Research On Development And Application Technology Of Botanical Fumigants Of Stored Grain Pests

Cryptolestes ferrugineus is a worldwide stored grain pest,and showed its serious insectcide resistance asin a long-term using mainly single chemical fumigants to control stored grain pestsin stored grain pest controling.It is very important to study and explore botanical insecticides for grain storage pests such as C.ferrugineus to realize green grain storage and ensure food safety and human health.In this study,from 15 kinds of plants,star anise（Illicium verum）were identified with good fumigation toxicity on C.ferrugineus adult,and the insecticidal activity of star anise volatiles,in addition to main insecticidal components of the volatile,,biochemical and molecular mechanism of action and so on were studied,the main research results are as follows:（1）Four kinds of plants,including Kaempferia galanga,Chenopodium ambrosioides,Radix aristolochia and Illicium verum,were identified from 15 kinds of plants with good fumigation effect on adult C.ferrugineus.The fumigation activity was 0.625-20g/L.Among them,the volatiles of star anise had strong fumigation effect on larva and adult of C.ferrugineus,and the LC₅₀ of 24 h was 8.42μl/L and 8.66μl/L,respectively.（2）The fumigation activity of volatiles from star anise to C.ferrugineus adult was not significantly different at the temperature of 15-35℃,and the fumigation activity of volatiles from star anise to C.ferrugineus adult was also better than that from Oryzaephilus surinamensis and Lasioderma serricorne.Within 48 h,it was effective to kill O.surinamensis and L.serricorne,with mortality of 89.6%and 98.3%,respectively.（3）The result of Gas chromatography-mass spectrometry（GC-MS）analysis shows that the main composition of star anise volatiles were trans-anethole（62.60%）,estragole（23.70%）,linalool（3.66%）and d-limonene（2.15%）,of which only trans-anethole has strong biological activity,30 ml/L trans-anethole fumigation 24 h,C.ferrugineus adult mortality rate of 100%;Estragole can significantly improve the fumigant toxicity efficiency of trans-anethole,showing an obvious synergistic effect.（3）Further study found that star anise volatiles and its main insecticidal active ingredient trans-anethole had an effect on the acetylcholinesterase activity of C.ferrugineus,and the acetylcholinesterase activity was significantly inhibited and decreased by 64.48%within 24 h.（4）The possible target of star anise volatiles and its main insecticidal active ingredient trans-anethole is acetylcholinesterase of C.ferrugineus.Both star anise volatiles and trans-anethole have obvious inhibitory activity against acetylcholinesterase,and the inhibitory rate of acetylcholinesterase activity within 24 h is 64.48%.（5）Through transcriptome data analysis,a total of 84601 annotated genes were successfully obtained.GO enrichment results showed that 12 h after treatment with star anise volaties,the enrichment genes were mainly focused on detoxification metabolism and catalytic activity.KEGG enrichment pathway results showed that 12 h after treatment,the enrichment pathway was a metabolic pathway including exogenous biodegradation and metabolism,lipid metabolism,cofactor and vitamin metabolism.In conclusion,the star anise and its volatiles in this study has effective fumigation activity against C.ferrugineus.trans-Anethole is the main component of star anise volatile,and work at least partly by affecting the nervous system of insects to show its the toxicity of fumigant to C.ferrugineus.Through transcriptome RNA-seq analysis technology,the insecticidal mechanism of star anise will be found from more metabolic pathways and gradually clarified.The results indicated that star anise had good potential as a plant insecticide for C.ferrugineus and the results provided a theoretical basis for the development of plant fumigants for stored grain pests.