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Wolbachia endosymbiont is a maternally inherited bacteria that infects a wide range of hosts, including parasitoids and their respective hosts. In this study, a total of 171 individuals of braconid endoparasitoids, consisting of Fopius arisanus, F. vandenboschi, Diachasmimorpha longicaudata, Psyttalia sp.1, Psyttalia sp.2, P. fletcheri and P. incisi, and their host tephritid fruit flies of Bactrocera dorsalis, B. papayae and B. carambolae infesting carambola were screened molecularly by the Wolbachia surface protein (wsp) gene. Interestingly, 21 (24.14%) wsp gene sequences were successfully isolated from 87 braconid samples tested, showing a low infection rate of Wolbachia. However, despite the close ecological contact between parasitoids and their hosts, none of the tephritid individuals were infected by Wolbachia. A comparison of wsp and host mitochondrial cytochrome c oxidase subunit I (COI) sequences found that braconids did not cluster in connection with Wolbachia infection, suggesting that selective sweep has not yet occurred because Wolbachia may have recently infected the braconid populations in Peninsular Malaysia (≈0.1 MYA). Despite of relatively recent infections of Wolbachia, the history of Wolbachia infection into F. arisanus populations of Peninsular Malaysia is complex, involving at least two independent occasions of infection and two secondary losses.

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Prostaglandins and other eicosanoids are known as regulating agents for cellular immune responses to pathogen threats in an insect's hemolymph. A novel synthetic peptide, WolFar, was customized from a conserved region of the Wolbachia surface protein (WSP), isolated from an economically important endoparasitoid species, Fopius arisanus. WolFar consists of nine amino acids (SYY VRL QYN) and was tested on the house cricket, Acheta domesticus. Three concentrations of peptides, 0.83 mmol/L (100%), 0.63 mmol/L (75%), and 0.42 mmol/L (50%), were injected and observed for 72 h. The regulation of prostaglandin E 2 (PGE 2 ) in the hemolymph of A. domesticus was determined using ELISA and by observation of nodules in the internal system of A. domesticus. The results showed that there were significant increases in PGE 2 in response to peptide injection at 24, 48, and 72 h after treatment. Furthermore, higher concentrations of peptide were directly proportional to the level of PGE 2 activity. These findings were supported by the abundance of nodules that formed in the internal system and fat body of A. domesticus, detectable at 72 h into the treatment. This indicates that WolFar is able to stimulate the immune system of insects and can be further developed as a potential biopesticide.