Abstract: 【Aim】 This study aims to make clear whether the exogenous jasmonic acid (JA)-induced resistance in green poplar, Populus cathayana Rehd., influences food utilization of larvae of the gypsy moth, Lymantria dispar (L.). 【Methods】 JA solution at the concentrations of 0.001 mmol/L and 0.1 mmol/L (diluted with 99.5% acetone first and then with distilled water) was sprayed onto green poplar seedlings, while the control was sprayed with the 0.2% acetone solution. The changes in the contents of primary and secondary metabolites, mainly proteins, soluble sugars, phenols, lignins, flavones and tannins, were tested on the 1st, 5th and 10th day post treatment. To assess the food utilization of L. dispar larvae, other green poplar seedlings sprayed with 0.1 mmol/L JA solution were used to rear the newly molted 2nd instar larvae, and the body weight, food consumption, feces and the duration of the 2nd instar larvae were measured. 【Results】 Compared to the control, the contents of proteins and soluble sugars in green poplar seedlings sprayed with exogenous JA solution decreased, but the contents of phenols,lignins, flavones and tannins increased significantly. The contents of soluble sugars and proteins in green poplar leaves decreased to the lowest level on the 10th day post JA treatment, and reduced by 46.5% and 49.1% in the high-concentration JA treatment group, and 30.6% and 22.8% in the the low-oncentration JA treatment group, respectively, compared to the control. The total content of phenols in green poplar leaves was at the highest level on the 10th day post JA treatment and increased by 102% in the high-concentration JA treatment group compared to the control. The contents of lignins, tannins and flavones in green poplar leaves reached a peak on the 5th day post JA treatment and increased by 113%, 75% and 57% compared to the control, respectively. The approximate digestibility, conversion rate, utilization rate of food for L. dispar larvae fed on the JA-induced green poplar leaves all decreased compared with the larvae fed on the normal leaves (not induced by JA). The food utilization rate of larvae fed on leaves induced for 1, 5 and 10 d by JA decreased by 29.4%, 27.6% and 28.2%, respectively. The larval body weight decreased and the developmental duration was prolonged after the larvae fed on the JA-induced green poplar leaves. 【Conclusion】 The results suggest that the biochemical resistance of green poplar to  L. dispar is induced by exogenous jasmonic acid, and this could be adopted in controlling the damage of the gypsy moth.

Key words: Lymantria dispar, green poplar, biochemical resistance, jasmonic acid, food utilization