Perception of Conspecific Female Pheromone Stimulates Female Calling in an Arctiid Moth, Utetheisa ornatrix

Abstract

Perception of the female sex pheromone in Utetheisa ornatrix (Lepidoptera: Arctiidae) is responsible for induction and adjustment of calling by females and the collective phenomenon termed "female pheromonal chorusing". We found five olfactory-active compounds in the U. ornatrix female gland. When females were exposed to the entire pheromone or to two of its (synthetically prepared) components, (Z,Z,Z)-3,6,9-eicosatriene and (Z,Z,Z)-3,6,9-heneicosatriene, they were more likely to call during a given night, begin calling earlier, and briefly increase signal frequency with which they extrude their abdomen, an observable indication of calling in this species. Some females even initiated calling during photophase when exposed to the pheromone components. In general, female U. ornatrix are more sensitive to the complete blend of pheromone than to its individual compounds. We also tested the hypotheses: 1) that abdominal extrusion per se increases the rate of pheromone release; and 2) that greater abdominal pumping rhythm increases pheromone release rate. Contrary to our expectations: 1) females did not respond more strongly to a pulsed pheromone stimulus than to the constant release of pheromone at the same average release rate; and 2) we did not find a relationship between the frequency of abdominal pumping and pheromone release rate. Possible explanations for these unexpected findings are discussed.

Pheromone production, male abundance, body size, and the evolution of elaborate antennae in moths

“…This was not feasible for the present study because comparative data on release rates for moth species are very sparse. Both pheromone titre and release rates vary within species and within individuals, relating to age, time of day, and proximity of other individuals (e.g., Sanders and Lucuik 1972; Raina et al 1986; Foster et al 1995; Lim et al 2007). Although there is evidence that release rates are limited by pheromone gland titres (Schal et al 1987), and that pheromone titre is reflective of pheromone release rate (see Methods), it is possible that using fixed quantities of pheromone as a substitute for the quantity released is simply too inaccurate.…”

Geographic and Temporal Variation in Moth Chemical Communication

“…Many female moths can perceive their own pheromone as well as pheromone compounds of other species (e.g., Ljungberg et al 1993; Schneider et al 1998; Groot et al 2005b; Hillier et al 2006). Also, most female moths produce their sex pheromone de novo every night (e.g., Raina 1989; Rafaeli 2002; Jurenka 2003), and can modulate the time and temporal patterning of pheromone release (calling) in relation to environmental conditions (Schal and Cardé 1985; Lim et al 2007) and presence of conspecifics (Conner et al 1980; Lim and Greenfield 2007, 2008). Hence, it may be possible that females can vary their biosynthesized as well as emitted pheromone blend to some extent depending on the prevailing olfactory cues in their habitat.…”

Non-Host Plant Volatiles Disrupt Sex Pheromone Communication in a Specialist Herbivore

“…Female calling behaviors are also modulated by sex pheromone reception5051, a form of autodetection that may mediate interaction among females to avoid competition. In general, mating disruption with synthetic chemicals may be costly, and its effect on female behavior may be limited52.…”