Effects of Wolbachia Infection, Parasitic Order, And Time Interval On The Outcome of Inter-Strain Intrinsic Competition Between Bisexual Strain And Wolbachia-Induced Thelytokous Strain of Egg Parasitoid, Trichogramma Dendrolimi

Parasitoids may deposit a second clutch of eggs on a host that has been parasitized by the same parasitoid species. This is termed “superparasitism”. Wolbachia infection increases the superparasitism frequency of Trichogramma females. We investigated the outcome and fitness cost of inter-strain intrinsic competition between Wolbachia-infected thelytokous strain (TDW) and uninfected bisexual strain (TDB) of Trichogramma dendrolimi. To determine the developmental rate of both strains, the size of immature stages of T. dendrolimi offspring at different times after parasitization was measured in single parasitism and superparasitism conditions. The results showed increased superparasitism by Wolbachia-infected females compared to uninfected females, regardless of the time interval between oviposition; Trichogramma females were unable to distinguish between host eggs previously parasitized by TDB or TDW females. When the first oviposition was performed by TDB females, the TDB offspring outcompeted TDW offspring deposited later. However, although the TDW offspring was deposited 8 h earlier than the TDB offspring, it gained no advantage over TDB offspring. Regardless of parasitism conditions, the differences in development rate and time between TDW and TDB offspring were not significant. This study revealed that albeit TDW females presented a higher tendency of superparasitism than TDB females, TDB offspring outcompeted TDW offspring even when the latter was deposited 8 h earlier. The negative effects of Wolbachia infection on the competitive ability of TDW offspring inside the host eggs were due to offspring’s low fitness rather than delayed development.

The Detection of Wolbachia in Tea Green Leafhopper (Empoasca onukii Matsuda) and Its Influence on the Host

Tea green leafhopper (Empoasca onukii Matsuda) is a critical pest in tea production. Wolbachia has attracted much attention as a new direction of pest biological control for its ability of manipulating the hosts’ reproductive biology. In this work, we focused on the detection of Wolbachia in tea green leafhopper and its effect on host reproduction and development. Polymerase chain reaction (PCR), real-time PCR, and fluorescence in situ hybridization (FISH) techniques were used to detect the distribution of Wolbachia in tea green leafhopper. Wolbachia infection levels were different in different organs of hosts in different insect stages. In addition, comparison between the infected populations and cured population (treated by tetracyclines) revealed that presence of Wolbachia apparently influenced the growth, life cycle, and other reproductive factors of tea green leafhopper, caused, for example, by cytoplasmic incompatibility (CI), thereby reducing number of offspring, shortening lifespan, and causing female-biased sex ratio. This research confirmed that the bacteria Wolbachia was of high incidence in tea leafhoppers and could significantly affect the hosts’ reproductive development and evolution.

Wolbachia Detection in Field-Collected Mosquitoes from Cameroon

Wolbachia spp., known to be maternally inherited intracellular bacteria, are widespread among arthropods, including mosquitoes. Our study assessed the presence and prevalence of Wolbachia infection in wild mosquitoes collected in Cameroon, using the combination of 23s rRNA Anaplasmatacea and 16s rRNA Wolbachia genes. Mosquitoes that were positive for Wolbachia were sequenced for subsequent phylogenetic analysis. Out of a total of 1740 individual mosquitoes belonging to 22 species and five genera screened, 33 mosquitoes (1.87%) belonging to eight species (namely, Aedes albopictus, A. contigus, Culex quinquefasciatus, C. perfuscus, C. wigglesworthi, C. duttoni, Anopheles paludis and Coquillettidia sp.) were found to be positive for Wolbachia infections. Wolbachia spp. were absent in A. gambiae and A. aegypti, the main vectors of malaria and dengue, respectively. Phylogenetic analysis of the 16S RNA sequences showed they belong mainly to two distinct subgroups (A and B). This study reports the presence of Wolbachia in about eight species of mosquitoes in Cameroon and suggests that future characterisation of the strains is needed.

An attempted transinfection of Wolbachia in the Western honey bee (Apis mellifera)

<p>Wolbachia, an intracellular endosymbiont found in up to 60% of arthropods, has been celebrated for its highly varied host-phenotype interactions. These effects are diverse, ranging from reproductive manipulations to obligate mutualisms and facultative symbiosis. These facultative effects include increased resistance to, and reduction in the ability to vector, a number of RNA viruses in insects. Artificial transinfection to mediate human vector-borne diseases such as Dengue fever and Zika virus in Aedes mosquitoes has had considerable success globally. However, using Wolbachia to mediate zoonotic disease directly in threatened species has not been examined. The Western honey bee (Apis mellifera) has shown significant global population declines across the US and Europe, suffering from a diverse range of pathogens, including viral RNA and parasite vector networks. Wolbachia infection in honey bees has only been detected once and its effects have not been investigated. Here, I present the first attempted transinfection of Wolbachia in the Western honey bee using established transinfection protocols. The natural, but rarely found, Wolbachia infection reported in A. mellifera was examined against a robust phylogeny of all existing Wolbachia supergroups, a feat that has not been updated in the literature since 2015. I discovered Wolbachia infection in Ancistrocerus gazella, the European tube wasp, where it has never been observed. I isolated the natural Wolbachia strain hosted by Drosophila melanogaster (wMel ) and more than 1200 individuals from a range of honey bee life stages (from eggs to adults) were used as potential Wolbachia recipients using sound microinjection protocols. Additionally, I present a novel transinfection avenue utilizing artificial insemination and honey bee breeding using Wolbachia-inoculated drone semen. When no individuals were successfully infected with Wolbachia in F0 or F1, I investigated the expression of several antimicrobial peptides to characterize the immune response in young larvae to Wolbachia microinjection. There was a significant upregulation of apidaecin when injected with live Wolbachia, but not heat-treated bacteria, which has never been reported in host immune response to Wolbachia previously. The findings presented in this study highlight the importance of Wolbachia strain selection, immune response to Wolbachia, and the potential requirement for cell line culture in future transinfection attempts into A. mellifera. These findings will help inform future transinfection attempts, which are encouraged.</p>

