Genetic Diversity within and Between Nursery Populations of Paria Fragariae Species Complex and Implications for Insecticide Resistance

The strawberry rootworm (SRW), Paria fragariae Wilcox, has been a growing pest of production nurseries in the southeastern United States since its introduction in the mid 1980’s. The small beetle feeds nocturnally on evergreen azaleas and causes severe damage to the leaves which diminishes the marketability of the plant. The strawberry rootworm species complex is currently subdivided into two subspecies, Paria fragariae fragariae Wilcox and Paria fragariae kirki Balsbaugh, but it is not confirmed whether these two groups interbreed. The presence of separate, non-interbreeding populations would reduce the amount of gene flow within and between populations and decrease the risk for insecticide resistance. However, the presence of fully interbreeding populations would increase risks for insecticide resistance and further the need for rotation of pesticide chemistries as part of an IPM approach to effectively manage SRW populations. Field sampling paired with sequencing of mitochondrial DNA has detected at least two distinct groups of the SRW species complex in MS, AL, and LA production nurseries. Further sampling will be required to determine frequencies and distributions of different populations in production nurseries in the southeastern U.S. as well as to detect any hybridization between supposed subspecies of SRW.