The uzifly, Exorista sorbillans (Diptera: Tachinidae), a parasitoid of the silkworm, Bombyx mori L. (Lepidoptera: Bombycidae), harbours Wolbachia (Rickettsia) endosymbionts. Administration of 0.05 mg/ml oxytetracycline to the adult uziflies removed Wolbachia endosymbionts and resulted in different reproductive disorders, such as i) reduction in fecundity of uninfected females, ii) cytoplasmic incompatibility in crosses between infected males and uninfected females, iii) sterility in the crosses between both males and females from uninfected populations, and iv) sex-ratio distortion in uninfected females irrespective of the presence of Wolbachia in males. However, tetracycline treatment did not have much effect on longevity of the uzifly. These results suggest that the interaction of Wolbachia with its uzifly host is one of mutual symbiosis as it controls the reproductive physiology of its hosts.

Wolbachia is a ubiquitous, Gram-negative,vertically transmitted, alpha-proteobacterium that causes an array of reproductive abnormalities including cytoplasmic incompatibility, feminization of genetic males, parthenogenesis in a number of insect species, among others. Wolbachia is now being exploited as an agent for pest and vector control. Previous surveys indicated that it is commonly seen in 16-76% of arthropods. In this paper, using polymerase chain reaction assay based on specific amplification of the ftsZ -A and -B supergroup Wolbachia gene fragments, we found that 30% of insects and pests screened were positive for Wolbachia. Among them 66.7% harbour double Wolbachia infection, while 33.3 % harbour single Wolbachia infection. These results indicate widespread infection with both double and single Wolbachia, and provide a wealth of information to exploit this endobacterium for the management of pests and vectors.

The cytoplasmically inherited bacterial symbiont, Wolbachia is well known for inducing a variety of reproductive abnormalities in the diverse arthropod hosts it infects. Wolbachia has been implicated in causing cytoplasmic incompatibility, parthenogenesis, and the feminization of genetic males in different hosts. In the present investigation, electron microscopy and PCR technology was applied on uzi flies of Exorista species (Diptera: Tachinidae), serious pests of silkworm Bombyx mori L. TEM examination of uzi flies of Exorista species showed Wolbachia in the reproductive tissues. Details of the ultrastructure of Wolbachia are described. The application of PCR technique revealed that the Wolbachia is present in uzi fly populations of Exorista species collected from different localities. Thereby it creates a lot of scope for future research on the management of uzi flies by means of Wolbachia.

Wolbachia are cytoplasmically inherited endosymbionts known to cause several reproductive alterations in insects which allow their spread in host populations. In the Uzifly Exorista sorbillans, endoparasites of silkworms, the prevalence of Wolbachia is high in the field. In the present study, we investigated Wolbachia's effects on the Uzifly fitness traits by measuring fecundity and hatching rate in crosses involving infected and cured individuals. We found evidence for positive fitness effects associated with Wolbachia infection in females which could help promote the spread of Wolbachia in E. sorbillans populations. We tested two types of treatments for removing Wolbachia, antibiotic therapy and high temperature treatment and found an influence on the reproduction: females treated by antibiotics have a lower fecundity than females cured by high temperature which could indicate a negative effect of the antibiotherapy on females' fitness. Furthermore, the monitoring of the Uzifly populations during 2 years revealed seasonal variations of the offspring production which may be linked to temperature.

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Wolbachia surface protein (WSP) is an eight beta-barrel transmembrane structure which participates in host immune response, cell proliferation, pathogenicity and controlled cell death program. The protein has four extracellular loops containing hyper variable regions separated by conserved regions. The WSP structure is homologous to Neisseria surface protein (Nsp A) which has about 34% similarity including antigenic variation and hydrophilicity. Recombination has a large impact on diversity of this protein including positive selection which is major constraint on protein evolution. The molecular mechanism through which Wolbachia induces various reproductive anomalies is unclear; a key feature observed for such anomalies might be because of Wolbachia undergoing extensive recombination. In Wolbachia, increased recombination is observed in ankyrin proteins, surface proteins and in some hypothetical proteins. Genetic divergence is extensive in the WSP gene, WSP is known to be a chimeric protein involved in host-symbiont interactions. Here we predicted the structural and functional variations in WSP sequences of Wolbachia present in D. melanogaster, A. tabida and in B. malayi.

Abstract. The uzifly, Exorista sorbillans (Diptera: Tachinidae), a parasite of the silkworm, Bombyx mori L. (Lepidoptera: Bombycidae), causes heavy losses to the silk industry. This parasitoid harbours a Wolbachia endosymbiont, which controls the fly's reproduction. In the present study a method for curtailing this notorious pest by administering Wolbachia-targeted tetracycline via its silkworm host's diet is investigated. Tetracycline not only influenced the larval growth of the silkworms' by decreasing larval duration, increased silk production and fecundity, without affecting hatchability, it also decreased the reproductive fitness of the uzifly endoparasite by killing the Wolbachia. The antibiotic exerts a beneficial influence by affecting the intestinal flora of silkworm larvae. On the other hand the reproductive fitness of uzifly was greatly reduced in terms of different reproductive abnormalities. When male and female flies that emerged from treated host silkworms were crossed and males from untreated hosts and females from treated hosts were crossed, approximately 72% and 97% of the eggs failed to hatch, respectively. However, of the eggs from crosses between male and female flies that emerged from untreated hosts and between males from treated hosts with females from untreated hosts, an average of 30% failed to hatch and the Wolbachia infection enhanced the fecundity of uziflies. These results demonstrate that the Wolbachia may be essential for uzifly reproduction and that Wolbachia-targeted antibiotics have a beneficial influence on silkworm growth while decreasing the reproductive fitness of the uzifly, E. sorbillans.