Effects Of Nitrogen Fertilizer On The Tritrophic System Of Rice-Cnaphalocrocis Medinalis Guenee-Apanteles Cypris Nixon

The abuse of chemical fertilizers is one of the key reasons for insect pest outbreaks. The mechanism of nitrogen fertilizer on the tritrophic system of rice -Cnaphalocrocis medinalis Guenee -Apanteles cypris Nixon is still unclear. Therefore, rice plants were grown in the aquatic cultures with five different levels of nitrogen and the effect of nitrogen fertilizer on the nutritional content in rice leaves, the indirect impacts of nitrogen fertilizer on the growth, development, fertility and nutritional content of larva of Cnaphalocrocis medinalis Guenee and the indirect impacts of nitrogen fertilizer on the parasitization of Apanteles cypris Nixon were investigated. The results are as follows:1 Effect of nitrogen fertilizer on the nutritional content of rice leavesWith the increment of nitrogen concentration, the contents of protein, reductive sugar, amino acids in rice leaves increased at the prophase, and decreased at the anaphase (N=62g/L, N=58 g/L , N=55g/L) . 2Effect of nitrogen fertilizer on the growth, development, fertility ofCnaphalocrocis medinalis GueneeThe moth prefered to lay eggs in the rice plants grown in the solutions with a higher nitrogen. There was no difference regarding the durations of larva and pupa developed in the rice plants grown in different nitrogen concentrations, but the weight of pupa became higher with the increment of nitrogen concentration. In addition, nitrogen significantly favored the longevity and oviposition of the moth. With the increment of nitrogen concentration, the contents of protein, reductive sugar, amino acids of larva again increased at the prophase, and decreased at the anaphase (N=62 g/L, N=58 g/L, N=58 g/L) . 3 Effect of nitrogen fertilizer on the parasitization of Apanteles cypris NixonThe wasp prefered parasitizing the larva of Cnaphalocrocis medinalis Guenee feeding on the rice plants growing in the solutions with a higher nitrogen and decreased at the anaphase (N=56 g/L) . Nitrogen significantly enhanced the longevity of the wasp.