Acute and chronic effects of neem on Myzocallis coryli (Homoptera: Aphididae)

Abstract

Adults and immatures of the filbert aphid, Myzocallis coryli (Goetze), a major pest of hazelnuts worldwide, were exposed to foliage treated with different concentrations of a botanical insecticide, Margosan-O, derived from extract of neem seeds. Both mature and immature stages were highly sensitive to this compound. Acute toxicity causing immediate mortality of young nymphs, particularly at higher rates (50 ppm or more), and chronic effects resulting in reduced offspring production, lengthening of nymphal development time and reduced survival of subsequent generation were recorded. The offspring production of adult aphids fed on treated leaves was reduced in a dosage-dependent manner, nearly 50% at 2.5 ppm to over 80% at 62.5 ppm. However, no nymphal survival was recorded at 25 ppm or higher doses. A repellency effect was also recorded, butthe feeding deterrence response was weak at best. Field trials also showed a marked reduction of aphid numbers on treated foliage, suggesting the effectiveness of neem against this major pest of hazelnuts.