Do bioflavonoids in Juniperus virginiana heartwood stimulate oviposition in the ladybird Coleomegilla maculata?

Authors: Riddick, Eric; Wu, Zhixin; Eller, Fred; Berhow, Mark

Submitted to: International Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2017
Publication Date: 2/28/2018
Publication URL: http://handle.nal.usda.gov/10113/5934966
Citation: Riddick, E.W., Wu, Z., Eller, F.J., Berhow, M.A. 2018. Do bioflavonoids in Juniperus virginiana heartwood stimulate oviposition in the ladybird Coleomegilla maculata? International Journal of Insect Science. 10:1-13. https://doi:10.1177/1179543318758409.

Interpretive Summary: Using beneficial insects (i.e., natural enemies) to reduce harmful insects on crop plants is an environmentally-friendly pest management option. Cost-effective rearing of natural enemies is necessary to provide the large numbers of individuals to release onto infested plants in gardens, nurseries, greenhouses, and high tunnels. One approach to reducing costs is to rear natural enemies on artificial foods or diets, which are less expensive than using live, natural prey. Unfortunately, artificial foods usually lack the stimulants to encourage natural enemies (adult females) to maximize their production of offspring, in rearing systems. In this study, we explored the possibility of using compounds derived from heartwood of the Eastern red cedar (Juniperus virginiana) to stimulate oviposition behavior in a mass-reared pink-spotted ladybird beetle (Coleomegilla maculata). In our chemical analyses (HPLC, LC-MS, etc.), we identified several bioflavonoid compounds in redcedar heartwood fractions. In our laboratory bioassays (in small cages), we discovered that bioflavonoid compounds (e.g., taxifolin, naringenin, and quercetin) attracted ladybird females and stimulated many of them to lay egg clutches. This study is the first to provide evidence that bioflavonoids stimulate oviposition in ladybird beetles. This study suggests that some bioflavonoids could help boost ladybird oviposition, which could be useful in mass-rearing programs.

Technical Abstract: Maximizing the reproductive potential of ladybird beetles fed factitious foods or artificial diets, in lieu of natural prey, is a major challenge to cost-effective mass-rearing for augmentative biological control. In this study, we tested the hypothesis that compounds in redcedar, Juniperus (J.) virginiana, stimulate oviposition in the ladybird Coleomegilla (C.) maculata. We also tested the prediction that several bioflavonoids, identified in heartwood fractions, elicited this behavioral response. Phenolic compounds were extracted from J. virginiana heartwood sawdust, separated into several fractions, then presented to adult beetles, in a powdered, pure form, in the laboratory. Females preferentially oviposited within 1-2 cm of fractions B, C, D, and E, but not A or the unfractionated extract, at the base of test cages. Chemical analysis identified bioflavonoids in heartwood fractions and subsequent bioassays using several identified in fractions C, D, and E confirmed that quercetin, taxifolin, and naringenin (to a lesser extent) stimulated oviposition. All tested fractions and bioflavonoids readily adhered to the chorion of freshly laid eggs, but did not reduce egg hatch. This study demonstrates that several bioflavonoids stimulate oviposition by C. maculata, which could be useful for mass-rearing programs.