A comparison of the juvenilizing effect of six juvenile hormone-like activity compounds on EgyptianCulex pipiensL.

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Abstract
Summary: Tests were made to determine the juvenilizing effects of TH6040, JH-25, Altosid, Altozar, ZR-777 and ZR-619 onCulex pipiensL. using the IC50value (dose to inhibit the emergence of 50% of adults) as a criterion. The descending order of activity was Altosid, TH6040, Altozar, ZR-777, JH-25 and ZR·619. Insignificant prolongations were recorded in the larval or pupal durations except in the case of TH6040 (Dimilin). The time lapse from larval treatment (early fourth instar) to adult emergence was prolonged by about 18·7% following treatment with 0·0001–0·1 μg/ml.Juvenilizing effects of the tested compounds applied to the early fourth instar extended to the adult stage ofCulex pipiensL. and affected the duration of the first gonotrophic cycle. The concentrations of TH6040, JH-25, Altosid, Altozar, ZR-777 and ZR-619 tested caused prolongation of the time between emergence and first oviposition by about 20–50% (at 0·0001–0·1 μg/ml), 3–26% (at 0·001–5μg/ml), 0–15% (at 0·1 × 10-8–0·001 μg/ml), 3-–23% (at 0·1 × 10-8–0·001 μg/ml), 9–27% (at 0·1 × 10-7–0·01 μg/ml), and 11–32% (at 0·1 × 10-7–0·01 μg/ml), respectively.The results obtained indicated that the sex ratio ofC.pipiensL. changed progressively in all treatments but with an inconsistent trend according to the concentration of each compound. This conclusion provides further evidence on the effect of juvenile hormone-like activity compounds on adults emerging from treated larvae. The numbers of females produced were increased by about 15–30%, 9–27%, 1–35%, 1–38%, 6–44% and 31–71% after treatment with 0·0001–0·1 μg TH6040, 0·001–5μg JH-25, 0·1x 10-8–0·001 μg Altosid, 0·1 x 10-8–0·001 μg Altozar, 0·1 x lO-7–O·Ol μg ZR-777 and 0·01 × 10-7–0·01 μg ZR-619‘sol;ml, respectively.