Effects and Control Potential of Insect Growth Regulators with Juvenile Hormone Activity on the Greenbug

Three novel insect-growth regulators (IGR’s) (based on 3,7,11-trimethyl-(2E,4E)-2,4-dodecadienoic acid) were tested against synchronized stages of Schizaphis graminum (Rondani). These compounds coupled high morphogenetic activity on nymphs (production of extranymphal instars) with direct sterilizing activity on 4th instars and adults. Compound ZR-619 (ethyl 11-methoxy-3,7,11-trimethyl-(2E, 4E)-2, 4-dodecadienethiolate) induced only temporary Sterilization, but ZR-699 (prop-2-ynyl 11-methoxy-3,7,11-trimethyl-(2E, 4E)-2,4-dodecadienoate) and ZR-777 (prop-2-ynyl 3,7,11-trimethyl-(2E, 4E)-2,4-deodecadienoate) induced permanent sterility in the survivors at spray dose rates of 0.01 and 0.1 percent, in addition to a high but delayed mortality. The nature of this lethal effect is not known; death occurred considerably more slowly than is normally the case with insecticides. The degree of plant damage produced by the aphid’s toxic salivary secretions was reduced considerably following application of the IGR’s, even before the actual number of aphids had been reduced significantly. Mortality, complete sterilization, and inhibition of the toxic salivary effect have not been demonstrated previously for any IGR. The data show that ZR-777 can become a useful, practical control agent.