Effects of the nematodes Ovomermis sinensis on the contents of free fatty acids,trehalose and reducing sugar in the haemolymph of its host, cotton bollworm Heliothis armigera

摘要

The insect parasitic nematode Ovomermis sinensis Chen et al., 1991 has the potential for the biological control of a range of insect pests because many many insect species are susceptible to this nematode. Studying the biochemical component in the haemolymph of one of its hosts, cotton bollworm Helicoverpa armigera offers the indispensable biochemical parameter to succeed in confecting the culture medium of in vitro . Changes in the content of reducing sugar, trehalose and free fatty acids in the haemolymph of H . armigera infected by O . sinensi s were studied by 3,5- dinitrosalicylic acid and gas chromatography . During the first three days of infection, the level of reducing sugar(mg/ ml) ( 0.551±0.035, 0.505±0.025 and 0.852±0.051, respectively ) in the haemolymph of H . armigera was significantly lower than that of the control group(0.655±0.041, 0.878±0.032 and 0.964±0.034, respectively). But on the fourth and fifth day of infection, it became significantly higher(1.016±0.051 and 1.016±0.042) than that of the control group(0.767±0.041 and 0.853±0.038). The sixth day, the level of reducing sugar of the infection group and the control group was 0.608±0.031 and 0.698±0.024 respectively. As for trehalose, the situation wasn’t the same as the reducing sugar. During the first three days of infection, the level of trehalose (0.349±0.029,0.374±0.027 and 0.479±0.046, respectively) was almost the same as that of the control group(0.383±0.026,0.374±0.023 and 0.483±0.034, respectively). After three days of infection, it (0.529±0.045, 0.584±0.041 and 0.428±0.041, respectively ) became lower than that of the control group(0.698±0.042,0.652±0.032 and 0.469±0.038, respectively). The relative levels (%) of unsaturated fatty acids in the infected and uninfected H . armigera were all 80% or so. The relative levels of palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid and linolenic acid etc in the haemolymph of H . armigera were much higher than that of other fatty acids. Changes in free fatty acids in the infected host were very complex. The results showed that the changes in the contents of reducing sugar, trehalose and free fatty acid in the haemolymph of H. armigera infected by O. sinensis benefited the growth of O. sinensis [ A cta Zoologica Sinica 51(2): 280–285, 2005].