How Do Trait-Mediated Non-lethal Effects of Predation Affect Population-Level Performance of Mosquitoes?

Non-lethal, trait-mediated effects of predation impact prey behavior and life-history traits. Studying how these effects in turn influence prey demography is crucial to understand prey life-history evolution. Mosquitoes are important vectors that claim several million lives every year worldwide by transmitting a range of pathogens. Several ecological factors affect life-history traits of both larval and adult mosquitoes, creating effects that cascade to population-level consequences. Few studies have comprehensively explored the non-lethal effects of predation and its interactions with resources and competition on larval, adult, and population traits of mosquitoes. Understanding these interactions is important because the effects of predation are hypothesized to rescue prey populations from the effects of density-dependence resulting from larval competition. Aedes aegypti larvae reared at two different larval densities and subjected to three non-lethal predator treatments were monitored for survival, development time, and adult size through the larval stages to adult eclosion, and adult females were monitored for survival and reproduction through their first gonotrophic cycle. Intraspecific competition increased larval development time, yielded small-bodied adults, and reduced fecundity in individuals exposed to predatory chemical cues as larvae. Exposure to cues from a living predator affected both body size and latency to blood feed in females. Analysis of life-table traits revealed significant effects of competition on net reproductive rate (R0) of mosquitoes. The interaction between competition and predator treatments significantly affected the cohort rate of increase (r) and the index of performance (r’). The index of performance, which estimates rate of population change based on the size-fecundity relationship, was significantly and positively correlated with r, but overestimated r slightly. Lack of significant effect of predator treatments and larval density on cohort generation time (Tc) further suggests that the observed effects of treatments on r and r’ were largely a consequence of the effects on R0. Also, the significant effects of treatment combinations on larval development time, adult body size and fecundity were ultimately manifested as effects on life-table traits estimated from adult survival and reproduction

Zinc finger nucleases: custom-designed molecular scissors for genome engineering of plant and mammalian cells

Custom-designed zinc finger nucleases (ZFNs), proteins designed to cut at specific DNA sequences, are becoming powerful tools in gene targeting—the process of replacing a gene within a genome by homologous recombination (HR). ZFNs that combine the non-specific cleavage domain (N) of FokI endonuclease with zinc finger proteins (ZFPs) offer a general way to deliver a site-specific double-strand break (DSB) to the genome. The development of ZFN-mediated gene targeting provides molecular biologists with the ability to site-specifically and permanently modify plant and mammalian genomes including the human genome via homology-directed repair of a targeted genomic DSB. The creation of designer ZFNs that cleave DNA at a pre-determined site depends on the reliable creation of ZFPs that can specifically recognize the chosen target site within a genome. The (Cys(2)His(2)) ZFPs offer the best framework for developing custom ZFN molecules with new sequence-specificities. Here, we explore the different approaches for generating the desired custom ZFNs with high sequence-specificity and affinity. We also discuss the potential of ZFN-mediated gene targeting for ‘directed mutagenesis’ and targeted ‘gene editing’ of the plant and mammalian genome as well as the potential of ZFN-based strategies as a form of gene therapy for human therapeutics in the future

How Do Trait-Mediated Non-lethal Effects of Predation Affect Population-Level Performance of Mosquitoes?

Non-lethal, trait-mediated effects of predation impact prey behavior and life-history traits. Studying how these effects in turn influence prey demography is crucial to understand prey life-history evolution. Mosquitoes are important vectors that claim several million lives every year worldwide by transmitting a range of pathogens. Several ecological factors affect life-history traits of both larval and adult mosquitoes, creating effects that cascade to population-level consequences. Few studies have comprehensively explored the non-lethal effects of predation and its interactions with resources and competition on larval, adult, and population traits of mosquitoes. Understanding these interactions is important because the effects of predation are hypothesized to rescue prey populations from the effects of density-dependence resulting from larval competition. Aedes aegypti larvae reared at two different larval densities and subjected to three non-lethal predator treatments were monitored for survival, development time, and adult size through the larval stages to adult eclosion, and adult females were monitored for survival and reproduction through their first gonotrophic cycle. Intraspecific competition increased larval development time, yielded small-bodied adults, and reduced fecundity in individuals exposed to predatory chemical cues as larvae. Exposure to cues from a living predator affected both body size and latency to blood feed in females. Analysis of life-table traits revealed significant effects of competition on net reproductive rate (R-0) of mosquitoes. The interaction between competition and predator treatments significantly affected the cohort rate of increase (r) and the index of performance (r'). The index of performance, which estimates rate of population change based on the size-fecundity relationship, was significantly and positively correlated with r, but overestimated r slightly. Lack of significant effect of predator treatments and larval density on cohort generation time (T-c) further suggests that the observed effects of treatments on r and r' were largely a consequence of the effects on R-0. Also, the significant effects of treatment combinations on larval development time, adult body size and fecundity were ultimately manifested as effects on life-table traits estimated from adult survival and reproduction

Data from: Playing it safe? behavioural responses of mosquito larvae encountering a fish predator

