Preparation of carbamate derivatives of 2-(4-hydroxybenzyl)-1-cyclohexanone with a juvenoid activity

The synthesis of four carbamate derivatives of 2-(4-hydroxybenzyl)-1-cyclohexanone displaying a juvenilizing effect in insects is described. The substances prepared have a greater stability and activity than their carba-analogues prepared earlier.

A comparison of the juvenilizing effect of six juvenile hormone-like activity compounds on Egyptian Culex pipiens L.

SummaryTests were made to determine the juvenilizing effects of TH6040, JH-25, Altosid, Altozar, ZR-777 and ZR-619 on Culex pipiens L. using the IC50 value (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 of Culex pipiens L. 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 of C. 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.

An Effect of Parasite Attack on Host Mortality, as Exemplified by Encarsia formosa and Trialeurodes vaporariorum

It is not unusual for parasite attack on insect hosts to have different consequences for individuals of the same species. An indication of the variation in types of alternative effects is given by a consideration of three host-parasite relationships. First, although most hosts in a population are susceptible to parasitization, some are immune to attack: about one in 3,000 larvae of the Mediterranean flour moth, Anagasta kühniella (Zeller), was found by Payne (1934) to be immune to attack by Bracon hebetor Say. Second, tile morphology of hosts may be modified differentially by parasitism: unhatched eggs of Aphdius platensis Brethes exert a juvenilizing effect on nymphs of Aphis craccivora Koch whereas parasite larvae sometimes cause the appearance of adult characters (Johnson, 1959). Third, some hosts are successfully parasitized whereas others are killed long before parasite progeny can mature: adult females of Metaphycus helvolus (Com.) kill the black scale, Saissetin oleae (Bern.), by parasitization, by mutilation with the ovipositor, and by host-feeding at wounds made by the ovipositor. Field tests showed that up to 97 per cent of a black-scale infestation may be killed by the parasite over a period of several months.