduced the amounts of fungi and bacteria in the extracts; however, the resultant extracts still led to OI behavior in L. migratoria. These results suggest that heat-stable and bleach-stable factors in fecal extracts are responsible for the OI effect in L. migratoria.

The desert locust Schistocerca gregaria is a dangerous pest for several fields and orchard crops. Great attention has been paid to use botanicals for controlling this pest. The current investigation aimed to assess the disturbing effect of margosan-O® (0.3% Azadirachtin) on the acetylcholinesterase (AchE)activity in haemolymph and fat bodies of S. gregaria. The penultimate (4th) instar nymphs were treated, via the fresh food, with two concentrations (0.9 and 0.4%) of margosan-O® and the activity of AchE was estimated in the last instar nymphs and newly emerged adults. The most important results could be shown as follows. In the present study, margosan-O® caused a predominantenhancement of AchE activity in the haemolymph of last instar nymphs and adults, regardless of the concentration. Also, the enzyme activity was induced in fat bodies of nymphs and adults, with exception of the late-aged nymphs, nymphs. In these late-aged nymphs, the AchE activity was inhibited in the fat bodies (60.8 and 65.3% decrements, at the higher and lower margosan-O® concentrations, respectively).

The infecting flight muscles of adult desert locust Schistocerca gregaria with the entomopathogenic fungus Beauveria bassiana were studied. The entomopathogenic fungus caused mortality percentages 85.56 and 81.11% in 5th nymphal instar and adults after 15 days of treatment; also, LT50 was 9.17 and 10.07 days. The histopathological studies of treated muscles showed that the nucleus, mitochondria, myofibrils and vacuoles were highly deformed. Estimation of total carbohydrates, total lipids and total protein were carried out. The results showed that the Haemolymph content of treated insects was highly affected and all the studied parameters were lower than in the control insects. The decrease in the Haemolymph contents increased with increasing the post-inoculation period.

Locusts are among the most dangerous agricultural pests. They are a group of short horned grasshoppers belonging to Acrididae family and are hemimetabolous insects. This group of grasshoppers have a unique character of changing habits and behaviors when they aggregate in a group and this habit is catalyzed by different environmental factors. In the adult stage, gregarious locusts migrate from one place to another in a swarm. Desert Locust, Schistocerca gregaria (Forksal), is one of those locusts which cause damage to different types of crop which fly in the direction of wind up to a distance of 150 km. Because of polyphagous feeding habits and swarming in a plague (large group of adults), this pest is considered as the hazardous migratory pest. These pests entered Nepal for the first time in 1962 and then in 1996. In 2020 the pest entered the country from India on three different dates 27th June and continued till 29th (5 districts), 12th July (1 district), and 16th July (2 districts). The swarms migrated to 53 districts and caused the considerable loss in agricultural and field crop in 1118 hectare. These pests are monitored on the basis of environmental factors and many tools and practices such as eLocust3, SMELLS (Soil Moisture for Desert Locust Early Survey), P-locust and SUPARCO Disaster Watch Desert Locust Situation Alert are being used. Their control is critical to food security. Many tools and techniques are integrated for prevention and management of these pests to minimize damage in the existing crops where they migrate. These are physical methods, cultural methods, use of botanicals, green muscle, PAN (phenylacetonitrile) and chemicals. Effective preventive management strategy relies on an improved knowledge of the pest biology, more efficient monitoring and control techniques.

