五种类型农药不同剂量与施药时期对麦蚜防治效果及麦粒农药残留的影响

采用喷雾法,研究了辛硫磷、高效氯氰菊酯、抗蚜威、阿维菌素和吡虫啉5种类型农药的3种剂量在不同施药时期对麦长管蚜Sitobion avenae(Fabricius)和禾谷缢管蚜Rhopalosiphum padi(Linnaeus)的防治效果、防后对小麦千粒重的影响和籽粒中农药残留分析。结果表明,不同剂量的各种药剂,第1次施药药后1d对麦长管蚜与禾谷缢管蚜的防治效果均在80%以上,药后3d防效分别在90%和84%以上,药后5d防效分别在95%和92%以上;不同种类或不同剂量处理的防治效果之间存在显著差异(P<0.05)。第2次施药后1～5d对麦长管蚜的防效均在90%以上。与对照比较,施药1次小麦千粒重增加率为2.02%～11.93%;施药2次,千粒重增加率为8.01%～15.87%。农药残留检测结果显示,不同种类不同剂量浓度下在冬小麦扬花末期喷施1次农药和间隔5d的灌浆中期第2次农药,以及春小麦田相似农药处理,其籽粒中农药残留均有一定程度的检出,但均未超出限定标准;而在小麦乳熟期(与第1次施药间隔10d,距离成熟收获15d)喷施第2次农药,其中高效氯氰菊酯和吡虫啉已经达到或超出残留限量标准。     

吡虫啉亚致死剂量对禾谷缢管蚜生长和繁殖的影响

室内测定了吡虫啉亚致死剂量对禾谷缢管蚜Rhopalosiphum padi(Linnaeus)连续两个世代实验种群生长和繁殖的影响。结果发现,吡虫啉LC10剂量处理禾谷缢管蚜成蚜后,可导致亲代成蚜种群的存活率、平均寿命和产蚜量均低于对照种群,但差异不显著;F1世代吡虫啉处理组与对照组禾谷缢管蚜种群的存活率、寿命和繁殖水平无显著差异。结果表明,吡虫啉亚致死剂量对禾谷缢管蚜连续两个世代实验种群的生长和存活无明显影响,未发现亚致死剂量刺激禾谷缢管蚜当代和子代成蚜的增殖现象。     

高温天数和吡虫啉互作对麦长管蚜世代内与世代间生态表型的影响

麦长管蚜Sitobion avenae是麦类作物主要的害虫之一,严重影响麦类作物的质量和产量.为了探究不同高温天数和农药互作对麦长管蚜世代内与世代间生活史性状的影响,调查了成蚜经高温事件34℃/3 h持续1d、3d和5d与低剂量吡虫啉互作,对生活史性状的影响.结果 表明,在世代内,随着高温天数增加,存活率随之下降,仅高温处理下由67.5％下降为12.5％,与农药结合后由70％下降为10％,但对寿命、繁殖却没有影响(P＞0.05).不同高温天数和吡虫啉的互作延迟效应主要加剧了对繁殖的负面影响,尤其是在高温天持续3d和5d(P＜0.05),显著抑制了母代种群参数的增长.在世代间,母代单独经历不同高温天数后,对子代存活、发育、繁殖和寿命均没有显著影响(P＞0.05).高温天数和吡虫啉的互作主要对子代存活产生了负面影响,下降率可达33.3％,但两者的互作却对子代成蚜寿命、繁殖产生了正面刺激作用,大大减缓对子代种群参数的影响.上述结果将为气候变暖和农药双重胁迫下麦长管蚜种群动态的预测、防控提供一定的理论指导.     

不同寄主及地理来源的16株绿僵菌对桃蚜的毒力比较

害虫生防真菌绿僵菌的不同种及变种被广泛应用于害虫微生物防治,但罕见以蚜虫等同翅目刺吸式害虫作为靶标。从两种绿僵菌的4个变种中精选16个不同寄主及地理来源的菌株,用喷塔接种桃蚜(Myzus persicae)无翅成蚜并在25±1℃和12L∶12D条件下饲养观察,所获生物测定数据进行时间-剂量-死亡率模型模拟分析。结果显示,高接种剂量(~1000个孢子/mm2)下7d内死亡率达67%~100%的10个菌株均为金龟子绿僵菌Metarhiziumanisopliae(Ma)及其金龟子变种M.anisopliaevar.anisopliae(Maa);而高剂量处理下仅感染致死个别或少数蚜虫的菌株包括金龟子绿僵菌及其金龟子变种、大孢变种M.anisopliaevar.majus和蝗变种M.anisopliaevar.acridum以及黄绿绿僵菌小孢变种M.flavoviridevar.minus。杀蚜活性优异的2个菌株分别为Ma 456和Maa 3332,接种后第4天的LC50分别为113和260个孢子/mm2,第5天为32和43个孢子/mm2,第6天为17和26个孢子/mm2,第7天仅11.4和19.9个孢子/mm2。这两个菌株具有用于蚜虫微生物防治的良好开发潜力。     

