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We propose a reaction-diffusion model to describe the interactive wild and sterile mosquito populations in spatially heterogeneous environments, where the vital dynamics of mosquito populations, e.g., offspring produced per mate, the death rates, the amount of releasing sterile mosquitoes, depend on its location habits and the distribution of wild mosquito populations. First, we show the model may present multiple positive steady states with either Neumann or Dirichlet boundary conditions. Then we investigate the interactive dynamics of mosquito populations with the different initial data. Our results show that wild mosquitoes can be eradicated or suppressed within a certain range with different releasing amounts. Finally, numerical simulations further show that the spatial variability environment within the habitat may play a crucial role in extirpating wild mosquito populations in the context of the sterile insect techniques (SIT). [ABSTRACT FROM AUTHOR]

Wolbachia continue to be reported in species previously thought to lack them, particularly Aedes aegypti mosquitoes. The presence of Wolbachia in this arbovirus vector is considered important because releases of mosquitoes with transinfected Wolbachia are being used around the world to suppress pathogen transmission and these efforts depend on a lack of Wolbachia in natural populations of this species. We previously assessed papers reporting Wolbachia in natural populations of Ae. aegypti and found little evidence that seemed convincing. However, since our review, more and more papers are emerging on Wolbachia detections in this species. Our purpose here is to evaluate these papers within the context of criteria we previously established but also new criteria that include the absence of releases of transinfections within the local areas being sampled which has contaminated natural populations in at least one case where novel detections have been reported. We also address the broader issue of Wolbachia detection in other insects where similar issues may arise which can affect overall estimates of this endosymbiont more generally. We note continuing shortcomings in papers purporting to find natural Wolbachia in Ae. aegypti which are applicable to other insects as well. [ABSTRACT FROM AUTHOR]

The emergence of antimicrobial resistance (AMR) in pathogens and their spillover into the environment have become a global public health menace. Insects can acquire these pathogens from the environment and would serve as mechanical and biological vectors. The current study assessed the ability of Culex quinquefasciatus mosquitoes to acquire methicillin-resistant Staphylococcus aureus (MRSA) through the exposure of the mosquitoes to the pathogen via rearing water, blood feed, or a feeding membrane under laboratory conditions. In addition, mosquito immatures collected from their habitat in the vicinity of hospitals, veterinary dispensaries, and butcher shops at 15 study sites in Puducherry were screened for MRSA infection. All samples were subjected to the culture-based isolation of S. aureus from the surface and homogenate. The presence of the S. aureus-specific nuc gene and the genes that confer resistance to methicillin (mecA and mecC) were screened using PCR tests. MRSA was not evident either on the external surface or in the homogenate of the mosquitoes emerging from the larvae reared in the MRSA-spiked water or those fed with MRSA through blood or smeared membranes. Furthermore, the presence of MRSA was not evident in any of the field-caught mosquitoes. Hence, we conclude that C. quinquefasciatus mosquitoes are impervious to MRSA colonization. [ABSTRACT FROM AUTHOR]

Most insects, including human-targeting mosquitoes, detect odors through odorant-activated ion channel complexes consisting of a divergent odorant-binding subunit (OR) and a conserved co-receptor subunit (Orco). As a basis for understanding how odorants activate these heteromeric receptors, we report here cryo2electron microscopy structures of two different heteromeric odorant receptor complexes containing ORs from disease-vector mosquitos Aedes aegypti or Anopheles gambiae. These structures reveal an unexpected stoichiometry of one OR to three Orco subunits. Comparison of structures in odorant-bound and unbound states indicates that odorant binding to the sole OR subunit is sufficient to open the channel pore, suggesting a mechanism of OR activation and a conceptual framework for understanding evolution of insect odorant receptor sensitivity. [ABSTRACT FROM AUTHOR]

Sterile Insect Technique (SIT) is a biological insect (or pest) control tool aiming to reduce or eliminate wild insect (or pest) populations by releasing sterile insects (or pests). In this paper, we propose and study a stage- and sex-structured entomological model describing the dynamics of wild-type mosquito population and observed that the extinction equilibrium of the model is globally asymptotically stable when the basic offspring number is less than unity. However, when the basic offspring number is greater than unity, the extinction equilibrium becomes unstable, followed by the emergence of the stable interior equilibrium. We extend the model by introducing sterile male mosquitoes as a biological control agent against wild-type mosquito species. We have considered the Allee effect in the fertile female mosquito population due to the presence of non-egg-laying females in the mosquito population. While the wild mosquito-free equilibrium of the SIT model is always locally asymptotically stable, there exists either no interior equilibrium or a pair of interior equilibria, among which one is always unstable, and the other is always locally asymptotically stable. We observed that the wild mosquito population of the SIT system goes to extinction, followed by a saddle-node bifurcation when the supply rate of sterile males increases through some critical threshold value. As an alternative to the eradication policy, we formulated an optimal control problem to suppress the wild mosquito population, which suggests increasing the investment in awareness campaigns to suppress the mosquito population. [ABSTRACT FROM AUTHOR]

Sustainable and effective means to control flying insect vectors are critically needed, especially with widespread insecticide resistance and global climate change. Understanding and controlling vectors requires accurate information about their movement and activity, which is often lacking. The Photonic Fence (PF) is an optical system that uses machine vision, infrared light, and lasers to identify, track, and interdict vectors in flight. The PF examines an insect's outline, flight speed, and other flight parameters and if these match those of a targeted vector species, then a low-power, retina-safe laser kills it. We report on proof-of-concept tests of a large, field-sized PF (30 mL × 3 mH) conducted with Aedes aegypti, a mosquito that transmits dangerous arboviruses, and Diaphorina citri, a psyllid which transmits the fatal huanglongbing disease of citrus. In tests with the laser engaged, < 1% and 3% of A. aegypti and D. citri, respectfully, were recovered versus a 38% and 19% recovery when the lacer was silenced. The PF tracked, but did not intercept the orchid bee, Euglossa dilemma. The system effectively intercepted flying vectors, but not bees, at a distance of 30 m, heralding the use of photonic energy, rather than chemicals, to control flying vectors. [ABSTRACT FROM AUTHOR]

