Larger ejaculate volumes are associated with a lower degree of polyandry across bushcricket taxa

Abstract

In numerous insects, including bushcrickets (Tettigoniidae), males are known to transfer substances in the ejaculate that inhibit the receptivity of females to further matings, but it has not yet been established whether these substances reduce the lifetime degree of polyandry of the female. The aim of this study was to test the hypothesis that larger ejaculate volumes should be associated with a lower degree of polyandry across tettigoniid taxa, controlling for male body mass and phylogeny. Data on ejaculate mass, sperm number, nuptial gift mass and male mass were taken primarily from the literature. The degree of polyandry for 14 species of European bushcrickets was estimated by counting the number of spermatodoses within the spermathecae of field-caught females towards the end of their adult lifespans. Data for four further species were obtained from the literature. Data were analysed by using both species regression and independent contrasts to control for phylogeny. Multiple regression analysis revealed that, as predicted, there was a significant negative association between the degree of polyandry and ejaculate mass, relative to male body mass, across bushcricket taxa. Nuptial gift size and sperm number, however, did not contribute further to interspecific variation in the degree of polyandry. A positive relationship was found, across bushcricket taxa, between relative nuptial gift size and relative ejaculate mass, indicating that larger nuptial gifts allow the male to overcome female resistance to accepting large ejaculates. This appears to be the first comparative evidence that males can manipulate the lifetime degree of polyandry of their mates through the transfer of large ejaculates.

Male Mating History in Antheraea mylitta and its Effect on Ejaculation Size and Female Reproductive Fitness

“…Such a huge quantity of sperm ejaculation by male in to the body of female might be the reason behind monoandrous nature which ceases the receptivity of the female further in this wild species. Larger ejaculate volumes associated with low degree of polyandry that are reported in bushcricket texa, agrees with our findings (Vahed, 2006).…”

Female bushcrickets fuel their metabolism with male nuptial gifts

“…The d 13 C breath of females feeding on nuptial gifts from males of group 1 (open circles) remained constant, whereas that of females feeding on nuptial gifts from males of group 2 (closed circles) decreased in 13 C enrichment over time. Vahed & Gilbert 1996;Vahed 2006). Females may then benefit from spermatophore consumption and combustion by not having to search for additional food (see Boggs 1990), and by being less likely to fall prey to predators (Heller 1992).…”

Social cues of sperm competition influence accessory reproductive gland size in a promiscuous mammal

“…Evidence from comparative studies indicates that species in which levels of sperm competition are high may also have relatively large accessory reproductive glands, which function in the production of these proteins (e.g. [13,14], but see [15,16]). For example, high levels of sperm competition among rodents are associated with relatively large seminal vesicles, and relatively large copulatory plugs transferred during mating [14].…”