Utilization of quercetin as an oviposition stimulant by lab-cultured Coleomegilla maculata in the presence of conspecifics and a tissue substrate

Authors: Riddick, Eric; WU, ZHIXIN; Eller, Fred; BERHOW, MARK

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/26/2018
Publication Date: 6/29/2018
Publication URL: http://handle.nal.usda.gov/10113/6472327
Citation: Riddick, E.W., Wu, Z., Eller, F.J., Berhow, M.A. 2018. Utilization of quercetin as an oviposition stimulant by lab-cultured Coleomegilla maculata in the presence of conspecifics and a tissue substrate. Insects. 9:1-14.

Interpretive Summary: A major challenge to biological control is providing sufficient quantities of natural enemies (predators) to control plant pests in greenhouses, high tunnels, gardens, and nurseries. Utilizing plant-based compounds to stimulate predators to lay more eggs, so that more predators are available to control pests, could be advantageous. In this study, researchers tested the bioactivity of a flavonoid compound (quercetin) to stimulate egg production in a predatory ladybird beetle (Coleomegilla (C.) maculata). They discovered that the flavonoid was effective. Female ladybirds preferred to lay their eggs within 1-2 cm of quercetin powder in solitary cages (containing a single female) and in communal cages (containing 10 females). The placement of a tissue paper substrate close to the quercetin powder tended to encourage some females to lay slightly more egg clutches than when the tissue was absent. This study proves that quercetin can help boost egg laying in the ladybird C. maculata. In turn, more offspring could be produced and then released in high tunnels etc. for pest control.

Technical Abstract: Background: The discovery of natural products to improve reproductive performance of mass-reared predators is an important aim for successful augmentative biological control. We tested the hypothesis that quercetin (a bioflavonoid) stimulates oviposition by the predatory ladybird Coleomegilla maculata. Methods: We conducted bioassays in solitary cages (housing 1 female) and communal cages (housing 10 females) to estimate daily oviposition site preferences, egg production in response to quercetin in the presence or absence of a tissue paper substrate, and female “resting” positions. Results: Females preferentially oviposited within 1-2 cm of quercetin powder, held in a tiny dish, at the base of cages. When given a choice, females preferred ovipositing in the dish with quercetin over a tissue paper substrate. But they produced slightly more egg clutches, regardless of oviposition site, when quercetin and tissue were in close juxtaposition. Females often “rested” on the tissue in the presence or absence of quercetin. Conclusion: This study provides evidence that quercetin can be utilized as an oviposition stimulant by C. maculata in a rearing system. Future research should determine if quercetin stimulates oviposition in other ladybird beetle species.