Effectiveness of field‐exposed attract‐and‐kill devices against the adults of Popillia japonica (Coleoptera: Scarabaeidae): a study on duration, form and storage

BACKGROUND The Japanese beetle Popillia japonica Newman is an insect pest native to Japan that has spread into North America, the Azores and, recently, into continental Europe. Here, we present a study assessing the effectiveness of a long‐lasting insecticide‐treated net (LLIN), assembled in semiochemical‐baited attract‐and‐kill devices (A&Ks) as a low environmental impact means to control P. japonica in the field. We compared the attractiveness of three different forms of A&Ks that were left outdoors throughout the summer, and the residence time of P. japonica landing on them. Moreover, we performed a preliminary study testing the effectiveness of new LLINs after storage. Collected data also allowed us to investigate the beetles' diel flight patterns in relation to meteorological conditions. RESULTS Killing effectiveness of the field‐exposed A&Ks declined steadily over the flight season (from 100% to 37.5%) associated with a decrease in residues of α‐cypermethrin, the active ingredient in the LLINs. The different A&K forms (pyramidal, octahedral and ellipsoidal) attracted similar numbers of beetles. Individual beetles' residence time ranged from 75 to 95 s and differed slightly between A&K forms. Effectiveness of LLINs decreased by ≈30% after 1 year storage. Based on numbers landing on A&Ks, the beetles' flight activity peaked about 14:30 h and was inversely correlated with relative humidity. CONCLUSION This study indicates that semiochemical‐baited A&Ks are effective for controlling P. japonica in the field. Because of active ingredient decay, the LLINs should be replaced after 30–40 days of field exposure to ensure that the A&Ks remain fully functional. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. Correlation between the decrease of effectiveness in mortality of Popillia japonica adults treated with field‐exposed LLINs and the decrease of α‐cypermethrin content in the LLINs over time.