Biological Activities Of Illicium Verum Extracts Against The Two Stored Product Insect Pests And Their Influences On The Enzymes

Sitophilus zeamais (Motschulsky) is a kind of prime storage grain pest, once classified as a top grain storage pest by department of national food; Cryptolestespusillus (Schonherr) is an important kind of later grain storage pest. Botanical pesticides belong to green pollution-free pesticides, it makes less resistant for pests. In this research, three kinds of organic solvents were used from extracting dried fruit of Illicium verum, to explore Ⅰ. verum extracts insecticidal activity to2kinds of pests and its mechanism for the development of environment friendly botanical insecticide, main results are as follows:1Effects of different solvents on the extraction of dried fruit of I. verumThe dried fruit of Ⅰ.verum were extracted by organic solvents of methanol, ethyl acetate and petroleum ether. Extracts rates from big to small is:methanol> ethyl acetate> petroleum ether.2I. verum dried fruit extracts from different solvents to two kinds of grain storage pests in biological activity2.1Contact activity of Ⅰ.verum extracts to two kinds of grain storage pestsThree kinds of solvent extracts of Ⅰ.verum of dried fruit to S. zeamais and C. pusillus adults in contact action were assayed with residual film method, five treatment dose of9.29,18.58,37.16,74.32and148.63μg/cm2used. With the dose of148.63μg/cm2in72h, the corrected mortality rates to S. zeamais of methanol, ethyl acetate and petroleum ether extracts of maize were85.43%,94.50%and85.43%respectively; corrected mortality rates to C. pusillus were87.85%,90.98%and94.44%respectively. The ethyl acetate extract effect was the best on S. zeamais, the petroleum ether extract better than others on C. pusillus, the effects of methanol and petroleum ether extract on S. zeamais greater than its effect on C. pusillus under the same dose, the ethyl acetate extract just the opposite. Three kinds of solvent extracts tag effects are significantly increased with the increase of treatment dose, showing the obvious dose effect.The LD50of methanol, ethyl acetate and petroleum ether extract to S. zeamais adults in72h were36.11,21.19and24.65μg/cm2, the LD50to C.pusillus28.21,23.51and19.23μg/cm2, showing the obvious contact action effect.2.2Repelling activity of I. verum extracts to two kinds of grain storage pestsThree kinds of solvent extracts ofⅠ.verum of dried fruit to S. zeamais and C. pusillus adults in repelling action were assayed with residual film method, five treatment dose of7.72,15.43,30.86,61.73and123.46μg/cm2used. The higher the dose of same Ⅰ.verum solvent extracts was, the greater repelling action to S. zeamais and C. pusillus adults. The average of repelling rate of highest dose (123.46g/cm2) of methanol, ethyl acetate and petroleum ether solvent extract to S. zeamais adults were53.15%、76.88%and69.49%, repelling grade level Ⅲ, Ⅳ and Ⅳ respectively. The average of repelling rate of highest dose (123.46g/cm2) of methanol, ethyl acetate and petroleum ether solvent extract to C. pusillus dults3kinds of solvent extracts were62.23%、73.22%and40.16%, repelling grade level Ⅳ, Ⅳ and Ⅲ respectively. Three kinds of solvent extracts of star anise dried fruit repelling action to S. zeamais order was ethyl acetate extract>carbinol>petroleum ether, repelling action to C. pusillus order ethyl acetate extract> petroleum ether> carbinol, showing ethyl acetate extract effect significantly better than others.2.3Fumigation activity of Ⅰ. verum extracts to2kinds of grain storage pestsThree kinds of solvent extracts of Ⅰ.verum of dried fruit to S. zeamais and C. pusillus adults in fumigation action were assayed with container fumigation method, five treatment dose of1.25,2.5,5.0,10.0and20.0mg/L used. All of them had great effects, effects increasing with the increase of the dose. With the dose of20.0mg/L in72h, the corrected mortality rates to S. zeamais of methanol, ethyl acetate and petroleum ether extracts of maize were90.26%>95.89%and92.57%respectively; Corrected mortality rates to C. pusillus were89.93%>96.71%and91.56%respectively, showing ethyl acetate extract effect was highest, methanol extract lowest.The LD50of methanol, ethyl acetate and petroleum ether extract to S. zeamais adults in72h were7.10,3.93and4.55mg/L, the LD50to C. pusillus7.16,4.57and5.42mg/L, showing the obvious fumigation action effect.3The effects of different kinds of solvent extracts of Ⅰ.verum on enzymes in the body of two kinds of grain storage pests3.1Dosage effects of Ⅰ. verum extracts on detoxification enzymes of two kinds of grain storage pestsS. zeamais adults were treated by fumigating with the dose of20.0,10.0,5.0,2.5and1.25mg/L of three kinds of solvent extracts of Ⅰ.verum dried fruit, activity changes of AchE and GSTs in the body determined in24h. The results showed that3kinds of solvent extracts of Ⅰ.verum dried fruit dosage effect on AchE and GSTs of adult were obvious, inbibitional effect on two kinds of enzyme activity increasing with the rise of dose. Ethyl acetate extract inbibitional effect was the highest, petroleum ether and methanol second.C. pusillus adults were treated by fumigating with the dose of20.0,10.0,5.0,2.5and1.25mg/L of three kinds of solvent extracts of Ⅰ.verum dried fruit, activity changes of AchE and GSTs in the body determined in24h. The results showed that3kinds of solvent extracts of Ⅰ.verum dried fruit dosage effect on AchE and GSTs of adult were obvious, inbibitional effect on two kinds of enzyme activity increasing with the rise of dose. Low dose (1.25mg/L) of the methanol extract has certain inducing effect on the AchE; inbibitional effect order was ethyl acetate extract> petroleum ether>methanol. Inhibitory effect was positively correlated with fumigating effect overall, showing that activity AchE and GSTs decline may be the significant reason of adult death.3.2Time effects of I. verum extracts on detoxification enzymes of two kinds of grain storage pestsS. zeamais adults were treated the dose of LD50of three kinds of solvent extracts of Ⅰ. verum dried fruit, activity changes of AchE and GSTs in the body determined in12,24,36,48,60and72h. The results showed that the ethyl acetate extract inhibition effect on AchE was the highest in48h, petroleum ether highest in72h, petroleum ether and methanol extracts inhibition effect on GSTs highest in48h, ethyl acetate highest in48h.C. pusillus adults were treated the dose of LD50of3kinds of solvent extracts of Ⅰ. verum dried fruit, activity changes of AchE and GSTs in the body determined in12,24,36,48,60and72h.The results showed that3kinds of solvent extracts ofⅠ.verum dried fruit had obvious inbibitional effect on activity of AchE and GSTs. Petroleum ether and ethyl acetate extract inhibition effect on AchE and GSTs reached the highest in48h, methanol extract highest in60h.