Leaf Extracts from Cytokinin­ Overproducing Transgenic Plants Kill Sugarbeet Root Maggot (Tetanops myopaeformis) Larvae

The sugarbeet root maggot (SBRM), Tetanops myopaeformis von Roder (Diptera: Otitidae), is the major insect pest ofsugarbeet in the central and western United States and Canada and is capable of inflicting losses ranging from 10 to 100%. Currently, chemical insecticides are the only available measure for control of the maggot and a strong impetus exists for develop­ ment of alternative control measures. Insecticidal leaf extracts prepared from N. plumbaginifolia plants transformed with the cytokinin biosynthesis gene ipt (PI.. I1-ipt) were tested on the sugarbeet root maggot larvae. Exposure of first instar maggots to a 1 % suspension of the compounds in surface extracts of PI-I1-ipt plants induced an almost immediate, repetitive twitching and thrashing movement that was not detected when the larvae were placed in similarly prepared extracts from