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Open Access Research article

Wolbachia infections that reduce immature insect survival: Predicted impacts on population replacement

Philip R Crain1, James W Mains1, Eunho Suh1, Yunxin Huang2, Philip H Crowley2 and Stephen L Dobson1*

Author affiliations

1 Department of Entomology, College of Agriculture, University of Kentucky, Lexington, KY 40546-0091, USA

2 Department of Biology, Center for Ecology, Evolution and Behavior, University of Kentucky, Lexington, KY 40502-0225, USA

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Citation and License

BMC Evolutionary Biology 2011, 11:290  doi:10.1186/1471-2148-11-290

Published: 5 October 2011

Abstract

Background

The evolutionary success of Wolbachia bacteria, infections of which are widespread in invertebrates, is largely attributed to an ability to manipulate host reproduction without imposing substantial fitness costs. Here, we describe a stage-structured model with deterministic immature lifestages and a stochastic adult female lifestage. Simulations were conducted to better understand Wolbachia invasions into uninfected host populations. The model includes conventional Wolbachia parameters (the level of cytoplasmic incompatibility, maternal inheritance, the relative fecundity of infected females, and the initial Wolbachia infection frequency) and a new parameter termed relative larval viability (RLV), which is the survival of infected larvae relative to uninfected larvae.

Results

The results predict the RLV parameter to be the most important determinant for Wolbachia invasion and establishment. Specifically, the fitness of infected immature hosts must be close to equal to that of uninfected hosts before population replacement can occur. Furthermore, minute decreases in RLV inhibit the invasion of Wolbachia despite high levels of cytoplasmic incompatibility, maternal inheritance, and low adult fitness costs.

Conclusions

The model described here takes a novel approach to understanding the spread of Wolbachia through a population with explicit dynamics. By combining a stochastic female adult lifestage and deterministic immature/adult male lifestages, the model predicts that even those Wolbachia infections that cause minor decreases in immature survival are unlikely to invade and spread within the host population. The results are discussed in relation to recent theoretical and empirical studies of natural population replacement events and proposed applied research, which would use Wolbachia as a tool to manipulate insect populations.