Monday, December 11, 2006 - 11:11 AM

Efficacy and non–target effects of national organic program-compliant insecticides for soybean aphid (Aphis glycines) and multicolored Asian lady beetle (Harmonia axyridis)

Heidi Kraiss,, University of Wisconsin - Madison, Entomology, 1630 Linden Dr, Madison, WI and Eileen M. Cullen,, University of Wisconsin - Madison, 1630 Linden Dr, Madison, WI.

Soybean aphid (Aphis glycines) Matsumura) is a major pest of soybeans, Glycine max. While organic soybean growers rely primarily on cultural practices and biological control to manage insect pests, aphid densities periodically overcome these measures. In this study, we evaluated efficacy of four Organic Materials Review Institute or National List allowed insecticides against Aphis glycines. Because biological control is a required component of soybean aphid management in organic systems, insecticides must be compatible with biological control agents. The Asian lady beetle (Harmonia axyridis) is a key predator of soybean aphid in soybeans in the Midwest. We included H. axyridis in our study to determine non-target effects of the insecticides. Treatments included pyrethrum [PyGanic® EC 1.4 (2.92 l/ha], azadirachtin [Neemix® 4.5 EC .511 l/ha], insecticidal soap [M-Pede® 4.68 l/ha], and a narrow range horticultural mineral oil, [Omni Supreme® 18.68 l/ha]. Treatments, including a water control, were applied in a completely randomized block design laboratory bioassay using a Potter Spray Tower at the highest labeled field rate for aphids in soybeans or legume crops. Cohort A. glycines adults and nymphs were monitored for mortality to determine efficacy. H. axyridis eggs, first instar, third instar, pupae and adults were monitored for mortality to determine non-target effects. Results are discussed within the context of establishing fundamental information about the effectiveness of these materials against the soybean aphid and important considerations for related on-farm field experiments in certified organic soybeans.

Species 1: Hemiptera Aphididae Aphis glycines (soybean aphid)
Species 2: Coleoptera Coccinellidae Harmonia axyridis (multicolored Asian lady beetle)

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