The outbreak of large-scale desert locust plague in 2020 has attracted wide attention in the world and caused serious damage to food security and livelihood of African and Asian people. Remote sensing techniques can provide indirect feedback on locust plagues, facilitating quick, and real-time monitoring of the occurrence and development of locusts, which is of great significance for ensuring national and regional food security and stability. The hidden Markov model (HMM) is a classic machine learning model that has been widely applied in the fields of time-series data mining. In this study, we aim to predict the severity of locust plague in croplands using the time-series dynamic change features extracted from remote sensing data via HMM. In addition, we assess the damages on the croplands using change detection methods by comparing the crop spectrum before and after the locust plague from two-phase (Feburary 23 and March 7, 2020) hyperspectral images covering substudy area (northern Narok, Kenya). Evaluated by the ground truth data, the OA of predicted results of the plague severity in April, May, June, and July are 0.78, 0.71, 0.74, and 0.72, respectively. The land cover classification OA of the substudy area of the two-phase images are 97.45 and 96.14. Our study demonstrates the validity of the HMM-based method using the remote sensing time-series data to predict locust plague and evaluate its damage. The results of the cropland change detection suggest that the damage of locusts can be quantitatively evaluated using hyperspectral images.

This study aimed to understand the role played by haemocytes of Schistocerca gregaria adults in response to injection with Bacillus thuringiensis israelensis (Bti) into the hemocoel. Light microscopy recognized four types of haemocytes namely: prohaemocytes (PRs), plsamatocytes (PLs), granular cells (GRs) and coagulocytes (COs). Different responses were observed in the haemocyte populations at different time intervals (6, 12 24 and 48 h) following injection with a sublethal dose of bacteria; (1) Pathological consequences in the haemocytes including variation in the cell volume, vacuolization in the cytoplasm, distortion of the cell membrane and pycnosis in the nuclei, (2) Various changes in the differential haemocyte counts (DHCs), the most important is a decrease in the numbers of GRs and COs accompanied with an increase in PLs and PRs, (3) A marked decrease in the total haemocyte counts (THCs) at most time periods. (4) Phagocytosis was shown during all periods post-injection with peak at 6 h, and PLs were the essential phagocytic cell type. (5) A significant increase in nodule counts at all time intervals post-injection was observed above controls, with the peak was at 12 h post-injection.

available with the full text.

The desert locust (Schitocerca gregaria) swarms in numbers that decimate farmland, threatening an already vulnerable horn and Eastern region of Africa. The aim of this research was to assess the nutrient content and oil characteristics of the desert locust and for possible utilization as a food resource at industrial scale. The desert locusts were harvested from swarms in various regions of Kenya. Nutrient analysis was performed using standard protocols and physico-chemical characteristics of the extracted oil were evaluated. A 100 g sample contained 450Kcal energy, 46 g protein, 32 g fat and 4 g fibre. Calcium was the most abundant macro mineral (208.36 mg/100 g), iron was the most abundant trace mineral (4.83 mg/100 g) while α-tocopherol content of 267.47 µg/g was recorded. Oleic acid was the main fatty acid (30.78%) with total unsaturated fatty acids being 66.47% of the total fatty acids. The n-6:n-3 ratio of 2,4 was reported which indicated a significant nutritional quality of the locust oil. The locust oil had 0.94 specific gravity indicating potential industrial applications. Iodine value (75 g iodine/100 g oil), peroxide value (0.18 mEq/Kg) and saponification value (171 mg KOH/Kg) indicated an oil with relative stability and potential for industrial utilization in the food industry. As a result, locust control efforts could therefore include harvesting and consumption as part of the integrated management.

Hatching behaviors of the desert locust Schistocerca gregaria (Forskal) (Orthoptera: Acrididae) and the Bombay locust Nomadacris succincta (Johannson 1763) (Orthoptera: Acrididae) were observed to analyze the mechanisms controlling the hatching time and synchrony. At a 12-h thermoperiod of 25 °C and 30 °C under continuous illumination, most eggs hatched during the low temperature period in the desert locust, and the proportion of such individuals was lower in eggs kept in a mass than in those kept singly. In the Bombay locust, most eggs hatched during the high temperature period; however, the inter-pod variation was large. Both locusts hatched earlier with increasing the egg mass size in a range from 2 to 10 or 20 with similar hatching intervals. Desert locust eggs from different pods advanced the hatching but did not delay it to synchronize the hatching. In contrast, Bombay locust eggs advanced or delayed hatching depending on the age of the paired egg. The results suggested the presence of embryo–embryo interactions. In both locusts, a vibrational stimulus that was emitted by the embryo and transmitted via a piece of wire was likely to be responsible for synchronized hatching. The hatching patters of these species were compared with those reported previously for other taxa.

