Effects of differently induced plant resistance on the developmental performances of larval Spodoptera exigua (Lepidoptera: Noctuidae) and its parasitoid Meteorus pulchricornis(Hymenoptera: Braconidae)

[Aim] To identify the effects of induced plant resistance on the development of the beet armyworm, Spodoptera exigua(Hubner) and its endoparasitoid Meteorus pulchricornis(Wesmael).[Methods] The plants of Brassica campestris were induced by herbivory damage (HD), mechanical damage (MD), or spraying 0.01, 0.1 and 1 mmol/L exogenous methyl jasmonate (MeJA), and used to feed the newly-hatched larvae of S. exigua, which then were exposed to the parasitism of M. pulchricornis. The developmental performances of the host and its parasitoid were observed. [Results] The survival rate of S. exigua larvae fed on plants treated by HD and MeJA treatments decreased significantly, and the survival rate of S. exigua larvae had a negative correlation with MeJA concentration. The larval body weight of S. exigua fed on the plants subjected to 0.1 mmol/L MeJA treatment was significantly lower than that of the control. When S. exigua larvae fed on the plants subjected to HD and 0.1 mmol/L MeJA treatments, the mortality of the larv