Study On The Adaptation Of Aphidius Gifuensis Ashmead To The Hosts Of Wheat Aphids And Low Temperature

1Effects of Fluctuating Thermal Regimes on the cold tolerance of Parasitoid Wasps Aphidius gifuensis AshmeadIn order to understand the effects of fluctuating thermal regimes (FTRs) on cold tolerance of Aphidius gifuensis female and male adults, explore the mechanism of the biochemical process in their body, we determined the supercooling point (SCP), freezing point (FP), water, fat, protein and carbohydrate contents in the body of A. gifuensis female and male adults after FTRs treatments in mummies of Schizaphis graminum. The results showed that the cold tolerance was observably enhanced after1week of4℃22h/20℃2h (T1) and4℃46h/20℃2h (T2) treatments. The SCP and FP were presented the downtrend in the different thermal treatments. The SCP and FP of female adults were the lowest (26.38±0.28℃and-25.51±0.32℃, respectivley) after1week of4℃22h/20℃2h (T1) treatment, while the SCP and FP of male adults were the lowest (-26.82±0.34℃and-26.38±0.48℃, respectively) after1week of4℃46h/20℃2h (T2) treatment. The SCP and FP of female adults were the lowest (-26.44±0.32℃and-26.12±0.35℃, respectivley) after2week of446h/20℃2h (T2) treatment, and the SCP and FP of male adults were also the lowest (-26.35±0.26℃and-25.63±0.41℃, respectively). Compared with the control of constant temperature (20℃), the carbohydrate and protein contents in the body of A. gifuensis female and male adults were raised, however the fat and water contents were declined after the different thermal treatments. Compared with the control of constant temperature (4℃), the enzyme activity of CAT, POD and SOD in the body of A. gifuensis were observably improved. The distinct changes were found in1and2weeks of4℃22h/20℃2h and4℃46h/20℃2h treatments. The results indicated that the enhanced cold tolerance of A. gifuensis adults after FTRs treatments was related to the biochemical adjustments in the body. The1and2weeks of4℃22h/20℃2h (T1) and4℃46h/20℃2h (T2) treatments were advantageous to the survival and practical application of A. gifuensis.2Effects of Schizaphis graminum and Macrosiphum avenae on the physiological and biochemical characteristics of Aphidius gifuensis AshmeadIn the laboratory (22±1℃,40%RH, a photoperiod of L:D=16h:8h), the adult physiological and biochemical characteristics of Aphidius gifuensis Ashmead were investigated after reared on the two species of wheat aphid, Schizaphis graminum and Macrosiphum avenae. The results showed that the head width (0.67±0.09mm,0.62±0.09mm),longevity (5.0±0.3d,4.6±0.2d), SCP (-25.7±0.42℃,-25.3+0.44℃) and FP (-24.9±0.37℃,-24.8±0.52℃) of female and male adults using M. avenae as host were enhanced significantly than the head width (0.56±0.07mm,0.53±0.06mm), the longevity (3.6±0.2d,3.1±0.ld), SCP (-24±0.28℃,-22.5±0.29℃) and FP (-23±0.35℃,-22.2±0.29℃) of female and male adults using S. graminum as host. The water, three kinds of energy materials contents and the enzyme activity of CAT, POD and SOD in the body of A. gifuensis from M. avenae were improved at different level as compare with that from S. graminum. The results indicated that A. gifuensis from M. avenae gets more anti-adversity characteristics for survive and reproduction than those from S. graminum.