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Lethal and sub‐lethal effects of thymol on honeybee ( Apis mellifera ) larvae reared in vitro
Author(s) -
Charpentier Gael,
Vidau Cyril,
Ferdy JeanBaptiste,
Tabart Jeremy,
Vetillard Angelique
Publication year - 2014
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.3539
Subject(s) - thymol , larva , biology , toxicology , honey bee , instar , pesticide , food science , acaricide , royal jelly , botany , ecology , essential oil
BACKGROUND Thymol offers an attractive alternative to synthetic chemicals to keep Varroa under control. However, thymol accumulates in bee products and is suspected of having adverse effects on colonies and especially on larvae. In this study, we investigated the effects of acute and chronic exposure to thymol on larvae reared in vitro with contaminated food and compared results to the theoretical larval exposure based on the amount of pollen and honey consumed by larvae during their development.RESULTS The laboratory assays reveal that, first, the 48 h‐ LD 50 of thymol introduced into larval food is 0.044 mg larva −1 . Second, the 6 day‐ LC 50 is 700 mg kg −1 food. A significant decrease of larval survival and mass occurred from 500 mg thymol kg −1 food ( P < 0.0001). Finally, vitellogenin expression, which reached a maximum at the fifth instar larvae, is delayed for individuals exposed to 50 mg thymol kg −1 food ( P < 0.0006). That is 10 times higher than the theoretical level of exposure.CONCLUSION Based on the level of thymol residue found in honey and pollen, these results suggest that the contamination of food by thymol represents no notable risk for the early‐developing larvae. © 2013 Society of Chemical Industry