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The effect of 3 insect growth regulators -methoprene, diflubenzuron and RO 13-5223, on the coccinelid Chilocorus bipustulatus L. was studied in the laboratory. Feeding on Chrysomphalus aonidum (L.) or Aspidiotus hederae Vallot (Diaspididae) treated with the IGRs at the concentration of 0.025 % a.i. revealed the following : cliflubenzuron caused a complete mortality of 1St instar larvae ; methoprene and RO 13-5223 did not arrest larval development but inhibited pupation ; fecundity of sexually mature females was not affected by the 3 IGRs but egg hatch was completely inhibited ; egg viability was regained when IGR-exposed females had been transferred to an uncontaminated environment.

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The insect growth regulator, RO 13-5223, applied at concentrations up to 0.1% ai., did not affect the normal development of immature stages of 2 hymenopterous parasites :Metaphycus bartletti Annecke & Mynhardt and Aphytis holoxanthus DeBach, parasitoids of Saissetia oleae (Olivier) and Chrysomphalus aonidum (L.), respectively. Spraying citrus trees at the rate of 7.5 g. a.i./tree had no adverse effect on the activity of the following parasitoids : Aphytis chrysomphali (Mercet) and Compe.riella bifasciata Howard, an ecto-and endoparasite of the California red scale, Aonidiella aurantii MaskeU, respectively ; Aphytis hispanicus (Mercet) and Prospaltella inquirenda Silvestri, an ecto-and endoparasite of the citrus chaff scale, Parlatoria pergandii Comstock, respectively.The wide spread and continuously increasing use of different types of non-selective pesticides in citrus groves in Israel, and elsewhere, disturbs the biological balance and causes outbreaks of insect and mite pests. Unfortunately, only a few selective insecticides are known, among them are mineral oil and various acaricides. The use of mineral oil has been gradually decreasing because of certain agrotechnical difficulties. In an integrated pest management programme one should try to employ selective pesticides or those which have a lesser adverse impact on nontarget organisms. Potentially selective or semi-selective insecticides are insect growth regulators (Franz et al., 1980; Peleg & Gothilf, 1980) which have been subjected to insect control Studies (Stall, 1975 ;Bullock & McCoy, 1978 ;Hoying & Riedel, 1980 ;Retnakaran, 1980 ; Peleg & Gothilf, 1981). Recently I tested a new insect growth regulator (IGR), RO 13-5223, in controlling scale insect pests. It was found (Peleg, 1982) that the chemical could be used to control soft scales, particularly the Florida wax scale, Ceroplastes floridensis Comstock, and the Mediterranean black scale, Saissetia oleae (Olivier). It is therefore of interest to examine the effect of the IGR on beneficial insects. The present work describes the effect of RO 13-5223 treatment on the development of immature stages of 2 hymenopterous parasites in the laboratory, as well as evaluates the impact of field application for soft scales control on the activity of 2 armoured scales parasites. 368 BA. PELEG MATERIALS AND METHODS LABORATORY EXPERIMENTSThe insect growth regulator used was RO 13-5223 [ethyl < 2-(p-phenoxyphenoxy) ethyl > carbamate ] 50 % W.P. (Dr, R. Maag Ltd., Dielsdoff, Switzerland). The chemical was disolved in water to the desired concentrations, and then sprayed with a hand sprayer to full coverage on plant material infested with parasitized scales. All laboratory tests were conducted in a room with ambient temperature of 26 -+ 1 ~ and R~. of 65 -+ 5 %. The parasites, their hosts and the way they were handled were as the following :Metaphycus bartletti Anneeke & Mynhardt (Encyrtidae) is a gregarious endoparasite of the Mediterranean black scale, Saissetia oleae (Coccidae). Potato sprouts, artificially inocula...