The mating behavior of two congeneric coccinellids, Coccinella novemnotata and Coccinella septempunctata: is hybridization possible?

The native nine-spotted lady beetle, Coccinella novemnotata, was once one of the most common coccinellid species in the northeastern U.S. but has not been collected in the region in almost 20 years. While the cause of this rapid and dramatic decline remains unknown its disappearance corresponds to the introduction and establishment of the closely related European lady beetle, Coccinella septempunctata. Several hypotheses involving interactions between these two species have been proposed to explain the disappearance of C. novemnotata. One hypothesis is that the two species can hybridize and the resulting offspring do not resemble the nine-spotted parent. Until recently, testing this hypothesis was not possible because of lack of access to virgin beetles and insufficient knowledge about the basic mating ecology of C. novemnotata. A successful lab colony, founded by field-collected adults from the western U.S., has made possible the observations and experiments necessary to begin to describe the behavior of this species. In this talk I will present and compare data on the basic reproductive behaviors of C. novemnotata and C. septempunctata including copulation duration, female lifetime fecundity, effect of multiple matings on fecundity, sperm storage, and virgin oviposition. I will also report on the relative success of intraspecific versus interspecific mating in these two species and discuss the implications of my findings to help explain the decline of the iconic nine-spotted lady beetle.