Factors in the Success and Failure of Microbial Insecticides in Vegetable Crops

A search for patterns in the success and failure of microbial insecticides in vegetable crops was conducted through review of four case studies: the use of Bacillus thuringiensis (B.t.) var. tenebrionis for control of the Colorado potato beetle, the use of B.t. var. kurstaki for control of the diamondback moth, the use of various B.t.s for control of lepidopterous pests in tomatoes and celery, and the use of a granulosis virus for control of potato tuber moth. With success defined in terms of achievement of technical goals (efficacy), commercial goals (end-user and insecticide manufacturer satisfaction) and social, or public goals (environmental and health safety), only certain of the case studies could be judged a success. These successes shared a variety of features including: (1) use of the microbial insecticide as a component, rather than as the sole agent, in an integrated crop management program; (2) unavailability of conventional insecticides, due to insecticide resistance, lack of registered products or mandatory IPM programs, provided incentive for the use of microbial insecticides; (3) modification of the expectation that microbial insecticides will perform within the chemical paradigm – fast, lethal and on contact; (4) exploitation of all possible benefits of the microbial insecticide, including safety to natural enemies, as well as efficacy against the target insect, and (5) support from large private and public institutions in the form of research, grower education, scouting programs, subsidized production, and economic and legal incentives to the use of microbial insecticides.     

Panel Discussion: Factors in the Success and Failure of Microbial Insecticides

Discussion

Panel Discussion: Factors in the Success and Failure of Microbial Insecticides     

Factors in the Success and Failure of Microbial Control in Turfgrass

Turfgrass is an important component of urban landscapes and turf associated products and services are valued at about $45 billion in the US alone. Turf insecticide market is about $500 million per year of which microbial insecticides constitute less than 0.1%. Major factors in the poor market penetration of microbial insecticides include low damage thresholds, narrow spectrum of activity, a definite pest monitoring requirement, shortage of quality products, and competition with the newly registered less-toxic chemical insecticides. Enhancement of market share of microbial insecticides in turf will depend upon successful development of more appropriate application strategies, an increase in the availability of quality products, and the development of a systems approach in which microbial insecticides are used together with chemical insecticides in a more compatible manner. The long-term benefits derived from the use of microbial insecticides must be documented to enhance acceptance of microbial control.     

Factors in the Success and Failure of Microbial Controlagents for Soil Dwelling Pests

The soil, being rich in microbes, should be an ideal environment in which to practise microbial control of insect pests, but relatively few organisms have been developed into successful microbial control agents for soil pests. Difficulty arises in implementation of microbial control, as the soil is a highly complex, competitive environment where survival of applied microbes is by no means assured. In addition, soil dwelling pests appear to show a high level of resistance to broad spectrum pathogens and microbial toxins. However, some significant successes have been achieved with bacteria, fungi and nematodes for control of a range of soil inhabiting pest species. The successful microbial controls are based on highly specific microbial/insect interactions where co-evolved pathogens can overcome the host's defences. These agents also have the ability to persist in the soil, either through the inherent stability of the organism or from recycling through the host population. While strain selection for high levels of pathogenicity and environmental competence is the essential first step in microbial control of soil dwelling pests, it must be followed by development of efficient production systems and quality control measures to ensure application of standardised, high quality products. Success in microbial control of soil dwelling pests depends on an appropriate combination of these factors, with failure likely to occur if any one of these essential components is overlooked.     

Factors in the Success and Failure of Microbial Agents for Control of Migratory Pests

Microbial control agents generally kill insects more slowly than chemical pesticides, and fast-moving migratory pests may not at first sight appear to offer the most promising targets for microbial control. Operators responsible for control may need to have recourse to chemical control agents. Nevertheless, there are many occasions when pests breed and feed outside the crop and a microbial control agent can be used. Similarly, immature stages may cause little damage and early treatment in the crop can avoid damage. Microbial control agents are particularly likely to be favoured if the pest breeds in a conservation area, and if a publicly-accountable agency is responsible for control.Other key points of importance are the IPM context, in particular detection, planning and forecasting of outbreaks and the role of natural enemies.With these points in mind, we identify several locust and grasshopper systems where microbial control is becoming established; additionally, Sunn pest of wheat and Armyworm are identified as promising situations forbreak microbials.     

