Preliminary Study On The Insecticidal Mechanism Of Deoxypodophyllotoxin

Deoxypodophyllotoxin belongs to lignans, it mainly exists in some plants such as vivaciousherbaceous group of Podophylloideae Dysosma,Sinopodophyllum,Diphylleia ,Podophyllum inBerberidaceae.Deoxypodophyllotoxin was extracted from non-essential oils of Sabina vulgris Ant.by the Research and Development Center of Biorational Pesticide of NWSUAF,the insecticidalactivity of deoxypodophyllotoxin was tested partly,Previous researchs showed thatDeoxypodophyllotoxin possed strong antifeedant against Mythimna separata W. and Pieris rapaeL.. Deoxypodophyllotoxin also had high stomach poisonous against Pieris rapae L.and Plutellaxylostella L.;Moreover, Deoxypodophyllotoxin had biological activity to such enzymes as themidgut protease of Pieris rapae L.,carboxylic acid esterase and multi-functional oxidase ,etc., andit had inhibition to nerve-muscle telex ,which caused worm's paralysis similarly.Based on aboveresults, using the cabbage caterpillar and armyworm as test insects, this paper make further studyon the function mechanism of Deoxypodophyllotoxin,results are as follows: 1 Deoxypodophyllotoxin have strong antifeedant and the function of development inhibitionto armyworm, strong antifeedant and stomach poisonous to cabbage caterpillar. 2 Deoxypodophyllotoxin have strong development inhibition to armyworm. The stage oftreated insects were delayed, pupation rate, eclosion rate and oviposition quantity all reduced,abnormal pupation rate is 31.58% higher than CK; the feedant quantity of treated insects is fewerthan CK, pupae and adult are all smaller than CK; the oviposition quantity reduced. 3 The strongest antifeedant action caused by Deoxypodophyllotoxin acts on the top ofantenna and the beard of submaxillary ,the antifeedant rates were 47.8005% and 44.2328%,respectively; The antifeedant rate caused by the rest sensory organs were all under 30%. 4 The content of the chitin in the epidermis in treated cabbage caterpillar depressed by22.51%. 5 After treated by Deoxypodophyllotoxin,the body wall,the cell in mid intestines and thespermatophore were came into being pathology change, the thickness of the wall is odds,andleanness under the wall. The nuclear membrane of the wall is not clearly and the nuclear isswelling.the content in the nuclear turnned sparsity. Some nutrition consume itself to be cavum,thecolor turned lighter; the thickness of midgut is odds , the gap of parietal cell of midgut becamegreater, microvillus shrink, destroyed and fall off ,sparseness. Organelle were lessen ,the linage ofendoplasmic reticulum foul-up and ribosome fall off. The dissepiment between closets ofspermatophore was melt and the content in closets were fewer. 6 Deoxypodophyllotoxin has definite action to mid intestines digest enzyme in cabbagecaterpillar, and it can activate mid intestines lipase and restrain amylase and albumen enzyme.7 Deoxypodophyllotoxin has strong activation to esterase.in cabbage caterpillar andinhibition to esterase.in armyworm. 8 Deoxypodophyllotoxin has strong influence on protection enzyme in cabbage caterpillarand armyworm. After deal with Deoxypodophyllotoxin, the activity of SOD in cabbage caterpillaris enhanced, and the activity of CAT is restrained at first, then enhanced, at last back to the level ofCK, and the POD is obviously enhanced. The SOD,CATand POD of the fourth instar armywormare all strongly restrained. 9 Based on above results, the function mechanism of Deoxypodophyllotoxin may be asfollowing:(1)Influenc on apocleisis and other chemical sense devices of mouthpart and producingprimary antifeedant reaction.(2) Act on digestive system, forming secondary antifeed reaction.(3)Counteract releasing of the peptide hormone, it cast off a skin hormone , assuare the younghormone is dripped degree to influence, suppress and grow and make reproduction strengthdrop;(4) The chitin of insect's epidermis was influenced,which results in growing and obstructingind...