Reduced survivorship, host preference, and feeding damage by Helicoverpa zea (Lepidoptera: Noctuidae) on cotton plants colonized by the endophyte Beauveria bassiana (Ascomycota: Hypocreales).

Abstract

The GHA strain of Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales) is known to establish symbiotic relationships with some plant species. The present study was developed to determine whether the foliar application of B. bassiana-GHA and B. bassiana ANT-03, another commercial B. bassiana, results in the successful colonization of cotton, Gossypium hirsutum L., and examine whether the endophyte can influence the survivorship and feeding damage by the corn earworm, Helicoverpa zea Boddie (Lepidoptera: Noctuidae). Using polymerase chain reaction, colonization success by B. bassiana-GHA, 3, 7, 14, and 21 days after inoculation was estimated at 83.3%, 100%, 91.7%, and 83.3%, respectively. The colonization success based on the mycelial outgrowth method was 41.7%, 66.7%, 58.3%, and 50%, 3, 7, 14, and 21 days after inoculation, respectively. Beauveria bassiana ANT-03 did not colonize cotton. Corn earworms preferred untreated plants over the neonicotinoid and B. bassiana-GHA treatments. The B. bassiana ANT-03-treated plants and controls were not distinguished from one another by the corn earworms. The corn earworm survivorship was higher on the control plants, compared to plants treated with B. bassiana ANT-03, B. bassiana-GHA, and the neonicotinoid insecticide. The neonicotinoid insecticide, B. bassiana-GHA, and B. bassiana ANT-03 reduced corn earworm damage compared to the untreated controls. Our results demonstrated the potential for B. bassiana-GHA to be used as a biological control agent against H. zea in cotton.