Expulsion and consumption of male ejaculates by promiscous female Euxesta eluta and Euxesta mazorca (Diptera: Ulidiidae)

ABRAHAM, SOLANA; RODRÍGUEZ, CHRISTIAN; OVIEDO, ANDREA; MURÚA, GABRIELA; RULL, JUAN

JOURNAL OF NATURAL HISTORY

TAYLOR & FRANCIS LTD

Lugar: Londres; Año: 2018 vol. 52 p. 1493 - 1508

0022-2933

While expulsion of male ejaculates by the females after copulationhas been reported for various animal groups, expulsionfollowed by consumption of the expelled ejaculate is a rarebehaviour outside spermatophylax-producing orthopterans.Among Diptera, this behaviour has been reported for a fewspecies of Piophilidae, Empididae and Ulidiidae. Here we reporton its occurrence among Euxesta eluta and Euxesta mazorca(Diptera: Ulidiidae). We also attempt to characterize the matingsystem of E. eluta in order to facilitate future hypothesis testingto understand the behavioural factors leading to the evolutionof this peculiar behaviour. For this, courtship sequences, copulationduration, frequency of ejaculate expulsion and subsequentconsumption, and latency to ejaculate expulsion forboth E. eluta and E. mazorca were recorded. The time of sexualmaturation, the time window of sexual receptivity during theday, and the mating frequency and variance in mating successfor males and females (degree of polygamy) were determinedfor E. eluta. Both E. eluta and E. mazorca males engaged inelaborate courtship sequences involving visual and tactile displaysbefore copulation. Females of both species almost invariablyexpelled and consumed ejaculates after copulation. FemaleE. eluta, required a 6- to 9-day period feeding on protein andsugar before becoming sexually receptive. Reproductive activityoccurred continuously over the day with an early morning andlate afternoon peak. Both males and females could mate multiply,with multiple partners over a 2-h observational period.Sexual network analysis revealed that some males and femaleshad greater mating success than others. Ejaculate consumptionappears to be widespread in the genus Euxesta. It is possiblethat females obtain nutrients from this behaviour while exertingsome control over egg fertilization.