EFFECTS OF DIFLUBENZURON AND PENFLURON ON WORKERS OF APIS-CERANA-INDICA F AND APIS-MELLIFERA L

Newly emerged adult workers of Apis mellifera and A cerana indica tole rated a topically applied dose of 100 mug diflubenzuron (DF) and penfl uron (PF) in acetone but the treated bees weighed less than control be es at 2 and 6 d of age. Oral administration of 100 mug DF (as Dimilin 25% wettable powder) in 10 mul sugar syrup proved fatal to A c indica. After 6 d of feeding 50 mug DF, hypopharyngeal gland development, mea sured as size of acini, was significantly suppressed in both bee speci es. The suppressed gland development in the treated group could be a c onsequence of poor gain in weight. Foragers of both bee species readil y accepted DF-contaminated sugar syrup and, with increasing doses, the re was decrease in time required to consume the contaminated sugar syr up in a dose-dependent manner. The treated bees weighed significantly less than the control bees. Thus, at higher doses chitin synthesis inh ibitors may also prove harmful to adult bees.