Involvement of esterases in diazinon resistance and biphasic effects of piperonyl butoxide on diazinon toxicity to Haematobia irritans irritans (Diptera: Muscidae)

Resistance to insecticides remains a major problem for the successful control of the horn fly, Haematobia irritans irritans (L.), one of the most important pests of cattle in many countries including the United States. The organophosphate (OP) insecticide diazinon has been used to control pyrethroid-resistant populations of the horn fly. There are only a few reported cases of horn fly resistance to diazinon in the United States and Mexico. Piperonyl butoxide (PBO) has been used successfully as a synergist of pyrethroid insecticides to control horn flies. PBO-synergized diazinon products are also available for horn fly control in the United States, although PBO is known to inhibit the bio-activation of certain OP insecticides including diazinon. A study was conducted to evaluate the effect of PBO on diazinon toxicity to horn flies using a filter paper bioassay technique. These bioassays in both the susceptible and diazinon-resistant horn fly strains revealed a biphasic effect of PBO on diazinon toxicity to horn flies. PBO inhibited diazinon toxicity when the PBO concentration used was high (5%), and no effect was observed when PBO concentration was intermediate (2%). However, at low concentrations (1% and lower), PBO significantly synergized diazinon toxicity. We demonstrated that enhanced esterase activity was associated with survivability of horn flies exposed to diazinon alone. PBO has been shown to inhibit esterase activity in other insect species. However, results of biochemical assays with esterases from this study suggest that PBO did not have significant effect on the overall esterase activity in the horn fly. The observed synergistic effect of PBO at lower concentrations on diazinon toxicity to horn flies could not be explained by reduced esterase activity due to PBO inhibition. It is likely that PBO synergized diazinon toxicity at lower concentrations by facilitating penetration of diazinon through the cuticle and/or inhibiting the oxidative detoxification of diazinon, and reduced diazinon toxicity at high PBO concentration by inhibiting the bio-activation of diazinon.     

增效剂对马尾松毛虫羧酸酯酶的抑制作用

对江西省十余个县（市）马尾松毛虫（ＤｅｎｄｒｏｌｉｍｕｓｐｕｎｃｔａｔｕｓＷａｌｋｅｒ）的测定表明，马尾松毛虫各种群对拟除虫菊酯的耐药力与羧酸酯酶活性有关；对溴氰菊酯、氰戊菊酯和氯氰菊酯耐药力强的种群，其羧酸酯酶活性亦强；应用五种增效剂对马尾松毛虫羧酸酯酶进行处理，ＳＶ＿１和ＴＰＰ表现出明显的抑制作用，且随ＳＶ＿１和ＴＰＰ剂量的增加，羧酸酯酶活性逐步降低；用相同剂量的ＳＶ＿１和ＴＰＰ处理马尾松毛虫后，羧酸酯酶均随时间表现出相似的变化规律。     

香蕉作物施用肥料增效剂的效应

以香蕉和粉蕉为试验材料,研究施用肥料增效剂的效果。结果表明:施用肥料增效剂能极显著增加蕉果产量,增产量为7 85t/hm2～22 15t/hm2,相对增产19 6%～57 8%,收益增加7704元/hm2～23150元/hm2,每公斤肥料增效剂增值8 87元～14 82元。肥料增效剂的适宜用量为1500kg/hm2,施用肥料增效剂能加快出叶速度,提早现蕾28～60天,增强蕉株抗寒力,明显增加蕉叶N、P2O5、K2O、MgO、S、Zn和B的养分含量。     

氮肥增效剂在小麦上的应用效果探索研究

为了探索氮肥增效剂在小麦上的应用效果,以为在沿江江南地区推广此类产品提供科学依据。在磷、钾肥用量相同的条件下,通过田间试验,研究了氮肥增效剂不同施用方法对小麦产量和生长性状、氮肥农学效率以及施肥效益的影响。结果表明：施用氮肥处理较不施氮对照增产3075~4410kg/hm²,增产幅度最低也可达88.9%;配施增效剂处理较相应氮肥处理有效穗平均增加100.1万/hm²,增幅15.61%;产量平均提高528.25kg/hm²,增幅达7.74%;氮肥农学效率平均提升3kg/kg,增幅为16.75%。氮肥减量25%配施伴能处理每公斤氮肥小麦生产效率最高,为25.36kg/kg;氮肥基追各半,基肥配施增效剂处理产量和净增收入均最高,分别达7869kg/hm²和8524.50元/hm²。在试验土壤肥力条件下,氮肥仍是小麦生长最关键的营养因子,氮肥增效剂的作用主要是促进有效穗增加,提高成穗率;氮肥增效剂能提高氮肥利用率和小麦生产效率,节约肥料用量及成本,促进小麦增产增收。综合考虑,氮肥基追各半,基肥配施增效剂可作为推荐施肥组合。     

