Enhancement of Bacillus Thuringiensis var. Kurstaki, an Entomopatholgenic Bacterium, and Flufenoxuron, an Insect Growth Regulator, to Control Spodoptera Littoralis (Boisd.), a Cotton Leafworm.... | ||
| Alexandria Science Exchange Journal | ||
| Volume 45, Issue 3, October 2024, Pages 57-64 PDF (501.93 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/asejaiqjsae.2024.389259 | ||
| Authors | ||
| El Shaimaa N. Ibrahim* 1; Nashwa S. Amein* 1; Aziza E. Abdelal* 1; Amal Th. Hussien* 2 | ||
| 1Plant Protection Research Institute, Agricultural Research Center, Dokki, Giza, Egypt. | ||
| 2Faculty of graduate studies and environmental Research | ||
| Abstract | ||
| The study examined the effects of two compounds, Bacillus thuringiensis var. kurstaki and Flufenoxuron (CSI) on the histology, physiology, and toxicity of Spodoptera littoralis (Boisd.), an Egyptian cotton leafworm, in its second and fourth instars respectively. The experiments were conducted in a laboratory setting. According to the findings, the LC10 and LC50 values of B. thuringiensis compound treatments on larvae in their second instar were found to be, respectively, 0.0027 and 0.2331 gm/ml. Flufenoxuron-treated larvae in their fourth instar had corresponding values of 1.4716 ppm and 0.0025 ppm. Interaction effects were noted when LC10 of flufenoxuron was applied in conjunction with LC50 of B. thuringiensis either immediately or 48H after B. thuringiensis treatment of the second instar larvae. After applying the IGRs, zero time and 48H, respectively, the average mortality rate of larvae treated with B. thuringiensis alone rose from 50.001% to 51.22 and 65.03%. In addition, 52.32% of LC10 Flufenoxuron mortality occurred after LC50 B. thuringiensis therapy. Ultimately, the results showed that the two tested B. thuringiensis and Flufenoxuron had longer mean larval and pupal durations for larvae in their second or fourth instar who survived treatment, compared to their LC50 values. Moreover, the studied chemical decreased all other biological effects, including pupation, pupal weight, adult emergence, and adult longevity in both sexes. After six days of treatment, the histological structure in the midgut of larvae that survived treatment of either B. thuringiensis or flufenoxuron, respectively, showed many alternations. These larvae were in their second and fourth in stars. There were signs of peritrophic membrane breakdown, microvilli disruption, and epithelial layer vacuolation. The addition of flufenxuron (LC10) to B. thuringiensis (LC50) resulted in the exfoliation of columnar cells, vacuolation, and loss of the compact look of the muscularis layer. When the LC50 of flufenoxuron was administered to 4th instars, the fat body of the surviving late 6th instars collapsed and there was minor vacuolization. | ||
| Keywords | ||
| B. thuringiensis; Flufenoxuron; Spodoptera littoralis; biological aspects; histology | ||
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