The Overwintering Biological Characteristics And The Effects Of Short-term High Temperature On The Survival And Reproduction Of The The Lygus Pratensis

Lygus pratensis Linnaeus is an important agricultural pest that attacks the cotton and fruits grown in southern Xinjiang.In recent years,its increasing destruction has posed a serious threat to the sustainable development of related industries.However,there was limited knowledge on the biological characteristics that make L.pratensis possible to survive winter and summer in southern Xinjiang’s unique temperate continental arid climate.This article is aimed to investigate the survival rate of overwintering L.pratensis,corresponding and influencing factors,the effects of temperature and photoperiod on the biological characteristics of adults after diapause at different overwintering stages,and the effects of short-term high temperature exposure on their survival and reproduction.The conclusions are as follows:1.Overwintering Survival Influencing Factors of L.pratensisAdults of the L.pratensis could live through winter successfully in soil that had a moisture content of 5-40%.When soil moisture content increased,the survival rate of overwintering would firstly increase and then decrease.The survival rate peaked at 28.9% when the soil moisture content is 15%,and reached the lowest at 5.5% when the soil moisture content was 40%.The survival rate of overwintering adults of the L.pratensis was related to their body color.The results show that the survival rate of overwintering adults with body color level 2 was 23%.In contrast,those with body color level 4 had a significantly higher survival rate of 30.5%.The survival rate(34.5%)of adult insects that were fed before overwintering was significantly higher than those that were not fed(27.5%).The overwintering survival rate of female adults of the L.pratensis is higher than that of male adults,with a rate of 28.75% and 24.06%,respectively.2.The Effects of Temperature and Photoperiod on the Biological Characteristics of Adult Diapause of L.pratensis at Different Overwintering StagesThe conditions of temperature 24 ℃ and photoperiod L15: D9 could benefit the relieving of the diapause for L.pratensis females whose egg laying rate after diapause reached 94.67%.There are significant differences in the oviposition duration,oviposition quantity,and female adult lifespan of the natural population of the L.pratensis in November and March at temperatures of 16,20,and 24 ℃ and different photoperiods(L15: D9,L12: D12,L9: D15).At photoperiod L15: D9,as the treatment temperature increased,the pre oviposition period,oviposition duration,and lifespan after releasing diapause was decreased,and the number of eggs laid was increased;Under the condition of 24 ℃,with the extension of light duration,the pre ovulation period was shortened but the duration and lifespan of egg laying was prolonged,and the number of eggs laid was increased.The length of overwintering period had a significant negative impact on the egg production and lifespan of the diapause adults of the L.pratensis.3.Effects of Short-term High Temperature Exposure on the Survival and Reproduction of the L.pratensisA short-term exposure had no significant effect on the hatching rate of eggs at 33-36 ℃,but it had a significant negative effect after treatment at 42 ℃.Only 6.33% of the eggs could hatch after 2 hours of exposure at 45 ℃.After being treated at 45 ℃ for 1 hour,the survival rate of nymphs significantly decreased,and the development period was 1.07 days longer than the control.Exposure of adults to high temperatures ranging from 33 to 36 ℃ for 2 hours has no significant impact on their survival rate,lifespan,pre oviposition,and egg production;After 2 hours of exposure at 39 ℃,the survival rates of male and female adults began to decrease significantly,reaching 84.44% and 78.89%,respectively;The survival rate,lifespan,pre oviposition period,and single female egg production of female insects treated at 45 ℃ for 2hours were 34.44%,21.45 days,8.43 days,and 157.83 eggs,respectively,with significant differences compared to the control.The population trend index after high temperature exposure at 33～45 ℃ was lower than that of the control at 25 ℃,among which the population trend index of the L.pratensis after high temperature exposure at 45 ℃ was 0.