Research Update: Asiatic Garden Beetle Population Genetics

Tilmon Lab graduate student Adrian Pekarcik received a USDA AFRI EWD Predoctoral Fellowship to investigate the Asiatic garden beetle (AGB), Maladera castanea, an annual white grub species that was introduced to the U.S. in 1921 and has spread to at least 25 states and 2 Canadian provinces. Historically it was a pest of turfgrasses and ornamentals, however, in the last 10 years AGB has emerged as a new pest of field corn in Indiana, Michigan and Ohio. Grub feeding on seedling roots in the spring causes plants to stunt, wilt, discolor and die. High grub densities result in extensive plant stand losses exceeding 40%. Interestingly, AGB populations have only recently infested field crops and only in the Great Lakes region in spite of their broad distribution and long history in the U.S. These infestations are localized in sandy soils characteristic of this tri-state region. We hypothesize that these beetles comprise a genetically distinct population and propose to use molecular genetic tools to compare genetic structure among North America AGB populations. This serves the longer-term goal to understand why AGB has emerged as a new pest. Our objectives are to (1) develop molecular markers for AGB, and (2) assess North American populations for habitat-specific variation and/or geographic variation. We propose a novel approach that utilizes specific-locus amplified fragments sequencing (SLAF-seq) to identify single nucleotide polymorphisms (SNPs) forAGB. This project fits within the USDA AFRI Education and Workforce Development Program Area of Plant Health and Production and Plant Products as host associated genotypes could help us predict populations at-risk of future infestations. Additionally, these tools will allow for future investigations into AGB.