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Competition is often cited as a central force that affects the distribution and performance of organisms. Ecological stoichiometry is the balance of elements within animal bodies that can be affected by resource acquisition and processing, as well as by intra‐ or interspecific interactions. Though relatively underexplored for mosquitoes, stoichiometry may provide a wealth of information linking ecological interactions to body nutrient content, and potentially on to pathogen transmission. Detritus, which often varies in nutrient content, forms the base of the food web within the small aquatic habitats occupied by larval mosquitoes, and detrital nutrient content can alter mosquito growth, survival, and population growth. The invasive mosquitoes Aedes albopictus (Diptera: Culicidae) and Aedes aegypti (Diptera: Culicidae) interact as larvae in aquatic systems, often altering their adult populations. Herein, we investigated how different detritus combinations as well as how intra‐ and interspecific densities of Ae. albopictus and Ae. aegypti would affect coexistence; we also measured how nutrient composition (carbon and nitrogen) and stoichiometry (C:N) of adults would vary with those interactions. Ae. albopictus survival, population growth, and stoichiometry were not affected by intra‐ or interspecific competition; nutrient values did vary with detritus ratios. However, Ae. aegypti nutrient content and stoichiometry and survival were negatively affected within the lowest nutrient environments in the presence of Ae. albopictus, but in the highest nutrient environments, both species showed high survival rates and population growth. This is the first study to show that adult mosquito body nutrients can be altered by interspecific interactions, and as nutrient content in adults has been linked to pathogen transmission, it provides a novel role of competition in affecting disease dynamics. [ABSTRACT FROM AUTHOR]

Understanding the environmental effects of chemicals used in pest control on aquatic systems is crucial to ensure the conservation of beneficial non-target organisms. Mosquito larvicides are commonly applied to aquatic habitats; however, their non-target effects are not well understood. Our goal was to determine lethal and behavioral effects of insect growth regulators (IGRs) and surface films (SFs) on predaceous diving beetle adults and larvae, and damselfly and dragonfly nymphs in roadside ditch habitats. Behavioral effects were determined via bioassays quantifying predator movement, location, and larval mosquito predation. Using Principal Components Analyses, correlated behaviors were determined for each taxa, and compared within SF and IGR treatment levels. Surface films were lethal to beetle adults in the genus Laccophilus (Dytiscidae) at recommended and high concentrations. Laccophilus adult behavior changed in response to IGRs, those exposed to recommended and high concentrations were more active than controls. Larval Laccophilus mosquito consumption varied between SFs and IGRs. We conclude that SFs can harm aquatic organisms that require atmospheric oxygen, and both larvicides may have sublethal effects on hunting behaviors of aquatic insects. Future studies should focus on different larvicides, and a wider variety of aquatic taxa that interact with mosquito larvae. [ABSTRACT FROM AUTHOR]

Food quality and quantity serve as the basis for cycling of key chemical elements in trophic interactions; yet the role of nutrient stoichiometry in shaping host–pathogen interactions is under appreciated. Most of the emergent mosquito-borne viruses affecting human health are transmitted by mosquitoes that inhabit container systems during their immature stages, where allochthonous input of detritus serves as the basal nutrients. Quantity and type of detritus (animal and plant) were manipulated in microcosms containing newly hatched Aedes aegypti mosquito larvae. Adult mosquitoes derived from these microcosms were allowed to ingest Zika virus-infected blood and then tested for disseminated infection, transmission, and total nutrients (percent carbon, percent nitrogen, ratio of carbon to nitrogen). Treatments lacking high-quality animal (insect) detritus significantly delayed development. Survivorship to adulthood was closely associated with the amount of insect detritus present. Insect detritus was positively correlated with percent nitrogen, which affected Zika virus infection. Disseminated infection and transmission decreased with increasing insect detritus and percent nitrogen. We provide the first definitive evidence linking nutrient stoichiometry to arbovirus infection and transmission in a mosquito using a model system of invasive Ae. aegypti and emergent Zika virus. [ABSTRACT FROM AUTHOR]

