The infectivity of Metarhizium anisopliae to two insect pests of coconuts

Papua New Guinea isolates of Metarhizium anisopliae from the rhinoceros beetles, Scapanes australis and Oryctes rhinoceros; the black palm weevil, Rhynchophorus bilineatus (Coleoptera); and three other insect orders (Hemiptera, Lepidoptera, and Dermaptera) were all short-spored (M. anisopliae var. anisopliae). Isolates from Scapanes were also pathogenic to Rhynchophorus and Oryctes. When a Scapanes isolate was grown on brown rice and released into the frond axils of young palms, 32% of dead Scapanes adults collected during the following 48 weeks were infected compared to 1% in the control nonrelease palms. Some infection of Rhynchophorus also occurred. Infection in Scapanes but not Rhynchophorus also increased in a plot of palms adjacent to the release zone. The rice inoculum could be recovered and the fungus reisolated up to 84 days after release, but infection of Scapanes continued to occur after all trace of the inoculum had disappeared.