Issn: e 2347-226x, p 2319-9857
农业核研究所,巴基斯坦信德省Tando Jam-70060
收到日期:24/06/2013;修订日期:27/06/2013;接受日期:02/07/2013
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害虫对作物是一种严重的威胁,会对植物的叶、茎、花、种子和根造成损害。对于巴基斯坦等发展中国家低投入农业系统的农民来说,综合害虫管理IPM是一种潜在的防治害虫的有效手段。IPM通常价格低廉、耐用、无污染且可在当地改进,使其成为综合作物保护的可持续组成部分。因此,本文讨论了综合害虫防治方案以增加或协同降低害虫密度和保护作物耐久性的可能性和建议。
害虫综合管理,IPM,昆虫,植物,作物。
目前,害虫造成的全球粮食损失总额估计占主要粮食作物和经济作物可实现产量的26%至40%不等[1].仅收获前因昆虫、植物病原体和杂草造成的损失估计就约为30%。收获后微生物、昆虫及啮齿动物造成的额外损失约为10%至20% [2].当然,在我们面临世界粮食短缺和世界人口不断增长的情况下,这是我们无法承受的损失。管理害虫种群的另一种方法是强调将多种方法纳入一个灵活的方案,这种方法对减少虫害造成的损失大有希望。这种被称为有害生物综合治理(IPM)的方法可以被描述为一种广泛的生态攻击,结合多种策略对所有有害生物种群进行经济控制和管理。它是一个决策支持系统,用于选择和使用病虫害控制策略,单独或协调地纳入管理战略,基于成本/效益分析,考虑到生产者、社会和环境的利益和影响[3.].最近,IPM通常被称为“作物保护/病虫害管理系统”,其含义是在农业系统的社会经济背景下进行方法和学科整合[4].综合防治措施依赖于生物、化学和培养防治方法的组合,以及使用抗性或耐药植物品种[5].IPM是一种以科学为基础的决策过程,可识别和减少病虫害和病虫害管理相关战略带来的危害[6].通过将技术带给农民,IPM在提高发展中国家的农业生产力和可持续性以及减少农药滥用方面发挥了重要作用[7].需要了解害虫、作物和环境之间的相互关系,以便设计出最佳的技术组合,以充分控制害虫,并对非目标生物和环境产生最小的影响。害虫的管理严重依赖于杀虫剂(4至10次喷洒),随着时间的推移,这些杀虫剂已从有机氯逐步发展到合成杀虫剂。由于化学制剂取得了显著的成功,害虫天敌的研究及其现场应用受到了冷落。对收获更多和大规模农业机械化的追求导致了现代农业系统的采用,这无疑严重依赖单一栽培、免耕和化学农药,这增加了新的害虫问题。Pretty等人。8]还表明,IPM技术使农药使用量下降了71%,而产量增加了42%。
巴基斯坦是一个多元化的国家,在这个关键时刻,两种种植类型即单一种植和条状种植都在实践中。害虫的复杂爆发多发生在单作而非混作,导致化学农药的滥用,而拖拉机安装的喷洒设备则过度简化了农药的使用。除了导致产量损失暂时减少外,它还造成了社会经济问题。尽管农药仍将是病虫害管理的一个组成部分,但在使用农药后,将导致病虫害问题频发、对农药的抗药性、人类健康问题和环境危害。制定一项可以保护和最大限度地提高天敌数量和效力的战略将是害虫管理的关键。有许多经典的例子表明,增加作物栖息地的多样性可以增加当地可利用的捕食者的种群密度,从而加强对害虫的生物控制。据报道,掠食性甲虫(Campoletis sonorensis)对来自特定植物组织的挥发性化学物质有反应,很少有(Macrocenrus grandi)被来自管理不善的植物的挥发性化学物质所吸引。寻找合适的栖息地是必要的,因为像所有的生物一样,昆虫的拟寄生物和捕食者对资源有需求,而不是宿主。然而,这些其他来源可能存在,也可能不存在于发现宿主的同一栖息地。在某些寄主生境(作物系统)中可能存在对特定的拟寄生虫、花蜜来源和庇护所的最佳小气候条件,而在其他生境中则不存在。 One assumes that the habitats in which parasitoids find hosts also provide other needed requisites at optimum levels. There is little empirical or experimental data, to support this to be true, even for unmanaged eco-systems. The objective of this study is also to ensure that the occurrence of as many essential parasitoid resources and hosts coinciding with time and space. The conservation of natural enemies by the direct enhancement of vegetation diversity has been a subject of intense study for many years. Earlier, it was hypothesized that lower levels of herbivores in diverse agro ecosystems were a result of higher levels of natural enemies “enemies hypothesis”. Much needed attention was given on the nature of the relationship between pest, crop and