Sensory exploitation as an evolutionary origin to nuptial food gifts in insects

Abstract

Nuptial food gifts given by males to females at mating are widespread in insects, but their evolutionary origin remains obscure. Such gifts may arise as a form of sensory trap that exploits the normal gustatory responses of females, favouring the selective retention of sperm of gift-giving males. I tested this hypothesis by o¡ering foreign food gifts, synthesized by males of one cricket species, to females of three nongift-giving species. Females provisioned with novel food gifts were`fooled' into accepting more sperm than they otherwise would in the absence of a gift. These results support the hypothesis that nuptial food gifts and post-copulatory female mating preferences coevolve through a unique form of sensory exploitation.

Free amino acids as phagostimulants in cricket nuptial gifts: support for the ‘Candymaker’ hypothesis

“…Evidence that sensory 'exploitation' may have been involved in the evolutionary origin of the spermatophylax in G. sigillatus was provided by Sakaluk (2000) and Sakaluk et al (2006). Sakaluk (2000) demonstrated that even in three cricket species that do not produce a spermatophylax, females readily accepted and consumed spermatophylaces obtained from G. sigillatus and accepted more sperm from their mates as a result of spermatophylax consumption.…”

“…Sakaluk (2000) demonstrated that even in three cricket species that do not produce a spermatophylax, females readily accepted and consumed spermatophylaces obtained from G. sigillatus and accepted more sperm from their mates as a result of spermatophylax consumption. The presence of phagostimulants within the nuptial gifts of G. sigillatus, as documented in the present study, provides a proximate mechanism underlying this result.…”

“…The presence of phagostimulants within the nuptial gifts of G. sigillatus, as documented in the present study, provides a proximate mechanism underlying this result. Sakaluk et al (2006) found that in one of the species of nonnuptial feeding crickets used in Sakaluk's (2000) experiments, the consumption of the spermatophylax appeared to delay the female from remating. It is possible that the high level of free glycine in the spermatophylax, demonstrated here, could account for this delay in remating.…”

“…Recently, nuptial feeding has been re-examined from the perspective of sexual conflict (reviewed in Vahed 2007;Gwynne 2008;Wedell et al 2008). Sakaluk (2000) and Sakaluk et al (2006) proposed that nuptial gifts may act as 'sensory traps' (Christy 1995). By 'exploiting' the female's normal gustatory responses, a male may be able to entice a female to accept superfluous matings, transfer a greater volume of ejaculate than is in the female's interests and/or transfer substances that manipulate the remating or egg-laying behaviour of the female to serve the male's interests (reviewed in Arnqvist & Rowe 2005;Vahed 2007).…”

“…If nuptial gifts do act as sensory traps, they will be selected to be attractive to the female, but need not necessarily be selected to provide her with nutritional benefits (Sakaluk 2000;Vahed 2007). This has been termed the 'Candymaker' hypothesis ( Warwick 1999).…”