TOXICITY OF 7 MONOTERPENOIDS TO TRACHEAL MITES (ACARI, TARSONEMIDAE) AND THEIR HONEY-BEE (HYMENOPTERA, APIDAE) HOSTS WHEN APPLIED AS FUMIGANTS

Laboratory bioassays were conducted to characterize the acute toxicity of 7 monoterpenoids to tracheal mites, Acarapis woodi (Rennie), and t heir honey bee, Apis mellifera L., hosts. Citral, thymol, carvacrol, a lpha-terpineol, pulegone, d-limonene, and menthol were applied as fumi gants to mite-infested honey bees. Thymol and menthol were the most to xic compounds to honey bees, and cc-terpineol was the least toxic. Men thol, citral, thymol, and carvacrol were more toxic to tracheal mites than to honey bees. Pulegone, d-limonene, and cu-terpineol were more t oxic to honey bees than to tracheal mites. Menthol was 18.9 times more toxic to tracheal mites than to honey bees at the LC50 concentrations ; however, as the concentration increased, bee mortality increased mor e rapidly than mite mortality, and menthol was only 5.7 times more tox ic at the LC90 concentrations. Probit regressions for bee and mite mor tality were parallel for citral and thymol. Citral and thymol were 2.9 (2.5-3.3) and 2.0 (1.0-3.6) times more toxic to tracheal mites, respe ctively, at all concentrations estimated.