Identification of cuticular lipids eliciting interspecific courtship in the German cockroach, Blattella germanica

Abstract

The cuticular surface of sexually mature females of the German cockroach contains a sex pheromone that, upon contact with the male's antennae, elicits a characteristic species-specific courtship behavior. This female-specific pheromone is a blend of several long-chain methyl ketones, alcohols and aldehydes, all derived from prominent cuticular hydrocarbons found in all life stages of this cockroach. We found that contact with the antennae of 5 out of 20 assayed cockroach species elicited courtship behavior in German cockroach males. The heterospecific courtship-eliciting compounds were isolated by behaviorally guided fractionation of the active crude extracts and compared to the native sex pheromone components. We identified two active compounds from the cuticular extract of the Oriental cockroach, Blatta orientalis -- 11-methylheptacosan-2-one and 27-oxo-11-methylheptacosan-2-one; the former compound was confirmed by synthesis and proved to independently stimulate courtship in German cockroach males. These compounds share common features with, but are distinct from, any of the known contact sex pheromone components. This suggests that sex pheromone reception in the male German cockroach is unusually promiscuous, accepting a wide range of compounds that share certain features with its native pheromone, thus resulting in a broad spectrum of behavioral response to other species. We propose that several characteristics of their mating system -- chiefly, absence of closely related species in the anthropogenic environment, resulting in relaxation of selection on sexual communication, and a highly male-biased operational sex ratio -- have driven males to respond with extremely low thresholds to a wide spectrum of related compounds.

The production of female sex pheromone in Bactrocera oleae (Rossi) young males does not influence their mating chances

“…1992; Ruther et al . 2001), cockroaches (Eliyahu et al . 2008), flies (Curcillo & Tompkins 1987; Vaias et al .…”

“…any advantages. The production of female sex pheromones and/or attractants in young individuals of both sexes was ascertained in several insects including beetles (Haynes et al 1992;Ruther et al 2001), cockroaches (Eliyahu et al 2008), flies (Curcillo & Tompkins 1987;Vaias et al 1993) and parasitic wasps (Steiner et al 2005;Ruther & Steiner 2008). To date, several cases of the evolution of sex pheromones from originally noncommunicative semiochemicals being present in both sexes were reported.…”

Variation in mate recognition specificities among fourCallosobruchusseed beetles

“…This species harbors eight contact sex pheromone compounds derived from dimethylalkanes, and each of these compounds can independently elicit courtship behavior (Nishida & Fukami, 1983; Schal et al., 1990; Eliyahu et al., 2004, 2008a). The dissected antennae of some closely related species of B. germanica were found to elicit courtship in some males of B. germanica (Nishida & Fukami, 1983; Eliyahu et al., 2008b), and the contact sex pheromone analogs identified from the Oriental cockroach, Blatta orientalis L. were found to elicit courtship behavior in males of B. germanica (Eliyahu et al., 2008b). In the case of the cockroach, it was suggested that the absence of closely related species in their environment had relaxed selection on the fine‐tuned, species‐specific, close‐range sexual communication compounds in B. germanica (Eliyahu et al., 2008b).…”

The evolution of species recognition labels in insects

“…When males detect these pheromones, or detached female antennae that have the pheromones on their surface, they exhibit a stereotypical courtship behaviour. Interestingly, experiments using detached antennae demonstrate that male German cockroaches responded positively to 5 of 20 roach species, some of which are very distantly related [30]. The authors suggest that this permissive mate acceptance behaviour may have evolved, in part, as a byproduct of relaxed selective pressure in the anthropogenic environment where German cockroaches live.…”