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This work aimed to assessment the damage caused by the infestation with some cereal aphid species on wheat plants at Sharkia Govern orate during 2017/2018 season. The results showed that the relationship between the yield of wheat plants and infestation of aphid was in negative correlation. The damage economic threshold level for aphid was 29.57 individuals/100 plant tillers, the economic injury level was 36.28 individuals/ 100 plant tillers. To assesse the efficacy of the tested insecticides against aphid under field conditions showed that chlorpyrifos was the most effective followed by thiamethoxam + abamectin and Beauveria bassiana. The residual effects of the tested insecticides were 100, 86.67 and 79.73% for the previous tested insecticides, respectively. The general effect of reduction percentages indicated 98.59, 69.75 and 79.73%, successively for the same tested insecticides in the first season (2016/2017). While the residual effect showed 80. 77 to Beauveria bassiana, 86.9 to thiamethoxam + abamectin and 100 to chlorpyrifos .On the other hand, the general effects in the second season (201712018) were Beauveria bassiana ( 80.77), thiamethoxam + abamectin (70.7) and chlorpyrifos ( 99.06 ). [ABSTRACT FROM AUTHOR]

A total of 35 bacterial cultures were isolated from dead and living larvae of cotton leafworm Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) and soil samples. Only one bacterial isolate (Bt1) exhibited the highest pathogenicity against the pest. Identity of one of the most potent isolates suspected and encoded as Bt1 was confirmed by amplifying its 16S rRNA gene. Partial nucleotide sequence of the amplified 16S rRNA gene of the tested strain was submitted in GenBank with accession number KU646830. Pathogenicity of Bt1 strain was tested against 2nd and 4th instars of S. littoralis larvae at different concentrations (2x109, 2x108, 2x107 and 2x106CFU/ml). Based on the LC50 value, the 2nd instar larvae were more susceptible than the 4th one. It recorded 1.9x109CFU/ml and 4.1x1011CFU/ml for 2nd and 4th larval instars, respectively, after seven days. Latent effect of Bt1 strain was recorded on some S. littoralis biological aspects as pupation, pupal weight and adult emergency that decreased, in addition to some failure in pupation and emergence of deformed adults. In vivo, screening of Bt1 strain culture filtrates against 2nd and 4th larval instars of S. littoralis cleared that filtrate including protease had significant effects on larval mortality. Purified protease gave single homogenous band of 68 kDa by SDS- PAGE. Also, its optimum pH and temperature were 7.0 and 35oC, respectively, with wide pH and thermal stabilities. Furthermore, purified protease showed high activity against 2nd and 4th instars S. littoralis larvae than crude protease. A field application was conducted to compare the efficacy of the recommended pesticides (Challenger Super and New benzuron) and Bt1 culture against the 2nd and 4th instars S. littoralis larvae. Results showed that Challenger Super was the most effective insecticide and caused 89.61, 93.6 and 88.68% reduction in S. littoralis population after 3, 7 and 10 days post treatment, respectively. However, Bt1 strain was the least toxic effect where the mean reduction was 40.5%. [ABSTRACT FROM AUTHOR]