Promiscuous mating systems are widely distributed among animals and can be promoted by operational sex ratios (number of receptive adults; OSR). In populations where OSR is not biased towards any sex, the possibility that males and females mate with several individuals increases. For both sexes to synchronize in time and space for reproduction, adults should possess or simultaneously acquire nutrients required to reach sexual maturity. Among synovigenic (without a full complement of eggs at eclosion) species, nutrient acquisition, protein in particular, may influence the OSR. In the Agave fly Euxesta bilimeki (Hendel) (Diptera: Ulidiidae), both sexes engage in multiple mating and females frequently expel all or part of the ejaculate. Here, we assessed the effect of protein intake on gonadic development, and estimated OSR from field-collected individuals. Body protein content was compared between wild and laboratory individuals with access to different diets, and mating frequency and individual mating rate were analyzed for cohorts at a 1:1 sex ratio. Both sexes required protein ingestion for gonadic development, but there were no differences in protein content between field-collected males and males fed protein and sugar in the laboratory, despite the fact that males assigned 9.3% of their corporal weight to testicles. Euxesta bilimeki is a promiscuous species where both males and females mate multiply with one or several individuals in short periods of time; thus, large testes size may be linked to the need of voluminous ejaculate production, and might be further exacerbated by female ejaculate expulsion.

中文翻译：

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性行为发育和工作性别比的模式促进Euxesta bilimeki（Diptera：Ulidiidae）的滥交

混杂交配系统在动物中广泛分布，并且可以通过工作性别比率（成年接受者的数量； OSR）来促进。在OSR不偏向任何性别的人群中，男性和女性与多个个体交配的可能性增加。为了使两性在时间和空间上同步繁殖，成年人应拥有或同时获得达到性成熟所需的营养。在滑膜增生（在羽化时没有卵的完整互补）物种中，营养物质的获取，特别是蛋白质，可能会影响OSR。在龙舌兰飞Euxesta bilimeki（Hendel）（Diptera：Ulidiidae），两性交配多次，雌性经常排出全部或部分射精。在这里，我们评估了蛋白质摄入对性腺发育的影响，并评估了田间采集的个体的OSR。比较野生和实验室饮食不同的人的身体蛋白质含量，并以1：1的性别比分析了人群的交配频率和个体交配率。男性和女性都需要蛋白质摄入才能发育，但是在田间采集的雄性和实验室中饲喂蛋白质和糖的雄性之间的蛋白质含量没有差异，尽管男性将睾丸的体重占9.3％。胆草是一种杂种，雄性和雌性都在短时间内与一个或几个个体交配；因此，大的睾丸大小可能与大量射精的需要有关，并且女性射精的排出可能会进一步加剧。