Electrophysiological and Behavioral Responses of Apis mellifera and Bombusterrestris to Melon Flower Volatiles

Simple SummaryHoneybees (Apis mellifera) and bumblebees (Bombus terrestris) are often used to pollinate melon flowers in facilities. The researchers identified the volatiles in male and female flowers of a common melon species (Cucumis melo) grown in facilities and measured the EAG and behavioral responses of honeybees and bumblebees when exposed to isolated volatiles from the melon flowers. These results provide basic data for the rational utilization of bees.AbstractAs important pollinators, honeybees and bumblebees present a pollination behavior that is influenced by flower volatiles through the olfactory system. In this study, volatile compounds from melon flowers were isolated and identified by headspace solid-phase microextraction (HS-SPME) and gas chromatography–mass spectrometry (GC-MS), and their effects onApis melliferaandBombus terrestriswere investigated by electroantennogram (EAG) and behavior tests (Y-tube olfactometer). The results showed that 77 volatile compounds were detected in melon flowers, among which the relative content of aldehydes was the highest (61.34%; 82.09%).A. melliferashowed a strong EAG response to e-2-hexenal, e-2-octenal, and 1-nonanal.B. terrestrisshowed a strong EAG response to e-2-hexenal, e-2-octenal, 2,5-dimethyl-benzaldehyde, benzaldehyde and benzenepropanal. In behavior tests, the volatiles with the highest attractive rate toA. melliferawere e-2-hexenal (200 μg/μL, 33.33%) and e-2-octenal (300 μg/μL, 33.33%), and those toB. terrestriswere e-2-hexenal (10 μg/μL, 53.33%) and 2,5-dimethyl-benzaldehyde (100 μg/μL, 43.33%). E-2-hexenal and e-2-octenal were more attractive toA. melliferathanB. terrestris, respectively (10 μg/μL, 10 μg/μL, 200 μg/μL). In conclusion, the volatiles of melon flowers in facilities have certain effects on the electrophysiology and behavior of bees, which is expected to provide theoretical and technical support for the pollination ofA. melliferaandB. terrestrisin facilities.Keywords:Apis mellifera;Bombus terrestris;flower volatiles;electroantennography (EAG);olfactory behavior;melon