Adaptability Of Spodoptera Frugiperda To Different Host-plant

Spodoptera frugiperda(Lepidoptera: Noctuidae),as a migratory pest,has invaded China in 2019 and has seriously damaged the crop yield.In view of S.frugiperda bioecology characteristic,this article bought a systemic study on the development of S.frugiperda based on the insect nutrition ecology theory,including the adult fecundity,the nutrition utilization,and the physiological reaction to the different host plants.The obtained results were summarized as follows:1.The supplementation of different nutrients resulted in significant effects on the fecundity of S.frugiperda at the adult stage.The group supplemented by 10% honey water and 10% sucrose water had the longest oviposition period and adult longevity.Besides,S.frugiperda supplemented with 10% honey water showed the highest female progeny and hatchability honey,reaching up to 983.20 eggs and 98.07%,respectively.2.The growth and development of S.frugiperda feeding on different hosts displayed obvious difference.The group fed on Zea mays had the highest survival rate(99.17%),the shortest larvae developmental duration(6.22 days),and the highest fecundity(1308 eggs),followed by the group fed on Triticum aestivum.The survival rate of the young larvae fed on Glycine max was the lowest(86.67%).The development duration of larvae fed on G.max and Eleusine indica was the longest,which was more than 17 days.Compared with other hosts,S.frugiperda fed on E.indica showed the lowest body weight in the 5th and 6th instar larvae and the lowest female progeny(994 eggs)in the adult period.3.The nutritional indexes of S.frugiperda were different by feeding on different hosts.The relative growth rate(RGR),efficiency conversion of digested food(ECD),and efficiency of conversion of ingested food(ECI)fed on Z.mays were markedly higher than other hosts.And the RCR was obviously less than those,The approximate digestibility(AD)of S.frugiperda fed on different host plants in larval stage displayes no remarkable difference.The ECD and ECI fed on G.max and E.indica were much lower than those of other hosts.4.The midgut digestive enzymes characteristic in S.frugiperd showed obvious differences after feeding different hosts.The midgut protein concentration of the larvae fed on Digitaria sanguinalis and G.max were higher than other host-plant,which were 7.10 μg/m L and 6.63μg/m L,respectively.The activity of amylase in the midgut was the highest fed on T.aestivum,followed by Z.mays.Feding on G.max,the activity of trypsin was the highest in the midgut of S.frugiperda.The activities of amylase and trypsin in midgut were the lowest and the activities of lipase were the highest of S.frugiperda which fed on D.sanguinalis.5.There wasa significant correlation between the phytochemical content of the host plants and the nutrient accumulation of S.frugiperda.The water and C/N content were related to the growth and development of S.frugiperda.The C/N content displated markble positive correlation with pupal weight,oviposition quantity,ECD,and ECI.The contents of protein,total amino acids and total phenols were mainly controlling the growth and development of S.frugiperda.Total phenol content has negatively correlated with survival rate,pupa weight,ECD,and ECI.The total flavonoid content has negatively correlated with the survival rate and relative growth rate at the larval stage.However,the soluble sugar content and tannin had no significant correlation with the growth,reproduction,and nutrient indices.6.There was significant correlation between the activities of the midgut digestive enzymes and the phytochemical content of the host.The midgut protein concentration has significant positive correlation with total amino acid content,total flavonoids content,tannin content and total phenol content,and has a significant negative correlation with C/N.Trypsin activity has positively correlated with soluble sugar content,protein content,and C/N content,and negatively correlated with water content,respectively.The lipase activity has positively correlated with the contents of total amino acids,total flavonoids,and tannin,respectively.Amylase activity has significantly negatively correlated with C/N and was significantly negatively correlated with total amino acid content,total flavonoids content,and total phenol content.In summary,our data revealed that 10% honey water bought the best nectar source for supplementary nutrition in the adult stage.According to the physiological and biochemical indexes of S.frugiperda fed on different host species,Z.mays and T.aestivum were the most suitable host species,while G.max and E.indica were not the suitable host species.The total amino acids contents,water content,C/N,total flavonoids and total phenols in the host phytochemicals were directly related to the physiological and biochemical reactions of S.frugiperda.The soluble sugar content and tannin did not play a vital role in the growth and development of S.frugiperda,but they played a crucial role in the activities of some digestive enzymes in the midgut of S.frugiperda.