Wolbachia infection suppresses inbreeding-avoidance in Habrobracon hebetor to increase the likelihood of female offspring and its transmission to the next generation
عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
In haplodiploid organisms including the parasitoid wasp Habrobracon hebetor (Hym.: Braconidae), sex is typically determined by a mechanism called complementary sex determination (CSD), in which males emerge from haploid unfertilized eggs and females are heterozygote diploid. A different situation comes about with inbreeding that resulted in sterile homozygote diploid males instead of diploid females. Generating sterile males is a flaw of the haplodiploid reproduction system as such it is not surprising that haplodiploid organisms prevent inbreeding. Previously, we showed that Wolbachia induces cytoplasmic incompatibility (CI) in H. hebetor. We also found that H. hebetor showed strong inbreeding avoid behavior that result in all male progeny. To test whether Wolbachia affects inbreeding avoidance behavior, two isolines of the parasitoid wasp e.g. Wolbachia infected (W+) and Wolbachia cured (W–) were generated using tetracycline treatment and maintained for 10 generations in the laboratory condition at 25 ± 5 ºC, 60 ± 5% RH and a photoperiod of 16:8 h. The individuals used in the crosses (i.e. W+♀× W+♂, W–♀ × W–♂) were derived from a propagation line and thus all individuals are expected to be closely related. Therefore, we used ten pairs for each crosses and the egg hatching rates, the mean of emerged adults and offspring sex ratio for five days were compared. The results showed that the percent of egg hatching rates of the W+ wasps within five days were lower than that of the W– ones ( i.e. 73.87% ± 1.335 and 91.71% ± 1.531, respectively). While, the average number of emerged adults were higher in the W+ wasps (the average number of adults: 72 ± 0.871) compared with W– wasps (the average number of adults: 53.7 ± 0.687). We found no difference in the number of emerged males in W+ wasps compared with W– wasps, however, the average number of females in the presence of Wolbachia was significantly increased (i.e. 50.8 ± 1.033 and 19.2 ± 1.527, respectively). Considering females as a result of sexual reproduction in this insect, these results revealed that Wolbachia infection promoted sexual reproduction in H. hebetor to generate more female offspring transferring this bacterium to the next generation. In conclusion, it seems that the Wolbachia interferes in inbreeding avoidance of H. hebetor to increase the probability of female progeny and enhance its transmission to the next generation.
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