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Toxic effects of monoterpenoids in the honey bee, Apis mellifera L., and its tracheal mite parasite, Acarapis woodi (Rennie)
Abstract
Bioassays were conducted to determine the toxicity of monoterpenoids to the tracheal mite, Acarapis woodi (Rennie), and its honey bee, Apis mellifera L. host. Compounds assayed included one terpene hydrocarbon (d-limonene), one terpene aldehyde (citral), one terpene ketone (pulegone), and four terpene alcohols (carvacrol, menthol, thymol, and $\alpha$-terpineol). The effects of exposure time, temperature, and humidity were examined for citral and menthol fumigations. In topical application studies, only citral and $\alpha$-terpineol were more toxic to tracheal mites. Citral was 7.0, 5.0, and 3.5 more toxic to mites at the LD$\sb{10}$, LD$\sb{50}$, and LD$\sb{90}$, respectively. $\alpha$-Terpineol was 3.5 times more toxic to mites at the LD$\sb{10}$; however, differences were not significant at the LD$\sb{50}$ or LD$\sb{90}$. In fumigation studies, menthol and citral were more toxic to tracheal mites. Menthol was 52.0, 18.8, and 5.7 times more toxic at the LD$\sb{10}$, LD$\sb{50}$ and LD$\sb{90}$, respectively. Citral was 2.9 (2.5-3.3) times more toxic to mites at all concentrations estimated. Thymol and carvacrol were numerically more toxic to mites, although the differences were not significant statistically. Menthol exhibited the greatest margin of safety in fumigation studies; however, menthol and thymol were more toxic to honey bees than other monoterpenoids. While menthol toxicity to adult mites was high, toxicity to eggs and larvae was limited. Menthol efficacy was not diminished by high or low humidity; however, bee mortality was reduced when applications were made at high relative humidity. Menthol toxicity to both bees and mites increased at higher temperatures. Citral was the only compound assayed that was more toxic to mites than bees in both topical and fumigant application studies. In fumigation studies, citral was highly toxic to all mite life stages. Citral was more toxic to mites at high temperatures, while bee toxicity increased at lower temperatures. Maximum mite control was achieved eight times faster with citral than menthol in fumigation assays.
Subject Area
Entomology|Toxicology
Recommended Citation
Ellis, Marion Dake, "Toxic effects of monoterpenoids in the honey bee, Apis mellifera L., and its tracheal mite parasite, Acarapis woodi (Rennie)" (1994). ETD collection for University of Nebraska-Lincoln. AAI9519533.
https://digitalcommons.unl.edu/dissertations/AAI9519533