The present study includes three points, i.e., wheat cultivar susceptibility, seasonal fluctuation of mite species, associated predators and evaluation of certain control materials against mites on wheat plants. The susceptibility of the three wheat cultivars (Sakha 93, Giza 168 and Gemiza 9) to investigation of mite species Petrobia tritici Kandeel, El-Naggar and Mohamed and two spotted spider mite, Tetranychus urtica) was inspected during the two successive seasons of 05/06 and 06/07 at Zagazig district. The obtained results revealed that the Sakha 93 cultivar was more susceptible to P. tritici infestation. The relatively higher numbers ranging 9.37-11.26 and 2.142-8.18 mite/leaf were recorded for the two mite species during the two seasons, respectively. The relatively lower mean numbers ranged 4.47-5.37 and 1.76-4.47 mite/leaf were recorded on Giza 168, while the moderate numbers of 6.36-8.47 and 2.08-4.7 mite/leaf were recorded on Gemiza 9 cultivar for the two mite species during the two study seasons. The yield of test cultivar was found in contrast with infestation levels, where the relatively lower yield ranging 3.68-4.0 g/plant was recorded for the more susceptible cultivar, Sakha 93; while the highest yield ranging 6.0-6.02 g/plant was recorded for the more tolerant cultivar, Gemiza 9 which infested by moderate number of mites. The result of seasonal fluctuation of the mite species infested the three tested cultivars revealed that the population of P. tritici recorded 1-2 peaks during the two seasons with the highest mean numbers of 28.0 and 34.33 mite/leaf on Sakha 93 at the first weak of April during the two seasons, respectively. The two spotted spider mite recorded 3-4 peaks on the tested cultivars during the two seasons with highest peak of 26.0 mite/leaf on Sakha 93 at early-April during the first season. During the second season, the highest peak of 7.0 mite/leaf was recorded at the end of March on Gemiza 9. The relatively higher total predators number ranging 7.33-11.67 and 3.0-6.33 individuals/plant were recorded in timing with the high number of phytophagous mites on tested cultivars during the first and second seasons, respectively. As evaluation of toxicant materials results, the all tested materials reduced the numbers of mites significantly compared with control with highest reduction percentages recorded for the convention pesticides followed by plant extracts and other materials. Regarding to reduction percentages, three groups were conducted, the first ranging 78.84-96.55 % (pesticides), 70.94-88.23 % (plant extracts) and 45.24-69.93 % (bio-products) during the two study seasons. Therefore, it could be concluded that the plant extracts and bio-products can be used as control agents for mites IPM programs in wheat fields.
This study was conducted to evaluate the effect of intercropping and neighbor cotton plants with other summer plants on the occurrence levels of some cotton pests in Graia village at Zagazig, Sharkia Governorate during 2003 and 2004 seasons. The results show that Intercropping cotton with tomato or onion increased Aphis gossypii ( Glover) average numbers significantly on cotton plants. While with cucumber and pepper the average numbers were decreased in both 2003 and 2004 seasons. The average numbers of Tetranychus spp. increased in intercropping system of cotton with tomato or cucumber, while the contrast results was found with onion or pepper intercropping system in comparing with the solid cotton plants during 2003 and 2004 seasons. The all intercropping systems increased the population density of Thrips tabaci (Lind.) on cotton plants in comparable with solid plants in both of seasons. The influences of intercropping systems on Bemisia tabaci (Genn.) and Empoasca sp. were differed from season to another and from system to another. With respect to the occurrence of associated natural enemies under intercropping systems, the highest population density of predators, Scymnus spp. and Orius spp. were recorded on cotton plants intercropped with tomato in both seasons. While, the highest number of predators ( Syrphus sp.,) Paederus alfierii, true spider mites, predator mite (Phytoseiulus sp.) and parasitoids, Encarsia sp. and Ertmocerus sp. were recorded on solid cotton plants compared to the intercropping systems in the two study seasons. The highest numbers of Chrysoperla carnea were detected on cotton plants intercropped with cucumber, whereas, the highest average number of Coccinella spp. recorded on cotton plants intercropped with onion in the first season and cotton plants intercropped with tomato in the second one. As neighbor effect, the numbers of Empoasca sp. and T.tabaci was increased on cotton plants, while the numbers of A. gossypii, B. tabaci and Tetranychus spp. were decreased in both of seasons 2003 and 2004. The neighbor of cotton plants by tomato, cucumber, onion or pepper was increased the numbers of predators (Chrysoperla carnea, Orius spp., Paederus alfierii) and parasitoid, Encarsia sp. on cotton plants; while the numbers of Coccinella spp. Scymnus spp., Syrphus spp., true spider mites and Ertmocerns sp. were decreased in both seasons.
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.
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