Predation is a strong selective force that affects prey population and ecosystem dynamics. Detecting predators and associated levels of threat is crucial to prey responses. Once a predator is detected, anti-predatory responses improve the chances of survival of prey. We used Aedes aegypti larvae to study behavioural responses to predation threat from guppies (Poecilia reticulata). Specifically, we tested the relative importance of chemical cues, both in isolation and in combination with physical cues, in eliciting anti-predatory behaviours. Larvae responded more strongly, by reducing the lengths of their wriggle bursts, when presented with a combination of chemical and physical cues than with chemical cues alone. Anti-predatory responses often come with an associated cost, and we expect that the ability to pay these costs should influence responses to predation risk. To test this, we compared wriggling patterns of satiated vs starved larvae in the same experiment. We found that, under predation risk, starved larvae were willing to take more risks than satiated larvae were. We sought to experimentally test the assumption that anti-predator behaviours increase the survival of prey. To do this, starved guppies were made to choose between displays of simulated larvae, moving in short and long wriggle bursts as observed in the previous experiment. The fish preferentially attacked larvae moving in long bursts, demonstrating the survival value of the larval anti-predatory response of shifting to a preponderance of short wriggle bursts.Our study identifies specific ways in which trade-offs between predation risk and energetic costs could affect anti-predator behaviour

Context-dependent interactive effects of non-lethal predation on larvae impact adult longevity and body composition

Predation impacts development, behavior and morphology of prey species thereby shaping their abundances, distribution and community structure. Non-lethal threat of predation, specifically, can have a strong influence on prey lifehistory characteristics. While investigations often focus on the impact of predation threat on prey in isolation, tests of its interactive effects with food availability and resource competition on prey survival and fitness can improve understanding of costs, benefits and trade-offs of anti-predator strategies. This study, involving Aedes aegypti mosquitoes as a model organism, investigates both simple and interactive effects of predation threat during the larval stage on survival, size at and time to maturity, stored teneral reserves of glycogen, protein and lipid in adults, and adult longevity. Our results show that development times of mosquito larvae were increased (by 14.84% in males and by 97.63% in females), and size of eclosing adults decreased (by 62.30% in males and by 58.33% in females) when exposed to lowered nutrition and elevated intraspecific competition, but that predation had no detectable effect on these simple traits. Teneral reserves of glycogen, protein and lipid and adult longevity were positively correlated with adult body size. Non-lethal predation threat had significant interactive effects with nutrition and larval competition on teneral reserves in males and adult longevity in males and females. The sexes responded differently to conditions encountered as larvae, with the larval environment affecting development and adult characteristics more acutely for females than for males. The outcome of this study shows how threat of predation on juveniles can have long-lasting effects on adults that are likely to impact mosquito population dynamics and that may impact disease transmission

R code - TEEE 1313785

R code for visualisation and analysis of dat

Raw data for experiment II: Predator responses to altered larval behaviour

This .csv file contains data on preference shown by fish to spot digital mosquito larvae simulated to wriggle in short and long bursts of wriggles

Raw data for experiment I: Larval behaviour

This .csv file contains data on larval wriggle count, wriggle burst length, surface visit frequency and time spent at the water surface

Survival analysis.

<p>Survival analysis.</p

Species-specificity in thermopreference and CO2-gated heat-seeking in culex mosquitoes

Combining thermopreference (Tp) and CO2 -gated heat-seeking assays, we studied the thermal preferendum and response to thermal cues in three Culex mosquito species exhibiting differences in native habitat and host preference (e.g., biting cold and/or warm-blooded animals). Results show that these species differ in both Tp and heat-seeking behavior. In particular, we found that Culex territans, which feed primarily on cold-blood hosts, did not respond to heat during heat-seeking assays, regardless of the CO2 concentration, but exhibited an intermediate Tp during resting. In contrast, Cx. quinquefasciatus, which feeds on warm blooded hosts, sought the coolest locations on a thermal gradient and responded only moderately to thermal stimuli when paired with CO2 at higher concentrations. The third species, Cx. tarsalis, which has been shown to feed on a wide range of hosts, responded to heat when paired with high CO2 levels and exhibited a high Tp. This study provides the first insights into the role of heat and CO2 in the host seeking behavior of three disease vectors in the Culex genus and highlights differences in preferred resting temperatures.Fil: Reinhold, Joanna M.. Virginia Polytechnic Institute; Estados Unidos. Virginia State University; Estados UnidosFil: Chandrasegaran, Karthikeyan. Virginia Polytechnic Institute; Estados Unidos. Virginia State University; Estados UnidosFil: Oker, Helen. Virginia Polytechnic Institute; Estados Unidos. Virginia State University; Estados UnidosFil: Crespo, José Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Vinauger, Clément. Virginia Polytechnic Institute; Estados Unidos. Virginia State University; Estados UnidosFil: Lahondère, Chloé. Virginia Polytechnic Institute; Estados Unidos. Virginia State University; Estados Unido