Effects of locally inducing Larix olgensis using exogenous methyl jasmonate on the growth and development of Lymantria dispar

Abstract In order to understand how local spraying of exogenous methyl jasmonate would affect the induced resistance level of trees to insects, we sprayed identical amounts of 0.01, 0.10 and 1.00mmol/L methyl jasmonate, respectively, on whole Larix olgensis seedlings or on specific parts of the seedlings. We analyzed the effects of the methyl jasmonate treatments on the growth and reproduction of the gypsy moth (Lymantria dispar). The results showed that feeding gypsy moth larvae on plant sprayed either partially or entirely with these three concentrations of methyl jasmonate could decrease significantly the average larval weight of 3rd to 6th instars, the survival rate of the larvae, pupal weight, pupal and adult eclosion rates and the fecundity of adult females, compared to the control group (P<0.05). The same concentration of methyl jasmonate applied either to parts or to entire seedlings had no significant difference in the effect on the insect growth (P>0.05). The 0.10mmol/L concentration of methyl jasmonate sprayed on parts of plant had the best inductive effects. The above results illustrate that all three concentrations of methyl jasmonate applied either to parts or to entire seedlings can enhance the ability of larch to inhibit the growth and development of gypsy moth, and the partial spraying methyl jasmonate on larch seedlings can achieve the same inductive effects as spraying on the whole seedlings.