| Neoseiulus barkeri(Hughes)is an important predatory natural enemy of spider mites.In this study,targeting potential possibility of using N.barkeri to control three important rubber mites,namely: Eotetranychus sexmaculatus(Riley),Eutetranychus orientalis(Klein),and Oligonychus biharensis(Hirst)through predator prey relationships were investigated.In the research,the predation efficiency and population adaptability of N.barkeri on these three spider mite species was examined.Analysing the research results,it has been revealed that the physiological responses of N.barkeri to different prey population were significant.By integrating transcriptomic and proteomic analyses,we also revealed the molecular regulatory mechanism of its adaptation to the pray.It,thus provides a theoretical basis for using predatory mites to sustainable green management and protection of ecological enviroment.The main findings are as follows:(1)The results of the study on the selectivity and predation efficacy of N.barkeri on the three spider mites showed that the selection coefficient and control efficiency of N.barkeri on E.sexmaculatus was the highest,and the predation efficiencies,represented by the number of eggs,larvae,nymphs,and female adult mites that were preyed upon,were4.67,108.72,30.54,and 12.70 individuals a day,respectively.However,by O.biharensis,the predation efficiencies on E.orientalis were the lowest.Under the same condition of prey density,the predation rate of N.barkeri decreased with the increase of its own density,which indicated that under certain spatial conditions,there are competition and mutual interference among the individuals of N.barkeri.On the other hand,the mutual interference coefficients between N.barkeri and E.sexmaculatus,E.orientalis,and O.biharensis were 0.441,0.379,and 0.487,respectively.(2)Different prey had significant effects on the growth,development,and reproductive ability of N.barkeri.E.orientalis was the most favourable prey for the development,survival,and reproduction of N.barkeri,with the shortest generational development period of 6.67 d and a survival rate of 100.00%.However,the lifespan of female adult and the number of eggs laid by a single female were 34.55 and 29.35 d,respectively.By contrast,N.barkeri feeding on E.sexmaculatus as prey had the longest developmental period,and the lowest survival rate and egg production(71.42% and 1.87eggs/female,respectively).Through the establishment of a population life table,we found that the net reproductive rate and intrinsic rate of increase of N.barkeri feeding on E.orientalis were the highest(29.650 and 0.226,respectively),followed by the population feeding on T.putrescentiae and O.biharensis.The net reproductive rate and intrinsic rate of increase of N.barkeri with E.sexmaculatus as prey were the lowest(2.556 and 0.041,respectively).It indicated that the population adaptability of N.barkeri was the best when E.orientalis was used as the prey,while E.sexmaculatus fed ones’ adaptability was the least conducive to its population growth,especially its egg-laying ability,which was significantly affected.(3)By determination of nutrient content in different prey,the results showed that the soluble protein and amino acid contents in E.sexmaculatus were the highest(8.46 mg/m L and 143.69 μg/mg prot,respectively),and that these numbers were significantly higher than those of E.orientalis and O.biharensis.The sugar content in T.putrescentiae was the highest(1.47 mg/mg prot),followed by E.sexmaculatus and O.biharensis.By performing correlation tests,we found that the generational development duration of N.barkeri was positively correlated with the contents of soluble protein,amino acids,and total sugar in the three prey spider mites,whereas the female adult lifespan and egg production were negatively correlated with these indicators.(4)By determination of related physiological indicators of N.barkeri after feeding on different prey,the results showed that with the three species of spider mites as prey,the activities of three protective enzymes(SOD、POD and CAT),three detoxification enzymes(Ach E,Car E,and MFO)and five metabolic enzymes(E1103、THL、SDH、α-AL and β-AL)were higher than those of the control group.The activities of SOD,POD,Ach E,E1103,THL,SDH,α-AL and β-AL were the highest when the prey was E.sexmaculatus,whereas the GST activity in this group was the lowest.This indicates that after feeding on different prey,N.barkeri responds to its adaptability to different prey by regulating the changes of a series of enzyme activities.(5)Transcriptomic analysis of N.barkeri after feeding on different prey,a total of57.87 Gb of data were obtained by sequencing using the DNBSEQ platform,and 26,353 Unigenes were obtained after assembling and de-redundancy of clean reads.The total length and GC content were 35902076 bp and 49.02%,respectively.After performing differential gene alignment,in the comparison between the T.putrescentiae group and the O.biharensis group(Tra＿ck vs Tra＿1),5071 genes were found to be up-regulated and5067 were found to be down-regulated.In the comparison between the T.putrescentiae group and the E.orientalis group(Tra＿ck vs Tra＿2),2196 genes were up-regulated and18,406 were down-regulated.And in the comparison between the T.putrescentiae group and the E.sexmaculatus group(Tra＿ck.vs Tra＿3),6814 genes were up-regulated and 6393 were down-regulated.Differential expressed genes are mainly enriched in signal transduction pathways.In the above pairwise comparisons,5,20,and 12 genes were respectively associated with reproductive function.Among them,the up-regulated expression of the POD gene is the most significant.It is speculated that this enzyme plays a key role in the digestion and metabolism of prey by N.barkeri.q RT-PCR was used to verify the expression of selected target genes,and the results were consistent with the transcriptome sequencing results.(6)Using 4D label-free quantitative proteomics technology,a total of 2,667,339 spectra were obtained,and 53,619 peptides and 6,012 proteins were identified.In the comparison between the O.biharensis group and the T.putrescentiae group(Pro＿1 vs Pro＿ck),662 proteins were up-regulated and 651 were down-regulated.In the comparison between the E.orientalis group and the T.putrescentiae group(Pro＿2 vs Pro＿ck),490 proteins were up-regulated and 619 were down-regulated.In the comparison between the E.sexmaculatus group and the T.putrescentiae group(Pro＿3 vs Pro＿ck),780 proteins were up-regulated and 784 were down-regulated.Differentially expressed proteins were significantly enriched in glycine,serine and threonine metabolism pathways.In the above pairwise comparisons,125,86,and 143 proteins were annotated with reproductive function,respectively.It is speculated that the down-regulated expression of GST and Vg1 is associated with reduced egg production of N.barkeri.Target proteins were analysed and verified by using the targeted proteome quantification technology(PRM),and their expression trends were consistent with the proteomic data. |
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