Spermatophylax

The spermatophylax is a protein-containing appendage to the spermatophores of long-feeler terrors (Ensifera). The spermatophylax probably evolved at least three times and is found today in most leaf locusts (Tettigoniidae) as well as some real crickets (Gryllidae) and Haglidae . Many female locusts remove the sperm packet some time after mating and begin to eat it up. It is therefore believed that the spermatophylax originally served to protect the sperm packet. This could also be proven by experiments in which sperm packages without spermatophylax were transferred to females, which were completely eaten, so that fertilization did not take place.

In some species, due to their size and protein content, the spermatophylax has a nutritional value that goes well beyond what would be necessary to keep the female from eating the sperm packet. In these cases it could be shown that the consumption of the spermatophylax led to a higher egg weight and an accelerated development of the young animals, so that the production of such a metabolically complex spermatophylax probably serves as a male investment in the fitness of the offspring.

The exact expression of the spermatophylax can, depending on the respective species, be subject to both sexual selection in the context of competition between the sexes and natural selection in the context of a direct transfer of the male's fitness to his offspring.

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• Darryl T. Gwynne: The evolution of edible sperm sacs and other forms of courtship feeding in crickets, katydids and their kin (Orthoptera: Ensifera) . In: Jae C. Choe, Bernard J. Crespi (Eds.): The evolution of mating systems in insects and arachnids . Cambridge University Press, Cambridge 1997, ISBN 978-0-521-58976-5 , pp. 110-129 (English).