The role of honey bee derived aliphatic esters in the host-finding behavior of Varroa destructor

Authors: LIU, JIAMEI - Fuijan Agricultural University; ZHANG, RUONAN - Guangdong Institute Of Applied Biological Resources; TANG, RUI - Guangdong Institute Of Applied Biological Resources; ZHANG, YI - China Pharmaceutical University; GUO, RUI - Fuijan Agricultural University; XU, GUOJUN - Fuijan Agricultural University; CHEN, DAFU - Fuijan Agricultural University; HUANG, ZACHARY - Michigan State University; Chen, Yanping - Judy; HAN, RICHOU - Guangdong Institute Of Applied Biological Resources; LI, WENFENG - Guangdong Institute Of Applied Biological Resources

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/22/2022
Publication Date: 12/25/2022
Citation: Liu, J., Zhang, R., Tang, R., Zhang, Y., Guo, R., Xu, G., Chen, D., Huang, Z., Chen, Y., Han, R., Li, W. 2022. The role of honey bee derived aliphatic esters in the host-finding behavior of Varroa destructor. Insects. 14(1). Article e14010024. https://doi.org/10.3390/insects14010024.
DOI: https://doi.org/10.3390/insects14010024

Interpretive Summary: Parasites locate potential hosts by using host-emitted chemical cues. Varroa mite is a parasite of honey bees and depends on honey bees for survival and reproduction. Since Varroa mite jumped from its native host Asian honey bee to the naïve host European honey bee, it has become a global threat to the European honeybee. However, the chemical cues that affect the host-finding behavior of Varroa mites are still not fully understood. In this study, we analyzed and compared the volatiles emitted by larvae of Asian honey bees and European honey bees and identified that chemicals, namely aliphatic esters, play an important role in Varroa host finding. Our results suggest that aliphatic esters could be used to produce attractants/repellents for monitoring and controlling Varroa in beekeeping industries in the future. The information gained from this study should be of interest to researchers, graduate students, beekeepers, and policymakers worldwide.

Technical Abstract: Varroa destructor is an obligate ectoparasite of honey bees and shifted from its original host Apis cerana to its new host European honey bees Apis mellifera in the 1940 - 1950s . The shift in host has since become the great threat to the health and survival of A. mellifera colonies worldwide. Chemical signals play a crucial role in all parts of the Varroa life cycle, including host finding. However, the chemical cues that affect the host-finding behavior of Varroa mites are still not fully understood. In this study, we systematically profiled the headspace volatiles of both worker and drone larvae of the two honey bee species using solid-phase microextraction followed by gas chromatography-mass spectrometry (SPME-GC-MS) methods and then utilizing electrophysiological recording and Y-tube olfactometer bioassay to study the potential roles of the selected compounds. The chemical profiling shows that there were four aliphatic esters, ethyl myristate (EM), methyl palmitate (MP), ethyl palmitate (EP), and ethyl oleate (EO) commonly detected from all four kinds of larval hosts. Among, them EM was a new substance identified from honey bee cuticular volatiles. Results from electrophysiological recordings indicate that all the aliphatic esters could elicit significant responses from Varroa olfactory organs in its forelegs. Moreover, the behavioral analyses show that EM could significantly attract V. destructor at a medium dose (10 µg), while MP had no effect on the mit,es and EP and EO were able to repel the parasites. Our findings suggest that host aliphatic esters play an important role of in Varroa host finding and provide new chemicals that could be used to produce attractants/repellents for Varroa monitoring and control in beekeeping industries in the future.