The sterile insect technique is based on the overflooding of a target population with released sterile males inducing sterility in the wild female population. It has proven to be effective against several insect pest species of agricultural and veterinary importance and is under development for Aedes mosquitoes. Here, we show that the release of sterile males at high sterile male to wild female ratios may also impact the target female population through mating harassment. Under laboratory conditions, male to female ratios above 50 to 1 reduce the longevity of female Aedes mosquitoes by reducing their feeding success. Under controlled conditions, blood uptake of females from an artificial host or from a mouse and biting rates on humans are also reduced. Finally, in a field trial conducted in a 1.17 ha area in China, the female biting rate is reduced by 80%, concurrent to a reduction of female mosquito density of 40% due to the swarming of males around humans attempting to mate with the female mosquitoes. This suggests that the sterile insect technique does not only suppress mosquito vector populations through the induction of sterility, but may also reduce disease transmission due to increased female mortality and lower host contact. The sterile insect technique involves the introduction of sterile males to induce sterility in females and reduce population size. Here, the authors show that sterile males may also reduce female density and inhibit female blood feeding through mating harassment. [ABSTRACT FROM AUTHOR]

Background: Taiwan's warm and humid climate and dense population provide a suitable environment for the breeding of pests. The three major urban insects in Taiwan are house flies, cockroaches, and mosquitoes. In cases where a disease outbreak or high pest density necessitates chemical control, selecting the most effective insecticide is crucial. The resistance of pests to the selected environmental insecticide must be rapidly assessed to achieve effective chemical control and reduce environmental pollution. Methods: In this study, we evaluated the resistance of various pests, namely, house flies (Musca domestica L.), cockroaches (Blattella germanica L. and Periplaneta americana), and mosquitoes (Aedes aegypti and Ae. albopictus) against 10 commonly used insecticides. Rapid insecticide resistance bioassays were performed using discriminating doses or concentrations of the active ingredients of insecticides. Results: Five field strains of M. domestica (L.) are resistant to all 10 commonly used insecticides and exhibit cross- and multiple resistance to four types of pyrethroids and three types of organophosphates, propoxur, fipronil, and imidacloprid. None of the five field strains of P. americana are resistant to any of the tested insecticides, and only one strain of B. germanica (L.) is resistant to permethrin. One strain of Ae. albopictus is resistant to pirimiphos-methyl, whereas five strains of Ae. aegypti exhibit multiple resistance to pyrethroids, organophosphates, and other insecticides. Conclusions: In the event of a disease outbreak or high pest density, rapid insecticide resistance bioassays may be performed using discriminating doses or concentrations to achieve precise and effective chemical control, reduce environmental pollution, and increase control efficacy. [ABSTRACT FROM AUTHOR]

The article focuses on the history and eradication of Cochliomyia hominivorax, commonly known as the New World Screwfly. It discusses the species' threat to livestock industries, historical eradication efforts led by Edward F. Knipling, and the development and implementation of the Sterile Insect Technique (SIT) as a successful means of control.

We formulate simple differential equation models to study the impact of releases of transgenic sterile mosquitoes carrying a dominant lethal on mosquito control based on the modified sterile insects technique. The early acting bisex, late acting bisex, early acting female-killing, and late acting female-killing lethality strategies are all considered. We determine release thresholds of the transgenic sterile mosquitoes, respectively, for these models by investigating the existence of positive equilibria and their stability. We compare the model dynamics, in particular, the thresholds of the models numerically. The late acting lethality strategies are generally more effective than their corresponding early acting lethality strategies, but the comparison between the late acting bisex and early acting female-killing lethality strategies depends on different parameter settings. [ABSTRACT FROM AUTHOR]

Some insects have a frustrating knack for avoiding a swatter. A new study shows that mosquitos not only evade the visual image of the looming threat, they also surf the wave of air the swatter creates. [ABSTRACT FROM AUTHOR]

The emergence of antimicrobial resistance (AMR) in pathogens and their spillover into the environment have become a global public health menace. Insects can acquire these pathogens from the environment and would serve as mechanical and biological vectors. The current study assessed the ability of Culex quinquefasciatus mosquitoes to acquire methicillin-resistant Staphylococcus aureus (MRSA) through the exposure of the mosquitoes to the pathogen via rearing water, blood feed, or a feeding membrane under laboratory conditions. In addition, mosquito immatures collected from their habitat in the vicinity of hospitals, veterinary dispensaries, and butcher shops at 15 study sites in Puducherry were screened for MRSA infection. All samples were subjected to the culture-based isolation of S. aureus from the surface and homogenate. The presence of the S. aureus-specific nuc gene and the genes that confer resistance to methicillin (mecA and mecC) were screened using PCR tests. MRSA was not evident either on the external surface or in the homogenate of the mosquitoes emerging from the larvae reared in the MRSA-spiked water or those fed with MRSA through blood or smeared membranes. Furthermore, the presence of MRSA was not evident in any of the field-caught mosquitoes. Hence, we conclude that C. quinquefasciatus mosquitoes are impervious to MRSA colonization.

Molecular tools for modulating transgene expression in Aedes aegypti are few. Here we demonstrate that adjustments to the AePUb promoter length can alter expression levels of two reporter proteins in Ae. aegypti cell culture and in mosquitoes. This provides a simple means for increasing or decreasing expression of a gene of interest and easy translation from cells to whole insects. [ABSTRACT FROM AUTHOR]

Simple Summary: Insect vectors are responsible for transmitting a range of diseases, leading to significant mortality rates annually. Their behavior and physiology can undergo shifts due to complex molecular interactions during mating and feeding. In this review, we provide an exhaustive overview of the current "omics" knowledge—spanning genomics, transcriptomics, proteomics, and metabolomics—across various vector species. We highlight potential molecular targets for vector control and outline the advancements and gaps in our understanding, which could pave the way for innovative and effective strategies to curb disease transmission. Female insects belonging to the genera Anopheles, Aedes, Glossina, and Rhodnius account for the majority of global vector-borne disease mortality. In response to mating, these female insects undergo several molecular, physiological, and behavioral changes. Studying the dynamic post-mating molecular responses in these insects that transmit human diseases can lead to the identification of potential targets for the development of novel vector control methods. With the continued advancements in bioinformatics tools, we now have the capability to delve into various physiological processes in these insects. Here, we discuss the availability of multiple datasets describing the reproductive physiology of the common blood-feeding insects at the molecular level. Additionally, we compare the male-derived triggers transferred during mating to females, examining both shared and species-specific factors. These triggers initiate post-mating genetic responses in female vectors, affecting not only their reproductive success but also disease transmission. [ABSTRACT FROM AUTHOR]