An attempted transinfection of Wolbachia in the Western honey bee (Apis mellifera)

<p>Wolbachia, an intracellular endosymbiont found in up to 60% of arthropods, has been celebrated for its highly varied host-phenotype interactions. These effects are diverse, ranging from reproductive manipulations to obligate mutualisms and facultative symbiosis. These facultative effects include increased resistance to, and reduction in the ability to vector, a number of RNA viruses in insects. Artificial transinfection to mediate human vector-borne diseases such as Dengue fever and Zika virus in Aedes mosquitoes has had considerable success globally. However, using Wolbachia to mediate zoonotic disease directly in threatened species has not been examined. The Western honey bee (Apis mellifera) has shown significant global population declines across the US and Europe, suffering from a diverse range of pathogens, including viral RNA and parasite vector networks. Wolbachia infection in honey bees has only been detected once and its effects have not been investigated. Here, I present the first attempted transinfection of Wolbachia in the Western honey bee using established transinfection protocols. The natural, but rarely found, Wolbachia infection reported in A. mellifera was examined against a robust phylogeny of all existing Wolbachia supergroups, a feat that has not been updated in the literature since 2015. I discovered Wolbachia infection in Ancistrocerus gazella, the European tube wasp, where it has never been observed. I isolated the natural Wolbachia strain hosted by Drosophila melanogaster (wMel ) and more than 1200 individuals from a range of honey bee life stages (from eggs to adults) were used as potential Wolbachia recipients using sound microinjection protocols. Additionally, I present a novel transinfection avenue utilizing artificial insemination and honey bee breeding using Wolbachia-inoculated drone semen. When no individuals were successfully infected with Wolbachia in F0 or F1, I investigated the expression of several antimicrobial peptides to characterize the immune response in young larvae to Wolbachia microinjection. There was a significant upregulation of apidaecin when injected with live Wolbachia, but not heat-treated bacteria, which has never been reported in host immune response to Wolbachia previously. The findings presented in this study highlight the importance of Wolbachia strain selection, immune response to Wolbachia, and the potential requirement for cell line culture in future transinfection attempts into A. mellifera. These findings will help inform future transinfection attempts, which are encouraged.</p>

Diet-induced changes in titer support a discrete response of Wolbachia-associated plastic recombination in Drosophila melanogaster

Plastic recombination in Drosophila melanogaster has been associated with a variety of extrinsic and intrinsic factors such as temperature, starvation, and parasite infection. The bacterial endosymbiont Wolbachia pipientis has also been associated with plastic recombination in D. melanogaster. Wolbachia infection is pervasive in arthropods and this infection induces a variety of phenotypes in its hosts, the strength of which can depend on bacterial titer. Here we test the hypothesis that the magnitude of Wolbachia-associated plastic recombination in D. melanogaster depends on titer. To manipulate titer, we raised Wolbachia-infected and uninfected flies on diets that have previously been shown to increase or decrease Wolbachia titer relative to controls. We measured recombination in treated and control individuals using a standard backcrossing scheme with two X-linked visible markers. Our results recapitulate previous findings that Wolbachia infection is associated with increased recombination rate across the yellow-vermillion interval of the X chromosome. Our data show no significant effect of diet or diet by Wolbachia interactions on recombination, suggesting that diet-induced changes in Wolbachia titer have no effect on the magnitude of plastic recombination. These findings represent one of the first steps toward investigating Wolbachia-associated plastic recombination and demonstrate that the phenotype is a discrete response rather than a continuous one.

RNA virome diversity and Wolbachia infection in individual Drosophila simulans flies

The endosymbiont bacteria of the genus Wolbachia are associated with multiple mutualistic effects on insect biology, including nutritional and antiviral properties. Members of the genus Wolbachia naturally occur in fly species of the genus Drosophila, providing an operational model host for studying how virome composition may be affected by its presence. Drosophila simulans populations can carry a variety of strains of members of the genus Wolbachia , with the wAu strain associated with strong antiviral protection under experimental conditions. We used D. simulans sampled from the Perth Hills, Western Australia, to investigate the potential virus protective effect of the wAu strain of Wolbachia on individual wild-caught flies. Our data revealed no appreciable variation in virus composition and abundance between individuals infected or uninfected with Wolbachia associated with the presence or absence of wAu. However, it remains unclear whether wAu might affect viral infection and host survival by increasing tolerance rather than inducing complete resistance. These data also provide new insights into the natural virome diversity of D. simulans. Despite the small number of individuals sampled, we identified a repertoire of RNA viruses, including nora virus, galbut virus, thika virus and La Jolla virus, that have been identified in other species of the genus Drosophila. Chaq virus-like sequences associated with galbut virus were also detected. In addition, we identified five novel viruses from the families Reoviridae, Tombusviridae, Mitoviridae and Bunyaviridae. Overall, this study highlights the complex interaction between Wolbachia and RNA virus infections and provides a baseline description of the natural virome of D. simulans.