Comparatively Studies on Some Bio and Chemical Insecticides Against Myzus Persicae and Aphis Gossypii Infested Two Potato Cultivars and Its Relation With Yield.

Abstract

In order to evaluate the effects of bio and chemical insecticides for reducing the aphid infestation and response on the potato yield, two bio products namely [Biofly (entomopathogenic fungi) and Jojoba oil (plant extract) and K.z oil (mineral oil)] were compared with five recommended insecticides namely; fenvalerate (Sumicidin), fenpyroximate (Kindo), carbosulfan (Marshal), dinotifuran (MTI-446), (neo-nicotionoid); and, diafenthiuron, (Polo). Two cultivars of potato plants diamant and spunta were sprayed with the tested compounds at the recommended rates twice against two species of aphids, the green peach aphid Myzus persicae (Sulzer) and the cotton aphid, Aphis gossypii (Glover), during two successive seasons of 2003 and 2004 at El-Kenaiat district, Sharkia Governorate. Reduction percentages cleared that A. gossypii exhibted slightly tolerant to tested compounds than M. Persicae. During the 1 st season (2003), the comparatively higher initial reduction percentages against M. persicae and A. gossypii were 97.5 and 98.37 % recorded for fenpyroximate against M. persicae on spunta cultivar at the 1 st and 2 nd sprays, respectively. The relatively higher residual effects were 95.16 and 94.83% recorded for carbosulfa and diafenthuron against M. persicae on spunta cultivar. The two bio products, Biofly, jojoba and mineral oil recorded relatively moderate general reduction percentages ranged between 50.42-73.42% against the two aphid species in the two potato cultivars. During the second season (2004) the relatively higher initial reduction percentages, recorded 97.99 and 96.67% for fenpyroximat against M. persicae infested spunta potato cultivar after 1 st and 2 nd spray, respectively. The two bioproducts and kz oil recorded reduction percentage ranged 50.47-74.04% against the two aphids species on the two tested cultivars. The aphids species infested diamant cultivar were more tolerant than that infested spunta cultivar, where the relatively higher reduction percentage recorded on spunta, that may be due to the food suitability and its effect insects response to tested compounds. In respecting to the yield, there were significant differences between the different treatments except these plots treated with fenpyroximate which recorded the highest yield (106.20 & 115.25 kg /plot) for both of diamant and spunta cultivars respectively at the 1 st season. yield of diamant (102.25k.g./plot) and the highest yield of spunta recorded for plots treated with carbosulfan (114.5 k.g./plot). On the other hand, the best yield for bio-product was recorded for Jojoba oil which gave (100.25 and 102 kg /plot) when sprayed on diamant and spunta at the 1 st season and 94 and 97 kg /plot at the 2 nd season respectively. Therefore, it could be decided that Jojoba was the most efficient compound when we wanted potato as a bio-crop to avoid the hazard of chemical insecticides on health and environment which represent the principal aim of IPM programs.