1. The preference-performance hypothesis ( PPH) predicts that organisms lacking parental care should oviposit in habitats that optimise offspring performance. Preference-performance relationships were investigated for the Asian tiger mosquito ( Aedes albopictus Skuse) and the southern house mosquito ( Culex quinquefasciatus Say) ( Diptera: Culicidae), two medically important container-breeding species, in response to an organic chemical blend mimicking decaying plant matter. Additionally, the effects of long-term laboratory colonisation of Cx. quinquefasciatus using wild and laboratory strains were evaluated. 2. Oviposition bioassays were conducted by releasing gravid mosquitoes into field enclosures with automobile tires containing low and high concentrations of the chemical blend, and water controls. The offspring were then reared in water collected from the tires in which they were deposited. 3. Aedes albopictus and wild Cx. quinquefasciatus laid more eggs in the chemical blend than water controls but did not differentiate between the low and high concentrations. Conversely, laboratory Cx. quinquefasciatus only preferred the high concentration to the low concentration. No statistical associations between oviposition preference and larval survival were found, as the chemical blend did not affect survivorship of either species. 4. The oviposition preference for the chemical blend over water controls suggests that both species oviposit in the best available resource environment, but further studies are needed before conclusions regarding preference-performance relationships can be drawn. 5. It was found that long-term laboratory colonisation affects the oviposition behaviour in Cx. quinquefasciatus, suggesting that behavioural studies on laboratory strains are not always applicable to wild populations. [ABSTRACT FROM AUTHOR]

Allocation patterns of carbon and nitrogen in animals are influenced by food quality and quantity, as well as by inherent metabolic and physiological constraints within organisms. Whole body stoichiometry also may vary between the sexes who differ in development rates and reproductive allocation patterns. In aquatic containers, such as tree holes and tires, detrital inputs, which vary in amounts of carbon and nitrogen, form the basis of the mosquito-dominated food web. Differences in development times and mass between male and female mosquitoes may be the result of different reproductive constraints, which could also influence patterns of nutrient allocation. We examined development time, survival, and adult mass for males and females of three co-occurring species, Aedes albopictus, Ae. aegypti, and Culex quinquefasciatus, across environments with different ratios of animal and leaf detritus. We quantified the contribution of detritus to biomass using stable isotope analysis and measured tissue carbon and nitrogen concentrations among species and between the sexes. Development times were shorter and adults were heavier for Aedes in animal versus leaf-only environments, whereas Culex development times were invariant across detritus types. Aedes displayed similar survival across detritus types whereas C. quinquefasciatus showed decreased survival with increasing leaf detritus. All species had lower values of 15N and 13C in leaf-only detritus compared to animal, however, Aedes generally had lower tissue nitrogen compared to C. quinquefasciatus. There were no differences in the C:N ratio between male and female Aedes, however, Aedes were different than C. quinquefasciatus adults, with male C. quinquefasciatus significantly higher than females. Culex quinquefasciatus was homeostatic across detrital environments. These results allow us to hypothesize an underlying stoichiometric explanation for the variation in performance of different container species under similar detrital environments, and if supported may assist in explaining the production of vector populations in nature. [ABSTRACT FROM AUTHOR]

1. Detritus that forms the basis for mosquito production in tree hole ecosystems can vary in type and timing of input. We investigated the contributions of plant- and animal-derived detritus to the biomass of Aedes triseriatus (Say) pupae and adults by using stable isotope (15N and 13C) techniques in laboratory experiments and field collections. 2. Laboratory-reared mosquito isotope values reflected their detrital resource base, providing a clear distinction between mosquitoes reared on plant or animal detritus. 3. Isotope values from field-collected pupae were intermediate between what would be expected if a single (either plant or animal) detrital source dominated the resource base. However, mosquito isotope values clustered most closely with plant-derived values, and a mixed feeding model analysis indicated tree floral parts contributed approximately 80% of mosquito biomass. The mixed model also indicated that animal detritus contributed approximately 30% of mosquito tissue nitrogen. 4. Pupae collected later in the season generally had isotope values that were consistent with an increased contribution from animal detritus, suggesting that this resource became more nutritionally important for mosquitoes as plant inputs declined over the summer. [ABSTRACT FROM AUTHOR]

