Studies On Controlling Alfalfa Thrips

The paper studied the species of the alfalfa thrips in BeiJing and investigated the population of thrips, it showed that the dominant species of thrips in the alfalfa was thrips Odontothrips loti through making microsection to observe in microscope and photographing living bodies in Electronic microscope to discriminate the morphological characteristics of different thrips.The population fluctuation of Thrips Odontothrips loti was investigated in alfalfa from June to September,2002. It showed that there were three peaks of population in late June,mid-July and early August.The predator species and dominant populations of alfalfa thrips were determined in BeiJing,through systematic field investigations and species identification. Field growth and decline of dominant species such as ladybeetles, predatory bugs and spiders was preliminarily studied,and the dynamic relationship between alfalfa thrips and the dominant predators was analyzed asinsects. The it showed that the predatory bugs is dominant species for thrips, the number of thrips appeared decline when the population of predatory bugs was peak.Throughout choice chemical insecticides and botanical insecticides to control alfalfa thrips, the results showed :1. chemical insecticides: field tests of six insecticides to control alfalfa thrips shows that six insecticides gave significant control, especial 25% thiamethoxam 5000x,10000x,15000x and 1.8% abamectin 1000x, 3 days after treatment, the control level attained were 85.63~93.30%. test of 25% thiamethoxam 15000x to control alfalfa thrips in different height of alfalfa shows that best time to control thrips is 30cm height of alfalfa,3dyas after treatment ,the control level attainde 90.31%2. botanical insecticides: field tests of comparing seven botanicla insecticides to one chemical insecticide show that seven botanical insecticides gave significant control, especial 0.3% deltamethrin, 2.5%nicotinamide-azadirachtin and 10%lemongrasstin ,and have not significant difference compare to 2.5% deltamethrim , 3 days after treatment, control level attained were 76.18%,63.42%,90.59% respectively.And 59 germplasm materials of alfalfa were investigated and evaluated in the field for their resistance to Haplothrips Chinese from August 2003 to August 2004. The results showed that there were significant differences among the materials in resistance to Haplothrips chinese, of which 1 material was rated as high resistant, 8 as moderate...