Canadian Forest Service Publications
Evidence of male hair pencil pheromone in Choristoneura fumiferana (Lepidoptera: Tortricidae). 2016. Roscoe, L.E., Silk, P.J., and Eveleigh, E.S. Journal of Insect Science 16(1): 27.
Issued by: Atlantic Forestry Centre
Catalog ID: 39568
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Male Lepidoptera often possess specialized scales, called hair pencils that emit volatiles that are critical to mating success. Spruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae), males will display hair pencils to females before attempting copulation. The importance of volatiles on these hair pencils is, however, not clear. We compared the proportion of successful copulations in unmanipulated mating pairs to pairs where males had their hair pencils either removed or chemically washed, and to pairs where females were antennectomized. Mean proportions of successful matings were significantly lower in pairs where hair pencils had been manipulated or where females had been antennectomized compared with unmanipulated mating pairs. There was no significant difference in mating success between treatments where hair pencils had been manipulated; however, mating success was significantly lower in hair pencil treatments than in antennectomized treatments. Mean copulation proportions in hair pencil/antennectomized treatments were also significantly less than in respective sham-operated treatments. Our results suggest that volatiles are associated with hair pencils, and they may be required for mating success in C. fumiferana.
Plain Language Summary
Communication between insects in typically conducted through chemicals. These chemicals, called pheromones, can communicate one or more processes to individuals. These can include availability for mating, the presence of an intruder, or the location of a food source. Many moth species produce pheromones, and in most cases, these are restricted to those produced by the female to attract males. Research has indicated, however that males may produce their own pheromones. Although slightly different in the roles in which they play within the mating sequence, their presence is often essential for mating to occur. The spruce budworm, Choristoneura fumiferana, is a tortricid moth of great economic and ecological importance in Atlantic Canada. Defoliation by the larval stage of this pest is an important threat to balsam fir and spruce forests throughout many affected areas. Consequently, much research has been conducted on management techniques for reducing damage by this pest. A critical component of this research is developing an understanding of the pheromones used by this species. Although the female pheromone ecology is well understood, the importance of male pheromones was largely unknown. Here, we determined that the presence of male pheromones was important to mating success. As well, we determined that these pheromones are very likely volatile and can be detected by the female via her antenna. This research represents a novel and potentially important component of spruce budworm pheromones research, and provides important clues as to the importance of male pheromones in other closely related and economically important species.