Potential Use of Fusarium Isolates as Biological Control Agents: Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) Case Study

Abstract

The cotton bollworm Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is a notorious agricultural pest with world-wide distribution, extreme polyphagy, high mobility and fecundity, facultative diapause, and significant resistance to chemical insecticides. Isolates from various Fusarium species were collected from soil, identified, and tested for their entomopathogenicity against H. armigera larvae in field experiments. Fungi of the genus Fusarium are ubiquitous and include phytopathogenic as well as entomopathogenic strains. Seven Fusarium species were identified and tested, including: F. algeriense, F. chlamydosporum var. chlamydosporum, F. fujikuroi, F. longifundum, F. pseudoanthophilum, F.solani, and F. tonkinense. All the collected fungi demonstrated a notable insecticidal effect on H. armigera larvae in field conditions, while some proved to be significantly lethal. The larval mortality of H. armigera ranged from 10 (103 conidia/mL) to 91% (108 conidia/mL) after 9 days (216 h). Larval survival time in treated plants ranged from 95 h (108 conidia/mL) to 208 h (103 conidia/mL). According to our results, F. solani isolate displayed the highest toxicity against H. armigera larvae and could be considered as a promising biocontrol agent of this serious pest.