提高苏云金杆菌对棉铃虫毒力的研究

在含有Ｂｔ毒素的人工饲料中,通过加入碱性化合物提高其对昆虫中肠的作用,或加入蛋白酶激活剂、无机化合物和有机来提高Ｂｔ的毒力效价。试验结果表明,加入碳酸钙、硫酸锌、氯化镁、苹果酸、马来酸、甲酸和巯基乙醇酸钠,可使Ｂｔ毒力效价分别提高０．９５１．２２,０．３７,０．４７,１．１７,２．１０和９．０倍,其中加入硫酸锌、甲酸和巯基乙醇酸钠的增效效果较好。     

Selection of bifenthrin resistance in cotton mealybug Phenacoccus solenopsis Tinsley (Homoptera: Pseudococcidae): Cross-resistance,realized heritability and possible resistance mechanism

Cotton mealybug Phenacoccus solenopsis Tinsley is an important pest of cotton in Pakistan, and its management is difficult due to the development of insecticide resistance. This research was conducted to characterize the bifenthrin resistance in populations of P. solenopsis and different parameters such as cross-resistance, realized heritability and possible resistance mechanisms were studied to improve the management of this important pest. A field-collected population was selected with bifenthrin in the laboratory for 14 generations and developed a resistance of 178-fold. The realized heritability of bifenthrin resistance was 0.54 in the selected population. The toxicity of bifenthrin was synergized by the addition of either piperonylbutoxide (PBO) or S,S,S tributylphosphorotrithioate (DEF) which suggests a general metabolic resistance due to possible involvement of mono-oxygenases or esterases. However, the resistant population did not develop a significant cross-resistance to either buprofezin, chlorpyrifos or lambda-cyhalothrin. These data suggest that alternative insecticide-based management programs can be developed for this pest in the short-term, but resistance management strategies which can reduce the sole reliance on insecticides are still needed.     

不同增效剂和调理剂对白银豆产量及品质的影响

研究了不同植物生长调节剂对白银豆产量及品质的影响.试验结果表明,DA-6、春雨1号、萘乙酸均能减少白银豆落花落荚,从而增加其产量,分别较各自的空白对照(不喷增效剂或调理剂)增产9.45%.7.77%和4.46%.各激素均能提高白银豆中可溶性蛋白质、淀粉、VC含量和降低NO3的含量,并达到差异显著.除萘乙酸能显著提高游离氨基酸含量外,其他处理对游离氨基酸含量影响不大.     

防治桑尺蠖新药万杀灵的研究

从5种农药单剂的10个2元组合中,选出对5龄桑尺蠖幼虫的协同毒力指数最高的组合,用共毒系数法和应用系数法对该组合的不同配比进行选优,选出的组配与5种增效剂混用,选出具有最佳增效作用的增效剂品种及其添加量,通过对其制剂学方面的研究,得到防治桑尺蠖新药30％万杀灵乳油,其田间防效达90％以上,对家蚕的叶部残毒期为12d左右。     

杀虫剂增效作用及其作用机理研究进展

简述了杀虫剂品种之间及其与增效剂、昆虫激素类物质、植物精油和矿物油、微生物杀虫剂、植物源杀虫剂混配后的增效作用研究现状,从影响杀虫剂的物理性状、对代谢解毒酶的影响、改变杀虫剂对表皮的穿透速率、靶标部位及其它生理机理等方面探讨了杀虫剂的增效机理.指出了杀虫剂增效作用的研究前景.     

聚天门冬氨酸对玉米生长的影响

[目的]筛选肥料增效剂聚天门冬氨酸对玉米生长的最适宜添加量.[方法]以玉米先科11号为供试材料,通过盆栽试验,研究不同浓度的聚天门冬氨酸添加到液体肥料后对玉米生长、肥料利用效率的影响.[结果]液体肥料中添加不同浓度的聚天门冬氨酸对玉米株高、生物量以及氮磷钾养分积累量等都具有明显的影响,有利于玉米的生长发育,同时提高肥料利用效率.[结论]在液体肥料中添加1％的聚天门冬氨酸处理效果最为显著.