云南丽江地区铁杉球蚜发生与环境因子的关系

铁杉球蚜Adelges tsugae Annand(Hemiptera:Adelgidae)是铁杉的主要害虫,在北美造成铁杉成片死亡。为有效地寻找控制铁杉球蚜的天敌,作者于2005年8~2006年12月,在云南省丽江地区的河源、牦牛坪、黑水河3个地点对铁杉球蚜的发生进行6次调查,统计不同树枝方位、不同树冠层次、不同取样地点、不同取样时间的铁杉球蚜的为害率。在多数情况下,铁杉北向和南向树枝上的球蚜为害率高于西向和东向;树冠下层的铁杉树枝上的球蚜为害率高于树冠上层;5月树冠上层球蚜为害率反而高于下层,树冠层次球蚜密度随着时间而变化的现象,与铁杉球蚜第2代发生高峰期相吻合。3个地点的每株树铁杉球蚜为害率平均为24.6%,河源的球蚜为害率又高于牦牛坪和黑水河。对来自3个地点的12块样地的每样地铁杉球蚜为害率与环境因子进行偏相关分析表明,坡向、年均相对湿度、年均降雨量与铁杉球蚜发生呈显著正相关。在调查铁杉球蚜的发生或采集球蚜天敌昆虫时,应在不同时间依据树枝方位和树冠层次来分别进行。在选择调查采集地点时,应以林区坡向、相对湿度、降雨量等环境因子为依据。     

菜蚜迁飞期短期预测的研究Ⅰ

在1961年及1963—65年,我们在北京和天津对十字花科蔬菜上的两种蚜虫——桃蚜Myzus persicae(Sulzer)和菜缢管蚜Hyadaphis erysimi pseudobrassicae(Davis)——分别在留种白菜、留种萝卜、甘蓝、苤蓝、小白菜、小油菜、秋白菜,以及春天的风障菠菜上进行了系统的蚜群分析。研究表明,在蚜群中出现有翅若蚜前,繁殖力有下降趋势;因而若蚜与成蚜数量的比值亦逐渐下降。降到一定的比值,蚜群中即将出现有翅若蚜。因此,可以通过系统调查,用统计蚜群中若蚜与成蚜的数量比,来作蚜虫迁飞期的短期预测。 数量分析表明:桃蚜出现有翅若蚜前4—6天,其若蚜与成蚜的数量比为2.17—2.91(95%置信限)或2.03—3.05(99%置信限)。菜缢管蚜有翅若蚜出现前5—6天其比值为8.56—9.76(95%置信限)或8.29—10.03(99%置信限)。     

区域性农田景观格局对棉蚜种群数量的生态学效应

农田景观格局的变化显著影响害虫的发生和危害,不同景观格局会对害虫的种群数量产生不同程度的影响,因而明确农田景观格局对害虫的生态学效应是控制害虫的重要前提之一。以山东省的棉花种植区为研究区域,选取14个典型的尽量临近不同土地覆盖类型的棉花生产县,通过卫星遥感影像和土地覆盖分类数据综合分析获得取样县/区的景观因子指数,并系统调查对应县/区的棉蚜种群数量。省级范围的大空间尺度下分析景观组成、景观构成和景观结构等多因子分别与棉田中苗蚜和伏蚜种群的相关性。研究结果表明棉蚜的种群数量与景观格局有密切的关系,且棉蚜发生的两个时期苗蚜和伏蚜对景观因子的响应特征并不完全一致。苗蚜的种群数量与景观总面积、耕地的分形指数、县域范围的蔓延度和县域范围的回旋半径等呈显著正相关,与Simpson多样性指标呈显著负相关;伏蚜的种群数量与斑块丰富密度、居住工业交通的蔓延度等呈显著正相关。总之,苗蚜和伏蚜对景观的蔓延度(形)响应基本上是一致的,景观的破碎化程度越小,伏蚜和苗蚜发生越重。而苗蚜和伏蚜对景观多样性(质)的响应不一致,景观多样性高的农田景观不利于苗蚜的发生,对伏蚜的影响不显著;而丰富度密度有助于伏蚜的发生,却对苗蚜没有显著影响。这一结果显示了农业害虫的不同发生时期对农田景观格局响应的复杂性。     

