The Influence of Climatic Factors on the Flight Activity of the Japanese-Beetle (Coleoptera: Scarabaeidae) : Implications for Use of a Microbial Control Agent

Abstract

Abstract The effects of meteorological parameters on flight activity of the Japanese beetle, Popillia japonica , on Terceira Island, Azores, Portugal were studied using an Omnidata portable weather station and Japanese beetle traps baited with the floral attractant, phenethyl propionate and eugenol (3:7). In the absence of inclement weather, flight toward an attractant source occurred throughout the day with an activity peak between 1300 and 1500 h. Cloud cover that reduced solar radiation below 0.6 Langleys (Ly)/min and wind velocity above 20 km/h markedly reduced flight activity. Average climatic conditions during the time of maximum attraction to baited traps were temperature of 25.5°C, little or no cloud cover with light intensity of 1.1 Ly/min, relative humidity of 59.4%, and wind of 12.9 km/h. Changes in weather from optimal conditions for flight of the beetle to those that inhibit flight can be abrupt and occur often on Terceira. The influence of meteorological factors on beetle behavior indicates that applications of microbial and conventional insecticides would be most effective if made during climatic conditions that encourage aggregations of beetles on host plants and at other attractive locations. Because conventional insecticidal applications against adult beetles appear to be of limited value on Terceira, the use of entomopathogenic fungi for the microbial control of P. japonica may provide a viable alternative for suppressing this pest. Metarhizium anisopliae , especially in combination with attractive traps, appears to offer good potential for control of P. japonica . A 4- to 5-day delay in onset of mortality of adult beetles that were exposed to a lethal concentration of M. anisopliae spores allows sufficient time for dissemination of the fungus by beetles. The infected adults could then serve to create new foci of infection for larval P. japonica .