Summary
Hybridization is rarely studied for invasive pests. The few studies that have been completed focus on the threat of hybridization for the integrity of a native species after hybridization with an introduced species. An overlooked effect is that the movement of genes between non-native and native species could directly affect the spread and impact of an invasive pest. This has not been explored in invasive insects, perhaps due to the cryptic nature of hybridization without detailed genetic studies. A recent outbreak in New England of the non-native winter moth (Operophtera brumata) from Europe provides an unprecedented opportunity to examine the effects of hybridization because we discovered that it is hybridizing with the native Bruce spanworm (O. bruceata). Forest Service scientists at the agency’s Northern Research Station and their partners developed two new sets of genetic markers that confirmed the presence of multi-generation asymmetric hybridization, as suggested by the occurrence of hybrid backcrosses with the winter month, but not with the Bruce spanworm. The reason for this pattern of one-way hybridization is not yet known, and the scientists are continuing to explore the impact that this might have on the spread of winter moth and on the damage that it causes to forest and orchard trees.
