Control of the Citrus Mealybug with Insect Growth Regulators with Juvenile Hormone Activity13

The insect growth regulators (IGR’s) ZR-619 (ethyl 11-methoxy-3,7,11-trimethyl-(2E,4E)-2,4-dodecadienethiolate), ZR-512 (ethyl 3,7,11-trimethyl-(2E,4E)-2,4-dodecadienoate), ZR-520 (ethyl 11-methoxy-3,7,11-trimethyl-(2E, 4E)-2,4-dodecadienoate), and ZR-777 (Prop-2-ynyl 3,7,11-trimethyl-(2E, 4E)-dodecadienoate) with generally high morphogenetic activity on Homoptera were tested for control potential against both synchronized and nonsynchronized populations of Planococcus citri (Risso). Of these compounds, only ZR-777 produced high subacute mortality when sprayed at 0.1% and 0.01% on all developmental stages tested. All compounds drastically reduced the numbers of viable progeny when sprayed on parthenogenetic female adults. This reduction was due to adult mortality as well as to sterility induced in the surviving adults. ZR-777 applied topically to the last female nymphal instars at doses of 2.0 and 0.2 µg per insect also gave significant reduction in the total number of offspring produced per female, but a lower dose (0.02 µg per insect) produced a sharp increase in the number of offspring when compared with the controls. ZR-777 also gave very promising control of all instars sprayed at a dose rate of 0.01%.