A research group led by Kazutaka Yoshida, a second-year doctoral student at Kagoshima University (in addition, Kyushu Okinawa Agricultural Research Center, Saga University, Agricultural Research Organization), said that symbiotic bacteria are caused by breeding strains of Himetobiunka, which is a pest such as paddy rice. We confirmed the existence of a resistance gene to "male killing" and clarified its genetic pattern.
In some populations of Himetobiunka, in addition to the symbiotic bacterium Wolbachia, which performs a reproductive operation called "cytoplasmic incompatibility" (modifying reproduction conveniently), a symbiotic symbiosis that performs "male killing" (a phenomenon that kills only the male host). Bacterial spiroplasma is infected.In spiroplasma infection, males die between hatching and emergence, and the sex ratio is large and biased toward females.
Since male killing is disadvantageous to the survival of the host, it is said that "resistance" that nullifies male killing appears rapidly in nature.However, it is very difficult to observe the evolutionary process of insects for which male killing has been disabled because there is no abnormality in appearance, and only two cases have been reported in which resistance to male killing emerged and spread among insects.
This time, one of the breeding strains of Himetobiunka was found to have a sex ratio of 1: 1 despite being infected with spiroplasma.As a result of mating experiments, it was found that this "male killing resistance" is a trait that is overtly (dominantly) expressed in simple Mendelian inheritance.This is the world's first report of resistance to male killing in insects of the order Hemiptera and resistance to "late-type male killing" in which males die during the larval stage.
Currently, the identity of the male killing resistance gene and its mechanism are unknown, but this discovery will be an important finding for elucidating the interaction between male killing bacteria and host insects, and will be detailed in future research on reproductive manipulation by symbiotic bacteria. It is expected that it will be applied to pest control in the future.