Locust Plagues and the Dieldrin Controversy

Abstract

The accepted strategy for the control of locust plagues is to check an upsurge of population before swarms break out and start a widespread plague. The organisation, men and materials necessary for this work must be established before locust plagues are imminent. Primary targets for control are the hoppers. Red locust hoppers can be efficiently controlled only by vegetation baiting with dieldrin. The ULV drift-spraying method of application is particularly successful. Objections to the use of dieldrin on environmental grounds have been put forward but are without substance when the recommended method is used. A small aircraft can blanket spray 5,000 ha/h using the ultra low dosages necessary for desert locust hoppers. Three such aircraft could cope with the area of red locust hopper outbreaks although the dosage necessary for these is likely to be higher in the denser vegetation of their habitat. Field trials to establish the lowest dosage rate for red locust hoppers are urgently required.

If the facilities and resources needed to control locust plagues are not made available, it is hoped that FAO will provide expert teams to survey the economic and social effects of a locust plague, by investigation on the spot, so that responsibility can be assigned and an accurate history can be drawn up for the guidance of future governments. At the present time, governments have the choice of providing what is needed in the confident expectation of preventing plagues, or providing too little or nothing which will, sooner or later, inevitably lay a plague on their doorsteps.     

中国特色蝗灾治理技术体系及应用成效

中国有数千年蝗灾发生为害的历史,建国初期在政府的组织领导下,在科研人员和广大群众的努力下,提出并实施了“改治并举”的策略,改造东亚飞蝗发生基地近2/3,同时大规模使用化学农药进行防治,初步形成了以改造蝗虫发生基地为特色的蝗灾治理技术体系,经过长期实践,蝗灾得到有效遏制,保障了我国粮食生产安全和社会稳定,取得了世界瞩目的成绩。自20世纪80年代起,随着利用蝗虫微孢子虫Nosema locustae和绿僵菌Metarhizium spp.等微生物的治蝗技术获得突破性进展,我国已经形成了以生态控制（改造蝗虫发生基地）为基础,以生物防治为核心,以信息技术为辅助的具有中国特色的蝗灾治理技术体系,并走在国际前列。该技术体系的长期大规模应用,不但在有效防治蝗灾保障我国粮食安全生产、避免大规模使用化学农药造成环境污染和生态失衡等方面发挥了重大作用,而且也在支援国际蝗灾治理中做出了贡献。最后对未来蝗灾治理的关键问题和发展方向进行了探讨。     

主要蝗虫生态治理策略在我国的实践应用

蝗灾是全球性的重大自然灾害。20世纪末,由于全球气候变化和人类对自然资源的不合理开发利用,蝗灾呈持续加重趋势。2020年初,沙漠蝗Schistocerca gregaria大面积暴发,席卷了从西非到东非、从西亚至南亚的20多个国家,给农牧业生产带来巨大损失,严重威胁全球粮食安全。高效、长久的控制蝗灾成为人类面临的一个重大课题。本文主要总结蝗虫生态治理策略的概念以及草场改良、放牧调节、天敌招引等不同治理措施对蝗虫种群的影响,并指出蝗虫生态治理策略面临的一些问题,并对未来应用情况进行了展望。     

关中地区历史时期蝗灾统计及其影响浅析

历史时期关中地区蝗灾的发生频率具有明显的波动性,且随着历史的发展,有在波动中上升的趋势。唐朝中期以前,关中地区蝗灾的发生频率较低,波动幅度也较小,之后,关中地区蝗灾发生频率的波动幅度明显增大,蝗灾的发生次数明显增多。唐朝后期(801-850A.D.)、明末清初(1601-1650 A.D.)和清末至民国(1851-1950 A.D.)是关中地区历史上蝗灾记载最多的时期。与水灾的发生频率相比较,关中地区的蝗灾与旱灾的发生频率表现出更强的一致性,尤其是900AD(唐末)后,每一个蝗灾频率高峰几乎都与旱灾频率高峰完全同步,说明在关中地区蝗灾的发生与旱灾具更强的相关性。     

