Response Of Rhopalosiphum Padi Laboratory Population To Temperature Stress

Rhopalosiphum padi is an important wheat pest worldwide.This specie not only damages wheat by sucking the juice directly,but also transmits the barley yellow dwarf virus(BYDV),which caused yield reduction and quality decreased of the wheat every year.R.padi is parthenogenetic in most wheat growing regions.Aphids has small body size,relative big body surface and short life history,which make they are sensitive to environmental changes.The life history traits of R.padi can be influenced by the change of environmental temperature and humidity.With the global warming,how the insect response to the increasing temperature is becoming an important research topic of ecologists.In the current study,we treat the R.padi with moderate and high temperatures,and analyze the effect of temperature stress on the pest as well as the trans-generational maternal effect.Our results would be useful for the the population dynamics predication under the global warming and for the management of the serious pest.1.Effects of fluctuant temperature and constant temperature on R.padi adult longevity and fecundityFour temperature treatments,including the moderate constant temperature,the fluctuant moderate temperature,the constant high temperature and the fluctuant high temperature were used to analyze the effect of fluctuant temperature and constant temperature on R.padi adult longevity and fecundity.The results indicated that the adult longevity and fecundity of R.padi was not significantly affected by the moderate temperature treatments.The longevity was significantly shortened and the fecundity was significantly decreased after the high temperature treatment.Compared to the control,the the adult longevity decreased 30.64% and 57.75% after the constant and fluctuant temperature treatment,respectively,whilst the fecundity decreased 33.82% and 49.14%.The results suggest that the fluctuant high temperature had more affected on the adult longevity and fecundity thanthe constant high temperature.2.Effect of fluctuant high temperature at nymph stage on the adult of R.padiDifferent nymph stages of R.padi were treated by fluctuant high temperature for different days,and the life history traits were analyzed.The results showed that the total developmental duration was significantly prolonged,the longevity was significantly shortened,and the fecundity was significantly decreased when the nymph experienced fluctuant high temperature at the early stage(1-day-old,2-days-old and 3-days-old nymph),whilst the total developmental duration,the longevity and the fecundity was not significantly afftected when the nymph experienced fluctuant high temperature at 4-days-old and 5-days-old nymph nymph.The results showed that the R.padi was more sensitive to temperature treatment at the early stage of development,and the early temperature treatment could cause more dramatic changes in the life history traits.3.Trans-generational maternal effect of fluctuant temperature treatment on R.padiThe newly-born nymph(F0 generation)of R.padi were treated with fluctuant high temperature,and the life history traits were analyzed for exploring the trans-generational maternal effect.Compared to the control and the fluctuantmoderate temperature treatment,the total developmental duration was significantly prolonged,the longevity was significantly shortened,the fecundity and the intrinsic rate of increase was significantly decreased when the maternal generation experienced fluctuant high temperature.When the maternal generation experiencing fluctuant high temperature,the development duration of the offspring generation was significantly prolonged,the longevity,the fecundity and the intrinsic rate of increase was decreased.Compared to the control and the fluctant high temperature treatment,the total developmental duration was significantly shortened,and the intrinsic rate of increase was significantly increased when the newly-born nymph experienced fluctuantmoderate temperature.Compared to the control and the fluctant high temperature treatment,the longevity and the fecundity of the offspring generation was highest when the maternal generation experiencing fluctuantmoderate temperature,and the offspring generation developed fastest and the the intrinsic rate of increase was highest for the fluctant high temperature treatment after the maternal generation experienced fluctuantmoderate temperature.