D3061: New promising biological control approach for controlling corn earworm (Helicoverpa zea) and fall armyworm (Spodoptera frugiperda) on cotton

Cotton (Gossypium hirsutum) is a valuable crop due to its use in the textile industries, oil production, and livestock feeding. The corn earworm (Helicoverpa zea) and fall armyworm (Spodoptera frugiperda) are the most important pests that could severely impact cotton yield and quality in some locales. The application of entomopathogenic fungi, such as Beauveria bassiana (Ascomycota: Hypocerales), has been a recommended practice in some production areas. Recently, an endophytic strain of B. bassiana known as GHA has been introduced, which can colonize plants. The colonized plants with the endophytic entomopathogenic fungi have been reported to have faster and/or stronger induction of various cellular defense responses to biotic and abiotic stresses than untreated counterparts, effects that may be more persistent than the non-endophyte strains. The present laboratory bioassay was conducted to evaluate the colonization success of B. bassiana GHA on different parts of cotton plants following foliar application. We then evaluated the efficacy of the approach against corn earworm and fall armyworm. Beauveria bassiana successfully colonized different cotton plant tissues; colonization success was estimated to be 100, 64, and 28% in leaves, stems, and roots, respectively, within seven days of inoculation. The survivorship of the 2^nd instar larvae of H. zea and S. frugiperda reared on the B. bassiana GHA-treated plants was 48.33 % and 57 % respectively. The findings add to our understanding of interactions between the endophytic B. bassiana and host plants and demonstrate its potential as a new biological control approach to managing pests.