Aedes aegypti (L.) is an invasive mosquito responsible for vectoring diseases such as dengue, Zika and Chikungunya. Dengue affects a large proportion of the global population, with the World Health Organization estimating that half the global population is at risk, with 390 million infections occurring each year. Control of mosquito vector populations over large geographical scales can be improved and made economically viable by computer models with potential to aid decision support.We introduce a method for estimating mosquito abundance (population size) over time in biocontrol programmes that involve the release of sterilised insects. We employ Bayesian state‐space modelling to provide insight into population trajectories using data from an application of incompatible insect technique (IIT) biological control, in Far North Queensland, Australia. The general approach could be adapted to other insect species.We demonstrate how the modelling approach can estimate trajectories of abundance over time as an unmarked–release–recapture analysis. Additionally, it provides a means for quantifying population suppression in IIT programmes (a statistic that can be challenging to estimate in practice) using counterfactuals.Modelling results show that estimated population trajectories exhibit similar temporal patterns to raw trapping rate data collected in the field, for example, the presence of peaks (and troughs) associated with the timing of rainfall events. Additional confidence in our model was demonstrated through a cross‐validation study where we left out each of the six landscapes from our dataset, fit the model using the remaining five regions and assessed its predictive skill. Modelled counterfactuals allowed us to estimate that population suppression in treated landscapes was 95%–99%.Synthesis and applications. Our model can provide valuable insights that can shape decision support systems in sterile insect technique and incompatible insect technique programmes operating over large geographical scales. The model helps determine how many sterile/incompatible insects should be released over time and how population control is progressing (via use of counterfactual scenarios). These outcomes are achieved because the model provides estimates of wild‐type populations over time, even when there has been no differentiation between sterile/incompatible and wild‐type insects caught in traps. [ABSTRACT FROM AUTHOR]

Simple Summary: The tiger mosquito, Aedes albopictus (Skuse, 1894), is a competent vector of arboviruses such as dengue, Zika, and chikungunya among others. The sterile insect technique (SIT) is presented as an innovative and environmentally friendly control method to be implemented as a main component of integrated vector control management (IVM). In the Valencian region (Spain), an IVM pilot project led and funded by the Department of Agriculture, based on the use of SIT to control Ae. albopictus, has been carried out from 2017 to 2020. It has proven to be effective in reducing tiger mosquito populations. This manuscript analyzes the impact of the migration of wild individuals from peri-urban areas into non-isolated urban centers on the control strategy. In recent years, Aedes albopictus (Skuse, 1984) has expanded its distribution globally due to its high ecological plasticity. This expansion has increased the population's susceptibility to contracting diseases such as dengue, Zika, and chikungunya, among others, which are transmitted by this mosquito species. In the absence of effective control methods, the application of the sterile insect technique (SIT) is proposed as part of an integrated vector management (IVM) program. From 2007 to 2020, this strategy has been tested in a non-isolated mosquito population urban area of 45 ha, representative of the municipalities of the Valencian region (Spain). The population levels of adult females and eggs collected in the traps have been reduced by 70–80% compared to the control area, demonstrating its efficacy in reducing mosquito populations. This work analyzes the impact of the migration of the wild mosquito population from the peri-urban area to the urban core. [ABSTRACT FROM AUTHOR]

Dengue hemorrhagic fever (DHF) has been endemic in Indonesia for decades. Insecticides are necessary to manage the transmission of the dengue virus. However, prolonged use of insecticides can lead to insecticide resistance. This study aimed to examine the genotype of mosquitoes using the allele-specific polymerase chain reaction (ASPCR) method. The ASPCR method was chosen for genotype detection due to its high sensitivity, affordability, and ease of design. Five mosquitoes were collected from human habitation in four different areas of Surabaya, Indonesia, namely Kranggan, Ulul Azmi Mosque, Ploso, and Kalijudan. Among them, three samples were identified as Aedes albopictus (A1, A2, and A5) and two samples were identified as Aedes aegypti (A3 and A4). The frequency of resistant alleles was analyzed using the Hardy-Weinberg package in RStudio version 2023.03.1. This study revealed that two mosquitoes carried homozygous mutant alleles with a band of 113 bp and three mosquitoes carried homozygous wild-type alleles with a band of 93 bp. Cysteine-to-cysteine (C/C) mutations and phenylalanine-to-phenylalanine (F/F) mutations at codon 1534 were observed in Aedes aegypti and Aedes albopictus mosquitoes. The homozygous mutant alleles were found in Kranggan, Surabaya, Indonesia. Further research is required to assess insecticide resistance and knockdown resistance (kdr)-like mutation by collecting more representative samples from larger areas within the region of Surabaya. Nevertheless, this study can be used as a reference for vector control and early prevention of dengue fever. [ABSTRACT FROM AUTHOR]

Abstract Mosquito species belonging to the genus Aedes have attracted the interest of scientists and public health officers because of their capacity to transmit viruses that affect humans. Some of these species were brought outside their native range by means of trade and tourism and then colonised new regions thanks to a unique combination of eco-physiological traits. Considering mosquito physiological and behavioural traits to understand and predict their population dynamics is thus a crucial step in developing strategies to mitigate the local densities of invasive Aedes populations. Here, we synthesised the life cycle of four invasive Aedes species (Ae. aegypti, Ae. albopictus, Ae. japonicus and Ae. koreicus) in a single multi-scale stochastic modelling framework which we coded in the R package dynamAedes. We designed a stage-based and time-discrete stochastic model driven by temperature, photo-period and inter-specific larval competition that can be applied to three different spatial scales: punctual, local and regional. These spatial scales consider different degrees of spatial complexity and data availability by accounting for both active and passive dispersal of mosquito species as well as for the heterogeneity of the input temperature data. Our overarching aim was to provide a flexible, open-source and user-friendly tool rooted in the most updated knowledge on the species’ biology which could be applied to the management of invasive Aedes populations as well as to more theoretical ecological inquiries. Graphical Abstract

