Transinfection of buffalo flies (Haematobia exigua) with Wolbachia and effect on host biology

A widespread insect endosymbiont Wolbachia is currently of much interest for use in novel strategies for the control of insect pests and blocking transmission of insect-vectored diseases. Wolbachia -induced effects can vary from beneficial to detrimental depending on host biology and the genetic background of the infecting strains. As a first step towards investigating the potential of Wolbachia for use in the biocontrol of buffalo flies (BF), embryos, pupae, and adult female BF were injected with three different Wolbachia strains ( w AlbB, wMel and w MelPop). BF eggs were not easily injected because of their tough outer chorion and embryos were frequently damaged resulting in less than 1% hatch rate of microinjected eggs. No Wolbachia infection was recorded in flies successfully reared from injected eggs. Adult and pupal injection gave a much higher survival rate and resulted in somatic infection and germinal tissue infection in surviving flies with transmission to the succeeding generations on a number of occasions. Investigations of infection dynamics in flies from injected pupae confirmed that Wolbachia were increasing in numbers in BF somatic tissues and ovarian infections were confirmed with w Mel and w MelPop in some instances, though not with w AlbB. Measurement of fitness traits indicated reduced longevity, decreased and delayed adult emergence, and reduced fecundity in Wolbachia -infected flies in comparison to mock-injected flies. Furthermore, fitness effects varied according to the Wolbachia strain injected with most marked reductions seen in the w MelPop-injected flies and least severe effects seen with the w AlbB strain.