The Research On The Rule Of Occurrence And Preventative Technology Of Trialeurodes Vaporariorum And Bemisia Tabaci In Luoyang

This study done in October 2005—2009, focuses on Trialeurodes vaporariorum and Bemisia tabaci in Luoyang city and Yichuan county, which has conducted a general survey of the two's host crops and the severity of the two pests'and has done a dynamic study of their occurrence. Besides, this research also centers on the demonstration and popularization of the preventative measures. The results are as follows:1. Trialeurodes vaporariorum and Bemisia tabaci's hostsThrough local research and looking up in related documents, we have found that in Luoyang, the major hosts of Trialeurodes vaporariorum have 14 sections,63 breeds (variation); the major hosts of Bemisia tabaci have 20sections,78breeds (variation). Trialeurodes vaporariorum and Bemisia tabaci's major target crops mostly belong to solanaceae, cucurbitaceac, composite and leguminosae, and the most severely affected crops include cucumber, pumpkin, vegetable marrow, tomato, eggplant, kidney bean, oil sunflower and Indian mallow. Their difference is that Bemisia tabaci harms a wider range of crops, mainly in Cruciferae, especially broccoli; whileTrialeurodes vaporariorum generally doesn't harm Cruciferae. Besides, tobacco, cotton and poinsettia, which are seriously harmed by Bemisia tabaci, are little affected by Trialeurodes vaporariorum. In terms of environmental circumstances, in general yearsTrialeurodes vaporariorum's harm is relatively small in dewy areas, while in winter, its harm is severe in protective areas; Bemisia tabaci's harm is severe both in dewy areas and protective areas.2. The study of the rule of occurrenceThrough four years of study and research in a row, we've found that in the fields in Luoyang District, with the seasonal change and the harvest and rotation of crops, Trialeurodes vaporariorum has a regular transference in its host crops. Around April, a few Trialeurodes vaporariorum imagoes in the greenhouse fly through the intakes to nearby posts such as the Indian mallow, spring-sowed cotton, bean, peanut and vegetables which live through the winter or planted in spring. From the last ten days of May to the middle ten days of June, the reproduction rate of Trialeurodes vaporariorum gradually increases in greenhouse vegetables and other hosts after their films being lifted and before they are harvested. The density of larva gradually rises. Apart from continuing to reproduce and do harm to its original hosts, part of the imagoes of Trialeurodes vaporariorum transfer to crops such as tomatoes, eggplants, cucumbers, oil sunflowers, cotton in succession and rapidly reproduce on these new hosts, and move to the greenhouse before wintry low temperature comes. In November, when most planted hosts like late autumn Chinese cabbages and turnips are harvested, the number of Trialeurodes vaporariorum on a few greenhouse vegetables like tomatoes, eggplants and cucumbers which grow against the wind and towards the sun and are covered with two films gradually increases, and they live through the winter in these hosts. Trialeurodes vaporariorum can reproduce more than 10 generations in dewy areas and protective areas all the year round.Compared with Trialeurodes vaporariorum, Bemisia tabaci starts late. Generally speaking, in the suburb of Luoyang, Bemisia tabaci becomes imagoes at the beginning of July and its population rapidly increases during the first ten days of August, and reaches its yearly peak in the later days of August. By the middle of September, with the decrease of temperature, its density quickly goes down, by the beginning of October, Bemisia tabaci imagoes in the fields gradually disappear. In the mountainous areas, Bemisia tabaci imagoes appear in mid-July and the first yearly imago peak happens in mid-August, then the population keeps on a relatively high level. By the end of August and the beginning of September, the second peak appears in the field, but the population is much smaller than that of the first one. The growth of the nits is basically the same with the imago, while the nymphae lag behind the nit for about 7-10 days. Bemisia tabaci can also reproduce more than 10 generations in dewy areas and protective areas all the year round.3. The establishment of comprehensive preventative measuresAfter our predictive research which has lasted for four years, we have made clear the rule of occurrence of the two pests, developed the physical and agricultural preventative measures:forecast and predict and treat respectively; protect and make use of their natural enemies; agricultural measures; trap and kill by yellow board; cover in greenhouses under high temperature; use chemical pesticide. Besides, we have screened out the appropriate pesticide to prevent the pests:10%Imidacloprid,1.8% Abamectin,0.26%Matrine,5% Acetamiprid,5%Fipronil,25%Buprofezin and such kind of highly effective pesticides with little poison.4. Demonstration and popularizationAfter experimenting in five small areas, demonstrating in the fields and investigating three rural residents, we compared the benefits of fields which have been applied comprehensive preventative measures and those which have not. The result shows that in dewy preventative areas different crops per mu can save 17.1-528.7 RMB, while in protective areas the number is 449.1～1308.8 RMB.