| Thiamethoxam is a neonicotinoid insecticide with the activity of stomach toxicity,tag out and systematic action which has an excellent control effect against phloem-sucking pests,such as aphids,planthoppers and whiteflies and so on.Cinnamomum cassia is one of the main economic forest trees in South China.The oil extracted from the bark and leaves is called cinnamon oil.Major components of cinnamon oil are cinnamaldehyde(75-90%),cinnamyl alcohol,cinnamic acid and acetophenone,etc.In this article,the biological activity of cinnamon leaf meal,thiamethoxam and their mixture on poinsettia niacin was tested,and the influence of the various components on the distribution of Bemisia tabaci adults on poinsettia was researched.The main research contents are as follows:In the laboratory determination of the toxic activity,thiamethoxam showed excellent antifeedant and toxic activity on nymphs and adults of Bemisia tabaci,cinnamon leaf meal showed excellent repellent activity on adults of Bemisia tabaci,and the repellant rate in 3 minutes and 1 hour were both above 43%,up to 93%.In the pot experiment,various types of drugs can significantly inhibit the number of insect populations of Bemisia tabaci and nymphs,and have obvious repellent effect on adults and certain control effect on various insect states.Both Cinnamon leaf powder and thiamethoxam can rapidly reduce the number of insect populations.The average number of nymphs dropped from 127.7 insects/plant and 131.6 insects/plant to 46.2 insects/plant and 43.1 insects/plant,and then the number of insects recovered slowly.The average number of insects was 79.7insects/plant and 75.4insects/plant on the 40th days after treatment.The effect of the mixture of cinnamon leaf meal and thiamethoxam on the population of insect population was slower at the initial stage,,but the inhibiting effect gradually increased with the the extension of time,while the number of insect density decreased gradually with the extension of time.The average population of nymphs would decrease from 128.2 insects/plant to 87.2insects/plant on the first day after application,and 40.3insects/plant on the 40th day after treatment.The inhibitory effect of the mixture on pupa is similar to that of nymphsEach treatments showed obvious repellant activity on adult insects.5g of cinnamon leaf powder treated poinsettia,the repellent rate increased from 49.92%to 62.61%from the first day to the 7th day;The repellant effect on adult B.tabaci on lower leaves was distinct,which increased from 61.25%to 82.50%from the first day to the 7th day after treatment.The control effect on adult insects on upper,middle and lower leaves showed that the control effect of of each part was higher than 45%in the first day after treatment of cinnamon leaf powder,and above 40%in the 7th day.The control effect on lower leaves was distinct and above 75%in the 7th day after treatment.However,the control effect on middle and upper leaves was lower and above 40%;The control effect decreased in the 21st day after treatment.Thiamethoxam had the best effect in the 7th day after treatment in the pot experiment,with the lowest effect on upper leaves(75%),and effect on middle and lower leaves was above 82%.However,the control effect decreased after the 7 day and had no obvious effect after the 21 day.Thiamethoxam was mixed with cinnamon leaf powder,the control effect of each part was above 55%after treatment one day and above 75%in the 7th day.Afterwards,the control effect decreased,which was obvious on the top,but 61%on lower leaves.According to the rate of plants suffering from injury,it decreased at early stage after plant roots were treated with thiamethoxam,increased to 45.02%in the 14th day;It continued to increase after 14 day and finally became 68.19%in the 40th day.However,the rate of plants suffering from injury decreased after roots were treated with the mixture.It wasn't obvious in the first day,but decreased to 36.7%afterwards.It increased to 41.58%in the 40th day.The mixture showed certain level of slow release effect,increasing the control duration.The distribution and dynamic study of thiamethoxam in soil showed that in the treatment of single thiamethoxam,its concentration in the upper layer soil(0-10cm)was 8.07mg/kg in the first day after treatment,1.51mg/kg in the 5th day,increased back to 4.97mg/kg in the 7th day and decreased continuously to zero in the 40th day.The concentration of thiamethoxam in the middle layer soil(11-20cm)experienced decrease,increase and decrease again,which conformed to the up and down flow feature of insecticides.It was 4.44mg/kg in the first day,Omg/kg in the 7th day,while increased back to 3.33mg/kg in the 14th day,decreased to Omg/kg again in the 20th day;It slightly increased to 1.45mg/kg in the 30th day and decreased back to 0.20mg/kg in the 40th day.Its concentration in the lower layer soil(21-30cm)was fluctuated unstable from the highest level of 3.65mg/kg in the 14th day and the lowest level of 0.76mg/kg in the 40th day.In the treatment of thiamethoxam and cinnamon leaf powder mixture,the concentration of thiamethoxam in the upper layer soil was relatively stable with the highest level of 3.49mg/kg in the 5th day and the lowest level of 0.52mg/kg in the 40th day.Its concentration in the lower layer soil was zero in the first day and the 3rd day,then it fluctuated between Omg/kg and 6.02mg/kg,and increased back to 2.54mg/kg in the 40th day.It showed that thiamethoxam was relatively maintained in the upper layer soil by cinnamon leaf meal,making it slowly sink to lower layer soil to avoid rapid loss,which could reduce environmental pollution at some level,extent effect duration and save insecticide using and labor cost.The result of the pot experiment showed that cinnamon leaf meal,thiamethoxam and their mixture had effects on the growth of the seedlings.In the treatment of single thiamethoxam and the mixture,the number of leaf buds increased respectively by 65%and 40%in the 30th day,while only 17%in the control group.Mixture treatment could promote the growth of the length and width of some leaves,and the growth amplitude was above 23%and 14%at 30 days,but had little effect on the height and width of plants.The result of this study showed that cinnamon leaf powder had certain activity and control effect on Bemisia tabaci on Euphorbia pulcherrima,with the strongest rellent activity and more obvious on the lower leaves of the plant;Cinnamon leaf powder had a synergistic effect on the control on thiamethoxam in preventing and controlling Bemisia tabaci,not only increased the persistence period,but also influenced the distribution and digestion of thiamethoxam in the plant and the soil,decreasing the loss of insecticides.There was no significant effect on the growth of seedlings by using cinnamon leaf powder Euphorbia pulcherrima. |
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