International audience; Highlights:• Temperature and vegetation effects are keys to control marching locust bands.• A band of south American locust in Argentina displayed thermoregulation behaviours.• Gut contents at different times of the day showed continuous feeding activity.• Walking speed and travelled distances of the band decreased with vegetation density.• Marching and thermoregulation are similar for south American and desert locust.Abstract:At high density, juvenile locusts create marching hopper bands. Understanding the roles of temperature and vegetation on the movement of these bands shall allow to better forecast and control them. Following a hopper band in North Argentina in November 2019, we explored the thermoregulation behaviours of the South American locust, Schistocerca cancellata. Gut-content samples informed about the feeding status at different time of the day. Hoppers' body temperature was above cold air temperature in the mornings during basking and group-basking activities and before the onset of marching behaviour. Marching by walking or hopping was dominant at body temperatures close to 40°C. Jumping, stilting, shading and perching on plants were seen as thermoregulatory behaviours to avoid ground temperatures above 50°C. Feeding was observed throughout the day with continuous high gut contents despite an intermittent pattern of feeding-resting-marching. Speed and daily travelled distance of the front of the hopper band was depending on the type of encountered vegetation. Daily behavioural patterns, thermoregulatory behaviours, walking speed and daily travelled distances of S. cancellata were similar to the ones observed for the Desert locust, S. gregaria, in Africa. High air temperatures recorded during the observation times could explain the continuous feeding patterns. These species may have evolved behaviours of alternating consuming a bit and marching as a migration strategy to avoid staying where no food is available after the havoc left behind large hopper bands. Recommendations made for the control of Desert locust hopper bands can be extended to South American locust ones.

Desert locust outbreak in East Africa is threatening livelihoods, food security, environment, and economic development in the region. The current magnitude of the desert locust invasion in East Africa is unprecedented and has not been witnessed for more than 70 years. Identifying the potential breeding sites of the pest is essential to carry out cost-effective and timely preventive measures before it inflicts significant damage. We accessed 9,134 desert locust occurrence records and applied a machine-learning algorithm to predict potential desert locust breeding sites in East Africa using key bio-climatic (temperature and rainfall) and edaphic (sand and moisture contents) factors. Ten days greenness maps from February 2020 to April 2020 were overlaid in model outputs to illustrate the temporal evolution of breeding site locations. This study demonstrated that vast areas of Kenya and Sudan, north eastern regions of Uganda, and south eastern and northern regions of South Sudan are at high risk of providing a conducive breeding environment for the desert locust. Our prediction results suggest that there is need to target these high-risk areas and strengthen ground surveillance to manage the pest in a timely, cost-effective, and environmentally friendly manner.

The desert locust, Schistocerca gregaria Forsk. (Orthoptera: Acrididae) is a peculiar insect that exhibits density-dependent phase polyphenism. Gregarious phase enables desert locust to form a large groups and mass migrations during which significant crop loss and food security issues may occur. Currently, the most recent upsurge of desert locust is prevailing across Eastern Africa and Southwestern Asia. Usually desert locusts are restricted to regions like semi-arid and arid regions. A super cyclonic storm, namely Amphan originated during May 2020, in the Bay of Bengal of North Indian Ocean has influenced numerous swarms to migrate from the Thar desert region to other parts of India. In this research, satellite data were used to investigate the reasons for this sudden swarm migration. The results that revealed the wind jets passing above the Thar desert region have integrated with the cyclogenesis of Amphan and led to the formation of conduits. The favorable conditions in the conduits include the open sky conditions, air temperature and fresh vegetation availability. Moreover, the wind settings in the conduits have enabled the swarm migrate to follow the downwind facing the sunrays during early mornings for an easy and successful take-off. It is observed that during the take-off session the wind speed at 850 hPa pressure level is mostly double than that of surface wind in both the conduits.

