Identification and virulence characterization of entomopathogenic fungus <Emphasis Type="BoldItalic">Lecanicillium attenuatum</Emphasis> against the pea aphid <Emphasis Type="BoldItalic">Acyrthosiphon pisum</Emphasis> (Hemiptera: Aphididae)

An entomopathogenic fungal strain was originally isolated on artificial medium from the corpse of a pea aphid (Acyrthosiphon pisum Harris) collected at Jingzhou, China (N30°21′18.15″, E112°08′41.63″). Based on tests of the morphological, physiological and biochemical characteristics and analysis of internal transcribed spacer (ITS) sequences, it was considered to be a strain of Lecanicillium attenuatum Zare & W. Gams. Therefore, the strain was designated L. attenuatum YZU 151121. The activity of the biological agents under study was determined at 26 °C and 90% relative humidity. The number of A. pisum killed was increased by increasing the concentration of L. attenuatum. The results demonstrated that L. attenuatum YZU 151121 showed a high efficacy against 3rd-instar nymphs (LC₅₀ = 2.91 ± 0.365 × 10⁵ conidia/ml) and adults (LC₅₀ = 3.12 ± 0.398 × 10⁶ conidia/ml) after 6 days of exposure. Crude extract from this strain was tested for contact toxicity and showed high activity in 3rd-instar nymphs and adults, with LC₅₀ values of 251.34 ± 49.54 and 315.46 ± 87.66 mg/l, respectively. In addition, crude extract at a concentration of 200 mg/l could significantly reduce fecundity in adults. These results revealed that the strain YZU 151121 may be useful in biopesticides for controlling pea aphid.