Significant genetic structure in Macrobathra moths feeding on Acacia auriculiformis – implications for prioritising biological control agents

Abstract

Acacia auriculiformis is a native Australian tree that has now become a category 1 invasive weed in Florida, USA. Previous research has identified Macrobathra moths as potential biological control agents for this weed, but little is known about the genetic diversity and structuring of these moths. In this study, we compared the genetic structure of four common Macrobathra moth species across the geographic distribution of A. auriculiformis and across regions where A. auriculiformis does not occur to assess whether any of these moth species may comprise unrecognised cryptic species. We found contrasting patterns of genetic structuring among the four moth species, indicating that host-specific cryptic species could be present in Macrobathra arrectella and M. diplochrysa. Furthermore, we identified a deep genetic disjunction in both M. arrectella and M. callipetala across the Gulf of Carpentaria, a pattern that is also found in A. auriculiformis. The geographic distribution and host plant associations of the distinct mitochondrial lineages of each of these moth species should be further evaluated with additional ecological sampling, and the species status of these lineages tested directly, using additional molecular screening and/or carefully designed cross-mating tests.