Identification Of Insecticidal Activity Of Areca Nut Alkaloids Components And Their Formulation Study

Alkaloids are important insecticidal active substance.At present,the alkaloid insecticides including nicotine,matrine,veratrine and so on have been developed and applied.Areca nut is the mature dry seed of Areca catechu.As a commonly used Chinese medicine,it is the only plant that contains alkaloids of Palm family.Areca alkaloids are the main components of areca nut.Currently,the main research reports on areca alkaloids mainly focus on the pharmacology,few studies on the insecticidal activity.In this paper,the insecticidal activity of A.catechu alkaloids on Plutella xylostella larvae was investigated.These results are very important for understanding the insecticidal activity of betel nut,exploring chemical structure of the alkaloids to lay the foundation for new biological pesticides.The bioactivity of different solvent extracts of areca nut against P.xylostella larvae was determined by methods of contact and stomachic toxicity.On this basis,the alkaloid components analysis of the highest insecticidal activity of methanol extracts of betel nut was tested qualitatively and quantitatively by Ultra-performance liquid chromatography coupled with hybrid triple quadrupole time-of-flight tandem mass spectrometry(UPLC-Triple-TOF/MS)and the insecticidal activity of the alkaloid compounds and their mixtiure on P.xylostella larvae were further determined.Finally,the water formulation of the chosed mixture was also investigated.The main results as following:1.The insecticidal activity of different solvent extracts of areca nut on P.xylostella larvae showed that the stomachic toxicity was higher than contact toxicity in four solvent extracts of areca nut.The adjusted mortality rates of methanol,ethanol,n-hexaneand and dichloromethane extracts of areca nut stomachic and contact treatment for 72 h were 49.60%,47.90%,49.73%,64.36%and 81.43%,63.49%,72.54%,83.97%,respectively.These results suggested that the insecticidal activityon P.xylostella larvae of the dichloromethane and methanol extracts of areca nut is significantly higher than other two reagents extracts.The components of methanol areca nut extract were qualitatively and quantitatively analyzed by UPLC-Triple-TOF/MS.The results showed that the alkaloid components of methanol crude extract include arecoline(7.88mg/g),arecaidine(25.48mg/g),guvacine(4.90mg/g),guvacoline(11.37mg/g),methyl nicotinate(0.02mg/g)and ethyl nicotinate(0.002mg/g)methy 1-piperidine-3-carboxylate(0.69mg/g),Ethyl 1-methylnipecotate(0.01mg/g).2.The biological activities of eight arecoline compounds and their mixture against P.xylostella larvae were determined.Areca nuts methonal extracts(ANME)and main alkaloids constituents were tested for insecticidal activity against 3rd instar larvae of P.xylostella.ANME was toxicity against P.xylostella larvae,with an LC50 value of 44.78mg/L.Among the main constituents tested individually,arecoline showed the highest activity with an LC50 value of 64.62mg/L,followed by guvacoline(92.413 mg/L),arecaidine(150.299 mg/L),whereas guvacine showed the lowest activity with LC50 value of 157.360 mg/L.The combination of arecoline+guvacoline,arecoline+arecaidine and arecoline+guvacine showed synergistic effect,additive effect respectively.3.Based on the resluts of joint action,their mixed water formulation was made.The three mixed components of arecoline+guvacoline,arecoline+ arecaidine,and arecoline+guvacine are respectively made into 2%water formulation,and their cold storage,thermal storage,dilution stability,contact angle and surface tension are measured.The results showed that three optimal formulation was arecoline+ guvacoline+APG0810octylglucoside,arecoline+arecaidine+APG0814 cocoyl glucoside and arecoline+guvacine+octanol polyoxyethylene ether.Their corrected mortality of the water formulations against P.xylostella larvae are respectively85%,76.67%and78.33%.