温度对蚜科专化菌暗孢耳霉休眠孢子形成的影响

为探究虫霉休眠孢子形成的关键影响因素,通过孢子浴接种和多浓度生物测定实验,观察蚜科专化菌暗孢耳霉(Conidiobolus obscurus)在5个温度处理(10,15,20,24,28℃)和3个接种浓度梯度下感染寄主桃蚜(Myzus persicae)的情况,并观测不同处理下蚜尸内产休眠孢子的比例。暗孢耳霉对桃蚜的毒力随温度和接种浓度升高而提高。同时,感病致死的蚜尸镜检结果表明:温度显著影响休眠孢子形成,温度越高,形成几率越大;接种浓度的影响次之,在15—24℃间,形成几率随接种浓度提高而增大。这一现象可能的解释:高温环境将使寄主种群增长停滞或消退,暗孢耳霉通过感知环境温度情况,倾向于在较高温时于寄主体内形成休眠孢子来规避接下来可能出现的寄主匮乏期。     

基于微卫星标记的苹果绵蚜种群遗传结构动态

【目的】苹果绵蚜是我国重要的入侵害虫,对苹果生产造成了严重危害。近年来,苹果绵蚜扩散面积增大,危害加重。了解苹果绵蚜入侵过程中的分子生态变化,可为该虫的综合防控提供依据。【方法】利用微卫星标记技术,选择6个微卫星位点对山东省6个地区(烟台、威海、青岛、潍坊、聊城、泰安)2012—2015年苹果绵蚜种群遗传结构变化规律进行分析。【结果】2012—2015年,山东省6个地区的苹果绵蚜遗传多样性随时间推移逐渐降低。其中,2012年的遗传多样性极显著高于2013—2015年;2013—2015年之间虽然差异不显著,但随时间推移,等位基因观测值(Na)和期望杂合度(He)等遗传多样性指数有逐渐降低的趋势。通过无限等位基因模型、双相突变模型和逐步突变模型分析发现,6个地区的苹果绵蚜均经历了瓶颈效应,是遗传多样性降低的主要原因。对6个微卫星位点分析发现,Erio20、Erio75和Erio78扩增到的苹果绵蚜等位基因数量以及这3个位点的多样性指数随时间推移逐渐降低。【结论】Erio20、Erio75和Erio78是引起苹果绵蚜遗传多样性降低的主要多态位点。苹果绵蚜可能进化出了"超级克隆"基因型,因此,其可在我国适应不同生态环境并增大扩散范围。     

玉米品种抗蚜性鉴定评价方法与标准研究

本研究以玉米蚜为研究对象,在云南省昭通地区通过田间调查和相关数据分析,研究了玉米蚜田间种群动态,评价了27个不同品种玉米的抗蚜性,探索了更为简便的玉米抗蚜性评价方法。结果表明:玉米蚜在田间的发生有两个高峰期,分别是抽雄散粉期和蜡熟期;采用玉米整个生育期蚜量比值法比较不同品种玉米的抗性,发现高抗品种有6个、抗性品种有6个、中抗品种有6个、感虫品种有4个、高感品种有5个,玉米蚜的种群数量在不同品种玉米间存在显著差异;采用玉米蚜暴发时期到玉米完熟期的蚜量比值来评价玉米抗蚜性可行。     

龟纹瓢虫对棉蚜的捕食行为

为探讨天敌对害虫的捕食作用机制,充分发挥生物防治的作用,本文从捕食能学角度,系统地观测了龟纹瓢虫Propylea japonica (Thunberg)对棉蚜Aphis gossypii Glover的捕食行为及影响的因素。结果表明：龟纹瓢虫对棉蚜的捕食行为依棉蚜的密度变化而逐渐转变;它在棉蚜密度高时,搜索活动下降;而在棉蚜密度低时,则搜索活动增加。产生这种行为是由于肠胃量与棉蚜遭遇率变化的综合作用结果。因此,将瓢蚜比调控在一定水平上,可以更有效地发挥以瓢治蚜的生物防治作用。     

