Volatile Organic Compounds as Signals in a Plant-Herbivore System: Electrophysiological Responses in Olfactory Sensilla of the Moth Cactoblastis cactorum

Abstract

The morphological sensillum types on the antennae of male and female Cactoblastis cactorum were visualized by scanning electron microscopy. Electrophysiological recordings were performed for the first time on single olfactory sensilla of C. cactorum. The male sensilla trichodea house a receptor cell responding to the putative pheromone component (9Z,12E)-tetradecadienyl acetate. The sensilla trichodea of the females were much shorter than those of the males and contained specialized receptor cells responding to certain terpenoids, the most frequent being the nerolidol-sensitive cell. The sensilla auricillica and sensilla basiconica of both sexes contained cells responding less specifically to terpenoid compounds as well as to green leaf volatiles. Cells of the sensilla coeloconica responded to aliphatic aldehydes and acids. Eight volatile organic compounds emitted by Opuntia stricta, a host plant of C. cactorum, were identified using gas chromatography-mass spectrometry, beta-caryophyllene being the major compound. Five compounds identified by gas chromatography in the headspace of O. stricta elicited responses in olfactory receptor cells of C. cactorum, nonanal being the most active compound and therefore a candidate attractant of C. cactorum.

Effects of elevated CO2 and O3 on leaf damage and insect abundance in a soybean agroecosystem

“…Although CO 2 is an attractant for western corn rootworm larvae in soil, the adult rootworms are not attracted to CO 2 (Bernklau and Bjostad 1998;Hammack and Petroski 2004). Like many other folivorous insects, western corn rootworms are attracted to plants and stimulated to feed by green leaf volatiles (Hammack 2001;Pare et al 2005;Pophof et al 2005). Greater production of green leaf volatiles measured in soybeans grown in elevated CO 2 relative to ambient air (B.F. O'Neill, unpublished) may have contributed to the higher numbers of western corn rootworm.…”

Antennal Structures Used in Communication by Egg Parasitoids

“…Given these features, we will refer to these sensilla as multiporous grooved peg sensilla (MGPS). Functionally, MGPS were identified as olfactory sensilla , Altner and Prillinger 1980, Pophof 1997, Diehl et al 2003, Pophof et al 2005, bi-modal chemo-thermoreceptors (Altner et al 1981, Altner andLoftus 1985) and thermo-hygroreceptors (Waldow 1970).…”

The expression pattern of four odorant-binding proteins in male and female silk moths, Bombyx mori

“…ever plant volatile-sensitive sensilla in moths have been studied extensively by electrophysiological recording, a great variety of functional subtypes has been observed (Todd & Baker, 1993;Anderson et al, 1995;Bichão et al, 2005;Pophof, 2005;Røstelien et al, 2005). The emerging complex expression pattern of OBPs in these sensilla in Bombyx is well compatible with such functional variability and would support the notion of a specific stimulus-carrier function of these OBPs.…”