Mating in katydids and crickets Orthoptera Tettigoniidae and Gryllidae

During copulation the males of many species of katydids and some crickets transfer elaborate spermatophores, which are attached externally to the female's genitalia. Each spermatophore consists of a large, proteinaceous, sperm-free portion, the spermatophylax, which is eaten by the female after mating, and a sperm ampulla, eaten after the spermatophylax has been consumed and the sperm

Spermatophylax

have been transferred to the female. The illustration shows a recently mated female Mormon cricket, Anabrus simplex, with a spermatophore attached to her gonopore; in the illustration on the upper right, the female is consuming the spermatophylax of the spermatophore (after Gwynne 1981). The schematic illustration underneath depicts the posterior of a female Mormon cricket showing the two parts of the spermatophore: the spermatophylax (hatched) and the sperm ampulla (stippled) (after Gwynne 1990). During consumption of the spermatophylax, sperm are transferred from the ampulla, and substances are ingested or transferred that "turn off" female receptivity to further males. Insemination also stimulates oviposition by the female, thereby increasing the probability that the male supplying the spermatophore will fertilize the eggs.

There are two main hypotheses for the adaptive significance to the male of this form of nuptial feeding. The spermatophylax may be a form of parental investment in which nutrients from the male increase the number or size of the eggs sired by that male. Alternatively, viewed in the context of sexual conflict, the "candymaker" hypothesis suggests that the spermatophylax is a "sensory trap" that lures the female into superfluous and/or prolonged matings that have a couple of possible benefits to the male. In particular, the spermatophylax may serve as a sperm-protection device by preventing the ampulla from being removed until after the complete ejaculate has been transferred, which may not be in the female's interests. Such prolonged insemination also may allow transfer of male secretions that manipulate the remating or oviposition behavior of the female to the benefit of the male's reproductive success. Of course, the spermatophylax may serve the purposes of both offspring nutritional investment and male mating effort, and there is evidence from different species to support each hypothesis. Experimental alteration of the size of the spermatophylax has demonstrated that females take longer to eat larger ones, but in some katydid species the spermatophylax is larger than is needed to allow complete insemination and, in this case, the nutritional bonus to the female may benefit the male's offspring. However, recent chemical analysis of the spermatophyllax of a Gryllodes cricket showed that its free amino acid composition was highly imbalanced, being low in essential amino acids and high in phagostimulatory amino acids that probably increase the attractiveness of a low-value food. The latter data lend support to the candymaker hypothesis. Nevertheless, some female orthopterans may benefit directly from consumption of the spermatophyllax, as it has been shown for the females of a European katydid able to route male-derived nutrients to their own metabolism within a few hours after spermatophyllax consumption. The function of the spermatophylax no doubt varies among genera, although phylogenetic analysis suggests that the ancestral condition within the Tettigoniidae was to possess a small spermatophylax that protected the ejaculate.

Beekeeping for Beginners

Beekeeping for Beginners

The information in this book is useful to anyone wanting to start beekeeping as a hobby or a business. It was written for beginners. Those who have never looked into beekeeping, may not understand the meaning of the terminology used by people in the industry. We have tried to overcome the problem by giving explanations. We want you to be able to use this book as a guide in to beekeeping.

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