The insect growth regulator NC-184, a juvenile hormone mimic, prevents moulting to the adult stage in the desert locust, Schistocerca gregaria (Forskål) (Orthoptera: Acrididae). Male nymphs treated in the penultimate or final nymphal instar with NC-184 exhibit precocious mating behaviour in the final instar. We examined whether this chemical affects the development of the internal reproductive organs of crowded nymphs. In treated males, both accessory glands and seminal vesicles were underdeveloped, and no sperm was found in the seminal vesicle, whereas these organs in control individuals had greatly increased in size 10 days after treatment, when all the insects had moulted to adults. Testis size in treated males was similar to that in controls, regardless of their smaller body size due to the inhibition of moulting. Oogenesis and development of spermatheca in females treated with NC-184 continued to some degree, but no eggs matured, unlike what occurred in the control. In conclusion, treatment of S. gregaria nymphs with NC-184 resulted in changes in the reproductive organs in both sexes.

Recently, interest in the benefits of insects for food and feed has increased, while desert locusts are rich in nutrients and can be easily grown sustainably, even though locusts classified as pests that ruin crops. This study aims to investigate the chemical content, nutritional content and amino acid (AA) profile in adults and nymphs of the desert locust Schistocerca gregaria Forskal (Orthoptera: Acrididae), such as crude protein (CP), crude fat (CF), total carbohydrate (TC), crude fiber (CF), ash, gross energy and minerals content. The analysis indicates that the presence of crude protein, crude fat, total carbohydrate, crude fiber, ash, dry matter and moisture content were (56.79 and 65.92%), (28.82 and 15.15%), (2.98 and 4.59%), (7.9 and 7.92%), (3.51 and 6.42%), (42.34 and 32.46%), and (57.66 and 67.54 %), gross energy content was (498.45 and 418.37 kcal), respectively in adults and nymphs. Generally, the results in both adults and nymphs showed that non-essential AA were the dominant ones of AA, followed by essential then semi-essential AA. Minerals represented by P (87.44 and 91.35), K (6732.78 and 7826.96), Ca (33.8 and 50.7) and Mg (13.56 and 18.24) ppm in adults and nymphs, respectively.

The water extract of desert locust, Schistocerca gregaria, frass collected in the wild had an oviposition inhibitory (OI) effect when mixed with sand and presented to adults. Likewise, the leaves of six plant species, as well as frass produced by desert locusts fed with these plants, exerted OI effects when compared with the control sand wetted with water alone. In general, frass extracts had a greater OI effect than the extracts of leaves. The OI effect was also observed when adult desert locusts were exposed to extracts of frass produced by two other locusts, the Bombay locust, Nomadacris succincta, and the migratory locust, Locusta migratoria, fed with rescue grass, Bromus catharticus. Among the three species of locust, desert locust and migratory locust frass exerted a greater OI effect than Bombay locust frass. Frass samples extracted with hot and cool water produced similarly high OI effects, indicating that bacterial involvement during extraction is unlikely. Hatching rates of desert locusts were significantly reduced by extracts of all of the above mentioned frass when the extracts were mixed with sand and used to incubate the eggs. In contrast, the lethal effects of leaf extracts on the hatching rates varied depending on the plant species. The embryos became deformed within four days when three-day-old eggs were incubated in sand containing frass extracts from desert locusts fed with rescue grass, whereas no apparent morphological changes were observed when seven-day-old eggs were similarly tested, although their hatching rate was significantly reduced.

The desert locust remains a major threat to global food security. Control operations are a crucial tool to manage crisis; this research investigated the nature of control operations conducted between 2019-2021. Historical data on desert locust and control operations were obtained from the survey reports at the FAO Locust Hub and analysed with respect to survey reports, land cover types, cropland/rangeland extent and crop productivity data. We found that 16.1% of the grid cells with locust presence and 14.9% of the grid cells with control operations had a proportion of rangeland higher than 0.75; while 13.3% of the grid cells with locust presence and 13.2% of the grid cells with control operations had a proportion of croplands higher than 0.75, highlighting that locust presence and control operations were reported in both rangeland and cropland. Control operations continue to be used both to reduce overall locust numbers and to protect crops. Furthermore, through identifying which crops were most at risk, our analyses indicate that wheat production was under the highest strain during periods of increased locust infestations.