真菌防治蝗虫研究进展

蝗虫是世界性重大成灾害虫,时常在草原、沙漠区或农作区暴发为害。当前的非洲沙漠蝗灾害再次提醒人们,蝗灾依然是粮食生产和生态安全的严重威胁。在寻求绿色可持续防蝗的新策略新技术研究中,昆虫病原真菌显现出种类多、毒力强、易规模化生产及环境友好等明显优势而倍受重视。近30年,真菌防蝗研究和应用进步加快,国际、国内都有真菌防蝗产品的注册登记和大规模应用。本文综述了真菌杀虫机理、防蝗菌株选育、规模化生产及应用进展,分析了存在的问题,提出了在蝗虫幼龄期施菌干预种群发展的建议,展望了未来发展前景,为蝗灾绿色防控提供参考。     

沙漠蝗生物学特性及防治技术研究进展

历史记载中,沙漠蝗Schistocerca gregaria(Forsk.,1775)主要在北非发生,对当地农作物构成严重威胁。大规模发生时,可向西亚等地继续扩散为害。2020年初沙漠蝗在巴基斯坦、印度大量发生,肆虐为害,对粮食安全和生态安全构成了严重威胁。因其具有迁飞性,周边多个国家面临重大入侵风险。因本次沙漠蝗发生规模与破坏程度堪比1985年非洲蝗灾,2020年2月11日,联合国粮农组织(FAO)向全球发布预警:"高度戒备正在肆虐的蝗灾,防止被入侵国家出现粮食危机"。本文介绍了沙漠蝗分类地位、形态学特征,概述了沙漠蝗生物学特性、监测预警与防治技术研究进展,为科学防控沙漠蝗提供理论支撑。     

蝗虫综合防控技术研究进展

蝗灾是世界性生物灾害,给农牧业生产造成巨大经济损失。2020年初沙漠蝗Schistocerca gregaria再次暴发,严重影响自然生态系统和社会经济的发展。进入21世纪以来,蝗虫防治的新技术和新策略不断发展。本文概述了我国蝗虫主要成灾种类、分布及其危害,总结了近年来蝗虫监测预警及防控技术相关研究进展,重点介绍了以生物防治为主,化学农药应急防控和生态调控为辅的蝗虫绿色可持续防控技术体系,并从不同方面对未来草原蝗虫综合防控技术体系的构建进行展望,以期为蝗灾科学治理提供理论支撑。     

Single nucleotide polymorphism detection at the Hypothenemus hampeiRdl gene by allele-specific PCR amplification with Tm-shift primers

The resistant Rdl allele for dieldrin insecticide was detected on the Hypothenemus hampei populations from Colombia using conventional PCR methods. Based on this sequence, a melting temperature (T_m) shift genotyping method that relies on allele-specific PCR is described for insecticide resistance-associated single nucleotide polymorphism (SNP) at the H. hampeiRdl gene. The method reported here uses GC-rich tails of unequal length attached to allele-specific primers containing 3′ terminal bases that correspond to SNP allelic variants. Specific PCR products are identified by inspection of a melting curve on a real-time PCR thermocycler using SYBR Green DNA binding dye. Resistant and susceptible alleles resulted in specific PCR products with T_m of 83.3 ± 0.1 °C and 86.0 ± 0.2 °C, respectively. The RdlT_m-shift genotyping method is a new method to identify the Rdl gene in the coffee berry borer H. hampei, the principal pest of coffee that in general show low genetic diversity and very few genetic strategies for control of this pest have been developed. The method supplies a high-throughput tool for dieldrin resistance-associated SNP diagnostic in the coffee berry borer which will be useful for resistance-management strategies and as genetic marker in the colombian insect populations for genetics research.     

Second International Symposium of the European Weed Research Society,Uppsala, August 1977

Abstract

The results of a discriminative spray application of decamethrin from a helicopter to fringing forest habitats of Glossina tachinoides in the Komoe valley, Upper Volta, are described. The insecticide formulated as a 2.5% emulsion concentrate was diluted with river water and applied from a Bell 47G-4A helicopter to the fringing forests of a 14 km long stretch of the River Komoe at a dosage of 12.5 g a.i./ha. The insecticide application equipment was so adjusted that when the helicopter was flown at 30 km/h, the effective swath width was about 30 m and the vmd of emitted spray was c.150 μm. Insecticide swaths were applied to the inner edges of fringing forests that were up to 100 m wide. Forests wider than 100 m received an additional insecticide swath.

