吡虫啉在杨树中持留量的动态变化研究

该文以二氯甲烷为提取剂 ,采用高效液相色谱法 ,测定了吡虫啉 (imidacloprid)在杨树 (北京杨 )中的持留量 .结果表明 ,采用打孔注药法在树干基部注入吡虫啉 (商品名 :康福多 ) ,药剂在树体内可持留 40d以上 ,其中叶片中的药剂含量最高 ,侧枝中的含量居中 ,树干中含量最低 .杨树主干韧皮部的持留量明显高于木质部的持留量 ,施药后 ,吡虫啉在树干木质部中的持留量是随时间而变化的 ,施药后 5d左右持留量最高 ,以后又逐渐下降 .树干基部的持留量为 0 2 8μg kg ,小于树干上部的持留量 0 64μg kg ;杨树主干韧皮部的持留量在施药后初期持留量呈上升趋势 ,10d左右达最大值 ,而后呈下降趋势 ,树干基部韧皮部的持留量为 3 3 9μg kg ,大于树干上部韧皮部的持留量2 11μg kg .杨树侧枝韧皮部的持留量为 3 0 9μg kg ,明显高于木质部的持留量 1 68μg kg ,施药 10d左右吡虫啉在侧枝韧皮部中的持留量最大 ,韧皮部的持留量随着侧枝高度的增加而增加 ;杨树侧枝韧皮部中的持留量在施药第 10d最大 .杨树下部 (4 0m以下 )叶片中吡虫啉的持留量先增加后降低 ,在施药后第 2 0d达到最大 ,而杨树上部 (4 0m以上 )叶片中的吡虫啉持留量则呈下降趋势 ,叶片中的吡虫啉持留量随树干高度的增加而减少

Dynamics of imidacloprid residue levels in poplar

The method for determining the residual amount of imidacloprid in poplar was des c ribed in this paper. Imidacloprid was injected into the bottom part of poplar tree trunks. Acetomitrile extracts of the injected trees were analyzed using HPLC. The results showed that levels of imidacloprid in poplar remained lo nger than 40 d after application with the highest in leaves, moderate in tw igs, and lowest in tree trunks. Residue level in phloem was much higher than th at i n xylem in tree trunks. Residue level of imidacloprid in xylem of tree trunks fluctuated with time. The peak level was detected on the 5th day after the t reatment. The level at the bottom of the tree trunk averaged 0 28 μg/kg, which was lower t han that in the upper part of the tree trunk (0 64 μg/kg). Residue level o f th e insecticide in phloem increased within 10 days immediately after the treatment, and culminated on the 10th day after the treatment and then decl ined. Imidaclopri d level in phloem was higher at the bottom part of tree trunk (3 39 μg/kg) tha n at the upper part(2 11 μg/kg). The average level of imidacloprid in phloem o f the twigs (3 09 μg/kg) was much higher than that in the trunk (1 68 μg/kg) , and reached peak on the 10th day after the treatment. Levels of imidaclop rid in leaves located at the lower part of a tree (<4 m) gradually increased aft er the treatment, and reached highest in 20 d, while that located at the upper p art (>4 m) declined with the increase of time after the treatment. The level of imidacloprid in phloem of a twig, and in the leaves increased with the height o f the twig or the leaf of a tree.