A Two-Component Female-Produced Pheromone of the Spider Pholcus beijingensis

Abstract

Chemical signaling plays an important role in spider sexual communication, yet the chemistry of spider sex pheromones remains poorly understood. Unlike insects and mammals, the identification of spider pheromones has seldom been attempted, and no multicomponent pheromones have been found. Empty webs of sexually receptive females of Pholcus beijingensis were more attractive to male conspecifics as compared to webs of sexually unreceptive females or to mature males. Coincidently, chemical analysis revealed that (E,E)-farnesyl acetate, diisobutyl phthalate, and hexadecyl acetate of the spider webs exhibited higher relative abundances in sexually receptive females than in sexually unreceptive females or males, indicative of possible pheromone components. Two-choice behavioral assays verified that the blend of (E,E)-farnesyl acetate and hexadecyl acetate (w/w: 2:1) attracted males at a dosage equivalent to the amounts of these compounds in one spider web, whereas neither compound alone aroused males. In addition, diisobutyl phthalate (a likely contaminant from contact with plastic) alone or in combination with either of the acetates did not evoke the males' attraction. The behavioral data suggest that (E,E)-farnesyl acetate and hexadecyl acetate comprise a two-component female-produced sex pheromone in P. beijingensis, the first multicomponent pheromone found in spiders.

Male-specific ( Z )-9-tricosene stimulates female mating behaviour in the spider Pholcus beijingensis

“…their palps at the last phase of the courting procedure will the females turn from passive to active, which leads directly to copulation (Xiao et al 2009). …”

“…Males abandon their webs after their last moult to search for potential mates while the females wait on their webs for males (Chen & Li 2005). We have demonstrated that a combination of (E,E )-farnesyl acetate and hexadecyl acetate acts as a female-produced sex pheromone in this species (Xiao et al 2009). The mate-searching males (MMs) can locate potential mates based on the sex pheromone associated with the female's silk.…”

“…In courtship sequences of P. beijingensis, the male unfolding its pedipalps towards the female is seen as a critical behavioural pattern because it implies courting success. At this point, the female turns from passive to active and approaches the male for mating (Xiao et al 2009). To determine whether the adults were reproductively active, we paired each male with an adult female on her web and checked for courtship behaviour.…”

“…The mate-searching males (MMs) can locate potential mates based on the sex pheromone associated with the female's silk. The approach of an MM, unlike a female or immature male, rarely triggers predatory or aggressive behaviour in the sexually receptive female (Chen & Li 2005;Xiao et al 2009). Therefore, we hypothesized that MMs might emit scents acting at a close range as sexual attractants and/or stimulants for the conspecific mature females.…”

Chemical Communication in Schizocosa malitiosa: Evidence of a Female Contact Sex Pheromone and Persistence in the Field

“…Most studies have reported polar solvents as more suitable (Gaskett 2007), and in fact the two characterized contact pheromones associated with female web threads from the linyphiid, Linyphia tringularis (Schulz and Toft 1993), and the ctenid, Cupiennius salei (Papke et al 2000), are both polar compounds bearing free hydroxyl and carboxyl groups, and therefore readily soluble in methanol or water. Nonetheless, non-polar to moderately polar fatty acid and methyl ester pheromones also have been described; cuticle and web contact pheromones in Tegenaria atrica (Agelenidae) (Prouvost et al 1999), the female-emitted volatile (8-methylnonan-2-on) from A. aperta (Papke et al 2001), and (E,E)-farnesyl acetate and hexadecyl acetate associated with the web of Pholcus beijingensis females (Pholcidae) (Xiao et al 2009). …”