title: Amino acid composition of the bushcricket spermatophore and the function of courtship feeding: Variable composition suggests a dynamic role of the nuptial gift.
abstract: Nuptial gifts are packages of non-gametic material transferred by males to females at mating. These gifts are common in bushcrickets, where males produce a complex spermatophore consisting in a sperm-containing ampulla and an edible sperm-free spermatophylax. Two non-mutually exclusive hypotheses have been suggested to explain the function of the spermatophylax: the paternal investment hypothesis proposes that it represents a male nutritional investment in offspring; the mating effort hypothesis proposes that the spermatophylax maximizes the male's sperm transfer. Because gift production may represent significant energy expenditure, males are expected to adjust their investment relative to the perceived quality of the female. In this study, we first examined the free amino acid composition and protein-bound amino acid composition of the nuptial gift in the bushcricket, Ephippiger diurnus (Orthoptera: Tettigoniidae). Second, we investigated whether this composition was altered according to female age and body weight. Our study represents the first investigation of both free and protein-bound amino acid fractions of a bushcricket spermatophylax. We found that composition of the nuptial gift varied both qualitatively and quantitatively with respect to traits of the receiving female: older females received larger amounts of protein-bound amino acids (both essential and non-essential), less water and less free glycine. This result suggests that gift composition is highly labile in E. diurnus, and we propose that gift allocation might represent a form of cryptic male mate choice, allowing males to maximize their chances of paternity according to the risk of sperm competition that is associated with mate quality.
authors.affiliation: Institut de Recherche sur la Biologie de l'Insecte, UMR CNRS 7261, Université François-Rabelais, Parc Grandmont, 37200 Tours, France. Electronic address: alicia.jarrige@gmail.com.
authors.forename: Alicia
authors.initials: A
authors.lastname: Jarrige
authors.affiliation: Institut de Recherche sur la Biologie de l'Insecte, UMR CNRS 7261, Université François-Rabelais, Parc Grandmont, 37200 Tours, France.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Body
authors.affiliation: Institut de Recherche sur la Biologie de l'Insecte, UMR CNRS 7261, Université François-Rabelais, Parc Grandmont, 37200 Tours, France.
authors.forename: David
authors.initials: D
authors.lastname: Giron
authors.affiliation: Institut de Recherche sur la Biologie de l'Insecte, UMR CNRS 7261, Université François-Rabelais, Parc Grandmont, 37200 Tours, France.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Greenfield
authors.affiliation: Institut de Recherche sur la Biologie de l'Insecte, UMR CNRS 7261, Université François-Rabelais, Parc Grandmont, 37200 Tours, France.
authors.forename: Marlène
authors.initials: M
authors.lastname: Goubault
mesh_terms: D000367:Age Factors; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D006135:Gryllidae / Q000502:physiology*; D008297:Male; D012727:Sex Characteristics; D012726:Sexual Behavior, Animal / Q000502:physiology*; D013093:Spermatogonia / Q000378:metabolism*
chemical_list: D000596:Amino Acids
keywords: Ephippiger diurnus; Free amino acids; Male mate choice; Protein bound amino acids; Strategic allocation