Gut bacteria differentially affect egg production in the anautogenous mosquito Aedes aegypti and facultatively autogenous mosquito Aedes atropalpus (Diptera: Culicidae).

Kerri L Coon,Michael R Strand,Mark R Brown

doi:10.1186/s13071-016-1660-9

Abstract

BackgroundAedes aegypti and A. atropalpus are related mosquitoes that differ reproductively. Aedes aegypti must blood-feed to produce eggs (anautogenous) while A. atropalpus always produces a first clutch of eggs without blood-feeding (facultatively autogenous). We recently characterized the gut microbiota of A. aegypti and A. atropalpus that were reared identically in the laboratory. Here, we assessed the effects of specific members of the gut microbiota in A. aegypti and A. atropalpus on female fitness including egg production.MethodsGnotobiotic A. aegypti and A. atropalpus larvae were colonized by specific members of the gut microbiota. Survival, development time, size and egg production for each treatment was then compared to axenic and conventionally reared larvae.ResultsMost species of bacteria we tested supported normal development and egg production by A. aegypti but only one betaproteobacterium, a Comamonas, supported development and egg production by A. atropalpus to equivalent levels as conventionally reared females. Aedes atropalpus females colonized by Comamonas contained similar stores of glycogen and protein as conventionally reared females, whereas females colonized by Aquitalea did not. Small differences in bacterial loads were detected between gnotobiotic and conventionally reared A. aegypti and A. atropalpus, but this variation did not correlate with the beneficial effects of Comamonas in A. atropalpus.ConclusionsSpecific members of the gut microbiota more strongly affected survival, size and egg production by A. atropalpus than A. aegypti.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1660-9) contains supplementary material, which is available to authorized users.

Highlights

Aedes aegypti and A. atropalpus are related mosquitoes that differ reproductively
We focused our assays on representative genera from each of the major bacterial phyla previously identified from the digestive tracts of our laboratory mosquitoes ([21]; Additional file 1: Table S1): Paenibacillus (Firmicutes: Paenibacillaceae), Chryseobacterium (Bacteroidetes: Flavobacteriaceae), Sphingobacterium (Bacteroidetes: Sphingobacteriaceae), Microbacterium (Actinobacteria: Microbacteriaceae), Leucobacter (Actinobacteria: Microbacteriaceae), Aquitalea (Proteobacteria: Neisseriaceae) and Comamonas (Proteobacteria: Comamonadaceae)
Several bacteria support normal egg production in A. aegypti but not A. atropalpus We focused on those species of bacteria that supported development of at least some A. aegypti and A. atropalpus to adulthood by assessing their effects on egg production by females

Summary

Introduction

Aedes aegypti must blood-feed to produce eggs (anautogenous) while A. atropalpus always produces a first clutch of eggs without blood-feeding (facultatively autogenous). We assessed the effects of specific members of the gut microbiota in A. aegypti and A. atropalpus on female fitness including egg production. Repeated cycles of blood-feeding and egg production underlie why several mosquito species have evolved into vectors that transmit pathogens that cause several serious diseases in humans and other animals. Autogenous species emerge as adults and lay a first clutch of eggs without blood-feeding but must blood-feed to produce additional clutches. Regulation of egg formation is best understood in the anautogenous mosquito Aedes aegypti, which vectors several human pathogens including the viruses that cause yellow fever, dengue fever and Zika virus disease. The fat body of newly emerged A. aegypti females becomes competent to produce yolk proteins

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