The Role of Heliothine Hairpencil Compounds in Female Heliothis virescens (Lepidoptera: Noctuidae) Behavior and Mate Acceptance

Abstract

Studies on numerous insect species suggest that male-produced sex pheromones play a role in attracting females; as aphrodisiacs, making females more quiescent; or as a means of inhibiting competing males. Male heliothine moths display abdominal hairpencils during courtship, but the specific effects of the odors released on female behavior have not yet been elucidated. This study investigates the role of male hairpencil compounds in female Heliothis virescens mating behavior. Female H. virescens were exposed to filter paper loaded with hairpencil extracts of male H. virescens, Heliothis subflexa and Helicoverpa zea, and observed for behavioral responses to odors. Single synthetic compounds found in the H. virescens hairpencil blend were also tested. In mating assays between single male and female H. virescens it was found that: (i) antennectomized females mated less frequently than sham-operated females; (ii) females mated less frequently with males whose hairpencils had been surgically removed; (iii) females mated with males with ablated hairpencils if a filter paper loaded with one male equivalent of H. virescens hairpencil extract was presented simultaneously; and (iv) this effect was species-specific, as presentation of H. subflexa or H. zea hairpencil extracts did not restore mate acceptance. This study suggests that odors released by male hairpencils are important in mate acceptance by female H. virescens, and may play a role in mate choice and species isolation.

Gene-silencing reveals the functional significance of pheromone biosynthesis activating neuropeptide receptor (PBAN-R) in a male moth

“…Sensitivity of olfactory receptor neurons in females to hexadecanol and sensitivity to octadecanol in both males and females was demonstrated (36), thus indicating their behavioral relevance. An increase in female abdominal extension, indicating sexual excitement and readiness to mate (19) in response to the hexadecanol and octadecanol components of male complexes was observed in Heliothis virescens (17). High levels of cis-11 hexadecanol in traps containing a female sex-pheromone blend significantly reduced captures of H. armigera and H. virescens males (19,37) and inhibited male orientation behavior in a wind tunnel (20,38) thus implicating its role in inhibiting malemale competition.…”

“…The behavioral role of male secretions is not well understood, but most often these odors have been considered important in courtship behavior for close-range recognition and acceptance by the female. In general, moth male-produced pheromones are considered to have many functions, such as aphrodisiacs to stimulate female receptivity during courtship (11,14); inducing calling behavior (15); as an arrestant of females to enable copulation (16,17); or as a male-to-male competition inhibitor (12,(18)(19)(20). Close-range male chemical cues have also been proposed as a trait used by females to assess male quality (21).…”

Hairpencil Volatiles Influence Interspecific Courtship and Mating Between Two Related Moth Species

“…In many species, HP volatiles have a clear effect on female behavior and influence the overall mating success of a courting male (Fitzpatrick and McNeil, 1988;Hillier and Vickers, 2004). In G. molesta, males 'flash' abdominal HPs directly in front of females that initiates short-range attraction (Baker and Cardé, 1979;Baker et al, 1981;Baker 1983).…”

“…The elaboration of male-specific structures, and the diversity of male courtship volatiles observed across taxa, suggest that HP volatile composition may communicate information that is species-specific (Hillier and Vickers, 2004). Male pheromones in courtship behavior are thought to be especially important between congeneric, sympatric species, particularly if the female sex pheromone composition is similar (Birch et al, 1990).…”

“…In H. virescens, HP volatiles facilitate mating with females capable of discriminating between HP mixtures of closely related species (Hillier and Vickers, 2004). HP composition in both H. virescens and H. subflexa is primarily a blend of saturated 14-18 carbon-chain alcohols, acetate esters, and carboxylic acids Tumlinson 1989, 1997;Teal and Oostendorp 1995).…”