Pathogenicity of Metarhizium anisopliae isolates on Nezara viridula and Dichelops melacanthus in wheat crop

Abstract

Bugs such as Nezara viridula (Linnaeus) and Dichelops melacanthus (Dallas) are considered the main insect pests of wheat crop in Brazil. The use of the entomopathogenic fungus Metarhizium anisopliae (Metschnikoff) may be an alternative for the management of these insects in the crop. The objective of this work was to verify the pathogenicity of different isolates of M. anisopliae on adults of N. ¬viridula and D. melacanthus under laboratory and greenhouse conditions. In the laboratory, isolates 05RA, 11RA, 08RA and 02RA were obtained from N. viridula and D. ¬melacanthus infested with M. anisopliae. Also, a high pathogenicity (100% of mortality) of both species was recorded in a bioassay of the topical application 8 Days After Application (DAA). However, compared to the other isolates, the 08RA isolate showed the highest pathogenicity in a shorter time interval for N. ¬viridula (Mean Time “MT” = 2.8 days) and D. melacanthus (MT = 4.0 days). Under greenhouse conditions, the 08RA isolate provided a mortality of 44.9% (N. viridula) and 35.7% (D. melacanthus) in the same evaluation period. However, at 14 DAA, the mortality was 100% for both species, with the MT values of N. ¬viridula and D. ¬melacanthus being obtained at 8 days and 10 days, respectively. The fungus M. anisopliae is a promising alternative for the control of adult N. viridula and D. melacanthus in wheat crop.