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The mosquitoAedes aegyptiis a competent vector of multiple pathogens including dengue, Zika, yellow fever, chikungunya, and Mayaro viruses.Ae. aegyptiis highly invasive and is currently present in the Americas, Oceania, Asia, and Europe, but its distribution and the pathogens it transmits are expected to change due to climate change. Relative humidity is an environmental variable that affects mosquito biology and distribution and can differ between location, habitat, and season, with mosquitoes facing significant variation in relative humidity during their lifespan. Low relative humidity can induce dehydration in mosquitoes, leading to alterations in physiological and behavioral responses relevant for pathogen transmission such as bloodfeeding and host-seeking behavior. In this study, we evaluated the short and long-term effects of dehydration stress on mortality and Mayaro virus vector competence in Ae. aegypti. Our results show that exposure to dehydration does not impact viral titers, nor infection, dissemination and transmission rates, in mosquitoes infected with Mayaro virus. However, we detected a significant effect of dehydration on mosquito mortality and blood feeding frequency regardless of infection status. The previously observed effects of higher feeding during dehydration and the current observation of altered survival along with no impact on vector competence suggest that the impact of dehydration on viral transmission in mosquitoes will likely be complex.

The mosquito midgut is an important site for bloodmeal regulation while also acting as a primary site for pathogen exposure within the mosquito. Recent studies show that exposure to dehydrating conditions alters mosquito bloodfeeding behaviors as well as post-feeding regulation, likely altering how pathogens interact with the mosquito. Unfortunately, few studies have explored the underlying dynamics between dehydration and bloodmeal utilization, and the overall impact on disease transmission dynamics remains veiled. In this study, we find that dehydration-based feeding in the yellow fever mosquito,Aedes aegypti, prompts alterations to midgut gene expression, as well as subsequent physiological factors involving water control and post-bloodfeeding (pbf) regulation. Altered expression of ion transporter genes in the midgut of dehydrated mosquitoes and rapid reequilibration of hemolymph osmolality after a bloodmeal indicate an ability to expedite fluid and ion processing. These alterations ultimately indicate that femaleA. aegyptiemploy mechanisms to ameliorate the detriments of dehydration by imbibing a bloodmeal, providing an effective avenue for rehydration. Continued research into bloodmeal utilization and the resulting effects on arthropod-borne transmission dynamics becomes increasingly important as drought prevalence is increased by climate change.

The Antarctic midge, Belgica antarctica, is a wingless, non-biting midge endemic to Antarctica. Larval development requires at least 2 years, but adults live only 2 weeks. The nonfeeding adults mate in swarms and females die shortly after oviposition. Eggs are suspended in a gel of unknown composition that is expressed from the female accessory gland. This project characterizes molecular mechanisms underlying reproduction in this midge by examining differential gene expression in whole males, females, and larvae, as well as in male and female accessory glands. Functional studies were used to assess the role of the gel encasing the eggs, as well as the impact of stress on reproductive biology. RNA-seq analyses revealed sex- and development-specific gene sets along with those associated with the accessory glands. Proteomic analyses were used to define the composition of the egg-containing gel, which is generated during multiple developmental stages and derived from both the accessory gland and other female organs. Functional studies indicate the gel provides a larval food source as well as a buffer for thermal and dehydration stress. All of these function are critical to juvenile survival. Larval dehydration stress directly reduces production of storage proteins and key accessory gland components, a feature that impacts adult reproductive success. Modeling reveals that bouts of dehydration may have a significant impact on population growth. This work lays a foundation for further examination of reproduction in midges and provides new information related to general reproduction in dipterans. A key aspect of this work is that reproduction and stress dynamics, currently understudied in polar organisms, are likely to prove critical in determining how climate change will alter their survivability.

