杀虫剂主要用于防治农业害虫和城市卫生害虫的药品.使用历史长远、用量大、品种多。在二十世纪,农业的迅速发展,杀虫剂令农业产量大升。但是,几乎所有杀虫剂都会严重地改变生态系统,大部分对人体有害,其它的会被集中在食物链中。我们必须在农业发展与环境及健康中取得平衡。 按杀虫剂的原料来源分类 1.有机合成杀虫剂:是通过人工合成的方法制成的有机化合物杀虫剂。这类杀虫剂用途广、效果高,所以发展很快,是目的和今后农药使用最主要的一类杀虫刘。这类农药在国内外生产的品种很多,如敌敌畏、溴氰菊酪等。这一类杀虫剂按照化学组成的不同又可分为下列几种。 (1)有机氯杀虫剂:村机氯杀虫剂的分子中部含有氯元素,毒杀芬等(图内已停止生产) (2)有机磷杀虫剂:有机磷杀虫剂的分子中都含有磷元杀螟松、敌百虫等 (3)有机氮杀虫剂:有机氮杀虫剂的分子中含有氮元素,如西维因、叶蝉散、螟蛉畏等。 4)拟除虫菊酯类杀山剂;拟除虫菊酯类杀虫剂是人工合成类似天然除虫菊酯的化合物。是—类当前发展最快的杀虫剂,如杀灭菊酯、溴氰菊酯等 2.无机杀虫剂:是指元机化合物的杀虫剂,如亚砷酸(白砒)、氟化钠等,此类杀虫剂也称为矿物性杀虫剂。 3.微生物杀以剂:微生物杀虫剂用于防治害虫的病原体(真菌、细菌、病毒等),如青虫菌、白僵菌、7216等。 4.植韧性杀虫剂,植物性杀虫剂是用天然植物加工制造的杀虫剂。它含有效成分是天然有机化合物,加除虫菊、烟草及各种植物性农药。 (二)按杀虫剂的作用方式分类 1.胃毒剂:药剂通过害虫的口器及消化系统进入体内,引起害虫中毒或死亡,具有这种胃毒作用的杀虫剂称为胃毒剂。如敌百虫、白砒等。此类杀虫剂适用于防治咀嚼式 口器害虫,如粘虫、蝼蛄、蝗虫等;另外,对防治舐吸式口器的害虫(蝇类>,也有效。 2.触杀剂:药剂接触害虫的表皮或气孔渗入体内,使害虫中毒或死亡,具有这种触杀作用的药剂称为触杀剂,如对硫磷(1605)、辛硫磷等。日前使用的大多数杀虫剂属于 此类。可用于防治各种类型口器的害虫 3.熏蒸剂:药剂在常温下以气体状态或分解为气体,通过害虫的呼吸系统进入虫体,使害虫中毒或死亡,具有这种熏蒸作用的药剂称为熏蒸剂,加磷化铝、氯化苦、棉隆 溴甲烷 等。熏蒸剂一般应在密闭条件下使用。 4.内吸杀虫剂:药剂通过植物的叶、茎、根部或种子被吸收进入植物体内,并在植物体内疏导、扩散、存留或产生更毒的代谢物。当害虫刺吸带毒植物的汁液或食带毒植物 的组织时,使害虫中毒死亡,具有这种内吸作用的杀虫剂为内吸杀虫剂,如内吸磷(1059)、甲拌磷(3911)、涕灭威等。此类药剂一般只对刺吸式口器的害虫有效 5.驱避剂:药剂本身没有杀虫能力.但可驱散或使害虫忌避.远离施药的地方,具订这种驱避作用的药剂为驱避剂,如樟脑丸、避蚊油等。 6.引诱剂:能将害虫诱引集中到一起,以便集中防治,一般可分食物引诱、件引诱、产卵引诱三种,如糖醋液、性诱剂等。 7.拒食剂:药剂被害虫取食后,破坏了虫体的正常生理功能,使其消除食欲而不能再取食以致饿死,如拒食胺、杀虫脒 吡蚜酮等 8.不育剂:药刘还过害虫体壁或消化系统进入虫体后,正常的生殖功能受到破坏,使害虫不能繁殖后代,这种不育作用一般又可分为雄件不育、雌性不育、两性不育三种,如噻替派、六磷胺等。 9.激素干扰刘:由人工合成的拟昆虫激素,用于干扰首次本身体内激康(是一类体内特殊腺体分泌物,控制和调节昆虫的正常代谢,生长和繁殖)的消长,改变体内正常的生理过程,使之不能正常的生长发育(包括阻止正常变态、打破滞育、甚至导致不育),从而达到消灭害虫的目的。此类众虫剂又称为昆虫生长调节剂。包括类保幼激素(如IR一515)抗保幼激素(早熟素)、几丁质合成抑制剂(灭幼脲类)等。 10.粘捕剂:用于粘捕害虫并使其致死的药剂。可用树脂(包括天然树脂和人工合成树脂等)与不干性油(如棕榈油、蓖麻油等)加上一定量的杀虫剂混合配制而成。上述各类杀虫剂中,目前大量生产使用的主要是前四类。其余几类又统称为特异性杀虫剂,目前国内还处于试验阶段,但都很有发展前途。对于绝大多数有机合成的杀虫剂来讲,它们的杀虫作用往往是多种方式,如乐果具打较强的内吸作用及触杀作用;对硫磷除有很强的触杀作用、胃毒作用外,还有一定的熏蒸作用;杀虫脒除具打胃毒、触杀作用外,还有拒食作用。 Insecticide An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind the increase in agricultural productivity in the 20th century. Nearly all insecticides have the potential to significantly alter ecosystems; many are toxic to humans; and others are concentrated in the food chain. The classification of insecticides is done in several different ways: Systemic insecticides are incorporated by treated plants. Insects ingest the insecticide while feeding on the plants. Contact insecticides are toxic to insects brought into direct contact. Efficacy is often related to the quality of pesticide application, with small droplets (such as aerosols) often improving performance. Natural insecticides, such as nicotine, pyrethrum and neem extracts are made by plants as defenses against insects. Nicotine-based insecticides are still being widely used in the US and Canada though they are barred in the EU. Plant-incorporated protectants (PIPs) are insecticidal substances produced by plants after genetic modification. For instance, a gene that codes for a specific Baccilus thuringiensis biocidal protein is introduced into a crop plant's genetic material. Then, the plant manufactures the protein. Since the biocide is incorporated into the plant, additional applications at least of the same compound, are not required. Inorganic insecticides are manufactured with metals and include arsenates, copper compounds and fluorine compounds, which are now seldom used, and sulfur, which is commonly used. Organic insecticides are synthetic chemicals which comprise the largest numbers of pesticides available for use today. Mode of action—how the pesticide kills or inactivates a pest—is another way of classifying insecticides. Mode of action is important in predicting whether an insecticide will be toxic to unrelated species, such as fish, birds and mammals.