Glutathione S-transferases (GSTs) are conserved in a wide range of organisms, including insects. In 2014, an epsilon GST, known as Noppera-bo (Nobo), was shown to regulate the biosynthesis of ecdysteroid, the principal steroid hormone in insects. Studies on fruit flies, Drosophila melanogaster, and silkworms, Bombyx mori, demonstrated that loss-of-function mutants of nobo fail to synthesize ecdysteroid and die during development, consistent with the essential function of ecdysteroids in insect molting and metamorphosis. This genetic evidence suggests that chemical compounds that inhibit activity of Nobo could be insect growth regulators (IGRs) that kill insects by disrupting their molting and metamorphosis. In addition, because nobo is conserved only in Diptera and Lepidoptera, a Nobo inhibitor could be used to target IGRs in a narrow spectrum of insect taxa. Dipterans include mosquitoes, some of which are vectors of diseases such as malaria and dengue fever. Given that mosquito control is essential to reduce mosquito-borne diseases, new IGRs that specifically kill mosquito vectors are always in demand. We have addressed this issue by identifying and characterizing several chemical compounds that inhibit Nobo protein in both D. melanogaster and the yellow fever mosquito, Aedes aegypti. In this review, we summarize our findings from the search for Nobo inhibitors. [ABSTRACT FROM AUTHOR]

Papular urticaria is commonly seen in emergency departments and primary healthcare clinics and is often incorrectly diagnosed as atopic eczema. This annoying condition is caused by a chronic relapsing hypersensitivity reaction to mostly biting insects. The lesions are intensely pruritic. Owing to continuous scratching, lesions often become secondarily infected. Although adults are also affected, children are more likely to suffer from papular urticaria. Lesions are typically confined to the skin, but in rarer cases, systemic involvement and even anaphylaxis may ensue in susceptible individuals. Insects may also be vectors of various viruses, bacteria and parasites and can transmit vector-borne diseases, for instance, malaria. Although this is a mostly benign condition that is outgrown, some patients with papular urticaria may have serious underlying systemic illnesses or may be immunocompromised. In this article, common offenders, including fleas, bed bugs and mosquitoes, are discussed; as an underlying cause of papular urticaria, scabies is also highlighted. Diagnostic guidance for primary healthcare practitioners, practical examples of insect and parasite eradication and avoidance strategies, in addition to the supportive treatments available in primary healthcare clinics and emergency departments, are explored. [ABSTRACT FROM AUTHOR]

The gene regulatory network for segmentation in arthropods offers valuable insights into how networks evolve owing to the breadth of species examined and the extremely detailed knowledge gained in the model organism Drosophila melanogaster. These studies have shown that Drosophila's network represents a derived state that acquired changes to accelerate segment patterning, whereas most insects specify segments gradually as the embryo elongates. Such heterochronic shifts in segmentation have potentially emerged multiple times within holometabolous insects, resulting in many mechanistic variants and difficulties in isolating underlying commonalities that permit such shifts. Recent studies identified regulatory genes that work as timing factors, coordinating gene expression transitions during segmentation. These studies predict that changes in timing factor deployment explain shifts in segment patterning relative to other developmental events. Here, we test this hypothesis by characterizing the temporal and spatial expression of the pair‐rule patterning genes in the malaria vector mosquito, Anopheles stephensi. This insect is a Dipteran (fly), like Drosophila, but represents an ancient divergence within this clade, offering a useful counterpart for evo‐devo studies. In mosquito embryos, we observe anterior to posterior sequential addition of stripes for many pair‐rule genes and a wave of broad timer gene expression across this axis. Segment polarity gene stripes are added sequentially in the wake of the timer gene wave and the full pattern is not complete until the embryo is fully elongated. This "progressive segmentation" mode in Anopheles displays commonalities with both Drosophila's rapid segmentation mechanism and sequential modes used by more distantly related insects. Research Highlights: Pair‐rule gene expression in mosquitoes reveals anterior to posterior progression of segmentationThis mechanism blends aspects of simultaneous and sequential modes and provides clues into the evolution of diverse insect segmentation mechanisms [ABSTRACT FROM AUTHOR]

Simple Summary: Three small RNA pathways, representing miRNAs, siRNAs and piRNAs, exist in insects. Of the three pathways, piRNAs and Piwi proteins appear to have the most complex biogenesis and functional roles. Significant progress has recently occurred in the understanding of the piRNA pathway in three major research areas, i.e., oogenesis and spermatogenesis in the fruitfly, antiviral response in mosquitoes and piRNA biogenesis in silkworm-derived BmN4 cells. Thus, it is timely to provide an overview of the knowledge accumulated so far. Studies in other insects are lagging behind but are highly anticipated since piRNAs and Piwi proteins are abundantly expressed not only in the germline but also in the somatic tissues. Due to the diversification of Piwi genes among insects, novel functions of piRNAs and Piwi proteins can be expected in the different species. This comprehensive review aimed to provide important background information about the current knowledge on piRNAs and Piwi proteins in insects that can function as a resource for future research. Research on Piwi proteins and piRNAs in insects has focused on three experimental models: oogenesis and spermatogenesis in Drosophila melanogaster, the antiviral response in Aedes mosquitoes and the molecular analysis of primary and secondary piRNA biogenesis in Bombyx mori-derived BmN4 cells. Significant unique and complementary information has been acquired and has led to a greater appreciation of the complexity of piRNA biogenesis and Piwi protein function. Studies performed in other insect species are emerging and promise to add to the current state of the art on the roles of piRNAs and Piwi proteins. Although the primary role of the piRNA pathway is genome defense against transposons, particularly in the germline, recent findings also indicate an expansion of its functions. In this review, an extensive overview is presented of the knowledge of the piRNA pathway that so far has accumulated in insects. Following a presentation of the three major models, data from other insects were also discussed. Finally, the mechanisms for the expansion of the function of the piRNA pathway from transposon control to gene regulation were considered. [ABSTRACT FROM AUTHOR]

