Investigation On Insect Community Of The Super-high-yield Wheat Field In Gaocheng And Control Of The Main Pests

Gaocheng is one of the super-high-yield wheat fields in Hebei Province. Its plantingarea is more than10000mu and the yield keep ahead for years. The changes ofplantation structure and management measures lead to the change of insect community,while there are few reports about it. Besides, in order to obtain high yield, there also existunreasonable phenomenons of chemicals used, which not only have bad effect on theenvironment, but also reduce the number of natural enemies. In order to control pestsreasonably, we investigated the insect community in the wheat field of Gaocheng andmastered the occurrence regularity of main insects. Through the efficacy trials, weselected high efficiency and low toxicity insecticides to control pests, which was of greatsignificance for high yield and low pollution of the wheat production.From recovering date to mature period, we used many methods, such as washing thesoil, sweeping, hanging the yellow board and so on, to investigate the crop insectcommunity of Gaocheng and combined the climatic factors such as temperature andhumidity to analyze the occurrence regularity of insects. In addition, focusing on themain pests we conducted the toxicities and field control effects to guide farmers to usehigh-efficiency and low toxicity insecticides or biological agents, which can reduce theenvironmental pollution and toxic to natural enemies. According to these results, we putforward the integrated control measure, which is suitable for the wheat insect pests in themiddle and south part of Hebei province. The main results were as follows:(1) The super-high-yield wheat field of Gaocheng is highly centralized managementand standardize, so the species of insects in the field is relatively few, only17species of11families in4orders. According to the severity, the main pests are wheat midge, wheataphids and soil pests. Among the pests the dominant species were SitodiplosisMosellana(Géhin), Macrosiphum avenae Fabricius, Schizaphis graminum (Rondani).There were4groups of natural enemies, including aphidiidaes, ladybugs, syrphid fliesand chrysopids, and the dominant species were Sitodiplosis Mosellana (Géhin) andMacrosiphum avenae Fabricius. (2) We carried on the investigation and analyzed the occurrence regularity of wheatmidge and wheat aphids in Gaocheng. In this area, wheat midge began activities on March20th when the temperature in the depth of10cm underground reaches10℃, and began topupate on April22th. On May4th, we can see a few wheat midge adults, and the numberof adult reached peak on May15th. Wheat midge is small and hidden, so the adult stage isthe critical period to control it. In Gaocheng wheat midge reached peak from May11th toMay15th, so this is the critical period for the prevention and treatment of wheat midge.Wheat aphids began to appear on April29th and reached the peak on May30th. InGaocheng wheat heading stage is at the end of April, and wheat aphids began to occur,take the prevention and control of wheat aphids at this point, not only can control thepopulation base, but also form a protective layer for the wheat. This is the critical periodfor the prevention and control of wheat aphids.(3) In order to achieve the green protection of the main pests include wheat aphidsand wheat midge in the super-high-yield wheat field of Gaocheng county, we conducttoxicities and field control effects with some commonly used insecticides. The resultsshowed that the insecticides include Omethoate, Chlorpyrifos, Beta-cypermethrin andImidacloprid all had good control effect, and the reduce rates are over80%. The reducerate from high to low in turn is: Omethoate, Chlorpyrifos, Beta-cypermethrin andImidacloprid. In these four kinds of insecticides, Omethoate belongs to high toxicity ofreagents, Chlorpyrifos have medium toxicity, beta-cypermethrin and imidacloprid belongto low toxicity pesticides. So according to the happening situation of wheat midge,choosing medium toxicity pesticides with low toxicity pesticides cross use, not onlyensure the control effect, but reduce the use of high toxicity pesticides.Beta-cypermethrin, Imidacloprid and Acetamiprid are all belong to low toxicitypesticides and have good control effect on wheat aphids. The reduce rates of this threeinsecticides are all over90%. Matrine·Nicotine and Beauveria bassiana strains BD015are belong to biological agent, and their reduce rates about wheat aphids are all over80%.So on the prevention and control of wheat aphids, according to the occurrence of wheataphids, we can choose the low toxicity pesticides and biological agents cross use. Notonly can we reduce the use of chemicals, but implement the green protection of wheataphids.