Impacts of transgenic Bt cotton and integrated pest management education on smallholder cotton farmers

Abstract

Comparative field research on transgenic Bt cotton and conventional cotton under different conditions (fields without pesticide inputs, fields managed by farmers with IPM education, fields managed by farmers lacking IPM education) were carried out in Hubei province of China in 2002. The amount of pesticide used on Bt cotton by non-IPM farmers was found to be around three times that used by IPM farmers. IPM farmers made significantly higher net profits from cultivating transgenic Bt cotton in comparison with non-IPM farmers. Other pest management practices had more significant influences on the population dynamics of predatory natural enemies and major insect pests than did the adoption of transgenic Bt cotton in the cotton ecosystem. Our study showed that IPM education, by increasing farmer capacity to critically evaluate inputs and their effects, monitor their fields and make informed decisions on pest management, enabled farmers to reduce pesticide use significantly, so resulting in improved production and profit margin. IPM farmer education thus, contributed to maximising the value of planting transgenic Bt cotton.     

麦套Bt棉田的经济效益和对棉蚜及天敌的影响

2004～2005年,在冀南棉区调查了麦套Bt棉田对棉花苗期蚜虫和天敌的影响及其经济效益。结果表明,麦套棉田的棉蚜数量均显著低于对照田(P<0.05),其高峰期的蚜虫种群数量低于防治指标,且受棉蚜的危害程度小于对照田。麦套棉田中的瓢虫和僵蚜的种群数量显著高于对照田和化防田,与对照田相比,麦套棉田中的瓢虫发生高峰期提前10天左右。化防田的籽棉产量高于麦套棉田和对照田,但麦套棉田2004和2005年的综合经济效益分别为1.7万元/hm2和2.08万元/hm2,比化防田多0.53万元/hm2和0.57万元/hm2。试验结果还表明,棉花苗期蚜虫能够显著影响棉花产量,采用套种等多熟种植模式可以作为Bt棉有害生物综合治理的重要组成部分。     

Comparative study of 2 protection strategies against Tuta absoluta (Meyrick) in late open field tomato crops in Tunisia

A comparative study of 2 protection strategies against Tuta absoluta (Meyrick) in open field tomato crops was performed. The first strategy used Integrated Pest Management (IPM) through mass trapping, release of Nesidiocoris tenuis and rational use of compatible insecticides. The second strategy was based on conventional use of synthetic insecticides (9 treatments). This study revealed at the end of the culture a 20% infestation rate of leaves in the IPM cropping system versus 98% in the conventional cropping system. The infestation rate of fruit was 18.2% in the IPM cropping system versus 46.8% with the conventional one.     

The selective feeding of cotton bollworms (Helicoverpa armigera) on transgenic and non-transgenic cotton leaves from consecutive cultivation fields

Abstract

The aim of this study was to determine whether target-insects selectively feed on transgenic or non-transgenic crops after consecutive cultivation in fields. We sampled leaves from insect-resistant single-transgenic cotton (expressing Cry1Ac gene), pyramided-transgenic (expressing Cry1Ac and CPTI genes) and conventional cotton that were consecutively cultivated for three years in a field. Cotton bollworm (Helicoverpa armigera) collected from the cotton field was reared and its next-generation larvae were fed the three types of cotton leaves in a laboratory. The leaf area damaged by the cotton bollworm larvae was not significantly different among single-transgenic, pyramided transgenic and conventional cotton leaves. There was no significant difference found in the leaf damage among the combination groups of the three cotton types. The survival rate of the bollworms was comparable among the combination groups. The results demonstrated that the cotton bollworms did not selectively feed on transgenic or non-transgenic cotton leaves after consecutive cultivation, which may be due to the resistance evolution of the target-insects and decreased Bt content in transgenic cotton leaves.     

Needs-based decision-making for cotton problems in Africa: A response to Hillocks

Abstract

This Forum contribution forms a response to the thoughtful article on the role of Bt cotton for African smallholders by Rory Hillocks in International Journal of Pest Management 51(2):131–141. We urge a more nuanced approach to consideration of pesticide-related and other technical issues in the conventional cotton sector, including recent estimates of external costs to health from current patterns of pesticide use, even at the low application levels in volume/area terms reported from Africa. We examine economic and institutional aspects of cotton production and the debates centred upon the potential of Bt cotton for resource-poor farmers in developing countries. Based on research and project experience over the last decade, we discuss the role of organic cotton and the benefits it provides for African men and women smallholders, and conclude with a summary of the potential for expansion and policy, research and development needs.     

