Wolbachia transinfections in Culex quinquefasciatus generate cytoplasmic incompatibility.

T H Ant,F Louis,S P Sinkins,C Herd,A B Failloux

doi:10.1111/imb.12604

Abstract

Culex quinquefasciatus is an important mosquito vector of a number of viral and protozoan pathogens of humans and animals, and naturally carries the endosymbiont Wolbachia pipientis, strain wPip. Wolbachia are used in two distinct vector control strategies: firstly, population suppression caused by mating incompatibilities between mass‐released transinfected males and wild females; and secondly, the spread of pathogen transmission‐blocking strains through populations. Using embryonic microinjection, two novel Wolbachia transinfections were generated in C. quinquefasciatus using strains native to the mosquito Aedes albopictus: a wAlbB single infection, and a wPip plus wAlbA superinfection. The wAlbB infection showed full bidirectional cytoplasmic incompatibility (CI) with wild‐type C. quinquefasciatus in reciprocal crosses. The wPipwAlbA superinfection showed complete unidirectional CI, and therefore population invasion potential. Whereas the wAlbB strain showed comparatively low overall densities, similar to the native wPip, the wPipwAlbA superinfection reached over 400‐fold higher densities in the salivary glands compared to the native wPip, suggesting it may be a candidate for pathogen transmission blocking.

Highlights

Culex quinquefasciatus (Say), the southern house mosquito, transmits a number of important human and animal pathogens, including arboviruses such as West Nile (WNV) and Rift Valley Fever (RVFV), and the filarial nematode Wuchereria bancrofti (Sudomo et al 2010)
The two novel Wolbachia transinfections in Cx. quinquefasciatus reported here could potentially contribute to control in two ways: by providing a source of sterile males for population suppression, and through pathogen transmission blocking via population replacement
Females of the wAlbB line were incompatible with wild-type males, a bi-directional cytoplasmic incompatibility (CI) pattern resulting in high invasion thresholds, ideal for a suppression strain

Summary

Introduction

Culex quinquefasciatus (Say), the southern house mosquito, transmits a number of important human and animal pathogens, including arboviruses such as West Nile (WNV) and Rift Valley Fever (RVFV), and the filarial nematode Wuchereria bancrofti (Sudomo et al 2010). It is significant from the perspective of wildlife conservation, since it transmits avian malaria (Plasmodium relictum) and avian pox virus on the Hawaiian Islands, where it has been incriminated in decline of several endangered bird species (van Riper et al 1986). Due to predominantly night-time biting and indoor resting, the distribution of insecticide-treated nets (ITNs) and the use of indoor residual spraying (IRS) for the control of malaria-transmitting Anopheles species has applied concomitant selection on Cx. quinquefasciatus populations, with high levels of insecticide resistance reported in Africa (Jones et al 2012; Norris and Norris 2011; Yadouléton et al 2015) and Asia (Yanola et al 2015)

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