non-crop plants, and their physical environment. As a result habitat manipulation seeks to manage these relationships to enhance the impact of natural enemies on pest population. Indeed this approach is one of the key elements in the use of indigenous natural enemies in IPM. Conservation which involves protection and maintenance of natural enemy population has proved crucial for maintaining local/ native natural enemies in ecosystems. Review revealed that conservation involved modifying pesticide application practices so that they occur only when the pest population exceeds specified levels, however, conservation of natural enemies can also be achieved by changing the active ingredient, rates, formulations, timing, and location of pesticide applications or by maintaining refuges. It is probable that the most dramatic increase in the utilization of biological control in agricultural IPM systems could come through the judicious use of selective pesticides in conjunction with effective natural enemies in location specific cropping systems. While, knowledge of pesticide selectivity is available, it is inadequate to generally allow such precise usage. As long as key pests cannot be controlled biologically, culturally, or through host plant resistance, agricultural chemicals will be essentially needed to achieve goal of IPM [9].
在IPM中,我们的目标是增加和培育有益生物,以帮助将害虫物种控制在经济阈值以下,从而减少对化学品的依赖。如果必须使用杀虫剂,那么如果可以选择的话,总是选择对有益的节肢动物和微生物伤害最小的一种。在田间,通常存在由几种主要害虫和次要害虫组成的害虫复合体。例如,可以有三种主要的田间害虫(蓟马、蜜虱和叶甲虫)和六种或六种以上的小害虫,从割叶蚂蚁到食叶毛虫。小害虫有时会扩展为大害虫,但通常是在有限的时间内或在一个有限的区域内。由于国际贸易体系,仓储害虫在世界范围内更加统一。收获的谷物通常会储存几个月,提供理想的高温和潮湿条件,使害虫数量迅速增加。对于IPM的目的,生长阶段是最重要的标准,因为昆虫伤害和作物损害之间的关系取决于伤害发生的阶段。研究人员已经确定,营养阶段的伤害通常不像生殖阶段那样对植物有害。首选的指标是根据植物是处于营养阶段还是生殖阶段。 The following is the system currently used, with representing vegetative stages and reproductive stages: Vegetative Stages- emergence, cotyledon + unfolding, unifoliate node, and trifoliate. Reproductive Stages- beginning bloom, full bloom, beginning pod, full pod, beginning seed, full seed, beginning maturity, and full maturity. Because crop response to insects is dependent upon the growth stage, economic thresholds vary with the stage. Thus, it is imperative that growers and IPM practitioners recognize these developmental stages.