The experimental area was protected from reinvasion by the establishment of dieldrin barriers at its extremities and along some tributaries and woodland/floodplain ecotones. The dieldrin was applied by the same method as was used to apply the decamethrin. The single discriminative application of decamethrin was extremely effective in controlling G. tachinoides for a period of at least 38 days, at the end of which time the wet season had commenced and there was evidence that flies were entering the experimental area from nearby unsprayed areas. The authors discuss the possible practical applications of the technique and make suggestions on how it might possibly be refined in order to reduce undesirable river water contamination and operational costs. The authors draw attention to the need for field trials, such as that reported upon, to be conducted on a sufficiently large scale and for the experimental areas to be well protected against reinvasion, if meaningful evaluation data are to be obtained.     

中国蝗虫学研究60年

蝗虫灾害是人类历史上三大自然灾害之一,对农牧业、环境和经济构成严重威胁。我国是世界上遭受蝗灾最严重的国家之一,有关蝗虫学的研究有较长的历史。60年前,通过改治结合,我国控制了大规模的飞蝗Locusta migratoria蝗灾发生,取得了举世瞩目的成就。60年过去了,中国蝗虫学研究发生了翻天覆地的变化。该文主要综述了最近60年中国蝗虫学研究的发现与创新,展示蝗虫分类学、生态学、生殖与发育生物学、分子生物学、基因组学研究以及蝗虫控制技术研究等多个方面的成就。这些研究成果是世界昆虫学研究的重要组成部分。特别是近30年,我国科学家深入揭示蝗虫两型转变的遗传和表观遗传机制,在国际上产生了重要影响。飞蝗的综合生物学研究积累使飞蝗成为继果蝇之后又一个昆虫模式系统。更重要的是,我国科学家开发的真菌生物农药和群聚信息素可以作为重要的防治手段用于蝗灾的治理。     

Penetration of insecticides through the foregut of the honeybee (Apis mellifera L.)

The rates of penetration of ¹⁴C-labeled insecticides (parathion, carbaryl, and dieldrin) through the foregut of the honeybee (Apis mellifera L.) were measured in vitro and in vivo. Uptake of the insecticides from the lumen of the foregut into foregut tissue was directly proportional to insecticide lipophilicity, but penetration through the foregut was not. Of the three insecticides studied, parathion appeared to possess the optimal physicochemical characteristics required for penetration. The uptake of carbaryl and release of dieldrin by the foregut tissues may limit their respective penetration rates. Insecticide penetration was found to be inversely proportional to the sucrose concentration in the lumen of the foregut in both in vitro and in vivo studies. The oral toxicity of carbaryl showed a similar dependence on the sucrose concentration of the solution in which the insecticide was fed. The data presented indicate that the honeybee foregut is permeable to lipophilic compounds and strongly suggest that this permeability may contribute substantially to the toxicity of orally ingested insecticides in this insect.     

Laboratory evaluation of fipronil,a phenylpyrazole insecticide,against adult Anopheles (Diptera: Culicidae) and investigation of its possible cross‐resistance with dieldrin in Anopheles stephensi

Adult mosquitoes from two strains of Anopheles gambiae and from three strains of Anopheles stephensi were exposed to 0.25% fipronil‐treated papers in WHO test kits or to 500 mg fipronil m⁻² impregnated mosquito netting in bioassay spheres. For comparison, tests were also carried out with the pyrethroid permethrin, using the same methods and doses, and on papers treated with 0.4 and 4% of the cyclodiene insecticide dieldrin. Compared with the same doses of permethrin, fipronil showed less and delayed activity. Two of the An stephensi strains were resistant to fipronil and dieldrin. To investigate whether this was due to a resistance mechanism in the An stephensi strains acting against both insecticides, the most fipronil‐ and dieldrin‐tolerant strain was further selected in two separate lines with one of the insecticides, followed by tests with the insecticide that the line had not been selected with. This indicated a concomitant rise of resistance to dieldrin in the fipronil‐selected line and vice versa. Repeated back‐crossing of the two lines with a susceptible strain and re‐selection with either dieldrin or fipronil gave evidence for the involvement of a single resistance mechanism to both insecticides. Permethrin resistance in both lines declined with selection for dieldrin or fipronil and confirms the absence of cross‐resistance between fipronil and pyrethroids. © 2001 Society of Chemical Industry     