Mosquito transgenesis and gene-drive technologies provide the basis for developing promising new tools for vector-borne disease prevention by either suppressing wild mosquito populations or reducing their capacity from transmitting pathogens. Many studies of the regulatory DNA and promoters of genes with robust sex-, tissue- and stage-specific expression profiles have supported the development of new tools and strategies that could bring mosquito-borne diseases under control. Although the list of regulatory elements available is significant, only a limited set of those can reliably drive spatial–temporal expression. Here, we review the advances in our ability to express beneficial and other genes in mosquitoes, and highlight the information needed for the development of new mosquito-control and anti-disease strategies. [ABSTRACT FROM AUTHOR]

The male, female, egg, third instar larva, and puparium of Atherigona (Acritochaeta) culicivora, new species, are described from Peninsular Malaysia and northern Thailand. The saprophagous larvae of A. culicivora develop in water-filled stumps of freshly cut young bamboo shoots. They are subaquatic facultative predators of mosquito larvae, which is unique in the otherwise terrestrial genus Atherigona Rondani. Eggs are laid on the wet bamboo wall above the water surface. The larvae float upside down in the water, with their posterior spiracles attached to the water surface. When mosquito larvae approach, they quickly grab them and wrap themselves around the prey. Mature larvae crawl ashore and secrete a protective foam during pupariation. The development of A. culicivora from egg to adult takes only 13-14 days, which is an adaptation to the ephemeral nature of decaying bamboo shoots. Feeding on mosquito larvae may provide additional or complementary nutrients that could, for example, accelerate the rate of development of A. culicivora. The transition of A. culicivora from a terrestrial to an aquatic lifestyle was probably facilitated by the lack of aquatic predators in its habitat. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a control strategy for applying the Sterile Insect Technique (SIT) to eliminate the population of Aedes mosquitoes which are vectors of various deadly diseases like dengue, zika, chikungunya... in a wide area. We use a system of reaction-diffusion equations to model the mosquito population and study the effect of releasing sterile males. Without any human intervention, and due to the so-called hair-trigger effect, the introduction of only a few individuals (eggs or fertilized females) can lead to the invasion of mosquitoes in the whole region after some time. To avoid this phenomenon, our strategy is to keep releasing a small number of sterile males in the treated zone and move this release forward with a negative forcing speed c to push back the invasive front of wild mosquitoes. By using traveling wave analysis, we show in the present paper that the strategy succeeds in repulsing the population while consuming a finite amount of mosquitoes in any finite time interval even though we treat a moving half-space {x > ct}. Moreover, we succeed in constructing a 'forced' traveling wave for our system moving at the same speed as the releases. We also provide some numerical illustrations for our results. [ABSTRACT FROM AUTHOR]

The strong suppression of Aedes albopictus on two Guangzhou islands in China has been successfully achieved by releasing males with an artificial triple-Wolbachia infection. However, it requires the use of radiation to sterilize residual females to prevent population replacement. To develop a highly effective tool for dengue control, we tested a standalone incompatible insect technique (IIT) to control A. albopictus in the urban area of Changsha, an inland city where dengue recently emerged. Male mosquitoes were produced in a mass rearing facility in Guangzhou and transported over 670 km under low temperature to the release site. After a once-per-week release with high numbers of males (phase I) and a subsequent twice-per-week release with low numbers of males (phase II), the average numbers of hatched eggs and female adults collected weekly per trap were reduced by 97% and 85%, respectively. The population suppression caused a 94% decrease in mosquito biting at the release site compared to the control site. Remarkably, this strong suppression was achieved using only 28% of the number of males released in a previous trial. Despite the lack of irradiation to sterilize residual females, no triple-infected mosquitoes were detected in the field post release based on the monitoring of adult and larval A. albopictus populations for two years, indicating that population replacement was prevented. Our results support the feasibility of implementing a standalone IIT for dengue control in urban areas. A field trial in Changsha, China, involving the release of a triple Wolbachia-infected strain of the mosquito, Aedes albopictus, demonstrates the feasibility of using an incompatible insect technique to suppress disease vector mosquito populations in urban subtropic environments. [ABSTRACT FROM AUTHOR]

Remote sensing techniques in the microwave frequency range have been successfully used in the context of bird, bat and insect measurements. This article breaks new ground in the analysis of freely flying insects by using a continuous-wave (CW) radar system in W-band, i.e., higher mm-wave frequencies, by measuring and analyzing the micro-Doppler signature of their wing beat motion. In addition to numerical and experimental methods, the investigation also includes the development of a new signal processing method using a cepstrogram approach in order to automatically determine the wing beat frequency. In this study, mosquitoes (culex pipiens) and bees (apis mellifera) are considered as model insects throughout the measurement campaign. It was found that 50 independent micro-Doppler measurements of mosquitoes and bees can be clearly distinguished from each other. Moreover, the proposed radar signal model accurately matches the experimental measurements for both species. [ABSTRACT FROM AUTHOR]

Chiffon is the sole Drosophila ortholog of Dbf4, the regulatory subunit for the cell‐cycle kinase Cdc7 that initiates DNA replication. In Drosophila, the chiffon gene encodes two polypeptides with independent activities. Chiffon‐A contains the conserved Dbf4 motifs and interacts with Cdc7 to form the Dbf4‐dependent Kinase (DDK) complex, which is essential for a specialized form of DNA replication. In contrast, Chiffon‐B binds the histone acetyltransferase Gcn5 to form the Chiffon histone acetyltransferase (CHAT) complex, which is necessary for histone H3 acetylation and viability. Previous studies have shown that the Chiffon‐B region is only present within insects. However, it was unclear how widely the interaction between Chiffon‐B and Gcn5 was conserved among insect species. To examine this, we performed yeast two‐hybrid assays using Chiffon‐B and Gcn5 from a variety of insect species and found that Chiffon‐B and Gcn5 interact in Diptera species such as Australian sheep blowfly and yellow fever mosquito. Protein domain analysis identified that Chiffon‐B has features of acidic transcriptional activators such as Gal4 or VP16. We propose that the CHAT complex plays a critical role in a biological process that is unique to Dipterans and could therefore be a potential target for pest control strategies. [ABSTRACT FROM AUTHOR]