一硫代磷酸酯类杀虫剂的微生物降解

在纯培养条件下测定了分离株 YF0 5对对硫磷等一硫代磷酸酯类杀虫剂的降解作用。在接种量 (OD4 15nm)为 0.2、pH7.0、30℃条件下 ,测得 10、25、50、100、200、500 mg/L对硫磷的降解符合一级动力学特征 ,其降解速率常数分别为 0.077、0.123、0.128、0.119、0.084、0 .013,高浓度对硫磷对 YF05菌有抑制作用 ;分离株 YF05在不同温度及 pH下对对硫磷的降解作用为 40℃ >30℃ >20℃ ,pH8.0 >pH7.0 >pH6 .0。同样条件下 ,YF05对杀螟硫磷和甲基对硫磷也有较好的降解作用 ,对甲基对硫磷的降解速率常数与对硫磷相仿 ,对杀螟硫磷的降解速率常数略高于对硫磷。     

昆虫病原菌防治萝卜黄曲条跳甲田间应用技术

黄曲条跳甲是为害十字花科蔬菜的世界性害虫。本文研究了昆虫病原菌苏云金杆菌工程菌G033A和金龟子绿僵菌CQMa421防治萝卜黄曲条跳甲田间应用技术。结果表明,采用昆虫病原微生物苏云金杆菌G033A和金龟子绿僵菌CQMa421土壤处理防治黄曲条跳甲均具有较好的防效,其中32000 IU/mg苏云金杆菌工程菌G033A可湿性粉剂300 g/667 m²土壤处理防治效果显著优于对照化学药剂,且持效期较长,具有明显的减药、省力、降成本作用。针对萝卜主要病虫害开展了全程生物防控技术示范,结果表明全程生物防控技术不仅防治效果好,且较常规化学防治技术增产达到14.8%,品质得到提升,商品优良率提高12%,可进一步大面积示范推广。     

昆虫杆状病毒杀虫剂研制与应用进展

本文对野生型昆虫杆状病毒和重组昆虫杆状病毒杀虫剂的研制与应用进展进行了综述，同时阐述了昆虫病毒杀虫剂的生产及其存在的问题。     

双酰胺类杀虫剂的现状与展望

双酰胺类杀虫剂作用于昆虫的鱼尼汀受体,作用机制新颖。本文综述了双酰胺类杀虫剂研究进展,对其作用机制、作用特点、主要品种等情况进行详细论述,并对未来双酰胺类杀虫剂的发展提出展望。     

微生物农药母药有效成分含量测定影响因子研究

微生物农药母药的溶解及分散程度对有效成分含量检测至关重要。本文采用平板菌落计数法研究了不同处理条件对3种微生物农药的有效成分含量测定结果的影响,以获得适宜的前处理方法,结果表明:3种微生物农药母药用0.5‰吐温-80溶解、浸泡30min、0.33W/cm2下超声振荡30min后检测的有效成分含量值最高。     

昆虫病毒生物杀虫剂产业化及其展望

昆虫病毒杀虫剂是环境友好、对非靶标生物安全、无毒无害绿色农用品,本文从昆虫病毒杀虫剂发展历史、现状、产业化研发和生产、市场和应用的多个方面,结合笔者从事此方面工作的经验和体会,进行总结和评述,希望以此为同行提供借鉴和参考,以促进我国病毒杀虫剂产业化及其应用的进程。     

A Rapid Method for Screening Insecticides in the Laboratory

An efficient method for rapidly mass-screening insecticides for use against sap-feeding virus vectors is presented with a case study of 30 chemicals. The method permits large numbers of insecticides to be tested simultaneously and relatively inexpensively in a sequence of laboratory bioassays. The sequence is designed to find the most effective pesticide at the lowest concentration giving control without phytotoxicity. The system was derived to test candidate insecticides to control tomato yellow leaf curl virus vectored by the tobacco whitefly, Bemisia tabaci Gennad., the most serious pest of greenhouse and field tomatoes in the Middle East. Although the insecticides were all more efficacious in the laboratory than in the field, bioassay results were highly correlated with results from field trials, giving high confidence that the screening process selected only the most efficacious insecticides. Most of the insecticides accepted by the screening process have since been adopted by vegetable growers in Israel. The method is not intended to eliminate field efficacy trials, but to reduce the number of trials and treatments that need to be performed, thereby reducing costs. The method provides for the optimization of application rates which will contribute to the expected life of insecticides before resistance develops, and will also help to reduce environmental contamination. In addition, the method is suitable for estimating relative efficacy for pesticide benefits assessments, a required part of the (re-)registration process for pesticides in some countries. Although developed for screening insecticides against virus-transmitting sap-feeding insects, the method could be modified to assess the efficacy of insecticides in controlling other insect pests.     

