Most used products to control Varroa destructor Anderson & Trueman, 2000, are organic acids, essential oils, and synthetic acaricides, which cause resistance phenomena, while none of them is able to solve the problem. Thus beekeepers are always looking for new products, even if not legally admitted. Among them rotenone, a pesticide allowed in organic farming, is applied on top bars as powder containing up to 1% a.i. This experimentation has been performed in order to test the toxicity of rotenone on honeybee and its acaricidal effect against varroa. Following the standard procedure for toxicological tests on honeybees, ingestion trials at the concentrations of 1000, 500, and 200 ppm and indirect contact trials at the concentrations of 500, 200, and 100 ppm were performed. Non-toxic thresholds were 200 ppm and 100 ppm, respectively. These concentrations were tested against varroa. In indirect contact trials groups of 30 mites were tested in Petri dishes containing paraffin wax sprayed with rotenone. After 4 hours of exposure mites were transferred in clean Petri dishes containing 6 honeybee prepupae. After 24 hours mortality was significantly higher in treated mites than in controls and it was almost total after 48 hours, while control mites still showed a low mortality. In direct contact trials with powdered products (wheat flour, flour + rotenone 1%, caolin clay, caolin + rotenone 0,7% and caolin + rotenone 1%) mortality was almost total after 24 hours in all samples containing rotenone and also in those containing caolin clay only, while it was very low in flour.

Laboratory assessment of rotenone toxicity to honeybee and Varroa

PORPORATO, Marco;MANINO, Aulo;PATETTA, Augusto
2008-01-01

Abstract

Most used products to control Varroa destructor Anderson & Trueman, 2000, are organic acids, essential oils, and synthetic acaricides, which cause resistance phenomena, while none of them is able to solve the problem. Thus beekeepers are always looking for new products, even if not legally admitted. Among them rotenone, a pesticide allowed in organic farming, is applied on top bars as powder containing up to 1% a.i. This experimentation has been performed in order to test the toxicity of rotenone on honeybee and its acaricidal effect against varroa. Following the standard procedure for toxicological tests on honeybees, ingestion trials at the concentrations of 1000, 500, and 200 ppm and indirect contact trials at the concentrations of 500, 200, and 100 ppm were performed. Non-toxic thresholds were 200 ppm and 100 ppm, respectively. These concentrations were tested against varroa. In indirect contact trials groups of 30 mites were tested in Petri dishes containing paraffin wax sprayed with rotenone. After 4 hours of exposure mites were transferred in clean Petri dishes containing 6 honeybee prepupae. After 24 hours mortality was significantly higher in treated mites than in controls and it was almost total after 48 hours, while control mites still showed a low mortality. In direct contact trials with powdered products (wheat flour, flour + rotenone 1%, caolin clay, caolin + rotenone 0,7% and caolin + rotenone 1%) mortality was almost total after 24 hours in all samples containing rotenone and also in those containing caolin clay only, while it was very low in flour.
2008
EurBee3- 3rd European Conference of Apidology.
Belfast, UK
8-11/09/2008
EurBee3- 3rd European Conference of Apidology.
Queen's University
86
86
M. PORPORATO; M. CORNOLTI; A. MANINO; A. PATETTA
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/46339
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