Desert locust is an important pest to agriculture. In 2019–2020, a major upsurge originated in the southern Arabian Peninsula and gradually spread to east Africa, then to south-west Asia, as far as Pakistan and India, even reaching Nepal, resulting in major agricultural losses. For the first time, a few swarms entered southern Tibet. Using field observations and experiments, we studied their path to the Tibetan plateau and their behavior at these very high altitudes. The locusts moved up the Tibetan valleys from low-lying areas (1700 m) to much higher elevations (5400 m). The low temperatures and high humidity put them under severe stress, their activities were limited, and they did not survive long or produce local offspring. It is clear that the high-altitude environmental conditions in the Himalayan mountains provided an important natural barrier that limited the northward expansion of the desert locust populations.

Early 2020 witnessed the emergence of global agrarian crisis with the widespread burgeoning of destructive migratory pest, Desert Locust (Schistocerca gregaria) in East Africa, Southwest Asia, Pakistan and India. Characterised 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 it 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 prompt the scientists worldwide to emanate an effective preventive management strategies that rely on updated knowledge of pest biology, ecology and behaviour along with efficient monitoring, data management, analysis, forecasting, resource deployment and control techniques. In addition, the integrated network of field teams, decision makers, analysts, rural governing bodies and farmers potentially offers better compliance of pest management strategies.

The 2019–2020 Desert Locust (DL) upsurge in East Africa threatened food security for millions in the region. This highlighted the need to track and quantify the damaging impacts of the swarming insects on cropland and rangelands. Satellite Earth observations (EO) data have the potential to contribute to DL damage assessments that can inform control measures, aid distribution and recovery efforts. EO can complement traditional ground based surveys (which are currently further limited due to COVID-19), by rapidly and cost effectively capturing the full spatial scale of the DL upsurge. However, EO-based techniques struggled to accurately quantify damage from this DL upsurge due to the sporadic and localized nature of infestations impacting scale, timing, and anomalous vegetation conditions. This study analyzed time series data from MODIS, the harmonized Landsat Sentinel-2 product, and C-band radar data from Sentinel-1 to distinguish DL damage from normal senescence or other confounding factors from January to June 2020. These data were compared to in situ locust swarm, band, and non locust observations collected by the Food and Agriculture Organization (FAO) and PlantVillage. The methods presented did not produce results that could confidently differentiate senescence from locust activity, and may represent a limitation of publicly available remotely sensed data to detect DL damage. However, the higher spatial resolution data sets showed promise, and there is potential to explore commercially available satellite products such as Planet Labs for damage assessment protocols.

BACKGROUND A poorly organised risk management system may dysfunction when used. The consequences can be dramatic for those supposed to be protected. Since the 1960s, preventive control strategies, with field officers as living memory, have been developed to monitor locusts. Preserving their experience of past plagues is consequently essential. Wrong use of their knowledge can disrupt the whole management chain. We explored these conditions using a multi-agent model representing a preventive system. We simulated how the field teams' tendency to repeatedly visit past outbreak areas (hotspots) by allocating them an attraction weight can help in preventing plagues. RESULTS When field teams' attention remained constant over time, there was dramatic decrease in the number of plagues, with increasing interest in hotspots, as long as interest was less than 2.5 times more than elsewhere. When the field teams were only attentive during recession times, plagues were better controlled using a low weight for hotspots. The spatial structure of hotspot distribution had an effect: the more frequent and the bigger the hotspots, the lower the optimal hotspot weighting needed to reduce plagues. CONCLUSION Orienting surveys towards hotspots particularly during recession times reduces plagues. The spatial structure of locust habitats may influence the way they are managed. Habitats located outside the multiple hotspots of species such as the desert locust should be visited more frequently than those with only one hotspot, such as the South American locust. The decline/loss of the field officers' experience highlights the need to save, capitalise and disseminate this knowledge. © 2021 Society of Chemical Industry.