Despite advances in metapopulation theory, recent studies have emphasized the difficulty in understanding and accurately predicting dynamics in nature. We address this knowledge gap by coupling 4 years of population data for the freshwater zooplankter Daphnia pulex, inhabiting 38 newly established ponds in Upstate New York, with (i) a spatially explicit stochastic model and (ii) a deterministic model where we have averaged the spatial dependencies. By modifying the identity of ponds stocked/removed in our model, we examine the effects of network structure on metapopulation dynamics and local occupancy patterns. From these modeling exercises, we show that the centrality of ponds (stocked or removed) has contrasting effects on metapopulation persistence when selecting ponds to initially stock versus preserve. The pond network was not robust to the removal of centrally located ponds as the simulated removal of these ponds resulted in rapid collapse of the metapopulation. However, when initially founding a metapopulation, the location of patches did not influence occupancy dynamics. Because stochastic simulations can be computationally expensive, we also introduce a quantity for use in a simple differential equation model that encompasses all spatial information in a single variable. Using this quantity, we show how the output of our simple differential equation model matched the quasi-steady state of the stochastic simulations in networks characterized by high connectivity. The method we use is general enough to be applied in other systems and can provide insights for habitat conservation and restoration efforts including how network structure can drive spatiotemporal metapopulation dynamics.

Predator-prey interactions can have a significant impact on the abundance and distribution of species, but the outcome of these interactions is often context-dependent. In small freshwater habitats, predacious copepods are potential biological control agents for mosquito larvae. Through laboratory experiments, we tested if the presence of a non-mosquito prey (neonate Daphnia pulex) influenced prey selection of the predaceous copepod (Acanthocyclops vernalis) on 1st instar Aedes mosquitoes (Aedes aegypti and Aedes albopictus). Copepods were starved for 12 h prior to being exposed to the two prey types (larval mosquitoes and Daphnia) at three densities: 25 mosquitoes:75 Daphnia, 50 mosquitoes:50 Daphnia, 75 mosquitoes:25 Daphnia. Single prey choice trials for each species as well as no-predator trials were also established for controls. Copepods were effective predators, with a single copepod consuming up to 37 1st instar mosquito larvae during the 24-h trials. The number of mosquitoes consumed increased with their relative density, but the proportion of mosquitoes consumed was highest when Aedes made up only 25% of the population. Results from our study show that in a simple predator/two-prey system, two species of larval mosquitoes (Ae. aegypti and Ae. albopictus) are preferentially consumed over an alternative zooplankton by the copepod predator Acanthocyclops vernalis.

The Antarctic mite (Alaskozetes antarcticus) is widely distributed on sub-Antarctic islands and throughout the Antarctic Peninsula, making it one of the most abundant terrestrial arthropods in the region. Despite the impressive ability of A. antarcticus to thrive in harsh Antarctic conditions, little is known about the biology of this species. In this study, we performed 16S rRNA gene sequencing to examine the microbiome of the final immature instar (tritonymph) and both male and female adults. The microbiome included a limited number of microbial classes and genera, with few differences in community membership noted among the different stages. However, the abundances of taxa that composed the microbial community differed between adults and tritonymphs. Five classes—Actinobacteria, Flavobacteriia, Sphingobacteriia, Gammaproteobacteria, and Betaproteobacteria—comprised ~ 82.0% of the microbial composition, and five (identified) genera—Dermacoccus, Pedobacter, Chryseobacterium, Pseudomonas, and Flavobacterium—accounted for ~ 68.0% of the total composition. The core microbiome present in all surveyed A. antarcticus was dominated by the families Flavobacteriaceae, Comamonadaceae, Sphingobacteriaceae, Chitinophagaceae and Cytophagaceae, but the majority of the core consisted of operational taxonomic units of low abundance. This comprehensive analysis reveals a diverse microbiome among individuals of different stages, with overlap likely due to their shared habitat and common feeding preferences as herbivores and detritivores. The microbiome of the Antarctic mite shows considerably more diversity than observed in mite species from lower latitudes.

Predator-prey interactions can have a significant impact on the abundance and distribution of species, but the outcome of these interactions is often context-dependent. In small freshwater habitats, predacious copepods are potential biological control agents for mosquito larvae. Through laboratory experiments, we tested if the presence of a non-mosquito prey (neonate

Background The stable fly, Stomoxys calcitrans, is a major blood-feeding pest of livestock that has near worldwide distribution, causing an annual cost of over $2 billion for control and product loss in the USA alone. Control of these flies has been limited to increased sanitary management practices and insecticide application for suppressing larval stages. Few genetic and molecular resources are available to help in developing novel methods for controlling stable flies. Results This study examines stable fly biology by utilizing a combination of high-quality genome sequencing and RNA-Seq analyses targeting multiple developmental stages and tissues. In conjunction, 1600 genes were manually curated to characterize genetic features related to stable fly reproduction, vector host interactions, host-microbe dynamics, and putative targets for control. Most notable was characterization of genes associated with reproduction and identification of expanded gene families with functional associations to vision, chemosensation, immunity, and metabolic detoxification pathways. Conclusions The combined sequencing, assembly, and curation of the male stable fly genome followed by RNA-Seq and downstream analyses provide insights necessary to understand the biology of this important pest. These resources and new data will provide the groundwork for expanding the tools available to control stable fly infestations. The close relationship of Stomoxys to other blood-feeding (horn flies and Glossina) and non-blood-feeding flies (house flies, medflies, Drosophila) will facilitate understanding of the evolutionary processes associated with development of blood feeding among the Cyclorrhapha.