A window of opportunity: Subdominant predators can use suboptimal prey

Introduced species have been linked to declines of native species through mechanisms including intraguild predation and exploitative competition. However, coexistence among species may be promoted by niche partitioning if native species can use resources that the invasive species cannot. Previous research has shown that some strains of the aphid Aphis craccivora are toxic to a competitively dominant invasive lady beetle, Harmonia axyridis. Our objective was to investigate whether these aphids might be an exploitable resource for other, subdominant, lady beetle species. We compared larval development rate, survival, and adult weight of five lady beetle species in no‐choice experiments with two different strains of A. craccivora, one of which is toxic to H. axyridis and one that is nontoxic. Two lady beetle species, Cycloneda munda and Coleomegilla maculata, were able to complete larval development when feeding on the aphid strain that is toxic to H. axyridis, experiencing only slight developmental delays relative to beetles feeding on the other aphid strain. One species, Coccinella septempunctata, also was able to complete larval development, but experienced a slight reduction in adult weight. The other two lady beetle species, Hippodamia convergens and Anatis labiculata, demonstrated generally low survivorship when consuming A. craccivora, regardless of aphid strain. All five species showed increased survival and/or development relative to H. axyridis on the “toxic” aphid strain. Our results suggest that this toxic trait may act as a narrow‐spectrum defense for the aphids, providing protection against only some lady beetle enemies. For other less‐susceptible lady beetles, these aphids have the potential to provide competitive release from the otherwise dominant H. axyridis.     

Potential cotton aphid,Aphis gossypii,population suppression by arthropod predators in upland cotton

The cotton aphid, Aphis gossypii Glover, predation rate of convergent lady beetle, Hippodamia convergens Guerin‐Meneville, was determined by assigning a single predator randomly to each of four prey density treatments in the laboratory. Prey densities included 25, 50, 100, and 200 aphids per Petri dish arena. Predation response was recorded at 1, 4, 8, 16, 24, and 48 h after assigning predators to their prey treatments. Rate of consumption increased through time, with all 25 aphids consumed during the first 4 h of the experiment. At the highest density, adult lady beetle consumed on average 49, 99, 131, 163, 183, and 200 aphids within 1, 4, 8, 16, 24 and 48 h, respectively. Predators showed a curvilinear feeding response in relation to total available time, indicating that convergent lady beetles have the potential to suppress larger populations of aphids through continuous feeding by regulating their predation efficiency during feeding. The analysis of age‐specific mortality in absence of prey revealed that lady beetles could survive for an extended period of time (more than 2 weeks) without prey. The ability of a predator to survive without prey delays or prevents the rebound of pest populations that is a significant factor in natural biological control. A two‐year field sampling of 10 cotton arthropod predator species showed that spiders (27%) were the most dominant foliage dwelling predators in the Texas High Plains cotton followed by convergent lady beetles (23.5%), hooded beetles (13.5%), minute pirate bugs (11%), green lacewings (9.5%), bigeyed bugs (7.5%), scymnus beetles (3%), soft‐winged flower beetles (2%), damsel bugs (1.5%), and assassin bugs (1.5%). A field cage study showed that one H. convergens adult per plant released at prey density of one aphid per leaf kept the aphid population below economic threshold for the entire growing season.     

Effects of reduced rates of two insecticides on enzyme activity and mortality of an aphid and its lacewing predator

By applying insecticides at lower rates of active ingredients per unit area, survival rates of the pests' natural enemies can be enhanced, whereas pest mortality can remain high. The effects of reduced application rates of the insecticides lambda-cyhalothrin and dimethoate on the mortality of bird cherry-oat aphid, Rhopalosiphon padi (L.), and lacewing Micromus tasmaniae Walker were determined in the laboratory and field. Cholinesterase (ChE) and glutathione S-transferase (GST) activities in survivors provided a measure of sublethal effects and general fitness. In the laboratory, lacewings were less sensitive than aphids to both insecticides, and dimethoate was more toxic than lambda-cyhalothrin. However, these results could not be recreated in the field, in part due to very low recapture rates. In summary, lambda-cyhalothrin seemed to have no effect on aphids, but it was toxic to lacewings. Dimethoate was far less toxic in the field, but aphids were still more sensitive than were lacewings. Cholinesterase activity was reduced by dimethoate exposure in the laboratory in both species, but there were species-specific differences. Dimethoate and lambda-cyhalothrin had no effects on GST activity in either species. The high mortality rate for lacewings and aphids exposed to dimethoate in the field suggests that the application rate could be reduced to as low as 10% of that recommended by manufacturers, and this should still be highly efficacious against aphids, while protecting the predatory lacewing. Measurement of enzyme activity could provide a useful indicator of "fitness" of survivors.     

