Preliminary Study On Control Effects Of Perilla Frutescens (L.) Britton On The Striped Flea Beetle, Phyllotreta Striolata (Fabricius)

In this dissertation, mechanism of control effect of Perilla frutescens (L.) Britton onstriped flea beetle, Phyllotreta striolata (Fabricius) was discussed preliminarily. P.frutescens (L.) was intercropped into cruciferous vegetables to examine the controleffects of the intercropping system on P. striolata (F.). And the antifeeding, repellant andtoxic effect of extracts of P. frutescens (L.) on P. striolata (F.)'s adult was also evaluated.The aim of the study was to provide scientific directions and references for sustainableeffectual control of P. striolata (F.) and boos pollution-free vegetable production. Themain results were as follows:1. Intercropping of P. frutescens (L.) and cruciferous vegetables influenced thepopulation of P. striolata (F.) significantly. The number of P. striolata (F.) in the P.frutescens (L.)-cruciferous vegetable intercropping fields was less than that incruciferous vegetable monoculture fields by 39.71%～58.33%. In different growingstages, the P. frutescens (L.) intercropped into cruciferous vegetables brought differentinfluence on the P. striolata (F.). In the seedling stage, the P. frutescens (L.) -cruciferousvegetable intercropping had few control effects on P. striolata (F.). Since P. frutescens (L.)grew to it's early stage, the number of P. striolata (F.) in the intercropping fields wasmuch less than that in cruciferous vegetable monoculture fields. Different plantingdensities of Perilla frutescens (L.) intercropped into cruciferous vegetables causeddifferent control effects on P. striolata (F.). When the density of P. frutescens (L.) washigher, the number of P. striolata (F.) in the intercropping fields was lower. Thisphenomenon become very notable in P. frutescens (L.)'s early stage. The range of a singleP. frutescens (L.) controlled the P. striolata (F.) was 110cm around. Beyond this range, there were few control effects. The relationship between the range and the control effectof a single P. frutescens (L.) on P. striolata (F.) is as this equation:y=79.8255/1+e^{-5.0209+0.07325x} (r=0.9947).2. Different organ of P. frutescens (L.) was extracted with petroleum ether,anhydrous alcohol and methanol respectively. The determination of biological activitiesindicated that different extracts had different effects on P. striolata (F.)'s adults indifferent degrees. The selective antifeedant rates and non-selective antifeedant rates ofthe three solvent extracts were 28.38%～100.00% and 33.71%～72.64% respectivelywithin 24h at 10 g·L^-1. The declining order of biological activities of extracts of differentorgans was calyx, root, leaf, caudex and seed. Among those, the antifeedant rates ofextracts from calyx and root were much higher relatively than others. In addition,selective repellence rates of methanol and anhydrous alcohol extracts of calyx, alcoholextract of seed and infusion of fresh leaf were 50.93%～97.46% within 24h at 10 g·L^-1.The selective repellence rate of essential oil extracted by SD was 84.98% at 2.5g·L^-1within 24h. Those indicated that the biological activity on P. striolata (F.)'s adults ofextracts of P. frutescens (L.)was only manifested in antifeeding and repellence.3. Extracted with petroleum ether, anhydrous alcohol and methanol respectively,the determination of biological activities indicated that the biological activity ofmethanol extracts was higher than that of anhydrous alcohol extracts of the calyx, leafand caudex. But the biological activity of the anhydrous alcohol extracts of the root washigher than that of the methanol extracts. From the seed, the biological activity ofpetroleum ether was better than others. Among 15 extracts, the methanol extracts andanhydrous alcohol extracts of the calyx had the best selective antifeeding effects, theselective antifeedant rates were 100% and 96.22% respectively within 24h at 10 g·L^-1.Also, the methanol extracts of the calyx and anhydrous alcohol extracts of root had thebest non- selective antifeeding effects, the non- selective antifeedant rate were 72.64%and 71.24% respectively.4. Different solvents were used to extract compounds of the root and calyx step bystep from low polarity to high polarity. And the effects on P. striolata (F.)'s adults of the extracts extracted by system method were tested. The result showed that extracts of theroot and calyx had high selective antifeeding effects on P. striolata (F.)'s adults. Within24h, the selective antifeedant rates were 60.37%～100.00% at 6 g·L^-1, and sustainedover 45.65% within 48h. Among those, the petroleum ether extracts of root had the bestselective antifeeding activity. And within 24h and 48h, the antifeedant rates were 100.00% and 84.76 % respectively. The AFC₅₀ of selective and non-selective antifeeding effectsof hexane extracts of calyx were 2.16g·L^-1 and 6.16g·L^-1 respectively. Except hexaneextracts of the root, every extract of the root and calyx had good non-selectiveantifeeding effects on P. striolata (F.)'s adults. Among those, the ethyl acetate extracts ofroot had the best non-selective antifeeding activity. The non-selective antifeedant rate ofethyl acetate extracts of the root was highest. Those indicated that active antifeedingsubstance on P. striolata (F.) mainly contained in moderate polarity to strong polaritysolvents.5. Extracting compounds from different organs of P. frutescens (L.) in differentways with different solvents led to different extracting rates. The results showed that thedeclining order of content of essential oil in different organs was leaf, stem and root.Efficiency of extracting essential oil by simultaneous distillation and extraction (SDE)was higher than that by steam distillation (SD), but the selective antifeedant rate of itwas lower. Different organ of P. frutescens (L.) was extracted with petroleum ether,anhydrous alcohol and methanol respectively. The result showed that the declining orderof content of lipophilic substances in different material of P. frutescens (L.) was seed, dryleaf and fresh leaf. In the dry materials, the content of hydrophilic substances in dry leafand calyx was higher than that in dry caudex and root. Extracting the same material ofP. frutescens (L.) with different solvents, the extracting efficiency of methanol was higherthan that of anhydrous alcohol.