Getting benefits out of a bad bug: On-farm composting of Japanese beetles, Popillia japonica (Coleoptera: Scarabaeidae)

In 2012, the Lincoln University (LU) Integrated Pest Management program evaluated mass trapping using modified traps baited with a sex pheromone and floral attractants as an organic management option for the Japanese beetle, Popillia japonica. More than 540 pounds of Japanese beetles were trapped at two LU farms and a private elderberry farm in central Missouri. This study was designed to examine (1) the feasibility of composting Japanese beetle carcass on a farm, and (2) the quality of the compost. Three types of high carbon/woody waste stream such as animal (horse) barn debris, cedar wood chips, and aged tree trimming wood chips, were composted with the beetles using the layering and the complete mixing methods. All composting piles showed elevated temperature for two months. Composting beetles with horse barn debris using a layer method generated the highest temperature (above 54.4°C) which persisted for the longest period of the first three weeks as compared to compost piles using cedar chips and aged wood chips. Beetle exoskeleton remained at the end of composting and the degradation of beetle soft biomass contributed to the increased N, P, K, and nitrate in the final composted products. The level of nitrogen nitrate in the cedar wood chip composted with beetles increased ca. 2,300-fold compared to the initial value of that carbon source. This study demonstrates that beetle carcass can be easily and successfully composted with high carbon/woody farm waste readily available at farms. Composting is also effective in reducing or eliminating odor of beetle decomposition. Beetle-based compost is a good quality soil amendment and can be used to augment fertilization to support organic crop production.