INHIBITORY EFFECTS OF SOME INSECT GROWTH-REGULATORS ON DEVELOPMENTAL STAGES, FECUNDITY AND FERTILITY OF THE FLORIDA WAX SCALE, CEROPLASTES-FLORIDENSIS

Four juvenile hormone analogs (JHAs), fenoxycarb, Pro-drone, R-20458 and dofenapyn, and three benzoylphenyl urea molt-inhibiting compounds (MICs), teflubenzuron, triflumuron and hexaflumuron, were evaluated in the laboratory at two concentrations (5 and 50 ppm) as to their effect on the Florida wax scale, Ceroplastes floridensis Comstock. In general, when the first nymphal stages were treated, the number of adults on treated guava plants at the end of the first generation was clearly reduced in comparison with that observed on untreated plants. The JHAs fenoxycarb and R-20458 arrested the development of the insect and no adults emerged at the end of the first generation. With 50 ppm of the JHA Pro-drone only 5.2% of the nymphs developed and transformed into adults. Triflumuron was superior to the other insect MICs in hampering development, as was dofenapyn. The adults emerging at the end of the first generation were used as parental scales for the next generation. Delayed adverse effects were observed on female fecundity and egg hatchability. There was a significant difference between the egg numbers laid by the females in the treatments and the control, and also between the different IGRs. No eggs hatched with dofenapyn and egg hatchability was 46% for teflubenzuron vs 88% for the control. Furthermore, in contradistinction to the control, insects on treated plants deposited only small amounts of wax in an irregular formation.