The Adaptability Of Wireworm For Several Environmental Factors

This study aimed to identify and understand the wireworms as the dominant species of underground pest. With the trend of great yield lost which caused by wireworms was getting worse, besides our lack of knowledge on the interactions between the wireworms population dynamics and the environmental factors, our research was concentrated on the aspect of respiratory metabolism, the adaptabilities changes of wireworms under different environmental factors which were temperature, humidity, illumination and oxygen. The ecological behaviors of wireworms have been studied when they move upward in soil filter and cause damage in spring, the physiological parameters of weight, molting times, water content, respiratory rate and energy substances were concerned under starvation regarding to the lack of food after the overwintering. The results are as follow:1. The CO₂ release rate (VCO₂)and range of Pleonomus canaliculatus was significantly influenced by temperature, and them were increased according to the warming (yVCO₂=5.9638e^0.4916x,R²=0.9362; yrange=14.849e^0.1169x,R²=0.9361). When the temperature rose from 25℃to 30℃, VCO₂ and range were slowly fluctuated. The results indicated that the optimum temperature range of P. canaliculatus for growth and movement is 10²0℃. There were no significant differences among the VCO₂ and range of P. canaliculatus under 7 different O₂ concentrations and 3 different air humidities. The oxygen concentration and air humidity changes had no significant contribution to respiration intensity. VCO₂ and range of P. canaliculatus under intense light source was two times higher than when they under dark (P<0.05). This convinced conclusion indicates that the light intensity play a main role in P. canaliculatus respiratory metabolism processes.2. The CO₂ tracer applied to P. canaliculatus under the specific condition (temperature 15℃, O₂ concentration 21%, air humidity 5%, dark), the results indicated that the breathing pattern of P. canaliculatus was the variable-amplitude oscillated type.3. The weight changes and molting times of P. canaliculatus and Melanotus caudex under 4 living conditions showed that: the insects weight changed little when soil or vermiculite was applied; the weight changes significantly when soil + wheat or vermiculite + wheat was mimiced; the molting times had no significant different among the 4 living conditions. It was showed that shortage of food will not affect the weight and molting times of wireworms.4. Under soil or vermiculite and host plant without for 5 months, the water content of P. canaliculatus remained between 63.34%⁶6.55%; The water content of M. caudex increased significantly (P<0.05), whereas there was no significant difference between two living conditions at the same time; As the living time increased, the respiratory rate was faint significantly. The mechanisms of resistance to hunger were different for the two species.5. Compared to control, the contents of glycogen stably maintained and glyceride significantly increased in soil or vermiculite treatments. T-test results showed that energy substances had no significant difference between two living conditions at the same time.