Biological studies and effect of treatment with two juvenile hormone mimics on the developmental stages of Icerya purchasi (Mask) and Planococcus citri (Risso).
Icerya purchasi Mask. and Planococcus citri (Risso), which are pests of various fruit and vegetable crops in Egypt, were successfully reared in the laboratory in Alexandria on squash fruits and potato tubers. The results obtained over 4-5 generations in 1976-77 indicated that the duration of the different stages and number of progeny varied considerably according to the food-plant and temperature used in rearing. Some squashes were treated with the synthetic juvenile-hormone analogues kinoprene (ZR-777) at 0.0001-0.1 p.p.m. and hydroprene (ZR-512) at 0.01-1 p.p.m., and crawlers of I. purchasi and P. citri were allowed to feed on them. Such treatment with the 2 compounds prolonged the duration of the total life-cycle by 12.5-27 and 3.9-29.5%, respectively. Both compounds also reduced female fecundity in both species. Male adult emergence in treated populations was observed only for the 2 lowest concentrations of kinoprene, and even these resulted in 20% inhibition of male emergence in P. citri and 40% inhibition in I. purchasi. Female emergence was much less affected; at 1 p.p.m., hydroprene caused only about 6% reduction in that of P. citri although it caused 74% in that of I. purchasi. The fixation rate of crawlers of both species was reduced by kinoprene at all concentrations and that of I. purchasi by hydroprene, to varying degrees, but that of P. citri was increased by hydroprene at 0.001 and 0.01 p.p.m. and was virtually unaffected at 0.1 and 1 p.p.m.