1. Investigations of competitive interactions emphasize non-detrital resources, even though detritus is a major component of most food webs. Studies of competing species focus usually on single resource types, although consumers in nature are likely to encounter mixtures of resource types that may affect whether competition results in exclusion or coexistence. 2. The invasive mosquito Aedes albopictus is capable of excluding the native mosquito Ochlerotatus triseriatus in competition for single detritus types in laboratory and field microcosms. In this study, we used nine ratios of two detritus types (animal and leaf) common in natural containers to test whether detritus ratios affect the outcome of competition. 3. Under intraspecific and interspecific competition, A. albopictus attained higher survival and estimated population growth rate than did O. triseriatus. Unlike past studies, both species had positive growth and high adult survival, with little evidence of competitive effects, under one resource ratio (10 : 1 ratio of leaf : animal detritus) regardless of mosquito densities, suggesting potential coexistence. 4. Path analysis showed that densities of larvae had negative effects on population growth for O. triseriatus but not for A. albopictus, indicating competitive superiority of A. albopictus. Population growth of both species was affected strongly by the direct paths from animal (positive) and leaf (negative) detritus, and the indirect effect of leaf detritus via bacterial production (positive). 5. Field sampling established that detritus entered real tree holes in ratios similar to those in our experiment, suggesting that natural variation in detritus ratios may influence local coexistence of these species. Seasonal variation in ratios of plant and animal detritus indicated that temporal as well as spatial variation in inputs may be important for potential coexistence. [ABSTRACT FROM AUTHOR]

Distributions of mosquito larvae likely are a consequence of multiple factors, although two commonly studied factors (quality of the larval environment and the terrestrial matrix in which these habitats reside) have rarely and simultaneously been varied in the field to understand distributions of larvae. We monitored aquatic containers of two leaf detritus levels within a forest, prairie, and industrial habitat across five months to understand the temporal and spatial colonization of aquatic invertebrates in Northcentral Illinois, USA. Data were collected monthly on mosquito populations and the composition of other invertebrates colonizing containers. Overall, six species of mosquitoes colonized containers, with Culex restuans and Aedes triseriatus having the highest relative abundances. There were strong seasonal abundance patterns for these two mosquito species, with the dominant species changing over time in the forest habitat. The responses of other mosquito taxa were more variable, with abundances reflective of either the terrestrial matrix or larval habitat quality. High detritus containers supported the highest abundances of most species encountered, regardless of habitat. Non-mosquito taxa were less common numerically, but analyses suggested that some taxa, such as syrphid larvae, often co-occurred with mosquitoes. Nested subset analysis indicated communities were strongly nested, and that both habitat type and detritus level were important in explaining nested patterns of aquatic invertebrates. Our data show that both the larval habitat and the surrounding terrestrial matrix shape patterns of container mosquitoes, and that other container invertebrates vary in similar ways as mosquitoes. [ABSTRACT FROM AUTHOR]

1. Variation in detritus quality and quantity can have significant effects on aquatic invertebrate food webs. Allochthonous inputs of detritus are the principal energy source for organisms in aquatic tree hole microsystems. We compared the effects of two major detritus types found in tree holes, senescent leaves (Sugar Maple and White Oak) and invertebrate carcasses (dead adult fruit flies and crickets), on several water quality characteristics of laboratory microcosms as well as on mass, survival and population performance of the dominant tree hole consumer, Ochlerotatus triseriatus (Diptera: Culicidae). To date, no study has documented the effects of animal detritus in tree hole microsystems or on resident consumers. 2. Aquatic environments receiving invertebrate carcasses had significantly greater total nitrogen, total reactive phosphorus and higher pH, than leaf-based environments. Decay rate of invertebrate carcasses was greater compared to leaf material. Consumption of O2 by micro-organisms increased with increasing detritus amounts, but we detected no difference between detritus types. 3. Ochlerotatus triseriatus larvae grew faster in animal-based treatments, and mean mass of larvae was significantly greater when more animal detritus was used. The effect of animal-based treatments on larvae translated into higher performance for adults, which were three times heavier than counterparts from plant-based containers. Survivorship and estimated population growth rates were significantly greater for O. triseriatus reared on animal-based versus plant-based detritus. 4. We hypothesise two mechanisms for the pronounced effect of invertebrate carcasses on mosquito performance relative to that associated with leaf detritus: (i) invertebrate carcasses decompose more quickly and release nutrients more effectively into the aquatic environment; or (ii) O. triseriatus larvae may directly ingest nutrient-rich components of invertebrate carcasses. Because even relatively small animal detritus additions can have strong effects on O. triseriatus populations, studies need to be conducted to explore the overall role of animal detritus in tree holes in nature. [ABSTRACT FROM AUTHOR]

