Pathogenicity induced by indigenous Beauveria bassiana isolate in different life stages of the cotton leafworm, Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) under laboratory conditions

Abstract

Background The invincible effects of the entomopathogenic fungi (EPF) under appropriate circumstances compensate for the flaws of chemical insecticides in the control programs. Beauveria bassiana is one of the most elaborated EPF of pest control all over the world. The potential of using the B. bassiana isolate (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. littoralis were significantly the most susceptible stage to B. bassiana isolate 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 × 109 spores 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. bassiana isolate showed an ovicidal effect to the eggs of S. littoralis that reached 100% mortality when treated with 1.0 × 108 and 1.0 × 109 spores ml−1, while the concentration 1 × 107 and 1.0 × 108 caused 65.0 and 87.0%, respectively. Reduction of adult emergence reached (0%) in case of treatment with the highest concentrations (1 × 108 and 1 × 109 spores 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.

Identification and evaluation of isolated entomopathogenic fungus from Egyptian soil against the black cutworm larvae of Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae)

“…(Ibrahim and Gabr 2020). In the present results, the fungus toxicity reached (100%) mortality for treated last instar larvae of A. ipsilon at a concentration of 2.9 × 10 6 spores/ml after 14 days while the study of Ibrahim and Gabr (2020) Fergani and Refaei (2021) recorded morphogenetic abnormalities of S. littoralis adults after treatment of larvae with 1 × 10 8 and 1 × 10 9 spores ml −1 of B. bassiana. The observed malformation of emerged adults resulted from lepidopterous larvae treated with different isolates of B. bassiana as stated in the present and several other studies may be due to the findings obtained in Kaur et al (2011) study.…”

First study on the root endophytic fungus Trichoderma hamatum as an entomopathogen: Development of a fungal bioinsecticide against cotton leafworm (Spodoptera littoralis)

“…Within the topical application of the spores, we did not report significant differences between the concentrations 10 8 -10 10 spores mL − 1 , being 10 8 the maximum concentration effective against S. littoralis larvae, although without exceeding 50% mortality. In the case of B. bassiana, its ability to infect S. littoralis L 3 larvae with mortality of up to 90% at 10 9 spores mL − 1 has been previously described, however, our commercial isolate did not report such efficacy (Fergani and Refaei, 2021). In the case of T. hamatum, our study is the first performed with this fungal species and with S. littoralis and any Trichoderma species, but a previous study with the species T. longibrachiatum and the lepidopteran Leocinodes ordinalis obtained mortality percentages of 85% with 10 8 spores mL − 1 (Ghosh and Pal, 2016).…”

“…Therefore, entomopathogenic fungi are being studied in recent years for the development of effective bioinsecticides against pests within the genus Spodoptera (Guo et al, 2020;Paredes-Sánchez et al, 2021). Specifically, against S. littoralis, the following species have been described as effective entomopathogenic fungi: B. bassiana (Fergani and Refaei, 2021), Metarhizium anisopliae (El Husseini, 2019), M. brunneum (Garrido-Jurado et al, 2020), Isaria fumosorosea (syn. Paecilomyces fumosoroseus) (Hussein et al, 2013), and different specific endophytic fungi (Saad et al, 2019;El-Sayed et al, 2020).…”

Field Evaluation of Organophosphorus Insecticides, Chlorpyrifos and Fungal Bio-Pesticides, Beauveria bassiana Towards the Sugar Beet Moth Scrobipalpa ocellatella (Lepidoptera: Gelechiidae) and Studying their Effect on the Population Size of the Associated Arthropod Predators in the Egyptian Sugar Beet Fields.

“…On the other hand, Biossiana® has a promising effect on the sugar beet moth especially in cases of early infestation with minimal effect on the associated predators compared to traditional insecticides. Entomopathogenic Hyphomycetes such as B. bassiana and Metarihizium anisopliae were suggested in control programs due to their high effectiveness with a wide range of pest populations Smith et al 1999and Ahmed et al 2020. Fergani and Refaei, (2021 proved that B. bassiana-based bio insecticides were more effective than other microbial pesticides causing high mortality percentage and morphogenetic abnormalities in different stages of larvae, egg and adult including pupation period in the soil in lepidopterous insects in the time it considered as an excellent alternative to conventional insecticides offering eco-friendly control agent with minimal residue (Fergani and Yehia 2020) and no hazardous to associated arthropod predators.…”