The Desert Locust, Schistocerca gregaria(Forskål), is the most devastating migratory pest in the world. The Desert Locust persists as the principal threat to food security in the infested region and beyond. In the inadequacy of reliable and efficient prevention and control measures, strategies for controlling and mitigating the trouble of the Desert Locust are focused on non-risk-free interventions such as chemical pesticides. We formulated and analyzed a mathematical model to assess the impact of this devastating pest on crop production. The theoretical analysis of the model shows that the trivial and locust free equilibriums are unstable, whereas interior equilibrium is asymptotically stable if crop growth rate r is greater than a maturity rate σ Numerical simulations of the model using the baseline parametric values are consistent with theoretical analysis. The conventional scenario projections for crop production (based on the baseline levels of anti-Desert Locust interventions considered in the study) increase by 70.44%(2663.26)kg per hectare) if the low depletion pesticide measures performed are maintained proportionally with locust population. This study notes that high-level depletion of the chemical pesticide spray measures could lead to devastating crop losses (similar to those projections before the onset of the pesticide spray) and severe human health and environmental risks. At a baseline harvesting coverage could shelter 44.43kg to 1176.82kg per hectare of mature crops. Combining early harvesting and low depletion chemical pesticide with ultra-low volume (ULV) spray devices and formulation could mitigate and eliminate Desert Locust infestation., Mathematical model; Crop and locust biomass; Early harvesting; Pesticides spray; Stability analysis; Numerical result.

Desert Locust is considered to be the most serious pests that cause a devastated damage to the crops and the other agricultural products during their invasions. The Desert Locust is a major threat for food security, livelihoods, environment and economic development in a region. The recent Locust Outbreak caused major damage to standing crops and vegetables in the Central and Western states of India, including Rajasthan, Punjab, Haryana, and Madhya Pradesh, with Rajasthan being the most affected. India had experienced such massive locust invasion after two decades. Establishing an Early Warning System for Locust Control in India is essential to reduce the impact by providing timely and relevant information in a systematic way contributing to increasing in resilience of the country. The distribution of Desert Locusts in Rajasthan, India has been presented from June 2019 to August 2020, along with the key Environmental Factors of Temperature, Rainfall, Soil Moisture and Prevalence of Vegetation significantly affecting Locust Activity. All the datasets used were obtained from Secondary sources. These datasets were obtained from Open Government Data (OGD) Platform. The Maps created in the study show the Distribution of Desert Locusts in Rajasthan, India; along with this the Choropleth map show Average- Temperature, Rainfall, Soil Moisture and Normalized Difference Vegetation Index (NDVI), all at District level. The Early Warning System for Desert Locust Control in India is a key integration of four key elements of: Risk Knowledge, Monitoring and Warning Service, Dissemination and Communication and Response Capability, and four-four sub elements of each key element. Establishing an Early Warning System for Locust Control in India is of paramount importance.