Comparison of native and non‐native predator consumption rates and prey avoidance behavior in North America and Europe

Novel predator–prey interactions can contribute to the invasion success of non‐native predators. For example, native prey can fail to recognize and avoid non‐native predators due to a lack of co‐evolutionary history and cue dissimilarity with native predators. This might result in a competitive advantage for non‐native predators. Numerous lady beetle species were globally redistributed as biological control agents against aphids, resulting in novel predator–prey interactions. Here, we investigated the strength of avoidance behavior of the pea aphid (Acyrthosiphon pisum) toward chemical cues of native lady beetles and non‐native Asian Harmonia axyridis and European Coccinella septempunctata and Hippodamia variegata in North America, hypothesizing that cues of non‐native lady beetles induce weaker avoidance behavior than cues of co‐evolved native lady beetles. Additionally, we compared aphid consumption of lady beetles, examining potential predation advantages of non‐native lady beetles. Finally, we compared cue avoidance behavior between North American and European pea aphid populations and aphid consumption of native and non‐native lady beetles in North America and Europe. In North America, pea aphids avoided chemical cues of all ladybeetle species tested, regardless of their origin. In contrast to pea aphids in North America, European pea aphids did not avoid cues of the non‐native H. axyridis. The non‐native H. axyridis and C. septempunctata were among the largest and most voracious lady beetle species tested, on both continents. Consequently, in North America non‐native lady beetle species might have a competitive advantage on shared food resources due to their relatively large body size, compared to several native American lady beetle species. In Europe, however, non‐native H. axyridis might benefit from missing aphid cue avoidance as well as a large body size. The co‐evolutionary time gap between the European and North American invasion of H. axyridis likely explains the intercontinental differences in cue avoidance behavior and might indicate evolution in aphids toward non‐native predators.     

Positive and negative effects of leaf shelters on herbivorous insects: linking multiple herbivore species on a willow

We experimentally examined the effects on other herbivorous insects of leaf shelters constructed by lepidopteran larvae on a willow, Salix miyabeana. Several insect species occupied the vacant leaf shelters. Our experiment using artificial leaf shelters showed that the number of aphids increased with the number of artificial leaf shelters on a shoot, as did the numbers of three ant species ( Camponotus japonicus, Lasius hayashi, and Myrmica jessensis) that entered leaf shelters to collect aphid honeydew. To determine the ant-mediated effect of leaf shelters on herbivorous insects that do not use leaf shelters, we transferred newly hatched larvae of a common leaf beetle, Plagiodera versicolora, to the leaves of shoots with and without artificial leaf shelters. One day after the transfer, larval survival rate was significantly lower on shoots with shelters than on those without shelters, and shoots with shelters had significantly more ants than did shoots without shelters. Our field experiments demonstrated clearly that shelter-making lepidopteran larvae increased the abundance of both aphids and ants and decreased the survival rate of leaf beetle larvae, probably because the larvae were removed by ants that were attracted to the leaf shelters by the aphid colonies.     

Target-oriented dissemination of Beauveria bassiana conidia by the predators,Harmonia axyridis (Coleoptera: Coccinellidae) and Chrysoperla carnea (Neuroptera: Chrysopidae) for biocontrol of Myzus persicae

Dissemination of microbial biocontrol agents via predators may have advantages for safe spore dispersal to targeted pests with the added benefit of predation. A laboratory study was conducted to test the target-oriented dissemination of conidia of Beauveria bassiana using larvae of both the multicoloured Asian lady beetle (Harmonia axyridis) and common green lacewing (Chrysoperla carnea) for control of aphids. Maximum dry conidial attachment occurred within approximately 7 min after exposure. After release of the treated predators on leaves of Chinese cabbage, within 12 hours lacewing larvae dispersed 89% of the attached conidia while Asian lady beetles dispersed 93%. Both predators dispersed conidia up to 2.4 m from the release site. Leaf disk bioassays were conducted to compare two application methods; the dissemination of conidia of B. bassiana by predators and the direct application of conidial suspensions. Mortality in sprayed aphids was 91±2.1% compared to 88±2.1 and 84±4.2%, respectively, when conidia were disseminated by lacewings and lady beetles. Predation was not affected in treated lacewing larvae whereas there was a 20% reduction in predation by lady beetle larvae. It appears that B. bassiana can be effectively delivered using certain insect predators.     

