Evaluation of a natural product for protection of roses from Japanese beetle (Popillia japonica)

Japanese beetle (Popillia japonica Newman) can be a pest of many agricultural and horticultural plants.  Neonicotinoid pesticides are commercially available to protect rose flowers from the damage caused by adult Japanese beetles.  When applied to flowers, these insecticides may come in contact with pollinators.  Therefore, identification of natural repellants or feeding deterrents that protects the plant from defoliation and skeletonization while reducing the need for neonicotinoids may be beneficial.  In the summer of 2012 we evaluated the effectiveness of a putative plant-based feeding deterrent against Japanese beetles on roses.  We compared the feeding deterrent to acetamiprid (a commercially available neonicotinoid) and water (control) applied to the flowers and leaves of hybrid tea roses.  The number of Japanese beetles on leaves and flowers, the number of defoliated leaves, the number of damaged flowers, and the flower stage were recorded 3 to 5 times a week for each plant.  We observed significantly fewer (P≤ 0.05) Japanese beetles on flowers and fewer defoliated leaves when roses were sprayed with either acetamiprid or the feeding deterrent.  Both acetamiprid and the feeding deterrent significantly (P≤ 0.05) decreased the Japanese beetle population on the plant compared to the control.  However, Japanese beetle populations increased on plants treated with acetamiprid within 3 days after application; such an increase was not seen on roses treated with the feeding deterrent. Our findings suggest that a plant-based feeding deterrent can supplement or even replace a neonicotinoid for managing Japanese beetles on roses.