Macronutrient composition of spermatophores of Cryptolaemus montrouzieri varies depending on male feeding

Many insect species produce nutritive ejaculates, which represent the
male’s contribution to female reproductive fitness. Studies on the
quantification of male contribution are assessed via indirect observations
and direct assessment through the post-copulation effect on female
reproductive performance, such as longevity and fecundity. Few studies
directly address the nutritive content transferred by males via
spermatophores. In species with multiple copulations, males produce
ejaculates whose proportion of allocated substances varies according to
the adult diet. We hypothesized that the spermatophores of C.
montrouzieri show significant variations in nutrient composition when
dietary modifications occur and whether this affects female fecundity and
fertility. To test this hypothesis, we analyzed the macronutrient
proteins, lipids, sugars, and glycogen using colorimetric methods. We
tested for quantitative changes in these macronutrients in adult males
well-fed with Planococcus citri mealybugs, under limited amounts of P.
citri (food scarcity), and with honey. The macronutrient profile of a
spermatophore from a well-fed C. montrouzieri is composed of
approximately 49.62 µg/ml lipids, 5.18 µg/ml glycogen, 3.25 µg/ml sugar,
and 0.27 µg/ml proteins. When compared to the spermatophores produced by
males subjected to food scarcity or honey, no significant difference was
found in the macronutrients. Fecundity was not affected, but there was a
significant reduction in fertility in females that mated with males fed
with honey.

诸多昆虫物种均可产生营养型射精物（ejaculates），此类物质乃是雄性对雌性生殖适合度的贡献。现有针对雄性贡献量化的研究，多通过间接观测，或是基于交配后对雌性生殖表现（如寿命与繁殖力）的影响开展直接评估。鲜有研究直接探讨雄性通过精荚（spermatophores）转移的营养物质含量。在具有多次交配行为的物种中，雄性产生的射精物中分配物质的比例会随成虫期饮食发生变化。本研究提出假设：当饮食条件改变时，C. montrouzieri的精荚营养成分会出现显著变化，且该变化会影响雌性的繁殖力与受精率。为验证该假设，本研究采用比色法分析了宏量营养素：蛋白质、脂质、糖类与糖原。本研究检测了以下三组成虫雄性的上述宏量营养素含量变化：以柑橘臀纹粉蚧（Planococcus citri）为充足食物的饱食组、以少量P. citri为食的食物匮乏组，以及饲喂蜂蜜组。饱食组C. montrouzieri的精荚宏量营养素组成约为：脂质49.62 µg/ml、糖原5.18 µg/ml、糖类3.25 µg/ml、蛋白质0.27 µg/ml。与食物匮乏组或蜂蜜饲喂组雄性产生的精荚相比，上述宏量营养素未出现显著差异。雌性的繁殖力未受影响，但与饲喂蜂蜜的雄性交配后的雌性，其受精率出现了显著下降。