Flight Activity of Popillia japonica (Coleoptera: Scarabaeidae) after Treatment with Metarhizium anisopliae

Field-collected adult Japanese beetles, Popillia japonica Newman, treated with conidia of Metarhizium anisopliae Sorokin were compared with nontreated beetles under held conditions on Terceira Island, Azores, Portugal, using mark-release-recapture techniques, Distance, direction, and day of capture were monitored with lure-baited Japanese beetle traps placed in four concentric circles 50 to 1000 m around the release point during July and August of 1990 and 1991. Significantly fewer treated beetles (2.5%) were recaptured than untreated individuals (5.2%). Approximately 70% of the recaptured beetles were caught within 50 m of the release point, but a small percentage (<1%) of individuals from each group flew as far as 1 km. Most of the marked beetles (80-86% of those caught) were recaptured within 24 h of release. Barely any (<1% of the marked beetles were detected in the traps 3 days following release. Flight of both treated and untreated beetles was predominantly against the wind. Monitoring of laboratory held subsamples of the treated groups indicated that mortality did not begin until 3-4 days following treatment. A week after treatment with the fungus, 100% mortality was observed. The delay in mortality and the flight distances observed for fungus-treated beetles indicate good potential for dispersal of M. anisopliae via infected adult Japanese beetles.