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

Abstract

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 analysed the macronutrients 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 with 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.