Attracted to the enemy: Aedes aegypti prefers oviposition sites with predator-killed conspecifics

Abstract

Oviposition habitat choices of species with aquatic larvae is expected to be influenced by both offspring risk of mortality due to predation, and offspring growth potential. Aquatic predators may indirectly influence growth potential for prey by reducing prey density and, for filter feeding prey, by increasing bacterial food for prey via added organic matter (feces, partially eaten victims), creating the potential for interactive effects on oviposition choices. We tested the hypothesis that the mosquito Aedes aegypti preferentially oviposit in habitats with predatory Toxorhynchites larvae because of indirect effects of predation on chemical cues indicating bacterial abundance. We predicted that A. aegypti would avoid oviposition in sites with Toxorhynchites, but prefer to oviposit where bacterial food for larvae is abundant, and that predation by Toxorhynchites would increase bacterial abundances. Gravid A. aegypti were offered paired oviposition sites representing choices among: predator presence; the act of predation; conspecific density; dead conspecific larvae; and bacterial activity. Aedes aegypti preferentially oviposited in sites with T. theobaldi predation, and with killed conspecific larvae, but failed to detect preferences for other treatments. The antibiotic Tetracycline eliminated the strongest oviposition preference. Both predation by Toxorhynchites and killed larvae increased bacterial abundances, suggesting that oviposition attraction is cued by bacteria. Our results show the potential for indirect effects, like trophic cascades, to influence oviposition choices and community composition in aquatic systems. Our results suggest that predators like Toxorhynchites may be doubly beneficial as biocontrol agents because of the attraction of ovipositing mosquitoes to bacterial by-products of Toxorhynchites feeding.

Contributions of temporal segregation, oviposition choice, and non-additive effects of competitors to invasion success of Aedes japonicus (Diptera: Culicidae) in North America

“…In contrast, Culex adults, including invasive Culex pipiens (L), are highly sensitive to conditions within aquatic environments, often avoiding oviposition sites with predators (Vonesh and Blaustein 2010). The worldwide invaders Aedes aegypti (L.) and A. albopictus (Skuse) exhibit less discriminating oviposition behavior toward aquatic predators (Juliano et al 2010; Vonesh and Blaustein 2010; Albeny-Simões et al 2014), but density of intra-or inter-specific competitors can affect oviposition choice by these invasive Aedes (Zahiri and Rau 1998; Allan and Kline 1998; Yoshioka et al 2012). These effects are context dependent, ranging from preference to avoidance of potential competitors, and may depend primarily on microbial abundances and only indirectly on density of larvae (Fader and Juliano 2014).…”

A multifaceted trophic cascade in a detritus‐based system: density‐, trait‐, or processing‐chain‐mediated effects?

“…The assay been used to quantify bacterial productivity in container mosquito experiments (e.g., Yee et al 2007a, Albeny-Simões et al 2014). We measured water column protein synthesis following Kirchman (1993) and refined by Kaufman et al (2001) for container systems.…”

Efficiency of the Induced Mating Technique for Toxorhynchites Theobaldi (Diptera, Culicidae)

“…This procedure has been critical for the production of a successful multi-year T. theobaldi colony in Brazil, and has lead to new and exciting research involving chemical and behavioral ecology (Albeny-Simões et al, 2014) and morphology (Pascini et al, 2011). Our goal in publishing this induced-mating methodology is to provide a template for colony establishment and successful mass rearing (i.e., for biological control) of Toxorhynchites species in Brazil and beyond, ultimately facilitating increased research involving this broadly important mosquito genus.…”