Enhancement of Attraction to Sex Pheromones of Spodoptera exigua by Volatile Compounds Produced by Host Plants

Abstract

We measured the effects of exposure to volatile compounds produced by host plants on the rate of capture of male Spodoptera exigua using synthetic sex pheromones. Exposure to volatile compounds stimulated strong electroantennographic responses of male S. exigua. The behavioral responses of male moths to combinations of sex pheromone and volatile compounds were tested in wind tunnel experiments. When lures were baited with synthetic sex pheromone plus benzaldehyde, phenylacetaldehyde, (Z)-3-hexenyl acetate, or linalool, respectively, the landing rate of S. exigua males was increased by 101.4%, 79.6%, 60.6%, and 34.3%, respectively, compared to sex pheromone alone. In field tests, traps baited with either pheromone + (E)-2-hexenal, pheromone + phenylacetaldehyde, pheromone + (Z)-3-hexenyl acetate, or pheromone + (Z)-3-hexenol enhanced moth catches by 38.8%, 34.6%, 24.6%, and 20.8%, respectively compared to traps baited with pheromone alone. In a second field experiment, more S. exigua males were trapped with a combination of a synthetic sex pheromone blend and several individual host plant volatiles compared to synthetic sex pheromone alone. These results suggest that some host plant volatiles enhance the orientation response of S. exigua male moths to sex pheromone sources.

Host plant volatiles serve to increase the response of male European grape berry moths, Eupoecilia ambiguella, to their sex pheromone

“…In the Weld, trap captures of male codling moth and H. zea were signiWcantly increased when the pheromone was dispensed with a mixture of green leaf volatiles ). An increase in pheromone attraction by the addition of plant volatiles is also reported for H. virescens and S. exigua Deng et al 2004). What is novel in our study is that the host plant chemostimuli are shown to reduce reaction time and Xight time of responding males to the pheromone.…”

“…In female corn earworm moths, Helicoverpa zea, the production of sex pheromone is enhanced by a factor of 20-30 in the presence of host plants or the host plant volatiles ethylene, 3-methyl-butan-1-ol or phenyl acetaldehyde (Raina et al 1992). However, for the perceiver of the pheromone, which in the case of moths is generally a male, enhancement and synergistic eVects of plant volatiles on male attraction to pheromones have been reported in Cydia pomonella (Yang et al 2004), Spodoptera exigua (Deng et al 2004), H. zea and Heliothis virescens . Such eVects have only been investigated to date in a few moth species and knowledge about pheromone-host plant volatile interactions in moths is still scanty.…”

Behavioral consequences of innate preferences and olfactory learning in hawkmoth–flower interactions

“…For male M. sexta, the D. wrightii floral odor may be an attractive chemical signal acting in parallel with the sex pheromone released by females. Plantderived odors are known to enhance male behavioral attraction to (41,42), and increase detection of (43), female pheromones. Because hawkmoths disperse widely, with few being recaptured in mark-release studies (44), the D. wrightii floral odor may serve as a beacon for males to locations where the probability of both food and sex is high.…”

Host plants and immatures as mate-searching cues in Heliconius butterflies

“…While not generally recognized as a mate-searching strategy, the ability of males to find plants is well known in other contexts among Lepidoptera. For example, males of certain butterflies and moths harvest alkaloids from withered plant tissue to use as defences and precursors for pheromones (Pliske et al 1976;Weller et al 1999), respond to female sex pheromones more effectively in the presence of plant volatiles (Emelianov et al 2001;Deng et al 2004;Yang et al 2004), or choose nectar sources using visual and chemical floral cues (Weiss 1997;Andersson & Dobson 2003;Cunningham et al 2006). Plants release a wide range of organic volatiles as a result of their interaction with herbivores (Pare & Tumlinson 1999).…”