Evaluation of entomopathogenic fungi and a nematode against the soil-dwelling stages of the crane fly Tipula paludosa.

BACKGROUND

Larvae of the crane fly Tipula paludosa (Diptera: Nematocera) are economically important pests of grasslands, nurseries and organically grown crops. This study was conducted to evaluate several entomopathogenic fungal strains, the entomopathogenic nematode Heterorhabditis bacteriophora and the organophosphate insecticide Dursban WG (75% chlorpyrifos) against larval stages of T. paludosa under laboratory and greenhouse conditions.

RESULTS

Metarhizium robertsii strain V1005 was the most virulent, causing 100% larval mortality 4 weeks post-inoculation. Eight other M. robertsii strains and M. brunneum (ARSEF 3297) caused mortality ranging between 0 and 60%, whereas strains of Beauveria bassiana, Isaria fumosorosea and Lecanicillium longisporum were non-pathogenic to T. paludosa. In greenhouse tests, medium (2 × 10(14) conidia ha(-1) ) and high (2 × 10(16) conidia ha(-1) ) concentrations of V1005 gave higher larval mortalities (90 and 100%) than lower (2 × 10(13) conidia ha(-1) ) concentrations (52 and 78%) at 4 and 8 weeks after treatment respectively. Dursban WG gave 100% larval mortality 4 weeks after treatment; H. bacteriophora UWS1 caused 28 and 65% mortality 4 and 8 weeks after treatment respectively.

CONCLUSIONS

This study shows that M. robertsii V1005 has considerable potential for the control of T. paludosa, thereby reducing the use of chemical insecticides.