For organisms with complex life cycles, larval environments can modify adult phenotypes. For mosquitoes and other vectors, when physiological impacts of stressors acting on larvae carry over into the adult stage they may interact with infectious dose of a vector-borne pathogen, producing a range of phenotypes for vector potential. Investigation of impacts of a common source of stress, larval crowding and intraspecific competition, on adult vector interactions with pathogens may increase our understanding of the dynamics of pathogen transmission by mosquito vectors. Using Aedes aegypti and the nematode parasite Brugia pahangi, we demonstrate dose dependency of fitness effects of B. pahangi infection on the mosquito, as well as interactions between competitive stress among larvae and infectious dose for resulting adults that affect the physiological and functional ability of mosquitoes to act as vectors. Contrary to results from studies on mosquito-arbovirus interactions, our results suggest that adults from crowded larvae may limit infection better than do adults from uncrowded controls, and that mosquitoes from high-quality larval environments are more physiologically and functionally capable vectors of B. pahangi. Our results provide another example of how the larval environment can have profound effects on vector potential of resulting adults.

1. Prey organisms can perceive cues to predation hazard and adopt low‐risk behaviours to increase survival. Animals with complex life cycles, such as insects, can exhibit such anti‐predatory behaviours in multiple life stages.2. Cues to predation risk may induce ovipositing females to choose habitats with low predation risk. Cues to predation risk may also induce larvae to adopt facultative behaviours that reduce risk of predation.3. One hypothesis postulates that anti‐predation behaviours across adult and larval stages may be negatively associated because selection for effective anti‐predator behaviour in one stage leads to reduced selection for avoidance of predators in other stages. An alternative hypothesis suggests that selection by predation favours multi‐component defences, with both avoidance of oviposition and facultative adoption of low‐risk behaviours by larvae.4. Laboratory and field experiments were used to determine whether defensive responses of adult and larval mosquitoes are positively or negatively associated. The study tested effects of waterborne cues from predatory Toxorhynchites theobaldi on oviposition choices and larval behaviours of three of its common prey: Culex mollis, Limatus durhamii and Aedes albopictus.5. Culex mollis shows strong anti‐predator responses in both life stages, consistent with the hypothesis of a multi‐component behavioural defence. The other two species showed no detectable responses to waterborne predator cues in either adult or larval stages. Larvae of these unresponsive species were significantly more vulnerable to this predator than was C. mollis.6. For these mosquitoes, species appear either to have been selected for multi‐component defences against predation or to act in ways that could be called predator‐naïve.

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For insects, choosing a favorable oviposition site is a type of parental care, as far as it increases the fitness of its offspring. Niche theory predicts that crickets should show a bell-shaped oviposition response to substrate moisture. However, lab experiments with mole crickets showed a linear oviposition response to substrate moisture. Studies with the house cricket Acheta domesticus also showed a linear juvenile body growth response to water availability, thus adult ovipositing females should respond positively to substrate moisture. We used a field experiment to evaluate the relationship between oviposition preference and substrate moisture in forest litter-dwelling cricket species. We also evaluated oviposition responses to substrate moisture level in Ubiquepuella telytokous, the most abundant litter cricket species in our study area, using a laboratory study. We offered cotton substrate for oviposition which varied in substrate moisture level from zero (i.e., dry) to maximum water absorption capacity. We used two complementary metrics to evaluate oviposition preference: (i) presence or absence of eggs in each sampling unit as binary response variable, and (ii) number of eggs oviposited per sampling unit as count response variable. To test for non-linear responses, we adjusted generalized additive models (GAMM) with mixed effects. We found that both cricket oviposition probability and effort (i.e., number of eggs laid) increased linearly with substrate moisture in the field experiment, and for U. telytokous in the lab experiment. We discarded any non-linear responses. Our results demonstrate the importance of substrate moisture as an ecological niche dimension for litter crickets. This work bolsters knowledge of litter cricket life history association with moisture, and suggests that litter crickets may be particularly threatened by changes in climate that favor habitat drying.

The establishment of an invasive species depends on reproductive success and dispersion capability in the new environment. One of the striking examples of invasion in urban environments is the mosquito Aedes aegypti Linnaeus, 1762 (Culicidae). The success of this species is primarily attributed to its ability to colonize urban environments, and some of the important adaptive strategies associated with this ability is the preference for humans as a blood source and intense occupation of residential (indoor) environments. This study evaluated the effects of location (indoor vs. outdoor) and water nutrient level (% organic matter) on the oviposition preference of A. aegypti in an urban environment. We used oviposition choice experiments to evaluate mosquito oviposition in containers holding 1:1 vs 1:0 ratios of water: organic matter placed indoors and outdoors. Eggs were sampled once per week for nine weeks. Our results revealed a strong oviposition preference for outdoor containers, with a significant preference for containers with higher concentrations of organic matter during the fifth to ninth weeks. However, mosquitoes occupying indoor environments did not prefer to lay eggs in containers with lower levels of organic matter. A better understanding of the preferences of A. aegypti regarding the nutrient level and location of oviposition containers can increase our understanding of the behavioral factors allowing mosquitoes to utilize anthropogenic environments.

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Metacommunity theory is a convenient framework in which to investigate how local communities linked by dispersal influence patterns of species distribution and abundance across large spatial scales. For organisms with complex life cycles, such as mosquitoes, different pressures are expected to act on communities due to behavioral and ecological partitioning of life stages. Adult females select habitats for oviposition, and resulting offspring are confined to that habitat until reaching adult stages capable of flight; outside-container effects (OCE) (i.e., spatial factors) are thus expected to act more strongly on species distributions as a function of adult dispersal capability, which should be limited by geographic distances between sites. However, larval community dynamics within a habitat are influenced by inside-container effects (ICE), mainly interactions with conspecifics and heterospecifics (e.g., through effects of competition and predation). We used a field experiment in a mainlandisland scenario to assess whether environmental, spatial, and temporal factors influence mosquito prey and predator distributions and abundances across spatial scales: within-site, between-site, and mainland-island. We also evaluated whether predator abundances inside containers play a stronger role in shaping mosquito prey community structure than do OCE (e.g., spatial and environmental factors). Temporal influence was more important for predators than for prey mosquito community structure, and the changes in prey mosquito species composition over time appear to be driven by changes in predator abundances. There was a negligible effect of spatial and environmental factors on mosquito community structure, and temporal effects on mosquito abundances and distributions appear to be driven by changes in abundance of the dominant predator, perhaps because ICE are stronger than OCE due to larval habitat restriction, or because adult dispersal is not limited at the chosen spatial scales.