The bacterial endosymbiont Wolbachia is associated with cytoplasmic incompatibility (CI), which shows promise as a mechanism for driving transgenes through mosquito populations. Most current transgenic control strategies involve altering the ability of mosquitoes to transmit pathogens (vector competence). However, due to the linear relationship between vector competence and population vectorial capacity (a measure of the pathogen reproductive rate), transgenic strategies that aim to reduce vector competence are relatively inefficient because traits must have strong effects to result in an epidemiologically meaningful reduction in vectorial capacity. The daily probability of mosquito survival, however, has a positive non-linear relationship with vectorial capacity. Disease control strategies that increase vector mortality are more efficient in reducing vectorial capacity than altering vector competence because relatively small changes in the daily survival rate can result in relatively large changes in the expected number of new infections. A pathogenic Wolbachia strain (popcorn) has been discovered in Drosophila that dramatically reduces host life-span. Successful introduction of a popcorn-like Wolbachia strain into vector populations has the potential to significantly reduce pathogen transmission by elevating vector mortality and altering mosquito population age structure. We developed a life-table simulation model to examine the population dynamics of a Wolbachia strain that affects mosquito survival and the effect of this Wolbachia strain on the ability of the vector population to sustain pathogen transmission. Empirical mortality data or mortality models can be entered into the Wolbachia model, and Wolbachia parameters (transmission efficiency, CI and fecundity) can be varied. Simulations indicate that within certain parameters (transmission ³95%, CI ³90%, fecundity effect £10%) and mortality models, pathogenic Wolbachia can spread to 95-100% in the mosquito population. Pathogenic Wolbachia spread can theoretically result in a 90-100% reduction in population vectorial capacity, depending on parameters and mortality model used.
Species 1: (Wolbachia, popcorn strain)
Keywords: Age-structure, Mathematical model
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA