| Cadmium(Cd)pollution has become one of the key environmental problems in public concern.Cd can be enriched in farmland soil through a variety of ways.As an important part of agricultural ecosystem,the effects of Cd exposure on energy metabolism and endogenous hormones and the influence mechanism of Spodoptera litura have been rarely discussed.In our research,S.litura was fed with artificial diets contained different concentrations of Cd.Newly emerged adults were used to study the effect of Cd stress on energy substances and endogenous hormones.We especially focused on the effects of Cd exposure on trehalose metabolism in adults of S.litura.Results are as follows:1?Effects of Cd stress on energy substances of S.lituraThe protein content in adults decreased significantly with the increase of Cd concentration.Compared with the corresponding controls,glyceride levels in adults significantly decreased.In the 0.2 mg/kg Cd treatment,the glyceride content in male was significantly higher than that in females.The contents of trehalose and trehalose synthase in adults decreased under Cd stress,and high dose Cd exposure also reduced the content of trehalase in males,but the content of trehalase in females was higher than that in control while the difference was not significant.2?Effects of Cd stress on endogenous hormones of S.lituraCd exposure at different concentrations significantly reduced the titers of JH,MH and insulin in adults,and the contents decreased with the increase of Cd concentration.Under the same Cd stress,there was no significant difference in the contents of all indexes between different sexes,except for insulin,which was significantly higher in female than in male under 12.8 mg/kg treatment.3?Effects of Cd stress on trehalose metabolism and endogenic hormone-related genes of S.lituraCd stress affected the expression of key genes in trehalose metabolic signaling pathway.(1)Cd inhibited the expression of key genes(TPP,TPS,Treh)in trehalose metabolism pathway in female.Compared with the corresponding control,the difference was all significantly in 0.2 mg/kg.Treh was only expressed in females.(2)In contrast with corresponding control,Cd stress significantly down-regulated the expression of JHEH?FaMeT in males,but had no significant difference in females.Cd also inhibited the expression of JHBP,but only showed significant differences in females under 12.8 mg/kg.(3)In contrast to the control,the expression of Dib?Sad were significantly decreased under Cd treatment,while the expression of Spook was up-regulated,and these genes were only expressed in females.(4)In contrast to the control,Cd significantly down-regulated the expression of PKA,PCLO 1820 and ABCC8 in females,which were related to insulin metabolism,and PCLO 1820 and ABCC8 were only expressed in females.4?Effects of Cd stress on trehalose and endogenous hormones in three successive generations of adults of S.lituraThe contents of trehalose,trehalase,trehalose synthase and endogenous hormones in adults were affected by three successive generations of Cd stress,but the variation of these indexes were different among different generations.The content of trehalose was significantly lower than the corresponding control in adults in the first two generations.However,in the third generation,trehalose was higher than the control,especially under high Cd concentration.In the first and third generation,trehalase were mostly decreased with the increase of Cd stress.On the contrary,trehalase increased with the increase of Cd concentration in the second generation.The ecdysis hormone titer decreased with the increase of Cd concentration in the first and third generation,but in the second generation,there was no significant difference among the three concentration treatments.In the first generation,insulin decreased significantly under cadmium stress,but compared with control,there was no significant difference in the expression of insulin in the third generation.Also,the adaptability of the adult to Cd stress increased with the increase of stress generation. |
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