A Preliminary Study On Distributing Phase And Sampling Methods Of Larva Braidysia Olaiphagelarva In Chinese Chive Field And The Techniques Of Its Control

The larva of Braidysia olaiphage,one of the main pests in Chinese chive production,is a major obstacle for the production of organic and green products.The chemical prevention of Braidysia olaiphage larva is a key measure to improve efficient and high-yield production. The right chemicals application and the correct methods of Chemical controlling are the main way and line of defence to control larva Braidysia olaiphage and produce healthy and pollution-controlled Chinese chive for consumer,so as to obtain this aim we should seek to find a highly efficient and lowly remnant chemicals and valid controlling methods,in order to get high quality and green Chinese chive and benefit consumer's health.We planned experiments from 2004 to 2006 on chemical controls for Bradysia odoriphaga larva and get some results of proper chemicals application quantity at different time and levels.At the same time,we study the field distributing pattern of Braidysia olaiphage larva in Chinese chive field by using methods of aggregation index,Iwao regression and Talor regression.The results show that Braidysia olaiphage larva distributed in aggregation manner,which follow the negative binomial distribution,which aggregation Characteristics is duo to the biologic habit of the larva.The U statistic analysis indicated that the ideal sampling Methods for this pest in Chinese chive field are Z-shape sampling,chessboard shape sampling and parallel sampling.The sampling date from 10sites,12sites and 14sites showed small dispersion,but 8sites sampling showed big dispersion and statistic error.We analyzed the relationship between Braidysia Olaiphage larva density and loss of production of Chinese chive by using regression analysis,the results show the population density of larva has a positive relationship with the loss of production(r=0.816);we figure out the loss coefficient and economic threshold value by analyzing recent data of the different price of chinese chive on market,Braidysia Olaiphage larva prevention experiments data and cost,which we can control the Braidysia Olaiphage larva economically,ecologically and efficiently. At meantime to achieve the goal of pattern that can forecast the targets of controlling Braidysia Olaiphage larva by using regression analysis on factors of ratio between investment and produce,larva population density,cost and effectiveness of controlling application. Braidysia Olaiphage larva(Braidysia olaiphage Yang et Zhang) was major hazard to the Chinese chive,the victim number of plants are generally from 20%to 30%,seriously it is as high as 100%,yield loss is from 30%to 80%and the economic loss is 30%.Longer history of Chinese chive growing,the greater the insect population base and the more serious harm it has.Serious development of pests on plant tends to incur disaster damage and loss on Chinese chive field.Prevention and treatment of chemical pesticides has played an important role on pest control.However,there is very low effectiveness the farms get because of less understanding of application technology and improper method applied of chemicals, sometimes using wrong pesticides leads to high cost and low efficiency,and this way has wasted lots of human force and material resources.The results show the effectiveness of different chemicals by comparing with different spraying time and chemical concentrations,it shows that the chemicals with the controlling effect similar to phorate are phoxim,lebensi and matrine;if we apply chemicals under rule of protection of circumstances,and produce pollution-free products,we should choose Lebensi and Phoxim,Matrine;if we want to control the cost of chemicals,we should choose 600×solution of Phoxim;we choose 350×solution of Matrine with consideration of requirements green products need.We analyzed the relativity between chemicals effectiveness and temperature by statistic method,we found there is a problem on chemicals spray time of controlling Braidysia Olaiphage larva,we need to do some experiments for relationship between proper period of rhythm of Braidysia Olaiphage larva activity with circumstance temperature,and make sure best time for controlling Braidysia Olaiphage larva and pesticides spray.when we analyzed the distribution pattern and samplling method of Braidysia Olaiphage larva,we integrated with technology of pollution -flee for chinese chive cultivation.