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.

Abstract:Endosymbiotic relationship between Wolbachia (Rickettsiales: Rickettsiaceace) and braconids species is a new topic to be discussed among researchers due to its potential as biocontrol agents of fruit flies species. In this study, Wolbachia Surface Protien (wsp) marker has been used to detect the existence of Wolbachia molecularly that associated with braconids (Opiinae) collected from several localities throughout Peninsular Malaysia. Our results revealed that five species of parasitoids viz. Fopius arisanus, F. vandensboschi, Psyttalia sp., P. fletcheri and P. incisi were symbiont positively with nine different strains of Wolbachia. A total of nine strains have been successfully sequenced and classified into three Wolbachia subgroups namely Mel, Ri, and Inc based on the results of clustering analysis. In this study, Inc Wolbachia group has been known as a novel group emerged of Wolbachia. These data should be useful in future Wolbachia-based biological control program that involving parasitoids and fruit flies.

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The aim of this study was to investigate the effect of gamma irradiation on survivability (adult emergence, sex ratio, adult longevity), fecundity (eggs hatchability, number of eggs produced), and morphological differences in the size of the ovary and testes of unirradiated and irradiated adults of Oriental fruit fly [Bactrocera dorsalis (Hendel)]. A dose of 100 Gy was determined as the minimum needed for inhibitory effects against B. dorsalis that would not deter adult emergence, sex ratio (male:female), and adult longevity, with 82.6 ±7.02, 1:1.09, and 107 ± 24.5, respectively. Doses from 50 to 400 Gy range did not completely prevent the adult emergence; however, the emergence decreased by increasing the radiation dose. Adult survivability significantly decreased among all the treatment groups of B. dorsalis, except for the 50 Gy and unirradiated flies. At a dose of 50 Gy, fertile females showed a significant reduction in fecundity by not producing eggs after mating with the sterile males. Meanwhile, the number of eggs laid decreased with increasing dose and no fertile egg was hatched starting at 100 Gy of irradiation. Testes and ovaries of 20-d old flies irradiated as pupae were smaller than those of control flies. In this study, 100 Gy was concluded as the minimum effective dose for the disinfestation and sterilization of B. dorsalis puparia. Results represent new findings used as a basis for sterile insect technique and quarantine programs for managing B. dorsalis, particularly in Malaysia.