重组杆状病毒杀虫剂的研究进展

本文从基因缺失、基因插入、改变宿主范围3个方面系统的介绍了杆状病毒杀虫剂的研究进展。     

Effects of Host and Microbial Factors on Development of Clonostachys rosea and Control of Botrytis cinerea in Rose

Development of Clonostachys rosea in rose leaves and petals and control of Botrytis cinerea by the agent were investigated. C. rosea germinated, established endophytic growth, and sporulated abundantly whether the tissues were mature, senescent or dead when inoculated. Germination incidence was moderate on mature and senescent leaves (47% and 35%) and petals (31% and 43%), and high (>98%) on dead tissues. Sporulation of C. rosea in tissues inoculated when mature, senescent or dead averaged 41%, 61%, and 75% in leaves, and 48%, 87% and 53% in petals. When leaves were wounded with needles before inoculation, germination of C. rosea increased from 45–56% to 90–92%, but sporulation became high (>75%) regardless of wounds. When leaves were inoculated with C. rosea at 0–24h after wounding and subsequently with B. cinerea, germination of the pathogen was reduced by 25–41% and sporulation by 99%. A humid period prior to inoculation of senescent or dead leaves promoted communities of indigenous fungi, reduced sporulation of C. rosea and B. cinerea, and, in dead leaves, increased control of the pathogen associated with C. rosea. Applied at high density, isolates of indigenous Penicillium sp. and Alternaria alternata from rose interacted with C. rosea and reduced control of the pathogen by 16% and 21%, respectively. In conclusion, C. rosea markedly suppressed sporulation of B. cinerea in rose leaves and petals regardless of developmental stage, minor wounds, and natural densities of microflora. This versatility should allow C. rosea to effectively control inoculum production of B. cinerea in rose production systems.     

盐碱土微生物功能群季节动态与土壤理化因子的关系

选取河西走廊东端永登县6种盐碱土壤类型,对各样地微生物功能群的季节动态与土壤理化因子之间的关系进行分析.结果表明:①盐碱环境中土壤细菌＞放线菌＞真菌,细菌和放线菌数量在夏季出现峰值,真菌数量在秋季和冬季出现峰值;不同微生物功能群基本上只有一个峰值且峰值出现的季节不同,与碳循环相关的纤维素分解菌功能群的峰值出现在冬季,与...     

Aerial Application of Insecticides for the Control of the Mango-Hopper

Abstract

Aerial application of malathion LVC at 893 and 1330 g/ha, malathion EC at 927 g/ha, carbaryl SP at 557, 841 and 1113 g/ha, and endosulfan ec at 432 and 649 g/ha was tested for the control of mango-hopper at 8 places in Hoshiarpur and Ropar districts of the Punjab using a fixed-wing aircraft for spraying in the end of February. The penetration of spray material through the deep canopy of seedling mango trees was good. There was 86–100% reduction in the pest population over control 9 days after treatment. Malathion LVC at 1330 g/ha proved to be the best. It gave an excellent knock-down and did not register any significant build-up in the mango-hopper population up to 51 days after spraying.     

中国农药使用成就回顾及展望

中国虽然早在 1 0 0 0ａ以前就已有应用硫磺、铜绿、砒霜以及多种植物性农药防治病虫害的经验 ,但作为农作物病虫害防治的一项科学技术 ,农药的生产和使用技术的发展还只是新中国成立以来 ,近半个世纪内的事。据统计 ,90年代全国平均每年发生农业病虫害面积 2 .5亿ｈｍ2 次 ,防治面积为 2 .7亿ｈｍ2 次 ,其中使用农药进行防治占 90 %以上 ,经防治每年挽回粮食损失约 4 0 0 0万ｔ,棉花 1 70万ｔ;平均每年药剂除草 0 .4 2亿ｈｍ2 ,挽回粮食损失 90 0万ｔ以上 ;平均每年药剂灭鼠约 0 .2亿ｈｍ2 ,挽回粮食损失 3 70万ｔ。另外 ,植物生长调节剂在…     

13种杀虫剂对暗黑蛴螬的毒力研究

本文采用灌注处理法测定了7种常用杀虫单剂及6种杀虫混剂对暗黑鳃金龟甲2龄幼虫的室内毒力。结果表明：7种单剂对暗黑蛴螬的毒力顺序为：甲基异柳磷＞对硫磷＞甲基对硫磷＞二嗪磷＞辛硫磷＞乐斯本＞＞敌百虫；6种混剂中以辛硫磷＋对硫磷表现毒力最高，而甲基对硫磷＋敌百虫表现毒力最低。联合毒力测定结果表明：辛硫磷＋对硫磷及辛硫磷＋敌百虫表现为显著增效，甲基对硫磷＋敌百虫表现为相加作用，其它3种混剂均表现为轻度增效。