Insecticidal activity of the extract, fractions, and pure steroidal saponins of Trillium govanianum Wall. ex D. Don for the control of diamondback moth (Plutella xylostella L.) and aphid (Aphis craccivora Koch)

BACKGROUND

Plutella xylostella L. is the major pest of crucifers globally, causing significant yield loss. Aphis craccivora Koch is the main sucking pest of legumes that transmit viral diseases, leading to economic yield reduction. To minimize loss due to pests, farmers/growers use synthetic insecticides frequently for their control, which led to insecticide resistance, detrimental to natural enemies of pest, environment, etc. Therefore, in this study, the insecticidal activity of plant extract, fractions, and pure steroidal saponins from Trillium govanianum was evaluated for their bio-efficacy against targeted pests.

RESULTS

Parent extract was found more effective (LC₅₀ = 1541.2 mg L^-1 ) against larvae of P. xylostella after 96 h than n-butanol, n-hexane, and ethyl acetate fractions (LC₅₀ = 3030, 3578 and 3878.1 mg L^-1 , respectively). For A. craccivora, ethyl acetate fraction (LC₅₀ = 2186.3 mg L^-1 ) was most effective after 96 h than n-hexane fraction (LC₅₀ = 2234.6 mg L^-1 ), n-butanol fraction (LC₅₀ = 2696.3 mg L^-1 ) and parent extract (LC₅₀ = 3709.1 mg L^-1 ). Among pure molecules, govanoside B was found more effective (76% mortality, LC₅₀ = 3279.5 mg L^-1 ) followed by borassoside E (74%, LC₅₀ = 3467.1 mg L^-1 ) against A. craccivora after 96 h.

CONCLUSION

Parent extract/fractions of T. govanianum showed promising efficacy against larvae of P. xylostella and A. craccivora. Further, field study is required for its bio-efficacy against targeted pests for validation and formulation development.