Monitoring long-term evolutionary changes followingWolbachiaintroduction into a novel host: theWolbachia popcorninfection inDrosophila simulans

Abstract

Wolbachiamay act as a biological control agent for pest management; in particular, theWolbachiavariantwMelPop (popcorn) shortens host longevity and may be useful for dengue suppression. However, long-term changes in the host andWolbachiagenomes can alterWolbachiaspread and/or host effects that suppress disease. Here, we investigate the phenotypic effects ofwMelPop in a non-native host,Drosophila simulans, following artificial transinfection approximately 200 generations ago. Long-term rearing and maintenance of the bacteria were at 19°C in the original I-102 genetic background that was transinfected with thepopcornstrain. The bacteria were then introgressed into three massbred backgrounds, and tetracycline was used to create uninfected sublines. The effect ofwMelPop on longevity in this species appears to have changed; longevity was no longer reduced at 25°C in some nuclear backgrounds, reflecting different geographical origin, selection or drift, although the reduction was still evident for flies held at 30°C.Wolbachiainfluenced productivity and viability, and development time in some host backgrounds. These findings suggest that long-term attenuation ofWolbachiaeffects may compromise the effectiveness of this bacterium in pest control. They also emphasize the importance of host nuclear background onWolbachiaphenotypic effects.