Effects of Aphis craccivora feeding on the contents of total chlorophyll and nutrients in the leaves of Astragalus membranaceus
The objective of this study was to clarify the interaction and mechanisms between Aphis craccivora and Astragalus membranaceus.The total chlorophyll and nutrient contents in the leaves of A.membranaceus were determined in an artificial climate chamber,with plants reaching a height of about 15-20 cm.The plants were attacked by 10-day-old adult aphids at densities of 10,20,30,40 aphids/plant,and 0 aphids/plant(CK)for two,four,six,eight days.The results indicated that the total chlorophyl and nutrient contents changed with increasing aphid population density and feeding duration.The total chlorophyll content gradually decreased with an increasing population density of aphids and feeding duration.Specifically,the total chlorophyll content decreased to 11.06 mg/g,which was 41.97％lower than CK at the population density of 40 aphids/plant two days after treatment.The contents of soluble protein and carbohydrates decreased with increasing population density under the same treatment duration.These contents decreased first,followed by an increase,and then decreased again with the extension of aphid feeding time at population densities of 10,20 aphids/plant,and 30 aphids/plant.However,they gradually decreased at density of 40 aphids/plant.The contents of soluble protein and carbohydrates decreased to 8.39 mg/g and 27.33 mg/g,respectively,at the population density of 40 aphids/plant eight days after treatment,which was 41.86％and 37.79％lower than CK.The content of free amino acids decreased with increasing population density under the same treatment duration.The content decreased first,then increased,and decreased again with the extension of aphid feeding time at density of 10 aphids/plant,but decreased at other population densities.The free amino acids decreased to 8.49 μmol/g and 7.69 μmol/g at the population densities of 30 aphids/plant and 40 aphids/plant two days after treatment,which was 40.30％and 45.92％lower than CK,respectively,but no significant difference was observed between the treatments for 4-8 days and those for two days.In conclusion,the total chlorophyll,soluble protein,soluble carbohydrates,and free amino acid contents changed with an increase in pest population density and the extension of aphid feeding duration.These results provide valuable insights for the control of aphids on A.membranaceus.
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