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Background: The susceptibility of pests and natural enemies to conventional insecticides is a critical element in judging the success of integrated pest management programs implementing biological control as a tactic. In this study, the susceptibility of the cotton leafworm Spodoptera littoralis(Boisd.) (Lepidoptera: Noctuidae) to an organophosphorus insecticide (chlorpyrifos) and the entomopathogenic fungus Beauveria bassianawas evaluated through field applications during two successive sugar beet seasons. The populations of the coccinellid, chrysopid, and formicid predators were estimated to indicate pesticide risk assessment strategy. The root and sugar yields were compared during the whole experiment to emphasize the impact of both control strategies on the pre-harvest loss in this strategic crop. Results: Results indicated that over the course of the two seasons of the investigation, chlorpyrifos significantly reduced the population density of S. littoralisand its associated predators. It showed a detrimental effect on S. littoralislarval population than untreated areas, causing an overall reduction of 97 and 92% during the 1st and 2nd seasons, respectively. The biopesticide based on entomopathogenic fungus Beauveria bassianacaused an overall reduction of S. littoralis, reaching 96 and 65% during the 1st and 2nd seasons, respectively. Meanwhile, B. bassianaslightly affects the population of predators compared to insecticide-free areas, so it was recommended for application in sugar beet fields without providing considerable risk to the associated insect predators. The sugar beetroot production and its sugar content increased significantly in both treatments during the two growing seasons compared to non-treated plots. Conclusion: Chlorpyrifos is not recommended for pest control; instead, B. bassianais considered an effective biopesticide in the Egyptian sugar beet fields infested with S. littoralisas part of an integrated pest management program. Their effect was direct through reducing pest population and indirectly increasing the sugar beetroot production and increasing its total sugar content. Hence, both the sugar beetroot quality and quantity were improved favoring the microbial agent over the chemical insecticide in application for mitigating the chemical hazards toward the associated predators.

Background: The invincible effects of the entomopathogenic fungi (EPF) under appropriate circumstances compensate for the flaws of chemical insecticides in the control programs. Beauveria bassianais one of the most elaborated EPF of pest control all over the world. The potential of using the B. bassianaisolate (Y-F_ITS1) was examined against different larval instars (L2, L3, L4, and L5), pupae, and eggs of the cotton leafworm, Spodoptera littoralis(Boisd.) (Lepidoptera: Noctuidae), using different concentrations under laboratory conditions. Results: In bioassay, 2nd instar larvae of S. littoraliswere significantly the most susceptible stage to B. bassianaisolate at P≤ 0.05. It is apparent from the results that the cumulative mortality percentage increased with elapsing time with typical symptoms of infection and sporulation. High efficacies ranging from 85.0 to 99.0% corrected mortality rates were recorded for 2nd instar larvae at the spore concentration (1 × 109spores ml−1). The mortality percentage reached 90.0% for the 3rd instar larvae treated with the same concentration after 5 days. The least mortality rates results were recorded at the 5th instar larvae. B. bassianaisolate showed an ovicidal effect to the eggs of S. littoralisthat reached 100% mortality when treated with 1.0 × 108and 1.0 × 109spores ml−1, while the concentration 1 × 107and 1.0 × 108caused 65.0 and 87.0%, respectively. Reduction of adult emergence reached (0%) in case of treatment with the highest concentrations (1 × 108and 1 × 109spores ml−1). Morphogenetic abnormalities were also recorded. Conclusion: Results of mortality rates and lethal concentration values resulted from the experiments indicated that the tested Y-F_ITS1 isolate was efficient and can be recommended as a potential biocontrol agent against S. littoralis. Further field evaluations are still needed.

The entomopathogenic fungi (EPF), as a biological control agent, can provide an alternative option for high-risk insecticides. Beauveria bassianais one of the most potential EPF of pest control all over the world. The EPF isolate Y-F_ITS1 was isolated from Egyptian fauna on Beauveria-specific selective medium (BS medium). Molecular screening of the B. bassianaisolate, using PCR amplification with B. bassiana-specific primers and nucleotide sequence analysis of the internal transcribed spacer (ITS) region, confirmed the isolate as B. bassiana(accession no. [MK773644.1]). Efficacy of the isolate Y-F_ITS1 was examined against fourth instar larvae of Galleria mellonellaL. as a model insect using concentrations from 104to 107spores ml−1in a contact toxicity assay under laboratory conditions. The pathogenicity experiment showed that all the tested concentrations caused mortalities ranged from 75 to 98.33%, within 5 days posttreatment with cumulative mortalities, reached 100%, before 7 days with typical symptoms of infection and sporulation. Further investigations are needed to prove its efficacy against different economic pests as a credible candidate of integrated pest management (IPM) program.