Feeding Essential Oils and 2-Heptanone in Sugar Syrup and Protein Diets to Honey Bees (Apis mellifera L.) as Potential Varroa Mite (Varroa destructor) Controls and Traced by SPME (Solid Phase Micro Extraction) Fibers

Authors: Sammataro, Diana; Finley-Short, Jennifer; LEBLANC, BLAISE - Pima Community College; WARDELL, GORDON - Safe Research And Development, Llc; AHUMADA-SEGURA, FABIANA - Safe Research And Development, Llc; CARROLL, MARK - University Of Florida

Submitted to: Journal of Apicultural Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/30/2009
Publication Date: 8/1/2009
Citation: Sammataro, D., Finley, J.V., Leblanc, B.W., Wardell, G., Ahumada-Segura, F., Carroll, M.J. 2009. Feeding Essential Oils and 2-Heptanone in Sugar Syrup and Protein Diets to Honey Bees (Apis mellifera L.) as Potential Varroa Mite (Varroa destructor) Controls and Traced by SPME (Solid Phase Micro Extraction) Fibers. Journal of Apicultural Research 48(4):256-262.

Interpretive Summary: Essential oils and oil components were fed to honey bees in a sugar syrup and liquid protein diet in order to determine if the oils were being incorporated into the bee larvae and could be traced by means of SPME. The compounds used were origanum, 2-heptanone, thymol and cinnamon oil. The main component of origanum is carvacrol and when fed in sugar syrup, this compound was found in Day 4 and Day 9 larvae. The four day old bee larvae had 0.13ppb of carvacrol and the nine day old larvae had over 3000ppb. Carvacrol was also detected in the cocoons. There was no activity in any bee larvae for the two different 2-heptanone formulations fed in sugar syrup. When the oils were fed in liquid protein diet, the Day 4 larvae had no detectable levels of either origanum (carvacrol) or thymol. The Day 6 larvae had 0.01 ppg of carvacrol but no thymol. Both Day 9 larvae and cocoons had large amounts of both carvacrol and thymol. The highest was over 1 million ppb in the whole Day 9 larvae. The thymol was only detected in the Day 9 larvae at 51,097 ppb. No 2-heptanone or cinnamon oil added to the liquid protein diet was detected in any of the larvae. The very high levels of both carvacrol and thymol in the whole Day 9 larvae would certainly be enough to protect them against Varroa infestation. More recent work in this area has shown that this is true and may explain why bees given certain essential oil treatments protect immature bees from invading Varroa mites.

Technical Abstract: Essential oils and oil components were fed to honey bees in a sugar syrup and liquid protein diet in order to determine if the oils were being incorporated into the bee larvae and could be traced by means of SPME. The compounds used were origanum, 2-heptanone, thymol and connamon oil. The main component of origanum is carvacrol and when fed in sugar syrup, this compound was found in Day 4 and Day 9 larvae. The four day old bee larvae had 0.13ppb of carvacrol and the nine day old larvae had over 3000ppb. Carvacrol ws also detected in the cocoons. There was no activity in any bee larvae for the two different 2-heptanone formulations fed in sugar syrup. When the oils were fed in liquid protein diet, the Day 4 larve had no detectable levels of either origanum (carvacrol) or thymol. The Day 6 larvae had 0.01ppg of carvacrol but no thymol. Both Day 9 larvae and cocoons had large amounts of both carbacrol and thymol. The highest was over 1 million ppb in the whole Day 9 larvae. The thymol was only detected in the Day 9 larvae at 51,097ppb. No 2-heptanone or cinnamon oil added to the liquid protein diet was detected in any of the larvae. The very high levels of both carvacrol and thymol in the whole Day 9 larvae would certainly be enough to protect them against Varroa infestation. More recent work in this area has shown that this is true and may explain why bees given certain essential oil treatments protect immature bees from invading Varroa mites.