Effect of Wild Radish on Preimaginal Development of Diabrotica balteata and Agrotis ipsilon

Abstract

Aqueous extracts of wild radish (Rhaphanus raphanistrum L.) roots, stems, and leaves combined were examined for antibiotic effects on hatching and larval development of the banded cucumber beetle, (Diabrotica balteata Le Conte [Coleoptera: Chrysomelidae]) and black cutworm (Agrotis ipsilon [Hufnagel] [Lepidoptera: Noctuidae]). Hatching was delayed significantly in eggs of D. balteata exposed to the wild radish extract for 18 h. In some trials, the hatching percentage increased to levels similar to other treatments by the third and final day of hatching; in others, the percentage hatching remained significantly less among eggs exposed to wild radish extract for the duration of the study. The mortality rate of D. balteata larvae was increased significantly by exposure to the wild radish extract. Hatching of A. ipsilon eggs was delayed significantly after an 18 h exposure to the aqueous wild radish extract 4 d after treatment in only one of the six trials. In that trial, all treatment results were similar by day 5. In other trials, hatching of A. ipsilon was decreased similarly in eggs exposed for 18 h in an aqueous wild radish treatment as well as the water control. Although this study shows an effect of aqueous wild radish extract on two insect species, supplemental studies which utilize methods that do not rely upon an aqueous solution may better define the insect suppression activity of wild radish.

KEYWORDS:

• black cutworm
• corn
• corn rootworm
• pest suppression
• preimaginal development
• vegetables
• wild radish

The authors thank Margaret Nakakande for technical support, and Gerald Carner, Michael Hood and two anonymous reviewers for suggestions on the manuscript. This research was supported in part by Southern Region SARE Project, “Suppression of Weeds and Other Pests in Fresh Market Vegetables Using a Wild Radish Cover Crop.” This is Technical Contribution No. 5286 of the Clemson University Experiment Station. Mention of a proprietary product does not constitute an endorsement of a recommendation.