主要昆虫区系:有效控制害虫的第一步是正确识别昆虫和其他危害植物的害虫。与野战警察有关的主要昆虫群通常根据它们造成的伤害进行分组。首先要考虑的是落叶虫,它们消耗叶子组织(落叶虫、甲虫、毛虫、昆虫复合体和环蝽)。第二类害虫是豆荚食虫(玉米耳虫Helicoverpa zea (Boddie)和豆甲虫)。最后一类害虫是那些以茎为食或缠绕茎的害虫(茎食虫和束虫,料斗)。它们的损伤会导致种子产量显著下降,种子质量下降,因为种子病原体通过取食疤痕进入。许多其他昆虫可以造成严重的伤害,需要使用杀虫剂进行治疗;这些问题通常存在于州、地区或地方层面。这一组中值得注意的害虫是两种斑点蜘蛛螨、蛆、叶蝉、蚱蜢和各种蛞蝓。虽然不被认为是“主要”害虫,但这类昆虫仍然引起了种植者的极大关注,这要求研究人员、植物保护代理人和其他IPM从业者参与他们的管理。
经济伤害程度:关于经济伤害水平(EIL)的一些评论是恰当的,因为在对昆虫的经济伤害水平发展之前,杀虫剂的应用往往是在仅仅看到昆虫种群时进行的。20世纪70年代初,根据昆虫摄食和发育的知识,通过计算植物对落叶的反应、与施用杀虫剂相关的经济成本和种植者的价格,可以容忍中等数量的昆虫,而不需要杀虫剂。在使用杀虫剂后,一些州的杀虫剂使用量急剧下降。昆虫伤害和作物反应之间关系的最重要方面是,植物具有巨大的能力来补偿低水平的落叶或减少的植物立地。这种自然耐受性使种植者能够接受一些伤害,因为他们知道产量损失不会发生。尽管在改进eil方面还有很多工作要做,但它们在许多作物种植州都得到了应用。由于当地的情况,种植者总是被建议联系当地的植物保护办公室,以获取有关他们特定情况的信息。雷竞技网页版一般情况下,在营养期落叶达到>50%,在开花、豆荚发育和豆荚填充期落叶达到15-10%,在某些作物从豆荚填充到收获期落叶达到>25%之前,不需要进行杀虫剂处理。有些州使用昆虫叶组织消耗的信息,并以每已知单位的昆虫数量表示EILs,如每线性英尺的昆虫数量,或每次清扫的昆虫数量。
昆虫的伤害:虽然在开发EILs方面的研究工作通常是将每一种昆虫作为一个单独的害虫来处理,但最近的努力已经转向开发一种更全面的方法来研究昆虫如何伤害植物。既然我们关心的是植物,研究人员讨论的是植物受伤的部分;因此,昆虫被分为叶食性,茎食性,豆荚食性。基于昆虫行会(根据植物受损部分分组)的EILs试图根据可能出现在田间的昆虫的复杂程度向种植者提供可用的水平。然而,这种方法有一个缺点,因为不是所有的昆虫都能产生类似的植物反应。例如,幼虫消耗大量的组织;当甲虫刮树叶表面的时候。最近的一种方法是根据损伤对植物生理的影响对其进行分类。因此,昆虫正在根据它们造成的伤害进行分类,例如林分减少、叶片质量减少、叶片光合速率降低、光照减少、种子或果实破坏等等。对植物的伤害导致植物或作物的损害,其定义为植物生长、发育的可测量的减少或产量损失。 By gaining a better understanding of these relationships, researchers hope to develop more useful EILs based on crop injury.
问题的发现:在昆虫取样和伤害测量方面已经做了很多工作。在评估昆虫种群时,使用一种适合有关昆虫和植物阶段的取样技术。在植物生长的早期阶段直接观察被认为是最好的选择,因为植物的体积小。当植物达到足够的大小时,大多数IPM程序建议使用地面或摇布,或扫网。研磨布或摇布虽然比扫网更笨重,但往往能给出昆虫(如毛毛虫或其他不会飞的幼虫(甲虫))的接近绝对数量。然而,其他昆虫很难用震动布取样,因为它们在受到干扰时会飞走(甲虫成虫)。对于大多数昆虫来说,要使用清扫网,将网扫过植物冠层一定次数,然后统计昆虫数量。扫网也不太麻烦,使用起来也不太费时,可以在更短的时间内对更大面积的区域进行采样。尽管清扫网提供的昆虫数量最多被认为与种群大小有关,并随植物大小和进行清扫的人而变化,但它们通常被认为是IPM规划中最合适的昆虫采样技术。通常昆虫造成的伤害是可以测量的; for example, defoliation levels are estimated, percent pod injury is calculated, or percent stand reduction is determined. These measurements are quite useful in determining when an EIL is being reached. However, it is still advisable to confirm the presence of an insect pest before making any insecticide application. Most IPM guidelines suggest the frequency of sampling to allow for efficient use of time. Recommendations are often advised at least weekly sampling during the growing season. Examinations of plant injury combined with insect sampling will allow for the identification of a potential pest population. As an insect population develops, more frequent sampling is often recommended; numerous insects have the capacity to reach large, damaging populations very quickly and weekly sampling is often too long to go between field visits.
