In the present study, two of the most toxic bacterial strains of Bacillus sphaericus against mosquito were identified with the most recent genetic techniques. The PCR product profiles indicated the presence of genes encoding Bin A, Bin B and Mtx1 in all analyzed strains; they are consistent with protein profiles. The preliminary bioinformatics analysis of the binary toxin genes sequence revealed that the open reading frames had high similarities when matched with nucleotides sequence in the database of other B. sphaericus strains. The biological activity of B. sphaericus strains varied according to growing medium, and cultivation time. The highest yield of viable counts, spores and larvicidal protein were attained after 5 days. Poly (P) medium achieved the highest yield of growth, sporulation, protein and larvicidal activity for all tested strains compared to the other tested media. The larvicidal protein produced by local strains (B. sphaericus EMCC 1931 and EMCC 1932) in P medium was more lethal against the 3rd instar larvae of Culex pipiens than that of reference strains (B. sphaericus 1593 and B. sphaericus 2297). The obtained results revealed that P medium was the most effective medium and will be used in future work in order to optimize large scale production of biocide by the locally isolated Bacillus sphaericus strains.
Laboratory experiments were conducted to study the potential impact of genetically modified corn hybrid, transgenic Bacillus thuringiensis (Bt)-expressing (Cry2Ab/1Ac), and the corresponding isogenic untransformed Bt-free hybrid on biological parameters of the green lacewing predator, Chrysoperla carnea (Stephens). The effectiveness of transgenic (Bt)-expressing (Cry2Ab/1Ac) on C. carnea developmental parameters (larval duration, pupal duration, mortality %, pupation %, adult emergence %, and adult duration time) was investigated in the first experiment. In the second experiment, the effect of Bt Cry2Ab and Cry1Ac partially purified toxins on the hatchability of C. carnea eggs compared to cypermethrin was examined. Additionally, the toxicity effect of Angoumois grain moth, Sitotroga cerealella, eggs sprayed with BtCry2Ab/1Ac mixture and cypermethrin on C. carnea was tested. The results showed that the mortality percentage of C. carnea fed on aphids reared on Bt corn (40%) was less than that fed on aphids reared on non-Bt corn (50%). Moreover, the larval mortality %, net pupation, and adults' emergence percentage of C. carnea larvae fed on aphids reared on Bt corn and non-Bt corn were not significantly different. On the other hand, the hatchability data showed that the chemical insecticide (cypermethrin) severely affected the C. carnea eggs compared to Cry2Ab/1Ac toxins. These findings proved that adopting biopesticide formulation based on Bt toxins or Bt-modified crops will not only affect C. carnea but also enhance its ability as a potential biological pest control agent.
Asca aegyptiaca sp. nov., is desc1ibed ti•om Egypt, the genus is recorded tor the tirst time and collected ti•om leaves and debris of soybean at Mcnia governorate (Midle Egypt).
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