Isaria fumosorosea (Hypocreales: Clavicipitaceae) And Beauveria bassiana (Hypocreales: Cordycipitaceae) as Potential Biocontrol Agents for Blue Alfalfa Aphid Acyrthosiphon kondoi (Hemiptera: Aphididae) in Alfalfa Medicago sativa

Abstract

Alfalfa (Medicago sativa L.) is a commonly grown crop in the low desert region of Arizona. One of the most damaging insect pests in this system is the blue alfalfa aphid, Acyrthosiphon kondoi (Hemiptera: Aphididae). Reports of aphids developing resistance to chemical pesticides and interest in conserving insect natural enemies, has renewed interest in developing biological control approaches for this pest. Recent observations of epizootic fungal infections in Arizona alfalfa aphid populations indicates entomopathogenic fungi could serve as biological control agents. Entomopathogenic fungi are a commonly used biological control for aphids. There are several species of entomopathogenic fungi currently commercially available for use as formulated insecticides. In this project I tested two commercially available mycopesticide formula, Isaria fumosorosea Apopka strain 97, PFR-97TM 20% WDG (Certis Biologicals, , Columbia, MD, USA) and Beauveria bassiana (Bals.), strain GHA, CX-10282 (Certis, USA) against a lab colony of A. kondoi. Direct and indirect application methods were used to determine the virulence of the tested fungi. Direct application of I. fumosorosea resulted in the highest observed mortality (47%) for the 1mg/mL dose, I. fumosorosea resulted in a lower mortality rate (33.2%) when applied with the indirect method. With respect to B. bassiana, the direct application of the highest tested dose (1mg/mL) yielded 33.6% aphid mortality, while the indirect application method resulted in a very low 18% mortality. These results provide guidance for the future consideration of the tested entomopathogenic fungi formulation in the control of blue alfalfa aphids.