Pathogenicity of two new isolates of Metarhizium anisopliae from Canadian soil to Melanoplus bivittatus (Orthoptera: Acrididae) and Tenebrio molitor (Coleoptera: Tenebrionidae)

Worldwide biological-control research has shown that the fungal entomopathogen Metarhizium anisopliae (Metschnikoff) is an alternative to chemical insecticides for controlling grasshoppers and locusts. The pathogenicity of two recently discovered isolates of M. anisopliae var. anisopliae Driver and Milner from Canadian soil to the key grasshopper pest Melanoplus bivittatus (Say) and the yellow mealworm, Tenebrio molitor L., was determined by means of laboratory bioassays. Insects were fed a single dose of 105 conidia suspended in sunflower oil on food (a standard-size lettuce wafer). Subsequent feeding activity, movement, and mortality were assessed daily. The isolates were equally pathogenic, and similar in pathogenicity to the industry standard, Green Guard (M. anisopliae var. acridum Driver and Milner). Treatment with the three isolates resulted in 50% grasshopper mortality in 5–6 days and 90% mortality in 6–7 days.