Effects of adult diet on reproductive fitness and offspring development of <italic>Dastarcus helophoroides</italic>（Fairmaire）

<bold>Objective</bold> In this study，the effects of artificial diet and exogenous water on the reproductive fitness and offspring development of <italic>Dastarcus helophoroides</italic>，an ectoparasitic natural enemy insect，were explored to provide a theoretical basis for large-scale indoor breeding of natural enemy insects. <bold>Method</bold> During 20 weeks observation，the following six different adult diets for newly emerged adult couples，namely artificial diet only（20D），exogenous water only（20W），artificial diet and exogenous water simultaneously（20DW），artificial diet for the first 10 weeks and then artificial diet and exogenous water simultaneously for the subsequent 10 weeks（10D+10DW），exogenous water for the first 10 weeks and then artificial diet and exogenous water simultaneously for the subsequent 10 weeks（10W+10DW），and no diet available（20N），were provided.Thereafter，the reproductive fitness of adults and the growth and development parameters of offspring were observed and measured under constant conditions. <bold>Result</bold> Adults in treatments of 20D and 20N did not lay eggs and had the lowest survival rate.The reproductive fitness of the other four treatments were significantly influenced by the adult diets，with adult in treatment of 20DW had the highest weekly and total fecundity，the highest egg fertility，and the longest lifespan.However，adults in treatment of 10D+10DW showed the lowest performance in all of measured fitness indicators.Furthermore，the developmental duration and morphological traits of offspring were also influenced by their parental diets.Offsprings in treatment of 20DW showed the highest larval parasitism rate，shortest developmental period，and largest adult body size，followed by the offsprings in treatment of 10W+10DW.Similarly，the offspring in treatment of 10D+10DW showed the lowest performance in various growth and development indicators. <bold>Conclusion</bold> <italic>D. helophoroides</italic> is a reproductive insect.Adult food is an important factor affecting the growth，development and reproduction of <italic>D. helophoroides</italic>，and exogenous water is an important limiting factor.