El-Ela N A, Talha M, El-Aziz A A
Tropical Health Dept., High Institute of Public Health, Alexandria University.
J Egypt Public Health Assoc. 1998;73(5-6):649-65.
The response and effect of two plant crude extract from dry Damsissa (Ambrosia maritima) and Neem seeds (Azadirachta indica) were tested against the first and third instar larvae of mosquito (Culex pipiens). The results showed that both extracts had a larvicidal effect. Neem seed extract was more toxic than Damsissa extract against both the first and third instar larvae. In addition, the young larvae (first instar) were more susceptible to Neem seeds than the old ones (third instar) as revealed from the LC50 values, while Damsissa showed nearly the same effect against both stages. Meanwhile, treatment of Neem seed extracts resulted in prolongation of the larval period accompanied with a decrease in larval activity. Moreover, the effect of the two extracts on larval total esterase isozymes was examined. Neem extract showed an adverse effect on the third instar larvae, since only one band (E1) was observed and the other 4 bands disappeared at all concentrations used, as compared with untreated control larvae (El, E2, E3, E4, and E5). Meanwhile, Damsissa extract treatment of the third instar larvae showed an additional band located between E3 and E4, and the absence of two bands (E2 and E3) after treatment with 0.5x10(4), 1x10(4) and 1.5x10(4) ppm, while treatment with 0.25x10(4) ppm did not result in any changes in larval total esterase.
对来自干达米萨（海蓬子）和印楝种子的两种植物粗提物针对蚊虫（致倦库蚊）的一龄和三龄幼虫的反应及效果进行了测试。结果表明，两种提取物均具有杀幼虫作用。印楝种子提取物对一龄和三龄幼虫的毒性均高于达米萨提取物。此外，从半数致死浓度值可知，幼龄幼虫（一龄）比老龄幼虫（三龄）对印楝种子更敏感，而达米萨提取物对两个阶段的效果几乎相同。同时，印楝种子提取物处理导致幼虫期延长并伴有幼虫活动减少。此外，还检测了两种提取物对幼虫总酯酶同工酶的影响。印楝提取物对三龄幼虫显示出不利影响，因为与未处理的对照幼虫（E1、E2、E3、E4和E5）相比，在所有使用浓度下仅观察到一条带（E1），其他4条带消失。同时，达米萨提取物处理三龄幼虫后显示在E3和E4之间有一条额外的带，在用0.5×10⁴、1×10⁴和1.5×10⁴ppm处理后两条带（E2和E3）缺失，而用0.25×10⁴ppm处理未导致幼虫总酯酶有任何变化。
