Influence Of Two Artificial Diets To Development And Cold Storage Of Arma Custos(Hemiptera: Pentatomidae)

Arma custos is one species of natural enemy insects with strong predation ability and easy artificial reproduction,so it has a great application potential to control the density of pest populations with artificial releases.Alternative diet(artificial diet)and cold storage technology are the obstacles to the use of insect natural enemies for biological control in large-scale applications.The objective of this study was to explore the effects of feed nutrition on the growth and development,reproductive index and cold storage tolerance,and to explain the physiology and molecular biology mechanism.A.custos were collected in the field,and then were reared for 12 generations with two artificial diets under laboratory conditions.The growth and development,reproduction,and the contents of biochemical substances related to cold storage were measured before and after cold storage,respectively.The differences in gene expression of A.custos fed by two diets were measured using the transcriptome sequencing technique.Then the metabolic pathways of A.custos fed by two diets were analyzed.The results are as follows:The two artificial diets(AP and TM)had different effects on growth and development,fecundity,and other growth performance.The development period of 2nd and 3rd instar nymph from colonies reared on AP was significantly lower than that for TM,while the development period of 4th and 5th instar nymph from colonies reared on AP was significantly higher than that for TM.The mortality of the 2nd and 3rd instar from colonies reared on AP were lower than that for TM,while the mortality of 4th,5th instar,and the average mortality from colonies reared on AP were higher than those for TM.The fertility rate of A.custos adults from colonies reared on AP was significantly higher than that for TM,but the intrinsic growth rate of the population was significantly lower than that for TM.The diet AP significantly shortened the development period of the young nymph,reduced the mortality and increased the fertility rate of the female,while diet TM was more suitable for the growth and development of the older nymph,and increased the adult acquisition rate and population growth rate.The survival rate,the life span of adults from colonies reared on TM was significantly higher than those for AP after 30-day cold storage,and the fecundity of adults from colonies reared on TM was significantly higher than those for AP after 40-day cold storage,but the super-cooling points(SCPs)was significantly lower than that of adults for AP.The contents of trehalose,mannose,sorbitol,and glycerol of adults from colonies reared on TM after 30-day cold storage were significantly higher than those for AP.While the content of saturated fatty acids of adults from colonies reared on AP was 129% higher than that for TM,but the content of unsaturated fatty acids was 28% lower than that for TM.The GAPDH,Na+K+-ATPase,and Ca2+Mg2+-ATPase activities of adults from colonies reared on AP were 2.53,2.00,and 3.10 times higher than those for TM,respectively.While the activity of FAS adults from colonies reared on AP was lower 37% than that for TM.The results of the structural equation model showed that diet affected the contents of trehalose,mannose,sorbitol,glycerol,and fatty acids through the activities of GAPDH,FAS,and Ca2+Mg2+-ATPase,and then indirectly affected the survival rate,fertility rate,and SCPs.A total of 33107 differential genes were selected by transcriptome sequencing,and 17829 genes were up-regulated in the adults from colonies reared on TM compared to AP.In these genes,the upregulated genes that related to cold storage tolerance were E3 ubiquitin-protein ligase,AFP gene,and PPAR signal transduction related genes.The down-regulated genes were mainly coenzyme Q reductase and acetyl-coenzyme AC-acetyltransferase.In this paper,the effect of diet on the growth and development,and cold storage tolerance of A.custos was analyzed through characteristic biology firstly,and then the physiological mechanism of these biological differences was discussed from the perspective of metabolism.Finally,the molecular biological mechanism of the above physiological changes was verified through the metabolic pathway using transcriptome sequencing.This study established the relationship between diet nutrition and cold storage tolerance of A.custos,which provided a theoretical basis for the development of artificial diet and cold storage technology of the natural enemies.