| Soybean aphid,Aphis glycines,and foxglove aphid,Aulacorthum solani,are the dominant aphid species in soybean,Glycine max,in Heilongjiang Province,China,which are important pests in soybean.In recent years,with the intensification of global warming,the temperature is keeping rising and high temperature occurs frequently in Heilongjiang.In the region,A.glycines and A.solani have to face important survival pressure.To make clear the possible adverse effects of high temperature on the aphids in soybean,studies on effects of high temperature on development,reproduction,and morph differentiation of A.glycines and A.solani were conducted.There were three trials,which were done as follows:(1)A.glycines and A.solani were reared at constant temperatures of 27,29,31,33 and 35±1℃,14L: 10 D photoperiod and 70±5% RH.The constant 25 ℃ was used as control.Effects of constant high temperature on development and reproduction of A.glycines and A.solani were conducted.(2)A.glycines and A.solani were reared at diurnal temperatures of 27,29,31,33,35 and 37±1℃,nocturnal temperature of 20℃,14L: 10 D photoperiod and 70 ± 5% RH.The diurnal temperature of 25℃ was used as control.Effects of diurnal high temperature on development and reproduction of A.glycines and A.solani were conducted.(3)A.glycines were exposed to diurnal 35℃ for 7 days from different developmental stages,and A.solani were exposed to diurnal 31℃ for 7 days from different developmental stages.Effects of the short-term high temperature on development,reproduction,and morph differentiation of the two aphid species were studied.The results were as follows:(1)The survival rate of A.glycines decreased gradually when the constant temperature increased from 25 to 35℃.At 35℃,nymphs of A.glycines only survived for 5 days and could not develop into adults.When the temperature increased from 25 to 35℃,the adult lifespan and life expectancy of A.glycines shortened and the adult body size,adult fecundity,and intrinsic rate of increase of A.glycines decreased gradually.When temperature increased from 25 to 29℃,the survival rate of A.solani decreased.At 31-35℃,the nymphs only survived for 3 to 5 days and could not develop into adults.When the temperatures increased from 25 to 29℃,the adult lifespan and life expectancy of A.glycines shortened,and the fecundity and body size of A.solani adult decreased.At 29℃,the survival rate of A.solani nymph was only 46%,all the adults died within 5days,and no aphids were deposited.(2)As the diurnal temperature increased from 25 to 35℃,the survival rate of A.glycines decreased.At diurnal temperature of 37℃,nymphs of A.glycines only survived for 6 days and could not develop into adults.As the diurnal temperature increased from 25 to 35℃,the adult lifespan and life expectancy shortened,and fecundity,body size,and reproductive value of A.glycines adult decreased.As diurnal temperature increased from 25 to 31℃,the survival rate of A.solani decreased and the life expectancy shortened.At diurnal temperature of 33-37℃,nymphs of A.solani could not developed into adults and were dead within 4-6 days.At diurnal temperature of29 and 31℃,the adult lifespan of A.solani was shorter than that of the control at diurnal 25℃,and the adult fecundity of A.solani was shorter than that of the control.As diurnal temperatures increased from 25 to 31℃,the body size of A.solani adult decreased gradually.(3)When A.glycines were exposed to diurnal 35℃ for 7 days from 1-4 stadium,the nymph stage duration and adult lifespan were shorter than that of control without short-term high temperature stress,and the adult fecundity,adult body size,and intrinsic rate of increase were significantly shorter than that of control.When A.glycines were exposed to diurnal 35℃ for 7days from different developmental stages,life expectancy of the first instar and the reproductive value were smaller than that of control.A higher proportion of gynoparae of and a lower proportion of males were deposited as offspring on day 13,when A.glycines were exposed to diurnal 35℃ for 7 days from 1-4 stadium and adult stage.The values of adult lifespan,fecundity,and life expectancy were all significantly smaller than that of the control,when A.solani were exposed to diurnal 31℃ for 7 days from 1-3 stadium.Adult lifespan of A.solani was as long as that of the control,when they were exposed to diurnal 31℃ for 7 days from the fourth stadium and adult stage.When A.solani were exposed to diurnal 31℃ for 7 days from 1-4 stadium,the body size of adult and intrinsic rate of increase were significantly smaller than those of control.Lower proportion of winged virginoparae were deposited on day 7 and 13,when A.solani were exposed to diurnal 31℃ for 7 days from the 1-4 stadium and the adult stage.It showed that constant and diurnal high temperature both inhibit development and reproduction of A.glycines and A.solani and the high temperatures affected A.solani considerably.Short-term high temperature inhibit development and reproduction of A.glycines and A.solani,and it also inhibit the morph differentiation of A.glycines gynoparae and males and A.solani winged virginoparae.These results provided important data for the study on development,reproduction,and morph differentiation of A.glycines and A.solani under high temperature,which is important for further studies on the population dynamics of the aphids in soybean under climate warming. |
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