Population genetics of Asiatic garden beetle: Are Great Lakes populations infesting agronomic crops unique?

The Asiatic garden beetle, Maladera castanea Arrow, is an annual white grub species that was introduced to North America in New Jersey 100 years ago and has since spread to 25 states and 2 Canadian provinces. Historically a pest of turfgrasses and ornamentals, M. castanea emerged as a new pest of field corn in Indiana and Michigan in 2007 and Ohio in 2013. High population densities can cause extensive plant stand losses in excess of 40%. It is interesting that M. castanea populations have only recently infested field crops and only in the Great Lakes region despite their broad geographical distribution and long history in the U.S. The long-term goal of this research is to understand why M. castanea has emerged as a new pest. We hypothesize that populations in corn in the Great Lakes region are genetically distinct. Our objectives are to (1) develop molecular markers (i.e., single nucleotide polymorphisms) for M. castanea using specific-locus amplified fragment sequencing, and (2) assess North American populations for habitat-specific variation and/or geographic variation. The identification of host associated genotypes could help us predict populations at-risk of future infestations if M. castanea continues to spread across North America, especially in the corn belt.