Control efficacy of isolates of Aspergillus nidulans and Aspergillus fumigatus against three destructive insect pests of stored grain

Abstract

Entomopathogenic fungi could be helpful in the management of stored insects and to reduce the use of synthetic broad-spectrum pesticides. Identifying the most virulent isolates of entomopathogenic fungi is important before any potential application for the control of stored products insect pests. This research aimed to assess the effectiveness of six isolates of Aspergillus nidulans (FCBP-EPF-1551, -1555 and −1579) and A. fumigatus (FCBP-EPF-1549, -1580 and −1605) in causing mortality and progeny suppression of three major storage insects, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) (the lesser grain borer), Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) (the red flour beetle) and Trogoderma granarium Everts (Coleoptera: Dermestidae) (the khapra beetle), under controlled environment. Each fungal isolate was evaluated at four different dose levels: 1 × 10⁴, 1 × 10⁶, 1 × 10⁸ or 1 × 10¹⁰ conidia kg⁻¹ wheat grains, and at three time intervals: 7, 14 and 21 d. Mortality count data of all insect species exhibited an increasing trend with increase in dose level and time interval. Generally, the isolates of A. fumigatus resulted in the highest mortality of all insect species along with a remarkable effect on progeny suppression in the next generation. Mortality and progeny suppression data revealed that R. dominica was the most susceptible species followed by T. castaneum and T. granarium. To sum up, the data of the present study clearly indicate the potential of A. nidulans and A. fumigatus isolates as biocontrol agents against tested insect species of stored grains.