Insecticidal metabolites produced by Penicillium spp., an endophytic fungus in Derris elliptica Benth

One strain of endophytic Penicillium sp. with insecticidal activities against Plutella xylostella and Lipaphis erysimi, was screened out from the fresh roots of Derris elliptica Benth. The total 12 fractions isolated from the chloroform extract of endophytic Penicillium sp. mycelia through silica gel column were bioassayed. The fraction E-4, E-5 and E-10 showed strong insecticidal activities, and their AFC₅₀ values against 3rd-instar P. xylostella larvae in no-choice test were 2.2209, 1.7485 and 2.0785 mg/mL after 24 h, respectively. Fraction E-4, E-5 and E-10 caused 81.8%, 89.1% and 92.3% contact mortalities of L. erysimi, respectively at 2.5 mg/mL. Furthermore, the efficiency of control at 10 mg/mL chloroform extract of endophytic Penicillium sp. was 90.0% after 7 days of treatment in greenhouse bioassay. Results in laboratory suggested that 2 h after treatment, both fraction E-4 and rotenone inhibited the respiration of the 4th-instar larvae of Bombxy mori. The respiratory restraining rate of fraction E-4 at a dosage of 200 g/larva was 49.2%, that was the similar respiratory restraining effect of rotenone at 5 g/larva. Both HPLC analysis and bioassay confirm that the fraction E-4 contains rotenone and its analogues.