The Natural History and Unusual Mating Behavior ofEuxesta bilimeki(Diptera: Ulidiidae)

Abstract

We report results of a 2-yr study aimed at describing the natural history and mating behavior of Euxesta bilimeki (Hendel) (Diptera: Ulidiidae) a picture-winged fly species associated with Agave atrovirens Karw. ex Salm-Dyck (Agavaceae) in the Mexican altiplano. The study consisted of direct field observations and a year-long population survey in the field complemented with laboratory experiments and observations. E. bilimeki was found to be multivoltine, able to resist temperatures below freezing during winter, and it developed on rotting agave leaves in large larvalpupal aggregations. Adults fed on carbohydrate and protein sources found on the plant, where they could be sighted all year long. Courtship was based on a sequence of visual and tactile displays that could result in female rejection of courting males. Males constantly harassed females, who mated multiple times, but frequently expelled and consumed ejaculates after mating. We discuss hypotheses on the evolution of this rare behavior and highlight the value of performing descriptive studies on the natural history of poorly known taxonomic groups to foster understanding of the evolution of behavior.

Spermatophore consumption in a cephalopod

“…Unlike previously reported species exhibiting gamete consumption [5][6][7][8][9][10], the sperm of male southern bottletail squid do not enter the female reproductive tract. All spermatangia (and their accompanying sperm) are retained in the external buccal cavity for approximately three weeks, after which time they appear to no longer persist for egg fertilization (figure 2b).…”

“…Despite ejaculate consumption being well documented in nature [1][2][3][4], actual sperm consumption is rare. Where it has been found, males transfer their ejaculates to females via either placement of packaged sperm (spermatophores) on the cuticle [5,6], or direct deposition into the reproductive tract [7][8][9][10]. Once transfer is complete, females may consume a portion of these ejaculates postcopulation.…”

Promiscous female Euxesta eluta derive nutrients for ovarian development by expelling and consuming ejaculates

“…The intake of protein from adult food is essential for egg maturation and therefore for successful reproduction in anautogenous insects (Attardo et al ., ; Roy et al ., 2018). Adult E. bilimeki have been observed in nature feeding on different protein sources such as bird and lizard faeces, dead arthropods, and rotting agave tissue (Brunel & Rull, ). Moreover, Rodriguez et al .…”

“…Examination of the natural history of Euxesta bilimeki Hendel, a fly associated to Agave atrovirens Karw. ex Salm‐Dyck, in the Mexican Altiplano, revealed that females expel and consume ejaculates after copulation (Brunel & Rull, ). More recent behavioral scrutiny on two corn infesting species, Euxesta eluta Loew, and Euxesta mazorca Steyskal (Abraham et al ., ), revealed that this peculiar behavior may be widespread among the entire genus.…”

“…After expelling ejaculates from males after copulation, consumption could provide females with nutrients and fluids for survival and/or reproduction. The testes in male E. bilimeki occupy 70% of the abdominal cavity (Brunel & Rull, ), large testes are thought to be the result of intense sperm competition in promiscuous mating systems (Simmons & Fitzpatrick, ), however ejaculate expulsion may result in little opportunity for the sperm of several males to interact in the female's tract. Ejaculate expulsion and consumption could be the result of females having the upper hand of a sexual conflict over mating rate, where males have to supply large amounts of nutrients before fertilizing eggs.…”