Superinfection of Laodelphax striatellus with Wolbachia from Drosophila simulans

Abstract

Wolbachia are maternally inherited, intracellular a-proteobacteria that infect a wide range of arthropods. They manipulate the reproduction of hosts to facilitate their spread into host populations, through ways such as cytoplasmic incompatibility (CI), parthenogenesis, feminization and male killing. The influence of Wolbachia infection on host populations has attracted considerable interest in their possible role in speciation and as a potential agent of biological control. In this study, we used both microinjection and nested PCR to show that the Wolbachia naturally infecting Drosophila simulans can be transferred into a naturally Wolbachiainfected strain of the small brown planthopper Laodelphax striatellus, with up to 30% superinfection frequency in the F 12 generation. The superinfected males of L. striatellus showed unidirectional CI when mated with the original single-infected females, while superinfected females of L. striatellus were compatible with superinfected or single-infected males. These results are, to our knowledge, the first to establish a superinfected horizontal transfer route for Wolbachia between phylogenetically distant insects. The segregation of Wolbachia from superinfected L. striatellus was observed during the spreading process, which suggests that Wolbachia could adapt to a phylogenetically distant host with increased infection frequency in the new host population; however, it would take a long time to establish a highfrequency superinfection line. This study implies a novel way to generate insect lines capable of driving desired genes into Wolbachia-infected populations to start population replacement.

Host Adaptation of aWolbachiaStrain after Long-Term Serial Passage in Mosquito Cell Lines

“…Unstable maternal transmission and variable infection frequencies are often commonly observed when Wolbachia is moved between distantly related hosts (17,35,40). After two rounds of selection for infection, populations progressed to fixation for infection and have remained stable (ϳ2 years).…”

“…The result is often the loss of infection within a few host generations. Not surprisingly, Wolbachia infections tend to be more susceptible to loss when they have been transferred between phylogenetically distant hosts (17,35). Similarly, those species that do not naturally harbor Wolbachia can be especially challenging to successfully transinfect (10,36).…”

Interspecific transfer ofWolbachiainto the mosquito disease vectorAedes albopictus

“…Presence of Wolbachia was detected using general Wolbachia primers (81F, 691R) (Zhou et al 1998). Wolbachia infection type was determined using primers specific for the wAlbA (328F, 691R), wAlbB (183F, 691R) and wRi (169F, 569R) infections (Zhou et al 1998;Kang et al 2003). As additional confirmation of infection type, primers specific for a prophage sequence (phgWOf, phgWOr) were used (Masui et al 2000).…”

“…albopictus infection in D. simulans hosts (Braig et al 1994). Prior transfection experiments suggest that the wRi infection is well suited for adaptation to distantly related hosts (Kang et al 2003). Furthermore, prior direct experience of the researchers with horizontal transfers of wRi reduces concern with Wolbachia viability during microinjection ).…”

Generation of a novel Wolbachia infection in Aedes albopictus (Asian tiger mosquito) via embryonic microinjection

“…Similarly, population replacement strategies also require an ability to generate novel infections. Although the artificial transfer of Wolbachia (transfection) has been successfully accomplished in other insect systems (Boyle et al, 1993;Sasaki et al, 2002;Hartmann et al, 2003;Kang et al, 2003), prior efforts to generate novel infections in mosquitoes have not proven successful (Sinkins and O'Neill, 2000).…”