INHIBITION OF AGGREGATION BEHAVIOR IN THE GREEN JUNE BEETLE (COLEOPTERA, SCARABAEIDAE) BY ANTIBIOTIC-TREATMENT OF FOOD SUBSTRATE

A trapping study using a Latin-cube design was conducted in an apple variety block in 1987 to determine the effect of microorganisms on the attraction of green June beetles Cotinis nitida (L.) (Coleoptera: Scarabaeidae) to fruit. Baffle and funnel traps baited with male beetles fed nystatin-treated peach puree diet caught significantly fewer beetles than beetles fed untreated peach puree, streptomycin-penicillin-treated puree, streptomycin-penicillin-nystatin-treated puree, 20% untreated glucose diet, and beetles caged with diet but prevented from feeding (P < 0.05). In 1988 a study was conducted in a vineyard using the same traps and a similar experimental design. Traps baited with beetles fed nystatin-treated diet caught significantly fewer beetles than traps baited with beetles fed untreated puree and beetles caged with untreated puree but prevented from feeding. Traps baited with beetles fed untreated puree again caught significantly more beetles than all other treatments (P < 0.05). These results suggest that yeasts contained in diet, and possibly in beetle digestive tracts, contributed significantly to the production of volatiles, which induce beetle aggregations on fruit. © 1990 Entomological Society of America.