The insecticide acetamiprid is widely used in controlling agricultural pests.The acute toxicity and chronic toxicity of acetamiprid to silkworm (Bombyx moii) were tested by using food intake method.Results of acute toxicity bioassay showed that 96 h median lethal concentration (LC50) of acetamiprid to the 3rd,the 4th and the 5th instar were 0.361,0.692 and 1.339 mg/L,respectively,indicating that acetamiprid is a high-risk or ultra-high-risk grade poison to silkworm.After treating the 3rd instar newly exuviated silkworm larvae continuously with low concentration of acetamiprid,the duration of each instar was prolonged,and the body weight of moulting or matured larvae,cocoon weight,cocoon shell weight and cocoon shell rate were all adversely affected.In addition,when the 3rd instar newly exuviated larvae were treated with acetamiprid of ≥ 0.011 mg/L,the superoxide dismutase (SOD) activity in larval midgut of day 6 of the 5th instar larvae was significantly activated (P ＜ 0.05),while the catalase (CAT) activity was markedly inhibited (P＜0.05).The activity of glutathione peroxidase (GSH-Px) was improved by low concentration (0.005-0.022 mg/L) of acetamiprid but was inhibited by high concentration (0.045 and O.090 mg/L) of acetamiprid.The results indicate that acetamiprid has extremely high risk to sericultural production and should be used in sericultural areas with caution Under high concentration,although SOD activity of silkworm larvae was activiated,but CAT and GSH-Px activities of silkworm larvae were both inhibited.This is the reason that acetamiprid can do harm to silkworm growth and development and to cocoon production.

There is potential risk to silkworm (Bombyx mori) health due to pesticide residues in mulberry field through enrichment by mulberry.A bacterial strain H2,which can degrade acetamiprid that is extremely hazardous to silkworm,was isolated from mulberry field with long-term pollution of pesticides using enrichment culture and streak plate method.Based on the morphological,physiological and biochemical characteristics and the phylogenetic analysis to 16S rDNA sequence,this bacterial strain was identified as Pseudomonas alcaligenes.The maximum tolerant concentration of this bacterium to acetamiprid was 1 200 mg/L.Cultivated in inorganic salt medium with 300 mg/L acetamiprid,the bacterial growth had a lag phase at 0-1 d,a log phase at 1-4 d,a stationary phase at 4-6 d,and a decline phase after 6 d.After 9 d culture in inorganic salt medium with initial acetamiprid concentration of 300 mg/L,the degradation rate of acetamiprid was 62.7％ It was also found that this bacterium could grow in inorganic medium containing 1 000 mg/L imidacloprid,1 000 mg/L nitenpyram,1 000 mg/L thiacloprid and 500 mg/L phoxim respectively,demonstrating its effectiveness in degrading various neonicotinoid and organophosphorus pesticides.Therefore,it is promising to further develop this bacterium into microbial degradation agents against neonicotinoid and organophosphorus pesticides in mulberry field.

吡虫啉(imidacloprid)是新烟碱类杀虫剂,在农林害虫防治中广泛使用.在已明确吡虫啉对家蚕的毒性基础上,采用质量法研究吡虫啉导致的家蚕慢性中毒对幼虫生长发育及食物利用的影响,并采用酶活力测定法分析吡虫啉对5龄幼虫中肠3种消化酶(淀粉酶、蔗糖酶、海藻糖酶)活性的影响.添食高浓度(10-1和10-2mg/L)吡虫啉药液对家蚕3龄和5龄幼虫的生长发育及食物利用有明显抑制作用,幼虫的体质量及其增加量、相对生长率、取食量、相对取食量、食物利用率、食物转化率均显著降低(P≤0.05),而近似消化率显著升高(P≤0.05);添食低浓度(10-3、10-4和10-5mg/L)吡虫啉药液对家蚕3龄和5龄幼虫的生长发育及食物利用则有促进作用,幼虫的取食量、相对取食量、消化量、食物利用率和近似消化率均显著高于对照(P≤0.05),同时体质量及其增加量、相对生长率也升高.添食低浓度吡虫啉药液对5龄幼虫中肠内淀粉酶和海藻糖酶的活性起促进作用;而添食高浓度吡虫啉药液在幼虫5龄1～5d时对中肠内淀粉酶和海藻糖酶的活性起抑制作用,随着幼虫的生长发育,酶活性逐渐恢复正常并高于对照.吡虫啉对5龄幼虫中肠的蔗糖酶活性具有抑制作用,且添食药液浓度越大,抑制作用越明显,至5龄后期又恢复到正常水平或高于对照.试验结果表明,家蚕添食不同浓度吡虫啉药液后的慢性中毒过程中,蚕体的生长发育、取食行为、对食物的利用和消化吸收等均发生了显著变化.

由于营养学知识的缺乏以及膳食结构不合理,核黄素缺乏状况很普遍.为探明儿童核黄素缺乏状况以及膳食结构对其影响,我们选取了城乡儿童共91名,分别对其体内核黄素水平进行了测定和膳食结构调查.