Thermal Adaptation Of Laboratory And Field Population In English Grain Aphid (Sitobion Avenae)

The English grain aphid(Sitobion avenae)is one of pests that occurs widely and seriously threatens the yield and quality of wheat in China,so it is very important to construct a prediction model for the control of wheat aphid.However,most of prediction models are constructed using the results of laboratory populations.In fact,obvious divergences between laboratory and field populations in genetic diversity,resistance,biology and thermal sensitivity have been found in other insect studies.The laboratory population and field population of wheat aphid live in constant temperature and fluctuating temperature for a long time,respectively.At present,whether there is a difference in thermal biology between laboratory population and field population has not been explained and whether the experimental results of laboratory population can be used to build prediction models to reflect the situation in the field has not been decided.In order to clarify the above problems,we have studied the basal heat tolerance,the response to different temperature amplitude,the response to a series of constant temperature and corresponding natural fluctuating temperature of field population and laboratory population.The main results are as follows: 1 The basal heat tolerance of the field population and laboratory population was determined.The basal heat tolerance of laboratory population was higher than that of field population,and the average value of CTmax was 37.11 ±0.27 ? and 36.03±0.32 ? respectively.2 The life history traits of field and laboratory population at 22 ±0 ?,22 ±5 ?,22 ±9 ? and 22 ±13 ? were determined.The fitness of field population to temperature variation was better than that of laboratory population.There was no difference between field and laboratory population in nymphal duration at 22 ±0 ?,22 ±5 ? and 22 ±9 ?,but the difference was significant at 22 ±13 ?.There were significant differences in longevity,total fecundity and overall survival at all temperatures between field and laboratory population.The fecundity and survival of field population is superior to that of laboratory population.3 The life history traits of the field population and laboratory population were determined under the constant temperature of 0-32? and the corresponding fluctuating temperature(±5?).The performance curves of field population and laboratory population under constant temperature and fluctuating temperature were fitted respectively.It was concluded that the responses of field population and laboratory population to low temperature and high temperature might be different.The performance of laboratory population was better than that of field population at lower population,but the results were opposite at higher temperature.The laboratory population showed the same performance under constant temperature and fluctuating temperature,but the field population showed better performance at constant temperature than at constant temperature.Based on the above conclusions,it was concluded that the basal heat tolerance,the response to temperature variation and the performance curve of the field population and laboratory population were different.Therefore,it can be preliminarily concluded that the results of laboratory population may not well reflect the thermal biology of the field population.