Mosquito-borne diseases persist as a global health challenge despite ongoing control efforts, necessitating the exploration of alternative control approaches. This research proposes a Filippov incompatible insect technique (IIT) model with a threshold policy control for suppressing mosquito population. The model implements biological and chemical control strategies only when wild mosquito density surpasses an economic threshold. The biological strategy involves releasing Wolbachia-infected male mosquitoes, offering advantages such as a shortened lifespan and disease blocking. Simultaneously, moderate insecticide and larvicide spraying serve as a chemical approach to expedite the control process. The model provides economic advantages by minimizing control costs and environmental benefits through the integration of biological strategies, thus reducing reliance on chemicals. By employing Filippov's convex method, we identify necessary conditions for the existence of sliding segments and determine the dynamics of the switching line. Theoretical analysis reveals the model's long-term dynamics, including sliding bifurcations, pseudo-equilibria, and their stability. The model exhibits boundary equilibrium bifurcations and transcritical bifurcations in both free and controlled systems. Varying threshold values significantly impact the control outcomes effectiveness. The main findings demonstrate that integrated strategies efficiently decrease the population density of wild mosquitoes. • A Filippov IIT model with threshold policy control (TPC) is proposed to suppress the mosquito population effectively. • Chemical and biological control strategies are applied when the mosquito population exceeds a specified threshold. • The existence of transcritical and boundary equilibrium bifurcations is studied. • This study has significant applications for the control of mosquito-borne diseases. [ABSTRACT FROM AUTHOR]

Mosquito species belonging to the genus Aedes have attracted the interest of scientists and public health officers because of their capacity to transmit viruses that affect humans. Some of these species were brought outside their native range by means of trade and tourism and then colonised new regions thanks to a unique combination of eco-physiological traits. Considering mosquito physiological and behavioural traits to understand and predict their population dynamics is thus a crucial step in developing strategies to mitigate the local densities of invasive Aedes populations. Here, we synthesised the life cycle of four invasive Aedes species (Ae. aegypti, Ae. albopictus, Ae. japonicus and Ae. koreicus) in a single multi-scale stochastic modelling framework which we coded in the R package dynamAedes. We designed a stage-based and time-discrete stochastic model driven by temperature, photo-period and inter-specific larval competition that can be applied to three different spatial scales: punctual, local and regional. These spatial scales consider different degrees of spatial complexity and data availability by accounting for both active and passive dispersal of mosquito species as well as for the heterogeneity of the input temperature data. Our overarching aim was to provide a flexible, open-source and user-friendly tool rooted in the most updated knowledge on the species' biology which could be applied to the management of invasive Aedes populations as well as to more theoretical ecological inquiries. [ABSTRACT FROM AUTHOR]

Background: The sterile insect technique (SIT), which involves area-wide inundative releases of sterile insects to suppress the reproduction of a target species, has proven to be an effective pest control method. The technique demands the continuous release of sterilized insects in quantities that ensure a high sterile male:wild male ratio for the suppression of the wild population over succeeding generations. Methods: For these releases, it is important to determine several ecological and biological population parameters, including the longevity of the released males in the field, the dispersal of the released males and the wild pest population size. The Lee County Mosquito Control District initiated a study in a 47-ha portion of Captiva Island (Florida, USA), an island with a total area of 230 ha, to define biological SIT parameters for Aedes aegypti (L.), an invasive disease-vectoring mosquito known to be difficult to control due to a combination of daytime biting activity, use of cryptic breeding habitats that are difficult to target with conventional night-time ultra-low volume methods, and emerging resistance to commonly used insecticides. Another goal was to assess patterns of dispersal and survival for laboratory-reared sterile Ae. aegypti males released over time in the pilot site. These parameters will be used to evaluate the efficacy of a SIT suppression program for Ae. aegypti on Captiva Island. Results: Over the course of seven mark-release-recapture studies using single- and multiple-point releases, 190,504 sterile marked males were released, for which the recapture rate was 1.5% over a mean period of 12 days. The mean distance traveled by sterile males of the local strain of Ae. aegypti that has colonized Captiva Island was 201.7 m from the release point, with an observed maximum traveled distance of 404.5 m. The released sterile mosquitoes had a probability of daily survival of 0.67 and an average life expectancy of ~ 2.46 days. Conclusions: These data together with the population size estimate and sterile:wild ratio provide a solid basis for planning the SIT operational phase which is aimed at mosquito population suppression. [ABSTRACT FROM AUTHOR]

Monoxenous (insect-restricted) trypanosomatids are highly diverse and abundant in nature. While many papers focus on the taxonomy and distribution of these parasites, studies on their biology are still scarce. In particular, this concerns trypanosomatids inhabiting the ubiquitous mosquitoes. To shed light on the circulation of monoxenous trypanosomatids with the participation of mosquitoes, we performed a multifaceted study combining the examination of naturally- and experimentally-infected insects using light and electron microscopy and molecular identification of parasites. Our examination of overwintering mosquitoes (genera Culex and Culiseta) revealed that their guts contained living trypanosomatids, which can be spread during the next season. Experimental infections with Crithidia spp. demonstrated that imagines represent permissive hosts, while larvae are resistant to these parasites. We argue that for the parasites with wide specificity, mosquitoes act as facultative hosts. Other trypanosomatids may have specific adaptations for vertical transmission in these insects at the expense of their potential to infect a wider range of hosts and, consequently, abundance in nature. [ABSTRACT FROM AUTHOR]

Insect vision starts with light absorption by visual pigments based on opsins that drive Gq-type G protein-mediated phototransduction. Since Drosophila, the most studied insect in vision research, has only Gq-coupled opsins, the Gq-mediated phototransduction has been solely focused on insect vision for decades. However, genome projects on mosquitos uncovered non-canonical insect opsin genes, members of the Opn3 or c-opsin group composed of vertebrate and invertebrate non-visual opsins. Here, we report that a homologue of Opn3, MosOpn3 (Asop12) is expressed in eyes of a mosquito Anopheles stephensi. In situ hybridization analysis revealed that MosOpn3 is expressed in dorsal and ventral ommatidia, in which only R7 photoreceptor cells express MosOpn3. We also found that Asop9, a Gq-coupled visual opsin, exhibited co-localization with MosOpn3. Spectroscopic analysis revealed that Asop9 forms a blue-sensitive opsin-based pigment. Thus, the Gi/Go-coupled opsin MosOpn3, which forms a green-sensitive pigment, is co-localized with Asop9, a Gq-coupled opsin that forms a blue-sensitive visual pigment. Since these two opsin-based pigments trigger different phototransduction cascades, the R7 photoreceptors could generate complex photoresponses to blue to green light. This article is part of the theme issue 'Understanding colour vision: molecular, physiological, neuronal and behavioural studies in arthropods'. [ABSTRACT FROM AUTHOR]

In our natural product screening program, we screened natural products for their repellency and toxicity against insect vectors. Methanolic extract of aerial parts of Stenaria nigricans (Lam.), with no published chemistry, was tested for repellency against mosquitoes and imported hybrid fire ants. Methanolic extracts showed biting deterrence similar to DEET (N,N-diethyl-3-methylbenzamide) against Aedes aegypti L. Based on this activity, the crude extract was fractionated into chloroform, ethyl acetate, and methanol subfractions. The active methanolic subfraction was further fractionated into 13 subfractions. These fractions were tested for their biting deterrence against Ae. Aegypti. Active subfractions were further characterized to identify the compounds responsible for this activity. Four undescribed iridoid glucosides (1–4) and three previously reported compounds (5–7) were isolated from active subfractions and tested for their biting deterrent activity. Based on BDI values, compounds 2, 3, 6, and 7, with biting deterrence similar to DEET, showed the potential to be used as repellents against mosquitoes. In an in vitro digging bioassay, none of these compounds showed any repellency against hybrid imported fire ants at a dose of 125 µg/g. This is the first report of biting deterrence and repellency of S. nigricans extract and its pure compounds, iridoid glucosides against mosquitoes and imported fire ants. Further studies will be conducted to explore the repellent potential of these compounds in different formulations under field conditions. [ABSTRACT FROM AUTHOR]

In recent years, Aedes mosquitoes have become a serious health threat in the Philippines, causing a dramatic increase in dengue incidence. To design and implement adapted vector control measures, knowledge of vector composition and abundance is essential. Surveillance of mosquito populations using ovitraps was conducted for about two years (from April 2018-February 2020) in two selected sites (Sitio Payong and Villa Beatriz in Old Balara, Quezon City). These areas were identified as potential sites for small-scale pilot trials of the sterile insect technique. Aedes aegypti and Ae. albopictus were present in both sites, but Ae. aegypti was about 20 times more abundant than Ae. albopictus. There was a significant difference between the two sites in the number of eggs collected weekly but not in the OI. The number of Aedes spp. eggs collected were found to positively correlate with the maximum daily temperature. These data provide comprehensive, evidencebased information that will help in the design and implementation of Aedes control measures, as part of wider public health interventions for prevention and control. [ABSTRACT FROM AUTHOR]

Simple Summary: My career in science, and specifically in insect biology, benefitted from post-war efforts to improve science education in the 1950s and 1960s and increased opportunities for women students and faculty; teachers, mentors, associates, colleagues and friends of all sorts helped along the way. Here, I recount the highlights of my research, focusing on studies involving the insect steroid hormone ecdysone, which regulates molting in insect larvae, and reproduction in adults. Ecdysone was the unknown "ovarian factor" involved in egg production in Aedes aegypti mosquitoes. In addition, ecdysone affects the process of cell division in cultured mosquito cells, causing a cell cycle arrest that enhances growth of an obligate symbiotic bacterium, Wolbachia pipientis. Since the mid-1920s, Wolbachia was known to infect ovaries of Culex pipiens mosquitoes. After Wolbachia sequences were discovered in DNA extracted from Drosophila, this obligate intracellular alpha proteobacterium was found to be widespread among insect species, and its effects on reproduction have important applications for control of insect pests. Most recently, effects of ecdysone on Wolbachia replication in mosquito cell lines led to insights that enhance production of infectious bacteria at levels suitable for microinjection into eggs and eventual genetic manipulation. In anautogenous mosquitoes, synchronous development of terminal ovarian follicles after a blood meal provides an important model for studies on insect reproduction. Removal and implantation of ovaries, in vitro culture of dissected tissues and immunological assays for vitellogenin synthesis by the fat body showed that the Aedes aegypti (L.) (Diptera, Culicidae) mosquito ovary produces a factor essential for egg production. The discovery that the ovarian factor was the insect steroid hormone, ecdysone, provided a model for co-option of the larval hormones as reproductive hormones in adult insects. In later work on cultured mosquito cells, ecdysone was shown to arrest the cell cycle, resulting in an accumulation of diploid cells in G1, prior to initiation of DNA synthesis. Some mosquito species, such as Culex pipiens L. (Diptera, Culicidae), harbor the obligate intracellular bacterium, Wolbachia pipientis Hertig (Rickettsiales, Anaplasmataceae), in their reproductive tissues. When maintained in mosquito cell lines, Wolbachia abundance increases in ecdysone-arrested cells. This observation facilitated the recovery of high levels of Wolbachia from cultured cells for microinjection and genetic manipulation. In female Culex pipiens, it will be of interest to explore how hormonal cues that support initiation and progression of the vitellogenic cycle influence Wolbachia replication and transmission to subsequent generations via infected eggs. [ABSTRACT FROM AUTHOR]

Lumpy skin disease virus (LSDV) is a poxvirus that causes severe systemic disease in cattle and is spread by mechanical arthropod-borne transmission. This study quantified the acquisition and retention of LSDV by four species of Diptera (Stomoxys calcitrans, Aedes aegypti, Culex quinquefasciatus, and Culicoides nubeculosus) from cutaneous lesions, normal skin, and blood from a clinically affected animal. The acquisition and retention of LSDV by Ae. aegypti from an artificial membrane feeding system was also examined. Mathematical models of the data were generated to identify the parameters which influence insect acquisition and retention of LSDV. For all four insect species, the probability of acquiring LSDV was substantially greater when feeding on a lesion compared with feeding on normal skin or blood from a clinically affected animal. After feeding on a skin lesion LSDV was retained on the proboscis for a similar length of time (around 9 days) for all four species and for a shorter time in the rest of the body, ranging from 2.2 to 6.4 days. Acquisition and retention of LSDV by Ae. aegypti after feeding on an artificial membrane feeding system that contained a high titer of LSDV was comparable to feeding on a skin lesion on a clinically affected animal, supporting the use of this laboratory model as a replacement for some animal studies. This work reveals that the cutaneous lesions of LSD provide the high-titer source required for acquisition of the virus by insects, thereby enabling the mechanical vector-borne transmission. [ABSTRACT FROM AUTHOR]