Improving preventive locust management: insights from a multi‐agent model

BACKGROUND

Preventive management of locust plagues works in some cases but still fails frequently. The role of funding institution awareness was suggested as a potential facilitating factor for cyclic locust plagues. We designed a multi‐agent system to represent the events of locust plague development and a management system with three levels: funding institution, national control unit and field teams. A sensitivity analysis identified the limits and improvements of the management system.

RESULTS

The model generated cyclic locust plagues through a decrease in funding institution awareness. The funding institution could improve its impact by increasing its support by just a few percent. The control unit should avoid hiring too many field teams when plagues bring in money, in order to ensure that surveys can be maintained in times of recession. The more information the teams can acquire about the natural system, the more efficient they will be.

CONCLUSION

We argue that anti‐locust management should be considered as a complex adaptive system. This not only would allow managers to prove to funders the random aspect of their needs, but would also enable funders and decision‐makers to understand and integrate their own decisions into the locust dynamics that still regularly affect human populations. © 2017 Society of Chemical Industry     

李光博院士在蝗虫治理研究与实践中的贡献——纪念李光博院士诞辰100周年

本文回顾了李光博院士在20世纪50年代对中国蝗虫治理研究与实践中的重要工作,包括蝗区发生情况的实地调查、蝗虫识别、防治飞蝗和土蝗技术的研究与推广示范等。李光博院士总结并探讨了毒饵治理飞蝗的经验和问题,研究提出了“利用青鲜毒饵防治土蝗”的新技术,并提出了新的治蝗方针,对于控制蝗虫灾害和保障我国粮食安全做出了重要贡献。     

Breeding system and its consequence on fruit set of a rare sand dune shrub Eremosparton songoricum(Fabaceae:Papilionoideae):implications for conservation

The breeding system and its consequence on fruit set of Eremosparton songoricum(Litv.) Vass.,a rare shrubby legume occurring in moving or semi-fixed sand dunes of Central Asian deserts,were examined by manipulative experiments and observational studies in natural populations during the period of 2007-2009.The results showed that E.songoricum exhibits a mixed mating system.It is self-compatible,but depends strictly on pollinators to set fruits.Only two effective pollinators were detected and they triggered the specialized pollination mechanism(a 'brush type' and 'tripping mechanism').Geitonogamy becomes predominant in natural populations,because(74.5±1.3)% of visiting activity happened within or between inflorescences and(24.3±1.4)% occurred between ramets.As a result,inbreeding depression caused by geitonogamous selfing inevitably happened under natural conditions,showing 2.36 times less fruit set than was achieved by hand cross-pollination.The results explained the rarity of the species due to its breeding system,and will assist to develop suitable conservation strategies in severe desert environments.     

A note on the mosquito oviposition pheromone

Mosquitoes of the genus Culex, e.g. Culex quinquefasciatus, release a volatile pheromone from their eggs that induces gravid females to oviposit around the pheromone source. Enantioselective synthesis by the Sharpless epoxidation method and chiral gas chromatography showed the major pheromone component to be (?)-(5R,6S)-6-acetoxy-5-hexadecanolide. Shortening the alkyl chain resulted in a loss of behavioural activity, whereas perfluorination of the alkyl chain or substitution of the acetoxy groups with the trifluoroacetoxy group gave active analogues. A simple large scale synthesis was devised to provide material for a fìeld trial. The pheromone, formulated in effervescent tablets, was used to concentrate oviposition in specific breeding sites where the larvae were controlled with a juvenoid-type insecticide.     

