Chemical control of Popillia japonica adults on high-value crops and landscape plants of northern Italy

The Japanese beetle (Popillia japonica Newman) is a pest native to Japan, recently recorded in Italy. The insect is highly polyphagous and it is causing considerable damage to herbaceous and perennial crops, nursery and ornamental plants. The appearance of an alien pest requires the integration of agronomic, biological and chemical actions to protect the crops. During the early stages of infestation, the use of readily effective insecticides is essential to sustain the immediate needs of plant protection. Here, we presented the effects of chemical and organic insecticides registered in Europe for adult beetle management on high-value crops (vine, peach and corn) and landscape plants (willow and Virginia creeper), evaluated by field trials carried out in 2019 and 2020. Two effects were considered for each product, i.e., topical and residual. Deltamethrin, lambda-cyhalothrin and the neonicotinoid acetamiprid were effective in killing beetles, with similar topical and residual effectiveness. The natural active ingredients/pathogens were ineffective but pyrethrin formulated with paraffinic mineral oil was effective. The data provide a valid support to update the European guidelines aimed at controlling P. japonica for growers, landscape managers and homeowners. The low selectivity of effective insecticides requires the integration into management strategies that envisage their use only whether strictly necessary, and in combination with containment measures based on natural enemies and cultural management practices.