蓟马危害苜蓿的产量损失及防治指标研究

A study on the yield loss and economic threshold of alfalfa damaged by thrip, Odentothrips lati

采用人工接虫的方法,研究了蓟马的虫口密度与苜蓿产量损失之间的关系和防治指标。结果表明,苜蓿干草产量损失率(Y)与20枝条虫量(X)的关系为Y=0.1021X-2.2461,相关系数r为0.9874,两者相关性极显著。按照防治的直接收益与成本,确定了宁夏旱地苜蓿和水地苜蓿蓟马的防治指标,即旱地苜蓿蓟马第1茬的防治指标为560头/100枝条,水地苜蓿蓟马第2茬的防治指标为390头/100枝条,第3茬的防治指标为580头/100枝条。

The tests on the damage and economic threshold of alfalfa was carried out by artificially modifying the density of thrip, Odentothrips lati.A correlation formula between thrip population density per 20 stems (X) and yield loss rate of dried hay (Y) was created as follows: Y=0.1021X-2.2461, r=0.9874.Based on the direct benefits and control costs, the economic thresholds in controlling thrips under various field conditions were determined as follows: 560 thrips per 100 stems of the first cutting alfalfa in dry fields; 390 thrips per 100 stems of the second cutting alfalfa and 580 thrips per stems of the third cutting alfalfa in irrigated fields.