Desert locusts are notorious for their widespread distribution and strong destructive power. Their influence extends from the vast arid and semiarid regions of western Africa to northwestern India. Large-scale locust outbreaks can have devastating consequences for food security, and their social impact may be long-lasting. Climate change has increased the uncertainty of desert locust outbreaks, and predicting suitable habitats for this species under climate change scenarios will help humans deal with the potential threat of locust outbreaks. By comprehensively considering climate, soil, and terrain variables, the maximum entropy (MaxEnt) model was used to predict the potential habitats of solitary desert locusts in the 2050s and 2070s under the four shared socioeconomic pathways (SSP126, SSP245, SSP370, and SSP585) in the CMIP6 model. The modeling results show that the average area under the curve (AUC) and true skill statistic (TSS) reached 0.908 ± 0.002 and 0.701, respectively, indicating that the MaxEnt model performed extremely well and provided outstanding prediction results. The prediction results indicate that climate change will have an impact on the distribution of the potential habitat of solitary desert locusts. With the increase in radiative forcing overtime, the suitable areas for desert locusts will continue to contract, especially in the 2070s under the SSP585 scenario, and the moderately and highly suitable areas will decrease by 0.88 × 106 km2 and 1.55 × 106 km2, respectively. Although the potentially suitable area for desert locusts is contracting, the future threat posed by the desert locust to agricultural production and food security cannot be underestimated, given the combination of maintained breeding areas, frequent extreme weather events, pressure from population growth, and volatile sociopolitical environments. In conclusion, methods such as monitoring and early warning, financial support, regional cooperation, and scientific prevention and control of desert locust plagues should be further implemented.

Given the impact of COVID-19 and the desert locust plague, the Ethiopian food security issue has once again received widespread attention. Its food crisis requires comprehensive and systematic research to achieve the United Nations Sustainable Development Goal of zero hunger. This review discusses the current situation and the causes of food security in Ethiopia. We focus on the challenges in the food security assessment field. The article lists seven typical causes of food insecurity and three roots of food security in Ethiopia. Long-term food security assessment and a comprehensive understanding and manageability for food security causes are considered as the main existing research challenges. Climate-resilient management, water management, and long-term ecosystem network monitoring and data mining are suggested as potential roadmap for future research.

Desert Locust is considered to be the most serious pests that cause a devastated damage to the crops and the other agricultural products during their invasions. The Desert Locust is a major threat for food security, livelihoods, environment and economic development in a region. The recent Locust Outbreak caused major damage to standing crops and vegetables in the Central and Western states of India, including Rajasthan, Punjab, Haryana, and Madhya Pradesh, with Rajasthan being the most affected. India had experienced such massive locust invasion after two decades. Establishing an Early Warning System for Locust Control in India is essential to reduce the impact by providing timely and relevant information in a systematic way contributing to increasing in resilience of the country. The distribution of Desert Locusts in Rajasthan, India has been presented from June 2019 to August 2020, along with the key Environmental Factors of Temperature, Rainfall, Soil Moisture and Prevalence of Vegetation significantly affecting Locust Activity. All the datasets used were obtained from Secondary sources. These datasets were obtained from Open Government Data (OGD) Platform. The Maps created in the study show the Distribution of Desert Locusts in Rajasthan, India; along with this the Choropleth map show Average- Temperature, Rainfall, Soil Moisture and Normalized Difference Vegetation Index (NDVI), all at District level. The Early Warning System for Desert Locust Control in India is a key integration of four key elements of: Risk Knowledge, Monitoring and Warning Service, Dissemination and Communication and Response Capability, and four-four sub elements of each key element. Establishing an Early Warning System for Locust Control in India is of paramount importance and a major achievement for the nation itself.

Locust outbreaks usually begin in remote unpopulated areas following higher than average rainfall. The need to survey such areas has suggested that unmanned aerial vehicles (UAVs), often referred to as drones, might be a suitable means of surveying areas with suitable detection devices to survey areas and detect important locust concentrations. This would facilitate determining where sprays need to be applied at this early stage and would minimise the risk of swarms developing and migrating to feed on large areas of crops. Ideally, a drone could also spray groups of hoppers and adults at this stage. To date, tests have shown limitations in their use to apply sprays, although it has been suggested that using a fleet of drones might be possible. The use of biopesticide in these areas has the advantage of being more environmentally acceptable as the spray has no adverse impact on birds.

