Olfactory Responses of Apis mellifera and Bombus terrestris to Floral Volatiles from Three Solanaceae Crops

Simple SummaryThe yields of solanaceous crops, including tomato (Solanum lycopersicum), pepper (Capsicum annuum), and eggplant (Solanum melongena), depend particularly on the pollination services provided by insects. However, whereas bumblebees (Bombus terrestris) are highly efficient pollinators of these crop plants, honeybees (Apis mellifera) frequently avoid their flowers. The mechanisms associated with this behavioral divergence have yet to be sufficiently clarified, and given the potential commercial implications, in this study, we investigated the olfactory perception and behavioral responses of these two bee species to volatiles emitted by the flowers of tomato, pepper, and eggplant. Compared withA. mellifera,B. terrestrisdisplayed significantly higher olfactory sensitivity to specific floral volatiles, whereas these compounds often failed to elicit preferential response in honeybees. Our findings thus enabled us to characterize the olfactory interactions between plants and bees mediated by floral volatiles, and will provide a scientific basis for developing novel strategies to attract pollinators in agricultural ecosystems, thereby enhancing crop pollination efficiency and promoting sustainable and eco-friendly agricultural production.The efficiency with which solanaceous crops are pollinated is determined by pollinator behavioral preferences. AlthoughBombus terrestristypically outperformsApis melliferain this respect, the chemo-ecological mechanisms underlying their divergent olfactory responses remain insufficiently determined. We combined behavioral assays, gas chromatography–mass spectrometry, and electroantennogram recordings to compare the responses of these bee species to the volatile organic compounds (VOCs) emitted by tomato, pepper, and eggplant flowers. WhereasB. terrestrisshowed a strong foraging preference for all three crop plants,A. melliferadisplayed distinct avoidance. Chemical analyses identified 82, 63, and 60 VOCs in tomato, pepper, and eggplant flowers, respectively. Among the 14 VOCs commonly emitted by all three crops, linalool, nerol, (E,E)-2,4-decadienal, 2-hexenal, tridecanal, and (E,Z)-2,6-nonadienal elicited significantly different electrophysiological responses in the two bee species, and are, thus, considered key compounds mediating their behavioral differences. Moreover, in behavioral assays,A. melliferaandB. terrestrisshowed significantly different responses to four concentration levels of linalool, nerol, (E,E)-2,4-decadienal, and tridecanal. This study elucidates the plant–pollinator olfactory interactions that contribute to determining the different foraging behaviors of two bee species in pollinating solanaceous crops, thereby providing a theoretical basis for optimizing pollinator attraction strategies.