Study On Bioactivity Of Extracts From Justicia Procumbens L.

Justicia procumbens is a kind of traditional Chinese Medicine. In order to ascertainbioactivity of extracts from J. procumbens, insecticidal activities and action ways ofextracts from J. procumbens against insects and fungicidal activities of extracts from J.procumbens against plant pathogens were bioassayed by combined method of cold-soakingand ultrasonic extraction in the greenhouse. The results as follow:（1） J. procumbens was extracted by five different polar solvents. The orders ofextracting rate showed as following: methanol> acetone> chloroform> ethyl acetate>hexane.（2） Extracts at8mg/mL with different polar solvents from J. procumbens had certaincontact effects against9species of insects（Ostrinia furnacalis, Plutella xylostella, Pierisrapae, Heliothis armigera, Spodoptera litura, Aphis glycines, Myzus persicae, Lipaphiserysimi and Panonychus citri）, in which, contact effects of methanol extracts against O.furnacalis, P. xylostella, P. rapae, H. armigera and S. litura were the strongest, themortality within72h after treatment was26.67%,73.33%,100.00%,23.33%and36.67%,respectively. Contact effects of ethyl acetate extracts from J. procumbens against Aphisglycines, Myzus persicae and Lipaphis erysimi were the strongest, the correct mortalitywithin72h after treatment was100.00%,98.94%and100.00%, respectively. Contacteffects of acetone extracts against Panonychus citri were the strongest, the correctmortality within72h after treatment was100.00%.（3） Methanol extracts from J. procumbens had certain contacting and betterantifeeding, stomach poisoning, growth inhibition activities against larvae of O. furnacalisand better oviposition deterrent activities against adult of O. furnacalis. The mortality ofextracts at the concentration of32mg/mL against3rd instar larvae of O. furnacalis within24and48h after treatment reached28.33%and43.33%, respectively. The choice and non-choice AFC₅₀values within24and48h after treatment in antifeeding test were3.10,3.90mg/mL and4.44,5.77mg/mL, respectively. The LC₅₀values of extracts against3rd instarlarvae of O. furnacalis within6and7d after treatment in stomach poisoning test were5.09and2.73mg/mL, respectively. The IC₅₀values within24and48h after treatment were0.84and0.53mg/mL, respectively. The AOC₅₀values within24,48and72h aftertreatment were6.73,9.71and12.29mg/mL, respectively.（4） Methanol extracts from J. procumbens had better contacting and antifeeding,stomach poisoning, growth inhibition activities against larvae of P. xylostella and betteroviposition deterrent activities against adult of P. xylostella. The LC₅₀values of extracts against3rd instar larvae of P. xylostella within24,48and72h after treatment incontacting test were5.17,4.05and3.06mg/mL, respectively. The choice and non-choiceAFC₅₀values within24and48h after treatment in antifeeding test were2.64,3.13mg/mLand3.70,4.54mg/mL, respectively. The LC₅₀values of extracts against3rd instar larvae ofO. furnacalis within4,5,6and7d after treatment in stomach poisoning test were8.13,3.65,2.88and2.23mg/mL, respectively. The IC₅₀values within24and48h aftertreatment were2.02and1.40mg/mL, respectively. The choice and non-choice AOC₅₀values within24,48and72h after treatment were2.61,3.66,4.58mg/mL and3.19,4.52,5.65mg/mL, respectively.（5） Methanol extracts from J. procumbens had better contacting and antifeeding,stomach poisoning, growth inhibition activities against larvae of P. rapae and betteroviposition deterrent activities against adult of P. rapae. The LC₅₀values of extractsagainst3rd instar larvae of P. rapae within24,48and72h after treatment in contactingtest were0.59,0.29and0.20mg/mL, respectively. The choice and non-choice AFC₅₀values within24and48h after treatment in antifeeding test were0.32,0.36mg/mL and0.46,0.57mg/mL, respectively. The LC₅₀values of extracts against3rd instar larvae of P.rapae within4,5,6and7d after treatment in stomach poisoning test were1.24,0.92,0.72and0.53mg/mL, respectively. The IC₅₀values within24and48h after treatment were0.25and0.18mg/mL, respectively. The choice and non-choice AOC₅₀values within24,48and72h after treatment were0.30,0.54,0.86mg/mL and0.51,0.84,1.10mg/mL,respectively.（6） Extracts at8mg/mL with different polar solvents from J. procumbens had certaininhibitory effects against8species of plant pathogenic fungus, in which, methanol extractshad better fungicidal activity against Colletotrichum gloeosporioides Peng., Phomopsisasparagi, Phytophthora capsici, Colletotrichum gloeosporioide Penz. and Botrytiscinerea, the value of EC₅₀were5.91,4.61,5.05,4.23and5.27mg/mL, respectively.Methanol extracts at0.25¹mg/mL showed strong inhibitory activity againstXanthomonas campestris, and its extracts at0.125mg/mL showed moderate inhibitoryactivity. MIC value of methanol extracts was0.0625mg/mL. Methanol extracts hadbetter efficacy against C. gloeosporioides Penz. and P. capsici by potcultureexperiment at the seedling stage. The efficacy was73.08%and75.86%at theconcentration of16mg/mL, and their EC₅₀values were5.54and5.81mg/mL,respectively.