BackgroundHalyomorpha halys(Stål), the brown marmorated stink bug, is a highly invasive insect species due in part to its exceptionally high levels of polyphagy. This species is also a nuisance due to overwintering in human-made structures. It has caused significant agricultural losses in recent years along the Atlantic seaboard of North America and in continental Europe. Genomic resources will assist with determining the molecular basis for this species’ feeding and habitat traits, defining potential targets for pest management strategies.ResultsAnalysis of the 1.15-Gb draft genome assembly has identified a wide variety of genetic elements underpinning the biological characteristics of this formidable pest species, encompassing the roles of sensory functions, digestion, immunity, detoxification and development, all of which likely supportH. halys’ capacity for invasiveness. Many of the genes identified herein have potential for biomolecular pesticide applications.ConclusionsAvailability of theH. halysgenome sequence will be useful for the development of environmentally friendly biomolecular pesticides to be applied in concert with more traditional, synthetic chemical-based controls.

The oribatid mite Alaskozetes antarcticus, one of the most abundant terrestrial invertebrates in Antarctica, survives extreme temperature fluctuation and desiccation, and thrives in the short growing season characteristic of this polar environment. Several aspects of the mite’s ecology and physiology are well studied, but little is known about its reproduction. In this study, we utilize sex- and development-specific next-generation RNA-sequencing (RNA-seq) analyses to identify differentially regulated transcripts underlying reproduction of A. antarcticus. Pairwise comparisons between males, females, and tritonymphs revealed more than 4000 enriched transcripts based on different transcriptional levels among sexes and developmental stages. More than 500 of these enriched transcripts were differentially upregulated over 1000-fold. Many of the highly enriched and sex-specific transcripts were previously uncharacterized or have no known orthology. Of the transcripts identified, gene ontology-based analyses linked the transcriptional distinctions to differences in reproduction, chemosensation, and stress response. Our comparative approach allowed us to determine sexually dimorphic transcript expression in A. antarcticus. We anticipate that this study will provide a baseline to better understand the mechanisms that underlie reproduction in both polar and non-polar oribatid mites.

Current insights into the mosquito dehydration response rely on studies that examine specific responses but ultimately fail to provide an encompassing view of mosquito biology. Here, we examined underlying changes in the biology of mosquitoes associated with dehydration. Specifically, we show that dehydration increases blood feeding in the northern house mosquito, Culex pipiens, which was the result of both higher activity and a greater tendency to land on a host. Similar observations were noted for Aedes aegypti and Anopheles quadrimaculatus. RNA-seq and metabolome analyses in C. pipiens following dehydration revealed that factors associated with carbohydrate metabolism are altered, specifically the breakdown of trehalose. Suppression of trehalose breakdown in C. pipiens by RNA interference reduced phenotypes associated with lower hydration levels. Lastly, mesocosm studies for C. pipiens confirmed that dehydrated mosquitoes were more likely to host feed under ecologically relevant conditions. Disease modeling indicates dehydration bouts will likely enhance viral transmission. This dehydration-induced increase in blood feeding is therefore likely to occur regularly and intensify during periods when availability of water is low.

People with more education tend to have relatively healthy lifestyles. Among other things, they smoke less than those with less education. This link between education and smoking (known as the "educational gradient") is frequently interpreted as causal: many researchers argue that education develops skills, habits, and preferences that discourage smoking and other unhealthy behaviors. However, an alternative possibility is that these skills, habits, and preferences develop early in life and determine the likelihood of both attaining a high level of education and avoiding smoking. I test the latter possibility using data from the Longitudinal Study of Adolescent to Adult Health (Add Health). In particular, I assess the degree to which indicators of self-control in adolescence explain the association between educational attainment and smoking in adulthood. Results from a series of regression-based tests indicate that self-control is a significant predictor of both outcomes, even when controlling for a host of other risk factors. However, it does not appear to explain the educational gradient.

