Wolbachia Infections in Aedes aegypti Differ Markedly in Their Response to Cyclical Heat Stress

Perran A Ross,Itsanun Wiwatanaratanabutr,Jason K Axford,Vanessa L White,Ary A Hoffmann,Nancy M Endersby-Harshman,Elizabeth Ann Mcgraw

doi:10.1371/journal.ppat.1006006

Perran A Ross, Itsanun Wiwatanaratanabutr + Show 5 more

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https://doi.org/10.1371/journal.ppat.1006006

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Abstract

Aedes aegypti mosquitoes infected with Wolbachia bacteria are currently being released for arbovirus suppression around the world. Their potential to invade populations and persist will depend on interactions with environmental conditions, particularly as larvae are often exposed to fluctuating and extreme temperatures in the field. We reared Ae. aegypti larvae infected with different types of Wolbachia (wMel, wAlbB and wMelPop-CLA) under diurnal cyclical temperatures. Rearing wMel and wMelPop-CLA-infected larvae at 26–37°C reduced the expression of cytoplasmic incompatibility, a reproductive manipulation induced by Wolbachia. We also observed a sharp reduction in the density of Wolbachia in adults. Furthermore, the wMel and wMelPop-CLA infections were not transmitted to the next generation when mosquitoes were exposed to 26–37°C across all life stages. In contrast, the wAlbB infection was maintained at a high density, exhibited complete cytoplasmic incompatibility, and was transmitted from mother to offspring with a high fidelity under this temperature cycle. These findings have implications for the potential success of Wolbachia interventions across different environments and highlight the importance of temperature control in rearing.

Highlights

Aedes aegypti mosquitoes transmit some of the most important arboviral diseases worldwide
We show for the first time that cyclical temperatures reaching a maximum of 37 ̊C during development reduce the expression of cytoplasmic incompatibility in the wMel and wMelPop-CLA infections of Ae. aegypti
We hypothesized that reduced hatch rate in wMel-infected mosquitoes could reflect the loss of Wolbachia infection under heat stress, leading to partial cytoplasmic incompatibility

Summary

Introduction

Aedes aegypti mosquitoes transmit some of the most important arboviral diseases worldwide. They are widespread in tropical and subtropical regions [1], inhabiting urban environments where they have adapted to breed in artificial containers [2]. Dengue and Zika are among the viruses they transmit and these are rapidly increasing their burden on global health. Dengue alone infects as many as 390 million people each year, and up to half of the world’s population is at risk of infection [1]. Efforts to reduce the spread of dengue and Zika rely on the direct control of Ae. aegypti populations. Though permanent mosquito eradication is unlikely to be achieved, several genetic and biological approaches are being utilized to reduce the burden of arboviruses [7]

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