Losing the Arms Race: Greater Wax Moths Sense but Ignore Bee Alarm Pheromones.

Yuan Li,Katrina Klett,Ken Tan,Shahid Mehmood,Junjun Zhang,Zhengwei Wang,Xingchuan Jiang,Yufeng Qu

doi:10.3390/insects10030081

Abstract

The greater wax moth, Galleria mellonella L., is one of main pests of honeybees. The larvae burrow into the wax, damaging the bee comb and degenerating bee products, but also causes severe effects like driving the whole colony to abscond. In the present study, we used electroantennograms, a Y maze, and an oviposition site choice bioassay to test whether the greater wax moth can eavesdrop on bee alarm pheromones (isopentyl acetate, benzyl acetate, octyl acetate, and 2-heptanone), to target the bee colony, or if the bee alarm pheromones would affect their preference of an oviposition site. The results revealed that the greater wax moth showed a strong electroantennogram response to these four compounds of bee alarm pheromones even in a low concentration (100 ng/μL), while they showed the highest response to octyl acetate compared to the other three main bee alarm components (isopentyl acetate, benzyl acetate, and 2-heptanone). However, the greater wax moth behavioral results showed no significant preference or avoidance to these four bee alarm pheromones. These results indicate that bees are currently losing the arms race since the greater wax moth can sense bee alarm pheromones, however, these alarm pheromones are ignored by the greater wax moth.

Highlights

The greater wax moth, Galleria mellonella (GWM), is a natural pest of honey bee colonies, which has already been reported to be harmful to Apis mellifera [1], Apis cerana [2] and Apis dorsata [3]
The electroantennogram responses of the greater wax moth to bee alarm pheromones were reduced in intensity as adults aged
The first day moths showed the highest EAG response, while the third day moths showed the medium EAG response, and the lowest EAG performances in the fifth day moths were less than 2 mV to all four components of bee alarm pheromones (BA: F2,27 = 24.25, p < 0.001, octyl acetate (OA): F2,27 = 14.186, p < 0.001, IPA: F2,27 = 17.928, p < 0.001, and 2-HP: F2,27 = 19.41, p < 0.001)

Summary

Introduction

The greater wax moth, Galleria mellonella (GWM), is a natural pest of honey bee colonies, which has already been reported to be harmful to Apis mellifera [1], Apis cerana [2] and Apis dorsata [3]. GWMs lay eggs in stored combs which may hatch later when the temperature warms [6,7,8]. The developmental durations for GWM eggs, larvae and pupae have been reported to be around five days, six to seven weeks, and two weeks respectively at 29–32 ◦ C [1]. As the larvae develop into pupae they progress through eight stages [5]. The larval development process can be prolonged up to 12 weeks at room temperature which is around 24 ◦ C.

Methods

Results

Discussion

Conclusion