We report that larvae of the winter tick Dermacentor albipictus, the only stage that will quest for a host, can tolerate short-term cold shock down to −25 °C and short-term heat shock as high as 46 °C. Unlike a three host-tick, larvae of D. albipictus have no preconditioning response to low or high temperature exposure by rapid cold hardening (RCH) or heat hardening, and poor ability to acclimate to low and high temperature extremes. Thermal tolerance limits were not improved as the result of larval clustering, and there was only a minimal effect due to changes in photoperiod. These larvae are freeze intolerant and die at higher temperatures (−5 to −10 °C) from contact with ice by inoculative freezing. In absence of cold-associated resistance mechanisms, winter survival requires that larvae procure a host before the first snow cover. Their low and high temperature tolerance, however, is a key survival element that adapts them for off-host periods during summer, which in the arctic could allow for northern expansion.

The Antarctic midge,Belgica antarctica, is a wingless, non-biting midge endemic to Antarctica. Larval development requires at least two years, but adult life lasts only two weeks. The nonfeeding adults mate in swarms and females die shortly after oviposition. Eggs are suspended in a gel of unknown composition that is expressed from the female accessory gland. This project characterizes molecular mechanisms underlying reproduction in this midge by examining differential gene expression in whole males, females, and larvae, as well as in male and female accessory glands. Functional studies were used to assess the role of the gel encasing the eggs, as well as the impact of stress on reproductive biology. RNA-seq analyses revealed sex- and development-specific gene sets along with those associated with the accessory glands. Proteomic analyses were used to define the composition of the egg-containing gel, which is generated during multiple developmental stages and derived from both the accessory gland and other female organs. Functional studies indicate the gel provides a larval food source and thermal and dehydration buffer, all of which are critical for viability. Larval dehydration stress directly reduces production of storage proteins and key accessory gland components, a feature that impacts adult reproductive success. Modeling reveals that bouts of dehydration may significantly impact population growth. This work lays a foundation for further examination of reproduction in midges and provides new information related to general reproduction in dipterans. A key aspect is that reproduction and stress dynamics, currently understudied in polar organisms, are likely to prove critical for determining how climate change will alter survivability.

Diseases that are transmitted by mosquitoes are a tremendous health and socioeconomic burden with hundreds of millions of people being impacted by mosquito-borne illnesses annually. Many factors have been implicated and extensively studied in disease transmission dynamics, but knowledge regarding how dehydration impacts mosquito physiology, behavior, and resulting mosquito-borne disease transmission remain underdeveloped. The lapse in understanding on how mosquitoes respond to dehydration stress likely obscures our ability to effectively study mosquito physiology, behavior, and vectorial capabilities. The goal of this review is to develop a profile of factors underlying mosquito biology that are altered by dehydration and the implications that are related to disease transmission.

BackgroundThe stable fly,Stomoxys calcitrans, is a major blood-feeding pest of livestock that has near worldwide distribution, causing an annual cost of over $2 billion for control and product loss in the United States alone. Control of these flies has been limited to increased sanitary management practices and insecticide application for suppressing larval stages. Few genetic and molecular resources are available to help in developing novel methods for controlling stable flies.ResultsThis study examines stable fly biology by utilizing a combination of high-quality genome sequencing, microbiome analyses, and RNA-seq analyses targeting multiple developmental stages and tissues. In conjunction, manual curation of over 1600 genes was used to examine gene content related to stable fly reproduction, interactions with their host, host-microbe dynamics, and putative routes for control. Most notable was establishment of reproduction-associated genes and identification of expanded vision, chemosensation, immune repertoire, and metabolic detoxification pathway gene families.ConclusionsThe combined sequencing, assembly, and curation of the male stable fly genome followed by RNA-seq and downstream analyses provide insights necessary to understand the biology of this important pest. These resources and knowledge will provide the groundwork for expanding the tools available to control stable fly infestations. The close relationship ofStomoxysto other blood-feeding (Glossina) and non-blood-feeding flies (medflies,Drosophila, house flies) will allow for understanding the evolution of blood feeding among Cyclorrhapha flies.

