Occurrence Of Thrips In Mango Orchard And Studies On The Biological And Chemical Control Of Frankliniella Intonsa

Thrips is the general name for Thysanoptera. Because the fruit species from Taiwan was introduced widely into Mainland China in recent years, accompanying with increasing in the plant area of mango and applied the pesticides, the balance of agricultural ecosystem had been seriously disrupted which pushed the little secondly pest thrips turning into the main pest. As a result, the production of mango has been severely influenced all nationwide, In this thesis, the preference of thrips to the different species of mango was investigated, the sensibility of thrips to the different kind of pesticides was tested, enemy predation model were constructed and the pesticide residue on mango trees with different spraying methods was analyzed. The result will help to clarify the mechanism of thrip infestation and have significant effects in guiding integrated pest management on thrips.1. The preference of thrips to the different species of mangoSweep net and observation methods were employed to survey the occurrence of three thrips on the four mango species, KAITE, JINHUANG, JIMANG, SIJI, from November 2009 to October 2011. The result showed that the occurrence peaks of three thrips on four species were all around May 2010. Scirtothrips dorsalis Hood did the most harm on mango trees and Scirtothrips dorsalis Hood did the least while Frankliniella intonsa(Trybom) was between them. In laboratory investigation on the preference from high to low of three thrips to the different species of mango were as follows:KAITE> SIJI> JINHUANG> JIMANG, which was consistent with the result of field investigation.2. The sensibility of thrips to the different kind of pesticidesResidual film method was adopted to determine the toxicity of 7 pesticides on thrips. The effect revealed that the toxicity of Chlorpyrifos with LC50 of 2.2146mg/L was the highest, while the highest LC50 value was Imidacloprid. The toxicity of Chlorfenapyr, Methidathion were higher than Dimethoate, Methomyl, Acetamiprid which could not be used for effectively control on thrips.3. The study on predation of its enemy Based on HollingⅡtype disc equation, functional reaction equation and its parameters of Amblyseius cucumeris were calculated when they preyed the larvea of thrips under different temperature conditions. Among the experimental temperature, A. cucumeris preyed one larva of Frankliniella intonsa(Trybom) under 33℃using up the least time and getting the maximum prey with the highest flash attack ratio. In contrast, the result under 17℃completely opposed. The average consumption and the predation of A. cucumeris on the larvae of thrips decreased gradually along with amplification of its own population density while its share-competition intensity changed adversely.4. The analysis on the pesticide residue on mango trees with different spraying methods treatmentResidual of five pesticides were investigated with LC-MS and GC. The result illustrated that the residue increased proportionately with the concentration of pesticide application. The residue on leaves with stem-injection treatment was firstly increased and then decreased, arrived the peak amount at 14th day and maintained relatively lower level after 40th day. Stem-injection method acquired a longer effective duration of pesticides than sparying method and had an outstanding effect on long period for thrip management.