Field and laboratory trials were conducted in Zagazig -Sharkia Governorate during 2007 and 2008 cotton seasons to evaluate the efficacy of emamectin benzoate (against cotton leafworm Spodoptera littoralis and pink bollworm Pectinophora gossypiella.Emamectin benzoate resulted in initial kill of 93.73 and 92.39 % reductions in the numbers of cotton leafworm Spodoptera littoralis, larvae, comparing with 98.22 and 95.93 % for the recommended IGR hexaflumuron (Consult) (while as the residual effect emamectin benzoate revealed to 83.69 and 82.35% reductions comparing with 95.07 and 93.93 % for the hexaflumuron, in 2007 and 2008 cotton seasons, respectively. The efficiency of emamectin benzoate in comparison with the recommended insecticide chlorpyriphos (Dursban) against cotton bollworm, pink bollworm, Pectinophora gossypiella, they resulted in 59.40 and 54.68% for emamectin benzoate, and 81.81 and 83.21% for chlorpyriphos as average seasonal reductions, during the two cotton seasons, respectively. Laboratory trials revealed that LC50 and LC 90 of emamectin benzoate were higher with cotton leafworm than pink bollworm, which were 2.783 and 1.656 ppm at LC 50 , while they were 29.096 and 11.193 ppm at LC 90 , respectively. The slope value of emamectin benzoate with cotton leafworm was 1.257 less than with pink bollworm which recorded 1.544.
The spores and supernatants of some fungal isolates; Paecilomyces violacea, Trichoderma harzianum and Beauveria bassiana; were evaluated to control the pink bollworm, Pectinophora gossypiella biologically at Plant Protection Research Institute, Sharkia branch, (ARC). All fungi were isolated from soil and dead pink bollworm larvae. B. bassiana was the most active isolate caused the greatest larval and pupal mortality, also the highest deformed adult, also, the lowest numbers of eggs and hatchability percentage. Protease and chitinase produced from B. bassiana. strain had high effects on percent of larval mortality, comparing with control. Identification of Beauvaria sp. was assured by using 18s rRNA with accession number MT644472.1.
Field experiments were conducted at Aga district, Dakahlia Governorate during 2011 and 2012 cotton seasons to study the effect of five pesticides; Methomyl, Profenofos, Cholorpyrifos, Deltamethrin, Lambada-Cyhalothrin and insect growth regulator (IGR), Chlorfluazuron; against eggs and larvae of Helicoverpa armigera and infested cotton buds. Results showed that in case of H. armigera eggs Chlorpyrifos caused the highest reduction percentage of in egg of bollworm (72.03%), followed by Deltamethrin 69.29% , Profenofos 68.93%, Lambada-Cyhalothrin 67.29% and Methomyl 65.98%, while the least reduction was 62.44% for Chlorfluazuron. In case of the larvae, the results showed Chlorpyrifos caused the highest reduction 79.58% followed by Chlorfluazuron 73.29%, Profenofos 72.54%, Deltamethrin 64.22% , Lambada-Cyhalothrin 58.40%. While the lowest reduction percentage was 56.68% for Methomyl. In case of the infested cotton buds, Chlorpyrifos caused the highest reduction with 75.54%, followed by Chlorfluazuron 72.05%, Profenofos 70.47%, Deltamethrin 57.18% and Lambada-Cyhalothrin 57.06%, while the lowest reduction was 48.54% for Methomyl.Generally Chlorpyrifos was most effective on the eggs and larvae of H. armigera and the infested cotton buds, while Chlorfluazuron was the least affective on H. armigera eggs, but Methomyl was the least effective on the larvae of H. armigera and infested buds.
Laboratory Experiment were carried out to study the effect of different temperature's degrees, (15, 20, 25, 27 and 30 °C) on the developmental stages of the American bollworm (ABW) Helicoverpa armigera (Hübner) reared on artificial diet. As temperature increased from 15 to 30 °C the life span decreased. The lower thermal threshold for the development of ABW eggs is 13.01 °C, for larvae is 11.98 °C, for pupal stage is 9.79 °C and for pre-ovipostion period is 12.83 °C. The thermal constant for the development of eggs is 36.69 day degree (DD's), for larvae is 245.17 DD's, for the pupal stage is 181.64 DD's and 34.99 DD's for the pre-ovipostion period. The lower thermal threshold for generation of ABW is 11.54 °C and the thermal constant is 494.39 DD's. Obtained results are essential information for predicting the field population of ABW.
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