Dynamics of the “Popcorn” Wolbachia Infection in Outbred Aedes aegypti Informs Prospects for Mosquito Vector Control

Abstract

Forty percent of the world's population is at risk of contracting dengue virus, which produces dengue fever with a potentially fatal hemorrhagic form. The wMelPop Wolbachia infection of Drosophila melanogaster reduces life span and interferes with viral transmission when introduced into the mosquito Aedes aegypti, the primary vector of dengue virus. Wolbachia has been proposed as an agent for preventing transmission of dengue virus. Population invasion by Wolbachia depends on levels of cytoplasmic incompatibility, fitness effects, and maternal transmission. Here we characterized these traits in an outbred genetic background of a potential target population of Ae. aegypti using two crossing schemes. Cytoplasmic incompatibility was strong in this background, and the maternal transmission rate of Wolbachia was high. The infection substantially reduced longevity of infected adult females, regardless of whether adults came from larvae cultured under high or low levels of nutrition or density. The infection reduced the viability of diapausing and nondiapausing eggs. Viability was particularly low when eggs were laid by older females and when diapausing eggs had been stored for a few weeks. The infection affected mosquito larval development time and adult body size under different larval nutrition levels and densities. The results were used to assess the potential for wMelPop-CLA to invade natural populations of Ae. aegypti and to develop recommendations for the maintenance of fitness in infected mosquitoes that need to compete against field insects.

Interaction ofWolbachiaand Bloodmeal Type in Artificially InfectedAedes albopictus(Diptera: Culicidae)

“…This observation is similar to a prior study of the single wMelPop infection (Suh et al 2009) while the life-shortening effect seemed to be relatively reduced comparing to prior studies of wMelPop-CLA (wMelPop cell line adapted) infection in Ae. aegypti (McMeniman et al 2009, Yeap et al 2011. YFU males, in contrast, experienced an increased life span, relative to naturally infected IH males (Fig.…”

“…These observations differ from prior studies in which wMelPop-CLA Wolbachia were observed to reduce embryonic survival in Ae. aegypti (McMeniman et al 2009, Yeap et al 2011. Such differential phenotypic effect could be due to genotypic differences in Wolbachia strains (wMelPop vs. wMelPop-CLA) and different mosquito species, resulting in differential density and tissue tropism of wMelPop in Ae.…”

“…Relative to the wMel Wolbachia type, the wMelPop infections are predicted to strongly reduce pathogen transmission because of a higher degree of pathogen inhibition (Chrostek et al 2013, Ferguson et al 2015. Furthermore, the wMelPop type shows a stronger life-shortening phenotype in adults (McMeniman et al 2009, Suh et al 2009, Yeap et al 2011 and egg stages (i.e., reduced egg longevity; McMeniman and O'Neill 2010, Yeap et al 2011). …”

“…The wMelPop Wolbachia infection has been shown to impose fitness costs on multiple life history traits of host individuals (Moreira et al 2009a;Turley et al 2009;McMeniman and O'Neill 2010;Yeap et al 2011Yeap et al , 2014Suh and Dobson 2013;Ross et al 2014), and theoretical studies suggest the invasion of the Wolbachia infection can be hindered by fitness costs (Hoffmann et al 1990, Crain et al 2011, Yeap et al 2011. Particularly, introduction of wMelPop into aposymbiotic Ae.…”

Larval Competition Extends Developmental Time and Decreases Adult Size of wMelPop Wolbachia-Infected Aedes aegypti

“…aegypti because it proliferates throughout the entire mosquito. 11,12,15 The wMelPop infection reduces adult longevity by as much as 50% and decreases egg viability, fecundity, 10,16,17 and blood feeding success of females. 18 Although the costs of wMelPop infection on adult Ae.…”