Interspecific transmission of Paederus endosymbionts: relationship to the genetic divergence among the bacteria associated with pederin biosynthesis

Summary. Endosymbiotic bacteria implicated in pederin production of Paederus (+)-females (Coleoptera: Staphylinidae) can be transmitted horizontally within and less frequently among the three species analyzed (P. melanurus, P. riparius, P. sabaeus). The 16S rDNA isolated from (+)-females reveals closely related bacterial sequences in the three species as well as in Paederus fuscipes and Paederidus ruficollis. This confirms the association of the undescribed endosymbiont and pederin biosynthesis in 5 of the 13 species that have been shown to contain the substance. In spite of the high sequence identities (> 99.5%), which suggest one species of endosymbiont, some of the heterospecific hosts were incompatible. This indicates adaptation and specific preferences of the endosymbiont for their natural host. Received 5 December 2001; accepted 11 March 2002.