Reduced competitiveness of Wolbachia infected Aedes aegypti larvae in intra- and inter-specific immature interactions

• We examine effect of Wolbachia on larval competition in A. aegypti.
• We examine effect of Wolbachia on larval behavior in A. aegypti.
• Wolbachia infected A. aegypti larvae experience reduced survival when competing.
• Wolbachia infected A. aegypti larvae react slower than uninfected larvae.

Wolbachia are maternally inherited intracellular bacteria that frequently infect a diverse range of arthropod species. Empirical and theoretical studies examining Wolbachia invasiveness have emphasized Wolbachia effects on adult hosts, but recent studies show that Wolbachia impacts on immature hosts can be important also. Here, we have examined for effects of Wolbachia infection in Aedes aegypti. Specifically, differential survivorship is observed when young larvae (1st instar) are exposed to older Aedes albopictus larvae (4th instar) or con-specific larvae. In an additional experiment, we have examined for differential behavior and observed that Wolbachia-infected larvae differ from uninfected larvae in their reaction to light stimulation. Our results support a hypothesized effect of Wolbachia on A. aegypti larval behavior. The results are discussed in relation to the ability of Wolbachia to invade natural populations and recently applied public health strategies that target the replacement or suppression of this important disease vector.

Reduced survival results when young A. aegypti larvae (first instar, L1) are infected with Wolbachia and compete with older larvae (fourth instar, L4). With both conspecific and heterospecific (A. albopictus) L4, Wolbachia infected L1 A. aegypti survive less than naturally uninfected larvae. However, if the competing L4 A. aegypti are also Wolbachia infected, L1 survival returns to normal. Behavioral assays show that Wolbachia infected A. aegypti larvae are slower in responding to light stimulation relative to uninfected larvae.Figure optionsDownload as PowerPoint slide