Entomopathogenic activity of a whitefly-derived isolate of Paecilomyces fumosoroseus (Deuteromycotina: Hyphomycetes) against the Russian wheat aphid, Diuraphis noxia (Hemiptera: Sternorrhyncha: Aphididae) with the description of an effective bioassay method

This is the first report of the potential of the hyphomycete fungus, Paecilomyces fumosoroseus (Wize) Brown & Smith, for the microbial control of aphids. The LD50 and LD90 of a strain of P. fumosoroseus isolated from Bemisia tabaci (Gennadius) from Multan, Pakistan and bioassayed against third instar Diuraphis noxia (Mordvillco) were 1.78*103 conidia/cm2 and 1.43*104 conidia/cm2, respectively. Strong dosage-mortality and dosage-mycosis responses were evident with larger proportions of individuals dying within the first three days post-treatment at the higher conidial dosages (1.25-3.75*104 conidia/cm2) than was observed for dosages equal to or lower than 3.75*103 conidia/cm2. The LT50s for D. noxia treated with 3.75*104 conidia/cm2 and 3.75*103 conidia/cm2 were 2.06 and 7.50 days, respectively. The entomopathogenic activity of P. fumosoroseus against D. noxia compares favorably with other Hyphomycetes reported in the literature. Based on the results reported here, further investigation of the potential of P. fumosoroseus for the microbial control of D. noxia and other aphids is warranted.In addition to data on the efficacy of P. fumosoroseus as a microbial control agent of D. noxia, a simple, but effective bioassay method for the evaluation of fungi against cereal aphids is described.