A Comparative Study of Healthy and American Foulbrood-Infected Bee Brood (Apis mellifera L.) through the Investigation of Volatile Compounds

Abstract

American Foulbrood (AFB) is a major endemic disease affecting the bee brood and the absence of chemical therapeutic treatments leads beekeepers to develop alternative management plans, based mainly on the prevention and accurate diagnosis of symptoms. One of the main symptoms of the disease is the unpleasant odor caused by the rot of dead larvae. In the present comparative study, we analyzed the odor profile of bee larvae and the presence of characteristic volatile compounds (Gas Chromatography-Mass Spectometry), in an effort to discriminate healthy and AFB-infected brood. A greater number of volatile compounds was identified in the affected brood than the healthy. The presence of (Ε)-β-ocimene was prominent in healthy brood samples in percentages from 85.25 to 99.14%, a compound also detected in all samples of infected brood but in lower percentages (37%). The compounds toluene, xylene, 1,3-dimethylbenzene, 2-nonanone, dimethyl disulfide, and dimethyl trisulfide were detected in 100% of the diseased brood samples, with the latter three being absent from the healthy brood, while 2-undecanone was found in some samples of diseased brood (40.0%). Further investigation of volatile markers may contribute significantly to the successful diagnosis of the disease, aiming at its rapid treatment.