When newly created habitats are initially colonized by genotypes with rapid population growth rates, later arriving colonists may be prevented from establishing. Although these priority effects have been documented in multiple systems, their duration may be influenced by the diversity of the founding population. We conducted a large-scale field manipulation to investigate how initial clonal diversity influences temporal and landscape patterns of genetic structure in a developing metapopulation. Six genotypes of obligately asexual Daphnia pulex were stocked alone (no clonal diversity) or in combination ('high' clonal diversity) into newly created experimental woodland ponds. We also measured the population growth rate of all clones in the laboratory when raised on higher-quality and lower-quality resources. Our predictions were that in the 3 years following stocking, clonally diverse populations would be more likely to persist than nonclonally diverse populations and exhibit evidence for persistent founder effects. We expected that faster growing clones would be found in more pools and comprise a greater proportion of individuals genotyped from the landscape. Genetic composition, both locally and regionally, changed significantly following stocking. Six of 27 populations exhibited evidence for persistent founder effects, and populations stocked with 'high' clonal diversity were more likely to exhibit these effects than nonclonally diverse populations. Performance in the laboratory was not predictive of clonal persistence or overall dominance in the field. Hence, we conclude that although laboratory estimates of fitness did not fully explain metapopulation genetic structure, initial clonal diversity did enhance D. pulex population establishment and persistence in this system.

BACKGROUND/OBJECTIVES: To evaluate outcomes from all British military patients who underwent eye removal during the Iraq and Afghanistan wars. SUBJECTS/METHODS: Retrospective case note review of all patients (n = 19) who had undergone either evisceration or enucleation, on a database of all military patients repatriated to the Royal Centre for Defence Medicine, Birmingham. RESULTS: Twenty eye removals were performed on 19 patients, of which 14 (70%) were eviscerations and 6 (30%) were enucleations. Orbital wall fractures were seen in 12 (61%) patients, with orbital floor fractures being the most common. The eye removal was a primary procedure in five of fourteen eviscerations, and five of six enucleations. Complications were seen after four (28.6%) eviscerations patients and two (33.3%) enucleations. Postoperative pain was problematic after three (21.4%) eviscerations but no enucleations. Orbital implants were placed during three of the five primary enucleations, with good outcomes in two. One patient however required implant retrieval and wound washout due to a high risk of infection and communication with the intra-cranial space. CONCLUSIONS: Evisceration and enucleation are both viable options in the management of severe ocular trauma in military patients. Evisceration and enucleation have similar complication rates and outcomes, and both have low rates of sympathetic ophthalmia. Primary orbital implants can be at high risk in cases with orbital roof fracture, but can provide good outcomes in select patients.

Mosquitoes are prone to dehydration and respond to this stress through multiple mechanisms, but previous studies have examined very specific responses and fail to provide an encompassing view of the role that dehydration has on mosquito biology. This study examined underlying changes in biology of the northern house mosquito,Culex pipiens, associated with short bouts of dehydration. We show that dehydration increased blood feeding propensity of mosquitoes, which was the result of both enhanced activity and a higher tendency to land on a host. Mosquitoes exposed to dehydrating conditions with access to water or rehydrated individuals experience no water loss and failed to display behavioral changes. RNA-seq and metabolome analyses following dehydration indicated that factors associated with energy metabolism are altered, specifically the breakdown of trehalose to yield glucose, which likely underlies changes in mosquito activity. Suppression of trehalose breakdown by RNA interference reduced phenotypes associated with dehydration. Comparable results were noted for two other mosquito species, suggesting this is a general response among mosquitoes. Lastly, field-based mesocosm studies usingC.pipiensrevealed that dehydrated mosquitoes were more likely to host feed, and disease modeling indicates dehydration bouts may increase transmission of West Nile virus. These results suggest that periods of dehydration prompt mosquitoes to utilize blood feeding as a mechanism to obtain water. This dehydration-induced increase in blood feeding is likely to intensify disease transmission during periods of low water availability.SignificanceDehydration stress has substantial impacts on the biology of terrestrial invertebrates. To date, no studies have elucidated the difference between dehydration exposure and realized water loss in relation to mosquito behavior and physiology. Our experiments show that direct dehydration stress increases mosquito activity and subsequent blood feeding, likely as a mechanism to locate and utilize a bloodmeal for rehydration. These dehydration-induced phenotypes were linked to altered carbohydrate metabolism that acts as a source of energy. This study provides important insight into the impact of mosquito-dehydration dynamics on disease transmission that is likely general among mosquitoes.