Multi-generational effects of salicylic acid on Lipaphis erysimi and induced defense in Brassica juncea.

Turnip aphid, Lipaphis erysimi Kalt. (Hemiptera: Aphididae), is an insecticide-resistant pest of Brassica spp. SA-salicylic acid, a hormonal regulator of systemic acquired resistance in plants, might prove to be a better option against resistant pests. Therefore, SA was applied exogenously in the four treatments with the concentrations of 0, 0.5, and 1 mM 24-hours before infesting the Brassica juncea (Chinese leaf mustard) plants with L. erysimi. Responses of aphid were noted for two generations (F1 and F2) on reproductive fitness parameters. Kaplan-Meier survivorship, developmental period, reproduction time, effective fecundity (Md), intrinsic rate of increase (rm), relative growth rate, generation time (Mgt), total progeny, proportion of nymphs reaching adulthood, and nymph survival were significantly affected at the concentrations of 1- and 0.5-mM SA over the control and 0 mM treatments. Plant chlorophyll, nitrogen, and crude proteins were greatest in 0.5 mM while 1 mM SA reduced it significantly. Flavonoid (myricetin and quercetin), hydrocinnamic acid (caffeic, ferulic, and sinapic acid), and phenolic acid (chlorogenic, gallic, and syringic acid) were activated in response to aphid attack which were enhanced in 1 mM SA followed by 0.5 mM. Therefore, SA could be a better tool in managing L. erysimi but field level studies are suggested to assess its efficacy in diversified environment. This study could help in reducing pest abundance in organic agriculture and improving plant biochemistry to breed resistant crops to ensure global food security.