Pak. J. Agri. Sci. Vol. 38(1-2), 2001 THE COMPARATIVE EFFICACY OF SOME INSECTICIDAL SPRAY SCHEDULES AGAINST THE SUCKING PEST-INSECTS ON FS-628 COTTON Muhammad Afzal, Zulfiqar Ahmad & Tasneem Ahmad' Department of Agri. Entomology, University of Agriculture, Faisalabad 'Department ofPlant Protection, Karachi The efficacyofthree insecticide spray schedules comprising eight insecticides viz. thiomethoxam,diafenthiruan, buprofezin, cypermethrin, fenpropathrin, methamidophos, endosulfan and quinalphos was compared, using recommended doses,against the sucking pest-insect complex of FS-628 cotton. All the insecticidal spray schedules tested, in general, were effective against the sucking pest-insects. On numerical basis, however, an insecticide spray schedule involving thiomethoxam followed by one spray of quinalphos and another with fenpropathrin + buprofezin was found as the most effective both against each individual sucking pest-insect and their overall complex. Key words: cotton, insecticides efficacy, sucking pest-insects INTRODUCTION Sucking pest-insects viz. cotton jassid, whitefly and thrips are the mostnotQrious pests of cotton crop and play havoc with it. To avoid such a situation, the application of the latest insecticide spray schedule is the only quick and safe escape. The previous investigation on the present lines revealed that probably none of the earlier workers tried the present insecticidal spray schedules/pest com- plex/crop combination. However, the information supplied byDhawan et al. (1988), Satpute et al. (1989), El-Shahaway et al. (1991), Bashir (1993), Wahla et al. (1996), Hussain (1997), can in some way be quoted in this context. The main objective of the present studies was to sort out the comparative efficacyof some ofthe latest spray schedules not only against cotton jassid, whitefly and thrips but also that of their complex on FS-628 cotton. MATERIALS AND MEmODS The materials employed in the present investigations were on field grown crop of FS-628 cotton and three spray schedules of eight different insecticides viz. Gammon 25 WG (thiomethoxam), Polo 500 SL (diafenthiuran), Pride 25 WP (buprofezin), Cypermethrin 10 EC (cypermethrin), Digital20EC (fenpropathrin),Trend 60 SL (methamidophos), Fezdion 35EC (endosulfan) and Taophos25 EC (quinalphos) as explained later through Table 1. The trials were laid out in randomized complete block design and there were 6 treatments including a control, having 4 repeats each. The spray materials were prepared according to the dose- schedules extended bythe insecticide promoters and sprayed over to the ,cropat an interval of fortnight starting from August, 1999.The data on the pest population were recorded separately for each pest species, from 15randomly selected leaves of 15 randomly selected plants/plot. The counts were, however taken four times after the insecticide application to the crop with a lapse of 24, 48, 72 hr and 7 days and considered to be an indirect reflection of the pest population. The significance of the difference in mean population of pest-insects was sorted out through the Duncan's multiple range test (Steel and Torrie, 1980) and the relationship between the toxicity of the test schedules on different species of sucking pest-insects as well as on that of their overall complex was also sorted out as far as possible. RESULTS AND DiSCUSSION The data on multiple comparison of mean values for the population of different species of sucking pest-insects are presented in Table 1. An overall perusal of the data concerning mean values from one treatment to another, reveals a highly significant variation in the incidence of each sucking pest-insect species individually as well as in that of their complex. The mean values of the overall population of the sucking pest-insects [Table 1 (A)] in T1-Ts' where, different insecticidal spray-schedules were applied to the crop, were found to be very significantly lower than those of T6 kept as control. Similarly, the mean values of the individual population ofjassid, whitefly, as well as those of the thrips [Table 1 (B to D)] in T1-Ts' where different insecticidal spray schedules were applied to the crop, were also found to be highly significantly lower than those in T 6 kept as control. Thus, the lower mean values in the treatment~ from T 1 to T, compared with those of T 6 would reflect on their killing potential against the sucking pest-insect species as well as against their overall complex. On iiumeri~al basis, however, lower mean values for the sucking pest- insects in T 1 involving spray schedule comprising one spray of Gammon 25 WG followed with one spray of ..•..•