Diet-driven reproduction: exploring the relationship between aphid feeding and fertility in the lady beetle Eriopis connexa (Coleoptera: Coccinellidae)

Abstract Eriopis connexa , a neotropical aphidophagous lady beetle important for various soft-bodied pest species control, requires feeding on aphids for enhanced reproductive output. To understand the physiological basis of this dependency, we investigated how the absence of the preferred prey, aphids, affects E. connexa reproductive fitness. We compared females fed only Ephestia kuehniella eggs (a factitious food) with those provided E. kuehniella eggs alongside limited access to the aphid Lipaphis pseudobrassicae (a preferred prey). Egg numbers were similar in females from both diets after 60 days. However, females on an aphid-supplemented diet cease oviposition around day 30, exhibiting egg viability around 35%. Conversely, females fed with E. kuehniella eggs alone cease oviposition around day 60, with egg viability close to 0. These females also exhibited greater longevity. At the molecular level, the lack of aphids resulted in females with a ~twofold downregulation of Vitellogenin 1 ( Vg1 ) and a dramatic ~40-fold upregulation of its receptor, VgR . Key genes in the insulin signaling pathway ( AKT and FoxO ) were also upregulated. Biochemically, the aphid-free diet led to females with higher glycogen levels, supported by the upregulation of Glycogen Synthase ( GS ). Therefore, the absence of aphids in E. connexa diet led to altered egg-laying pattern, reduced fertility and longer lifespan. This physiological shift, mediated by the insulin pathway and glycogen levels, highlights how preferred prey regulates reproductive success. These findings provide a basis for optimizing mass-rearing protocols, allowing for more cost/labor-effective maintenance of E. connexa in biological control programs.