Sterile insect technology (SIT) is an environmental-friendly method which depends on the release of sterile male mosquitoes that compete with the wild male mosquitoes and mate with wild female mosquitoes, which leads to the production of no offspring and as such reduces the population of Zika virus vector population over time, thereby eliminating the spread of Zika virus in a population. The fractional order sterile insect technology (SIT) model to reduce the spread of Zika virus disease is considered in this present work. We employed the use Laplace–Adomian decomposition method (LADM) to determine an analytical (approximate) solution of the model. The Laplace–Adomian decomposition method (LADM) produced a solution in form of an infinite series that further converges to the exact value. We compared solutions of the fractional model with the classical case using our plots and discovered that the fractional order has more degree of freedom and as such the system can be varied to get many preferred responses of the different classes of the model as the fraction (β) could be varied to the desired rate, say 0.7, 0.4, etc. We have been able to show that LADM can be used to solve an SIT model which has never been done before in literature. [ABSTRACT FROM AUTHOR]

The Incompatible Insect Technique (IIT) strategy involves the release of male mosquitoes infected with the bacterium Wolbachia. Regular releases of male Wolbachia-infected mosquitoes can lead to the suppression of mosquito populations, thereby reducing the risk of transmission of vector-borne diseases such as dengue. However, due to imperfect sex-sorting under IIT, fertile Wolbachia-infected female mosquitoes may potentially be unintentionally released into the environment, which may result in replacement and failure to suppress the mosquito populations. As such, mitigating Wolbachia establishment requires a combination of IIT with other strategies. We introduced a simple compartmental model to simulate ex-ante mosquito population dynamics subjected to a Wolbachia-IIT programme. In silico, we explored the risk of replacement, and strategies that could mitigate the establishment of the released Wolbachia strain in the mosquito population. Our results suggest that mitigation may be achieved through the application of a sterile insect technique. Our simulations indicate that these interventions do not override the intended wild type suppression of the IIT approach. These findings will inform policy makers of possible ways to mitigate the potential establishment of Wolbachia using the IIT population control strategy. [ABSTRACT FROM AUTHOR]

Human beings are greatly threatened by the dangerous pathogens spread by mosquitoes, especially malarial parasite transmitted by Anopheles sp., dengue virus by Aedes sp., and filarial worm by Culex sp. Insecticide-based control strategies were playing a significant part in controlling the vectors and thereby reducing the chances of disease spreading. Due to the insecticide resistance acquired by the mosquito, the diseases are now resurgent. New control tactics should be raised against the mosquitoes and the microbes can form an alternate way. Many microbes are now used to eliminate both adults and larvae of mosquitoes. Microbes have been isolated from various sources like soil, rocks, plants, etc. which possess the potential to be used for bioremediation. Even though the bacteria are the main members of the insect gut, other non-bacterial members like, viral, fungal and protist communities should be characterized and identified as they have a role in regulating the population size. Therefore to limit the extensiveness and competence of insect vectors of human diseases, the use of microbial symbionts and paratransgenesis can be a powerful tool. By analyzing the role of microbes in insecticide degradation inside the gut, a strategy for preventing insecticide resistance development can be developed. [ABSTRACT FROM AUTHOR]

Simple Summary: With the increasing burden of mosquito-borne diseases around the world and the traditional control methods showing drawbacks, the sterile insect technique (SIT) is now a potential new tool in the field of controlling mosquitoes. During the implementation of SIT, several steps, such as handling, transportation and release, are of great importance and stand a chance to be optimized. Here, we provide an overview of the key steps in the whole SIT process, listing the main handling, transporting and releasing methods described in the present studies in order to maximize the success of the SIT. With the relevant technical summary, the cognition of this technology can be more accurate; the explorations and results may evoke more follow-up research, making them more directional. The sterile insect technique (SIT) and its related technologies are considered to be a powerful weapon for fighting against mosquitoes. As an important part of the area-wide integrated pest management (AW-IPM) programs, SIT can help reduce the use of chemical pesticides for mosquito control, and consequently, the occurrence of insecticide resistance. The mosquito SIT involves several important steps, including mass rearing, sex separation, irradiation, packing, transportation, release and monitoring. To enable the application of SIT against mosquitoes to reduce vector populations, the Joint Food and Agriculture Organization of the United Nations (FAO) and the International Atomic Energy Agency (IAEA) Centre (previously called Division) of Nuclear Techniques in Food and Agriculture (hereinafter called Joint FAO/IAEA Centre) and its Insects Pest Control sub-program promoted a coordinated research project (CRP) entitled "Mosquito handling, transport, release and male trapping methods" to enhance the success of SIT. This article summarizes the existing explorations that are critical to the handling and transporting of male mosquitoes, offers an overview of detailed steps in SIT and discusses new emerging methods for mosquito releases, covering most processes of SIT. [ABSTRACT FROM AUTHOR]

Compensation and overcompensation under field conditions are confirmed in Aedes mosquitoes recently by Evans et al.: equal or increased densities of emerging adults may thus result from reduced larval densities. Here the consequences when applying the sterile insect technique and provide recommendations to avoid counterproductive effects are discussed. [ABSTRACT FROM AUTHOR]

Sterile insect technique has been successfully applied in the control of agricultural pests; however, it has a limited ability to control mosquitoes. A promising alternative approach is the Trojan Y Chromosome strategy, which works by manipulating the sex ratio of a population through the introduction of YY supermales that guarantee male offspring. To take the advantages of both approaches, a combined Trojan Y chromosome strategy and sterile insect technique (TYC-SIT) strategy considering intraspecies competition is modeled. The pure TYC method is compared with the pure SIT method by cancelling one-state variable. The dynamical analysis leads to results on both local and global stabilities of this combined TYC-SIT model. Optimal control analysis is also implemented to investigate the optimal mechanisms for extinction of mosquitoes. In particular, the numerical results affirm that the combined TYC-SIT enables near elimination of mosquitoes and works better than the pure TYC or pure SIT method. These conclusions have great significance for species controls with an XX-XY sex determinism system or ZZ-ZW system. [ABSTRACT FROM AUTHOR]