Potential of cell-free supernatants of Xenorhabdus and Photorhabdus bacteria for the control of virus-transmitting aphids (Myzus persicae)

Abstract Aims This study investigated the insecticidal activity of cell-free supernatants (CFS) from 36 Xenorhabdus bacterial strains, that produce various compounds that protect insect cadavers from competing organisms. Methods and Results The CFS were tested on Myzus persicae aphids by determining the number of live and dead individuals on the treated leaves over five days. The results showed considerable variability in the effects of the different bacterial strains, but CFS from many bacterial strains significantly increased aphid mortality. The strongest insecticidal effects were observed with X. bovienii (strains JAKUT, JAKUBSF, PARIS4), X. budapestensis (CHIN), X. khoisanae (SGI197, NGWA7), X. nematophila (EGY4, EGY2), X. poinarii (FL10.2), and P. luminescens (09.43). For some of these strains, the effect remained detectable even after 75% and 50% dilution, albeit at a lower intensity. Other CFS were less effective in killing aphids, but some of them appeared to inhibit the development of aphids, resulting in lower population increase. Conclusion CFS from certain Xenorhabdus strains show strong insecticidal activity against M. persicae, emphasising their potential as bio-based pesticides.