Genome of the hoverfly Eupeodes corollae provides insights into the evolution of predation and pollination in insects.

Background: Hoverflies (Diptera: Syrphidae) including Eupeodes corollae are important insects worldwide that provide dual ecosystem services including pest control and pollination. The larvae are dominant predators of aphids and can be used as biological control agents, and the adults are efficient pollinators. The different feeding habits of larvae and adults make hoverflies a valuable genetic resource for understanding the mechanisms underlying the evolution and adaptation to predation and pollination in insects.

Results: Here, we present a 595-Mb high-quality reference genome of the hoverfly E. corollae, which is typical of an aphid predator and a pollinator. Comparative genomic analyses of E. corollae and Coccinellidae (ladybugs, aphid predators) shed light on takeout genes (3), which are involved in circadian rhythms and feeding behavior and might regulate the feeding behavior of E. corollae in a circadian manner. Genes for sugar symporter (12) and lipid transport (7) related to energy production in E. corollae had homologs in pollinator honeybees and were absent in predatory ladybugs. A number of classical cytochrome P450 detoxification genes, mainly CYP6 subfamily members, were greatly expanded in E. corollae. Notably, comparative genomic analyses of E. corollae and other aphidophagous hoverflies highlighted three homologous trypsins (Ecor12299, Ecor12301, Ecor2966). Transcriptome analysis showed that nine trypsins, including Ecor12299, Ecor12301, and Ecor2966, are strongly expressed at the larval stage, and 10 opsin genes, which are involved in visual perception, are significantly upregulated at the adult stage of E. corollae.

Conclusions: The high-quality genome assembly provided new insights into the genetic basis of predation and pollination by E. corollae and is a valuable resource for advancing studies on genetic adaptations and evolution of hoverflies and other natural enemies.