| Aphis gossypii Glover is one of the main pests on cotton.A.gossypii uses piercing sucking mouthparts to insert into the back of cotton leaves or tender head tissues to suck on juice,causing the affected leaves to curl back.Honey dew were excreted on the surface of the leaves,which often breeds mold and leads to reduced cotton production.The impact of humidity changes on agriculture has attracted much attention.A.gossypii can cause severe damage in cotton producing area from southeast to Xinjiang(low humidity area)in China.Therefore,it is necessary to conduct research on the response of A.gossypii to different humidity treatments and drought resistance mechanisms.In this study,A.gossypii were reared under different humidity,the growth and development status,physiological metabolism activity of A.gossypii were measured to clarify the effects of different humidity on A.gossypii.The expression levels of genes related to the antioxidant enzyme and detoxification enzyme in A.gossypii under RH=10%and RH=70%were analyzed using qPCR technology.The results are as follows:(1)It was found that under the RH=10%treatment,the total nymph period of A.gossypii was the longest(5.87days),and there was a significant difference when compared to the RH=40%treatment(4.83 days);Compared with RH=70%treatment(4.77 days),there was a significant difference;There was no significant difference in the total nymph stage of A.gossypii between RH=40%and RH=70%treatments.Under the RH=10%treatment,the reproductive period of A.gossypii was the shortest(2.53 days),and there was a significant difference compared to the RH=40%treatment(18.83 days);There was a significant difference compared to the RH=70%(19.57 days)treatment.There was no significant difference in the reproductive period of A.gossypii between RH=40%and RH=70%treatments.Under RH=10%treatment,the total lifespan of A.gossypii was the shortest(22.00 days),and there was a significant difference compared to RH=40%treatment(29.80 days);and RH=70%treatment(31.20 days).There was no significant difference in the total lifespan of A.gossypii between RH=40%and RH=70%treatments.Under the RH=10%treatment,the litter size of A.gossypii was the lowest(37.11 heads),and there was a significant difference compared to the RH=40%treatment(53.33 heads);There was a significant difference compared to the RH=70%treatment(61.53 heads).There was a significant difference in the litter size of A.gossypii between RH=40%and RH=70%treatments.Under RH=10%treatment,the average generation cycle of A.gossypii was 11.093 days,and there was no significant difference compared to RH=40%treatment(10.750 days)and RH=70%treatment(11.116 days).The net reproductive rate R0 decreases with the decrease of humidity.Under the RH=10%treatment,the net reproductive rate of A.gossypii is the lowest(33.399),and there is a highly significant difference compared to the RH=40%and RH=70%treatments.The intrinsic growth rate rm of A.decreases with the decrease of humidity.Under the RH=10%treatment,the intrinsic growth rate of A.gossypii is the lowest(0.316),and there is a significant difference compared to the RH=40%treatment(0.358);There was a significant difference compared to the RH=70%treatment(0.364).There was no significant difference in the intrinsic growth rate of A.gossypii between RH=40%and RH=70%treatments.As the humidity decreases,finite rate of increase of A.gossypii is the lowest under the RH=10%treatment(1.372),and there is a significant difference compared to the RH=40%treatment(1.438);There was a significant difference compared to the RH=70%treatment(1.430).There was no significant difference in the finite rate of increase ofA.gossypii between RH=40%and RH=70%treatments.These results indicated that low humidity treatment(RH=10%)have an inhibitory effect on the growth,development,and reproduction of A.gossypii,which is not conducive to their population development.(2)By analyzing the antioxidant enzyme activity,detoxification enzyme activity and content of related substances of A.gossypii under different humidity conditions,it was found that with the decrease of relative humidity,superoxide dismutase activity in A.gossypii increased,which was the highest value(516.56 μmol·mg-1)under RH=10%treatment,and there was no significant difference compared with RH=40%treatment(455.14 μmol·mg-1);There is a significant difference compared to the RH=70%treatment(339.09 μmol·mg-1).The activity of catalase in A.gossypii increased,reaching its highest value(9.74μmol mg-1)under RH=10%treatment,with a significant difference compared to the RH=40%treatment(6.46μmol·mg-1);There is a significant difference compared to the RH=70%treatment(6.25μmol·mg-1).The peroxidase activity in A.gossypii increased,reaching the highest level under RH=10%treatment(668.78 μmol·mg-1),with a significant difference compared to RH=40%treatment(366.24 μmol·mg-1);There is a significant difference compared to the RH=70%treatment(196.68 μmol·mg-1).The activity of glutathione-S-transferase in A.gossypii increased,reaching the highest value(2.3 μmol·mg-1)under RH=10%treatment.There was a significant difference compared to the RH=40%treatment(0.86 μmol·mg-1)and RH=70%treatment(0.84 μmol·mg-1).The total antioxidant capacity of A.gossypii increased,reaching the highest value(7.56 μmol·mg-1)under RH=10%treatment.There was a significant difference compared to RH=40%treatment(4.91 μmol·mg-1)and RH=70%treatment(3.01μmol·mg-1).The content of MDA in A.gossypii increased,reaching the highest value(11.39 nmol·mg-1)under RH=10%treatment,and there was a significant difference compared to RH=40%treatment(4.32 nmol·mg-1);There is a highly significant difference compared to the RH=70%treatment(3.36 μmol·mg-1).The above results indicate that under low humidity conditions(RH=10%),A.gossypii can resist drought by increasing the activity of oxidase and detoxification enzymes in their bodies and increasing the content of related substances such as MDA.(3)The expression levels and differences of genes related to antioxidant enzymes and detoxification enzymes ofA.gossypii under low humidity environment(RH=10%)and control humidity environment(RH=70%)were analyzed by RT-qPCR.It was found that the relative expression levels of superoxide dismutase related gene SOD-1(EVM0011582)were significantly different under RH=10%and RH=70%.The relative expression level of catalase related gene CAT-1(EVM0004140)also showed significant differences under RH=10%and RH=70%conditions.The relative expression level of glutathione-S-transferase related gene GST-14(EVM0008293)showed significant differences under RH=10%and RH=70%conditions.There was a significant difference in the relative expression level of peroxidase related gene POD-13(EVM0013764)between RH=10%and RH=70%treatments;There is a significant difference in the relative expression level of peroxidase related gene POD-21(EVM0011073);There is a significant difference in the relative expression level of peroxidase related gene POD-19(EVM0004404);There is a significant difference in the relative expression level of the peroxidase related gene POD-22(EVM0004258).The above results indicate that these genes are likely to play a role in the resistance and detoxification metabolism of A.gossypii under low humidity conditions(RH=10%). |
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