Aedes albopictus has replaced Aedes aegypti in much of the latter species' historic range within the United States. The leading hypothesis for this displacement is exclusion via resource competition; however, the proximate mechanism producing a competitive advantage for A. albopictus over A. aegypti has not been identified. We performed laboratory experiments to test the hypotheses that these species differ in feeding behavior, and that these differences result in differences in survival when resources are scarce. Differences in feeding behavior were assessed in three environments with food (growing microorganisms) available: 1) in fluid only; 2) on leaf surfaces only; 3) or both in fluid and on leaf surfaces. We determined behavior of larvae in these environments, recording their positions (bottom, wall, leaf, top, or middle) and activities (browsing, filtering, resting, or thrashing) using instantaneous scan censuses. A. albopictus spent significantly more time at leaf surfaces, whereas A. aegtdpti spent more time engaging in nonfeeding activities. Both species showed a significant shift in foraging activity toward leaves when leaves were available. In a second experiment, we recorded survivorship for individuals raised in two treatment combinations: whole or half 17-mm disks of live oak leaves, with or without direct access to the leaf surface (controlled using nylon mesh, which allowed movement of microscopic organisms, but prevented mosquito larva movement between container sides). After 31 d, survivorship of A. albopictus was significantly greater than that of A. aegypti regardless of treatments. Moreover, A. albopictus showed significantly greater survivorship compared with A. aegypti when deprived of access to leaf surfaces and in whole leaf disk treatments, suggesting superior resource-harvesting ability for A. albopictus. Our experiments suggest that differences in foraging behavior contribute to the competitive advantage of A. albopictus over... [ABSTRACT FROM AUTHOR]

Simple Summary: Understanding the biodiversity of urban ecosystems is critical for management of invasive and pest species, conserving native species, and disease control. Mosquitoes (Culicidae) are ubiquitous and abundant in urban ecosystems, and rely on blood meals taken from vertebrates. We used DNA from freshly blood-fed mosquitoes to characterize the diversity of vertebrate host species in the San Juan Metropolitan Area, Puerto Rico. We collected two mosquito species that fed on a variety of vertebrates. Culex quinquefasciatus fed on 17 avian taxa (81.2% of blood meals), seven mammalian taxa (17.9%), and one reptilian taxon (0.85%). Aedes aegypti blood meals were from a less diverse group, with two avian taxa (11.1%) and three mammalian taxa (88.9%) identified. Domestic chickens dominated the blood meals of Cx. quinquefasciatus, both temporally and spatially, and no statistically significant shift from birds to mammals was detected. The species we detected from the mosquito blood meals provided a snapshot of the vertebrate community in the San Juan Metropolitan Area, most of which were domestic species. However, we also identified a variety of native and nonnative wild species. These results add knowledge about potential ecological factors that impact vector-borne disease management in urban habitats. Urban ecosystems are a patchwork of habitats that host a broad diversity of animal species. Insects comprise a large portion of urban biodiversity which includes many pest species, including those that transmit pathogens. Mosquitoes (Diptera: Culicidae) inhabit urban environments and rely on sympatric vertebrate species to complete their life cycles, and in this process transmit pathogens to animals and humans. Given that mosquitoes feed upon vertebrates, they can also act as efficient samplers that facilitate detection of vertebrate species that utilize urban ecosystems. In this study, we analyzed DNA extracted from mosquito blood meals collected temporally in multiple neighborhoods of the San Juan Metropolitan Area, Puerto Rico to evaluate the presence of vertebrate fauna. DNA was collected from 604 individual mosquitoes that represented two common urban species, Culex quinquefasciatus (n = 586) and Aedes aegypti (n = 18). Culex quinquefasciatus fed on 17 avian taxa (81.2% of blood meals), seven mammalian taxa (17.9%), and one reptilian taxon (0.85%). Domestic chickens dominated these blood meals both temporally and spatially, and no statistically significant shift from birds to mammals was detected. Aedes aegypti blood meals were from a less diverse group, with two avian taxa (11.1%) and three mammalian taxa (88.9%) identified. The blood meals we identified provided a snapshot of the vertebrate community in the San Juan Metropolitan Area and have potential implications for vector-borne pathogen transmission. [ABSTRACT FROM AUTHOR]