When the cerambycid, Phoracantha recurva, invaded California in the mid 1990's a parasitoid wasp was imported from its native range in Australia as part of a biological control program. The wasp was later identified to be Avetianella longoi, which had already been released years earlier to control the congener longhorned beetle, Phoracantha semipunctata. Despite being recognized as the same species, the two wasps exhibited differential success on P. recurva eggs, indicating the presence of two separate strains. Here we determine if the differentiating factor between the two strains of A. longoi is a heritable genetic trait. All four pairings between the two strains were conducted, resulting in two homogenous and two heterogeneous crosses. All crosses except one produced viable F1 female offspring. F1 females were allowed to oviposit on P. recurva eggs and the survival of their offspring was compared to determine if survival can be affected by paternal contributions. The result was that the offspring of females with fathers from the second introduced strain showed significantly increased survival compared to F1 females with parents from the first introduced strain. This increased survival demonstrated that there is a heritable dominant trait that is associated with increased survival on P. recurva host eggs.

Temporal isolation remains an understudied, and potentially under-appreciated, mechanism of reproductive isolation. Phenological differences have been discovered in populations of the pine white butterfly (Neophasia menapia), a typically univoltine species found throughout western North America. At two locations in the Coast Range of California there are two periods of adult emergence per year, one in early summer (July) and one in late summer/autumn (September/October). Differences in flight time are accompanied by differences in wing shape and pigmentation. Here we use a combination of population genomics and morphological analyses to assess the extent to which temporal isolation is able to limit gene flow between sympatric early and late flights. Not only did we detect both genetic and morphological differences between early and late flights at the two sites, we also found that the patterns of differentiation between the two flights were different at each location, suggesting an independent origin for the two sympatric flights. Additionally, we found no evidence that these sympatric flights originated via colonization from any of the other sampled localities. We discuss several potential hypotheses about the origin of these temporally isolated sympatric flights.