| Description |
There are two not mutually exclusive theories explaining the widespread presence of symbiotic bacteria belonging to the same Arsenophonus clade. Both the environmental progenitor model and lateral symbiont transfer theories have gathered some evidence. My aim was to find out whether experimental lateral transfer of secondary symbionts was possible between three different insectbacterium systems. The louse fly (Pseudolynchia canariensis), normally carrying Arsenophonus arthropodicus, was used as a test host and pupae were infected by microinjecting secondary symbionts of the tsetse fly (Glossina sp.) and the parasitoid wasp (Nasonia vitripennis). The co-injected Kanamycin-resistant strain of A. arthropodicus served as control and qRT-PCR was used to quantify bacterium cell numbers in pupae and flies. I found that microinjection resulted in stable colonization of pupae. The exogenous bacteria survived eclosion and were propagated to the next (F1) generation. The microinjection method decreased survival rates of pupae, and injection of S. glossinidius in particular decreased survival even further, and shifted the sex ratio of eclosed flies. Native symbiont colony size changes were minimal. As exogenous symbiont colonization prevalence and size decreased greatly by the second generation (F2), the colonization was not self-perpetuating. Unless the new endosymbionts grant a very fitness advantage to the hosts, they are not expected to survive any host defense mechanisms. Since colonization of injected pupae, eclosed flies and transmission to the first non-injected generation did occur, these results lend further experimental evidence that lateral symbiont transfer is not physiologically impossible, at least initially. The methods utilized in this study may be effectively used to further study lateral symbiont transfer and exogenous symbiont colonization of insects. |