The effects on resistant mosquitoes of interrupted exposure to insecticides

In paired tests on batches of malathion- and dieldrin-resistant Anopheles arabiensis, one of each pair received a continuous exposure to either malathion or dieldrin for 16 h or more, while the other received a non-exposed rest phase in the middle of the exposure period. Among dieldrin-resistant mosquitoes, the mortality rate was decreased in the group that experienced the interrupted, as opposed to the continuous exposures; however, the survival rate of malathion-resistant adults was unaffected by interrupted exposure. There was a significant positive correlation between the mortality rate and the adult age for malathion, but the responses to dieldrin were independent of age. Movement of adult mosquitoes to and from malathion deposits in sprayed houses should not impair the efficacy of this insecticide, whereas prolonged absence from contact with dieldrin would require even longer exposures to achieve the same mortality in the insects.     

放牧干扰对典型草原植被光谱及蝗虫密度的影响

为研究内蒙古典型草原不同放牧强度植被反射光谱与植被参数和蝗虫密度的关系,使用地物波谱仪于2015年和2016年对5个放牧梯度,共20hm~2样地进行调查研究。结果表明,不同放牧强度植被地上总生物量与归一化植被指数(NDVI)关系为y=0.034 8+0.002 9x(R~2=0.645 5,P=0.000 2),蝗虫密度与NDVI线性关系为y=0.067+0.013x(R~2=0.415,P=0.006)。对其进行冗余分析(RDA)发现,植被地上总生物量、植物高度、糙隐子草生物量是蝗虫数量和NDVI变化的主要影响因子,其中植被地上总生物量是显著性影响因子(P=0.001)。在不同放牧强度下蝗虫密度与草地NDVI显著相关(P0.05),随NDVI增大而增多。本文研究结果为进一步开展放牧区蝗灾遥感监测和科学合理地利用草地资源奠定了基础。     

Organochlorine insecticide residues in bovine milk and manufactured milk products in Illinois, 1971-76.

Monitoring activities were initiated in 1971 to survey the occurence and levels of organochlorine insecticide residues in bovine milk and manufactured milk products in Illinois. Dieldrin residues were the most prevalent, and were found in 96 percent of the samples. Dieldrin also accounted for the highest average residue concentration (0.09 ppm). Only 0.3% of the samples contained illegal insecticide residues. Levels of DDT and lindane were generally declining, but those for dieldrin and heptachlor epoxide tended to remain constant.     

杀虫剂防治水稻褐飞虱的有效利用率分析

通过综合分析杀虫剂对水稻褐飞虱的毒力测定结果、褐飞虱田间防治指标、杀虫剂田间推荐剂量及杀虫剂经稻田叶面喷施后在田间的分布等文献资料,发现杀虫剂防治褐飞虱的田间推荐剂量的有效利用率不足0.1%。理论上,通过室内毒力测定可获得杀虫剂杀死褐飞虱种群90%个体的致死剂量 (LD₉₀,单位:μg/头),用稻田中褐飞虱的发生量乘以LD₉₀值即为杀死90%田间虫量的杀虫剂有效用量;而实际上杀虫剂的田间推荐剂量却是其有效用量的千倍以上。分析出现这种现象的原因可能有:1) 在褐飞虱为害的水稻孕穗期和扬花期,采用手动喷雾器进行叶面喷雾时,杀虫剂在水稻上的沉积率为34.25%～46.10%,但其中82%以上分布在水稻冠层以上部位,分布在水稻基部茎秆部位的不足2%,只占杀虫剂使用量的0.5%左右;2) 褐飞虱获取致死剂量的杀虫剂后死亡,但杀虫剂和褐飞虱在田间的分布极不均匀,当最低剂量的杀虫剂和最多虫量的褐飞虱出现在同一株水稻上时,该剂量必须能够控制褐飞虱的为害,那么对于有更多杀虫剂和更少褐飞虱的植株而言,就必然造成杀虫剂的浪费,从而降低其有效利用率;3) 约有50%以上的杀虫剂洒落在稻田水中,经田水稀释后的质量浓度远远低于杀死褐飞虱种群10%个体的致死浓度 (LC₁₀值,单位:mg/L),不能有效杀死褐飞虱。作者认为,通过人工智能,将杀虫剂直接喷洒在褐飞虱发生为害的部位,并根据虫量进行变量施药,必将大幅提高杀虫剂防治水稻褐飞虱的有效利用率。