管理策略:当达到EIL时,需要采取治疗策略来防止对植物的进一步伤害;目前唯一可用的这种策略是使用杀虫剂。然而,应该指出的是,过去和目前的研究在降低必须使用的杀虫剂活性成分(AI)的量方面做了很多工作。在20世纪60年代和70年代,许多杀虫剂的每英亩1-2磅(AI)的使用量很常见;研究将这一比率降至每英亩0.5至0.75磅(AI)。使用较新的杀虫剂,我们可以看到每英亩0.01磅(AI)甚至更低。在制定预防策略方面已经做了大量工作,这些策略旨在降低昆虫的总体数量或增加植物的承载能力。虽然并不总是足以将害虫维持在经济水平以下,但我们认识到天敌(如捕食者、寄生性生物和病原体)在害虫生物防治方面的重要贡献,因为我们知道,自然发生的病原体可以在控制虫害暴发方面发挥重要作用。
人们正在努力培育抗虫作物品种。目前,只有少数品种被释放给种植者;然而,许多项目都在积极发展适应品种;许多具有高抗性的种质系已被开发出来,但它们目前的产量低于作为栽培品种释放所必需的产量。许多文化策略正在被研究和推荐。控制种植日期对于管理越冬害虫如甲虫和毛虫是有用的。这两种昆虫的成虫在仲春离开越冬地,倾向于进入较早种植的田地。因此,晚植被认为是防治这两种害虫的一种策略。与早期种植相关的是陷阱作物的使用,即在田地附近种植一种更受欢迎的吸引害虫的作物。另一个正在积极探索的预防策略是种植不同于通常在一个地区种植的成熟品种。 When cultivars of differing maturities are present, insects will often prefer one cultivar to another. Thus, a grower attempts to pass through a susceptible crop-growth stage before an insect reaches damaging numbers. This idea is being examined to manage the bug complex. Although researchers have a good understanding of the current insect problems, they are ever aware of potential pests that might occur in the future as growers adopt new and different practices. A change in grower practices might cause different insects to become problems or alter insect-injury/plant relationships. For example, a practice-gaining acceptance is conservation tillage, which leaves over 30% crop residue remaining on the soil surface. These systems can significantly alter an insect's habitat and can cause changes in population dynamics of a pest. It should be noted that changes in these production practices might also affect the various natural enemies that are present. Another practice gaining wider acceptance is the use of narrow or solid-seed rows; rather than planting in broad rows, growers use a drill to plant in row of narrow widths. Although not appearing to have a direct impact on insect population dynamics, row width might have an impact on insect-injury/plant-response relationships, which might alter economic injury levels. Research on row widths and plant response to defoliation is currently being conducted. A grower philosophy that is gaining acceptance is alternative agriculture. Although not specific grower practices, alternative agriculture places a greater emphasis on preventive pest management tactics and away from reliance on insecticides. Preventive tactics will make more use of cover crops, trap crops, resistant cultivars, and other cultural practices, which the grower might employ specifically for pest management. Their use will demand a much better understanding of the biology and life history of insect pests. For organic agriculture neem is the general-purpose botanical pesticide of choice. Neem EC is widely used in several countries around the world today either singly in integrated pest management or in conjunction with synthetic pesticides. Amongst the other known botanical pesticides such as rotenone and pyrethrins, neem EC is superior due to reasons cited below: Research has shown that neem extracts can influence nearly 200 species of insects. It is significant that some of these pests are resistant to pesticides, or are inherently difficult to control with conventional pesticides (floral thrips, diamond back moth and several leaf miners). Neem EC belongs to the category of medium to broad-spectrum pesticides. Neem EC works by intervening at several stages of the life of an insect. Control of insect pests by disrupting their ecological status such as through the use of organisms’ like predators, parasites and pathogens, is an environmentally sound and effective mean of mitigating or reducing pests and their effects [10].寄主植物抗性是植物抵御害虫侵袭的一种天然能力;长期以来,这种技术一直被认为是一种可行的非化学和环境友好的控制作物害虫的策略[11].在储存期间,收获的谷物受到虫害的严重破坏,使用抗病谷物品种是最便宜、有效和生态安全的保护谷物的方法[12].
IPM哲学建议与其他害虫学科(疾病、杂草和线虫)整合。全面整合的一个障碍是缺乏对植物对所有类型伤害的反应的了解。确定害虫的伤害可能会对植物的生理产生类似于植物病原体或杂草的影响,将大大促进发展真正综合的害虫管理方法。随着研究人员开始更好地了解所有害虫伤害对植物生理的影响,他们将能够制定统一的方法来管理害虫。IPM系统对作物产量影响大,应用适应性强。