INFECTION ENTEROCOCCUS FROM HELIOTHIS-VIRESCENS X H-SUBFLEXA BACKCROSS HYBRIDS (LEPIDOPTERA, NOCTUIDAE)

Plating assays have revealed the presence of a bacterium in extracts o f tissues from backcross hybrid insects, derived from crosses between Heliothis virescens and H. subflexa, a bacterium found rarely and in m uch lower abundance in either of the 2 parent species. The bacterium i s primarily localized within the gut but is also consistently recovere d in small numbers from other somatic and germinal tissues. Fatty acid profile analyses and the sequence of its 16s ribosomal RNA indicate t hat the bacterium is an Enterococcus related to Enterococcus sulfureus and E. casseliflavus, species that previously have been encountered i n insects and on plant tissues. Injection of the Enterococcus into H. virescens hosts results in the establishment of a bacterial infection similar to that of naturally infected backcross hybrids in terms of ti ssue distribution and relative magnitude among tissues. Like backcross hybrid males, almost 90% of H. virescens male moths infected as larva e were sterile in single pair test matings. The inability to either re scue male fertility in backcross lines cured of the Enterococcus or to observe characteristic abnormalities in sperm ultrastructure, however , casts doubt on the likelihood that this microorganism is the proxima te cause of male sterility in backcross hybrid insects.