The Prediapause Stage of Aedes japonicus japonicus and the Evolution of Embryonic Diapause in Aedini.

Jake Bova,John Soghigian,Sally Paulson

doi:10.3390/insects10080222

Jake Bova, John Soghigian + Show 1 more

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https://doi.org/10.3390/insects10080222

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Abstract

The genus Aedes is well known for its desiccation-resistant eggs, which frequently serve as an overwintering mechanism through diapause. Despite this, relatively little is known about the diapause and overwintering biology of most Aedes species including Aedes japonicus japonicus, an invasive mosquito in the United States. The importance of this mosquito in disease systems like La Crosse virus remain uncertain. Embryonic diapause is used by Ae. j. japonicus to survive temperate winters, and the persistence of this species in the Appalachian region is a result of overwintering, which has important implications for the transmission of this virus to humans. The objective of this study was to identify the prediapause stage, or the stage sensitive to environmental cues needed to induce diapause in this mosquito. By exposing each Ae. j. japonicus life stage independently to short-day photoperiods, we determined that the adult maternal life stage is the prediapause stage. Using the most recent phylogeny and prior literature on the prediapause stages in the genus Aedes, we were able to infer the evolutionary history of the prediapause stages of Aedes mosquitoes that overwinter or aestivate as eggs. This initial ancestral state reconstruction allowed us to hypothesize that Aedini mosquitoes that undergo obligate diapause may have evolved from those utilizing the embryonic prediapause stage, and that the ancestral prediapause state of Aedini appears to be maternally controlled.

Highlights

Many mosquitoes are faced with adverse weather conditions due to their geographic range, and a major survival strategy is to enter into a hibernal diapause to shield themselves from low temperature extremes
This initial ancestral state reconstruction allowed us to hypothesize that Aedini mosquitoes that undergo obligate diapause may have evolved from those utilizing the embryonic prediapause stage, and that the ancestral prediapause state of Aedini appears to be maternally controlled
Most temperate Aedes mosquitoes, as well as those within the tribe they belong to, the Aedini, overwinter as the pharate first instar within their egg, but the life-cycle stage that is sensitive to environmental cues that induce diapause, referred to as the prediapause stage, can differ between Aedes species

Summary

Introduction

Many mosquitoes are faced with adverse weather conditions due to their geographic range, and a major survival strategy is to enter into a hibernal diapause to shield themselves from low temperature extremes. Multivoltine, temperate mosquitoes utilize a facultative diapause usually driven by shorter photoperiods and temperature. Most temperate Aedes mosquitoes, as well as those within the tribe they belong to, the Aedini, overwinter as the pharate first instar within their egg, but the life-cycle stage that is sensitive to environmental cues that induce diapause, referred to as the prediapause stage, can differ between Aedes species. Either the developing embryo or maternal generation is sensitive to light and temperature to induce embryonic diapause (Figure 1) [1,2,3]. 22of environmental cues needed to enter diapause either in the Fn generation or Fn+1 generation.

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