The current study was done to investigate the potential of the systemic growth regulatory effects of various neem seeds products against immature stages of desert locust infesting potted millet plants in Sudan. The tests also covered the stability of the systemic action of neem seed powder (NSP) under conditions of water stress. Some (33-80%) of the exposed nymphs developed to the third stage without further moulting. Medium lethal time for neem seed water extracts (NSWE), neem seed organic extract (NSOE) and NSP ranged from 166 to 248 hours. All neem seed product induced significant systemic antifeedant activity, ranging from 52 to 99% against the immatures. Based on these findings, NSP, the simplest form, was found to possess systemic activity comparable to complicated forms of neem products. NSP was stable under conditions of delayed watering up to 10 days and the latter had effects on development, mortality and feeding comparable to immediate watering. All aspects studied indicated the superior systemic activity of various neem seed products. The fact that they were able to delay development, prevent further moulting of instars, stabilize under conditions of delayed watering, enabled them to confine the desert locust to their breeding sites as immatures without threat of swarm formation and limited damage to local growers. Key words: Desert locust, neem seed products, pearl millet, Sudan.

The efficacy of Agroecosystem Compounds, fipronil, spinosad and chlorantraniliprole as alternatives to the conventional insecticides on the mortality rates and haemolymph protein, lipid and carbohydrate contents were assessed in Schistocerca gregaria and Locusta migratoria migratorioides. One day old 5th nymphal instars of each of the mentioned species were treated by various concentrations of tested compounds by the feeding technique. The results indicated that Locusta migratoria migratorioides is more sensitive to all tested insecticides than Schistocerca gregaria. In both species, fipronil was the most effective followed by spinosad, and chlorantraniliprole was the least effective. LC30 concentrations of the three compounds were used to treat the 5th instar hoppers of both species to examine the effects of sub lethal concentrations of the mentioned insecticides on the haemolymph total proteins, total lipids and total carbohydrates. It was found that haemolymph proteins, lipids and carbohydrates contents were dramatically reduced for the treated hoppers when compared to the untreated ones of both species. Malformed hopper and wrinkled winged adult were seen in insects treated by sub lethal concentrations of fipronil and spinosad.

International audience; Locusts are able to migrate over long distances across areas with different vegetation structures. This work investigates how the spatial arrangement of vegetation might affect locust collective motion. The behavior of groups of third instar Schistocerca gregaria hoppers that had been fed or starved for 24 h was studied experimentally. Food patches were introduced into a circular arena where locust groups were marching. We tested two different types of food distribution: uniform and clustered. The starved locust groups were used to simulate how encountering vegetation affected locusts after crossing a large bare area. We analyzed the directed motion and mean speed of the locust groups. On the small scale of the arena, the results did not show any effects of vegetation distribution on the oriented motion and mean speed of the groups (fed group). However, encountering vegetation greatly affected the oriented movement and walking speed in the starved group, mimicking the crossing of a large bare area (group starved for 24 h). After feeding, the individuals entered a post-prandial period. That period was significantly longer for the starved hoppers than for the fed hoppers. After the post-prandial period, the hoppers started marching and did not return to feed on the food. It is therefore suggested that the marching activity of hoppers is not directly related to their hunger level. The effect of the spatial distribution of vegetation on the hunger status of hoppers and the implication for barrier treatments used in locust control are further discussed.

Desert locust plagues have threatened food security in northern African countries for centuries. To prevent their effects, current early warning systems in arid environments need to be improved using the latest and most advanced modelling techniques and Earth observation datasets. Previous studies have analysed certain environmental predictors such as NDVI or soil moisture individually in an effort to detect suitable areas. However, we introduce new variables (Surface Temperature, LAI and Soil Moisture Root Zone) from the SMAP satellite and apply different machine learning methods in our species distribution model in order to identify desert locust presence. We obtain highly satisfactory model results (KAPPA & TSS = 0.901 and ROC = 0.986) to detect the probability of presence and, hence, likely breeding areas based on environmental factors. The most relevant variables were surface temperature, NDVI and soil moisture at root zone under different time scenarios. This study also confirms the potential of the SMAP satellite to retrieve critical temperatures due to its time pass, in addition to reinforcing the NDVI product from MODIS as a reliable environmental predictor. These results demonstrate the validity of this new approach based on machine learning methods to identify favourable breeding areas in Mauritania.