Host nutritional status mediates degree of parasitoid virulence

Parasitic organisms rely on the resources of their hosts to obtain nutrients essential for growth and reproduction. Insect parasitoids constitute an extreme condition since they develop in a single host from which they typically consume all available resources. As a result, the host is killed following parasitism. However, a few intriguing cases of host survival have been reported wherein hosts resume foraging and may even reproduce following parasitoid emergence. Yet, the ultimate and proximate mechanisms responsible for host recovery remain unresolved. We tested the impact of host nutrition on host fate and parasitoid fitness, using the association between Dinocampus coccinellae and the spotted lady beetle Coleomegilla maculata. Under laboratory conditions, we fed parasitized ladybirds on different aphid diets, with or without pollen. In the field, we followed the fate of parasitized ladybirds during seasonal variations in pollen and aphid abundance. We found that ladybirds fed on aphids or a combination of aphids and pollen recovered more frequently from parasitism (from 65 to 81%) than those eating only pollen (48%). Field data suggest that the fate of parasitized ladybirds is also related to food availability. On the other hand, when hosts fed on a combination of aphids and pollen, consequences for parasitoid fitness were often ‘all‐or‐nothing’: parasitoid emergence rate was the lowest of all host nutrition regimes (～50%), but parasitoids that did emerge were larger than individuals emerging from other host nutrition regimes. Laboratory and field results concur to show that host nutritional status during parasitoid development significantly influences both host fate and parasitoid fitness.     

三种杀虫剂对麦田蚜虫和天敌的影响

通过对施用杀虫剂吡虫啉、抗蚜威、广谱性杀虫剂氧化乐果对麦田蚜虫和天敌的影响进行分析 ,结果表明 ,施用杀虫剂对麦田蚜虫防效高 ,对其天敌有保护作用 ,且瓢蚜比降低。使用 1 0 %吡虫啉( 1 0g 667m2 )后 5～ 2 5天瓢蚜比为 1∶34～ 1∶1 70 ;用 50 %抗蚜威 ( 5g 667m2 )后 1 0～ 2 0天瓢蚜比为 1∶31～1∶1 95;而广谱性杀虫剂氧化乐果 ( 50mL 667m2 )对麦田蚜虫防效好 ,对天敌杀伤力大 ,药后 1 5天瓢蚜比为1∶2 65。施用化学农药可使蚜茧蜂寄生率提高。     

USING FILTER PAPER TEST FOR DETECTING INHIBITORY FREQUENCY OF ORGANOPHOSPHATE TO ESTERASES IN COTTON APHIDS, APHIS GOSSYPII (GLOVER)

Abstract The individual esterase activity which is measured by filter paper test (FPT) method may determine the resistance of cotton aphids Aphis gossypii (Glover) against organophosphorus (OP) insecticides. For testing accurately resistant level caused by different insecticides, we applied FPT method for measuring inhibitory action of methyl-parathion, monocrotophos and omethoate to α-NA esterase of individual cotton aphids, and compared the inhibitory frequencies of these three insecticides to susceptible population (BCA) and resistant population (GCA). Results showed that their inhibitory frequencies of the susceptible population were evidently higher than that of the resistant population. The inhibitory rate of α-NA esterase in F1 generation individual cotton aphids by monocrotophos was low when the cotton aphid population had been treated in advance with monocrotophos, but it got to 75%-90% when the cotton aphid population had been untreated in advance with monocrotophos. Besides, the differences in esterase activity were not obvious between them. In same region when cotton aphids were treated with insecticides the inhibitory frequency of esterases in individual by the insecticides was lower than counterparts in individual cotton aphids which were not treated with insecticides. All these demonstrated that inhibitory frequency of α-NA esterase in individual cotton aphids by OP insecticides could be used as a technique of forecasting pest resistance.