A mite parasitoid,Pyemotes zhonghuajia,negatively impacts the fitness traits and immune response of the fall armyworm,Spodoptera frugiperda

Parasitoids are key regulators in ecological communities and widely used as agents in biocontrol programmes.The fall armyworm,Spodoptera frugiperda,recently invaded multiple continents and caused substantial economic losses in agriculture.Pyemotes zhonghuajia,a newly identified mite parasitoid,has shown potential for controlling various agricultural insect pests.Therefore,this study tested the performance of P.zhonghuajia in parasitising S.frugiperda.We also investigated the sublethal effects of parasitism by P.zhonghuajia on host fitness traits,transgenerational impacts,and cellular and humoral immunity.Our result showed that the fifth-instar larvae of S.frugiperda parasitised by 40 P.zhonghuajia were all dead(i.e.,a lethal effect),while parasitism by 5 or 10 P.zhonghuajia was considered sublethal since many S.frugiperda survived to adulthood and produced offspring after mating.The sublethal influences from parasitism by P.zhonghuajia resulted in reduced pupal weight,adult emergence rate and fecundity,but increased developmental time and longevity.Parasitism at both lethal(40 mites)and sublethal(10 mites)levels impaired the cellular and humoral immunity of S.frugiperda.This study presents the first empirical evidence that mite parasitoids can negatively influence host immunity.Moreover,it provides insights into the biocontrol potential of mite parasitoids and their interactions with hosts.

Age-specific mortality and fecundity of a spider mite under diet restriction and delayed mating

Numerous experimental life-history studies on aging are mainly baised on two classical models—fruit fly Drosophila melanogaster(Meigen)and nematode Caenorhab-ditis elegans(Maupas)—with relatively little attention given to other organisms with different life-history characters.Two-spotted spider mite Tetranychus urticae Koch(Acari:Tetranychidae)differs from many other arthropods in that the females continue their growth in the early adult stage and can reproduce sexually and asexually.In this study,the influences of dietary restriction and delayed mating on the aging patterns of the spider mite were examined with the prevailing survival and reproduction trade-off hypothesis of aging being tested.Significant sex-specific responses of the spider mites were found.The females showed longevity extension on diet restriction(fasting for 2 days in every 4 days)compared with their counterparts being fed ad libitum,and after delayed mating for 9 days,while the males displayed a decrease in lifespan when experiencing diet restriction but were not significantly influenced by delayed mating.Path analysis was used to investigate the relationship between mite survival and reproduction traits,including longevity,female lifetime reproduction,age at first reproduction,early reproductive efforts and late reproductive efforts,yielding no evidence for trade-offs between these life-history traits.The additive effects of dietary restriction and delayed mating in lifespan extension of female spider mites were confirmed,proving that diet restriction is a robust anti-aging intervention,and that later onset of reproduction can prolong adult lifespan in females.