Development of an integrated pest management programme for cotton. Part 1: Establishing and utililizing natural enemies

The strategy for the control of cotton pests, notably Helicoverpa spp., in Australia is insecticide-dependent with limited consideration of the role of beneficial insects. A programme for the development of an integrated pest management (IPM) approach commenced in cotton fields at Norwood near Moree in New South Wales in 1992. In this approach, an alternative crop, lucerne (Medicago sativa), was used in an interplant system plus spraying of cotton with a supplementary food (Envirofeast®), which served to attract and retain predators in treated plots. The predator complex consisted of predatory beetles, bugs, lacewings and spiders. The deployment of these two components, interplants and predator retention, reduced the number of Helicoverpa spp. eggs, very small and small larvae (first, second and third stages), medium and large larvae (fourth and fifth stages) and resulted in a cotton yield (2.72 bales ha^?1) that was significantly higher (p < 0.01) than the yield from the untreated control plot (0.59 bales ha -1 ). However, the yield from the interplants and food sprayed plot was significantly lower (p < 0.01) than in the insecticide-managed plot (7.12 bales ha^?1). Whenever the ratio of predators to Helicoverpa spp. (pests) per metre row of cotton was S 0.5, Helicoverpa pest numbers were maintained below the economic damage threshold. Though not successful in suppressing Helicoverpa spp. numbers, to avoid significant yield loss, further improvement could be made by introducing other potential components to the IPM strategy.     

Use of neem products/pesticides in cotton pest management

Products derived from leaves and kernels of neem (Azadirachta indica A. Jussieu) are becoming popular in plant protection programmes for cotton, mainly because synthetic pesticides have several undesirable effects. Neem derived pesticides have been found to be effective and economic in controlling major cotton pests. Neem products act both as systemic and as contact poisons and their effects are antifeedant, toxicological, repellent, sterility inducing or insect growth inhibiting. Furthermore, neem products appear to be environmentally safe and IPM compatible and have the potential to be adopted on a broad scale, together with other measures, to provide a low cost management strategy.     

Smallholder cotton production in sub-Saharan Africa: An assessment of the way forward

Abstract

The benefits of growing organic cotton were advocated in a recent contribution to this Forum. While welcoming a debate on this subject, we advocate a closer look at the history of cotton in Africa, whereby for decades farmers did grow cotton without insecticides. We believe that while there may be a market for ‘organic’ cotton production, it would be a retrograde step to ignore the technological advances that enable much higher yields to be obtained economically. What is needed is improved training and extension services backed up by an on-going research programme for IPM/ICM utilising the most appropriate technologies. Continuing research is needed to integrate new technology of benefit to the small-scale farmer, whether aiming at organic production or higher yields by integrating rational use of biotechnology and pesticides.     

转Cry1Ac/1Ab基因棉花对棉铃虫的控制效果及对甜菜夜蛾和斜纹夜蛾生长发育的影响

为评估转Cry1Ac/1Ab基因棉花对棉铃虫Helicoverpa armigera的抗性及对非靶标害虫甜菜夜蛾Spodoptera exigua和斜纹夜蛾S.litura生长发育的影响,采用室内生测法测定其对棉铃虫的抗性及对甜菜夜蛾和斜纹夜蛾不同龄期幼虫存活率、营养代谢及中肠酶活性的影响。结果表明,转Cry1Ac/1Ab基因棉花对棉铃虫第2代幼虫的抗性程度最高,幼虫校正死亡率达91.33%,但对甜菜夜蛾和斜纹夜蛾的抗性程度较低,幼虫校正死亡率分别为15.33%和13.33%。甜菜夜蛾和斜纹夜蛾各龄期幼虫取食转Cry1Ac/1Ab基因棉花后,其存活率与取食常规棉花对照无显著差异;甜菜夜蛾对转Cry1Ac/1Ab基因棉花叶片的相对取食量、近似消化率分别为16.68和93.12%,均高于取食常规棉花对照的10.72和92.00%,但差异不显著,而斜纹夜蛾取食转Cry1Ac/1Ab基因棉花后的各项营养指标均低于取食常规棉花对照,差异也不显著。取食转Cry1Ac/1Ab基因棉花后,甜菜夜蛾的过氧化物酶活性为0.02 U/mg prot,显著低于取食常规棉花的0.05 U/mg prot;斜纹夜蛾的酸性磷酸酶活性为0.15 U/mg prot,高于取食常规棉花的0.10 U/mg prot,但差异不显著,其它中肠酶活性均低于对照,亦无显著差异。     

Influence of pesticide applications on pest and predatory arthropods associated with transgenic<Emphasis Type="Italic">Bt</Emphasis> cotton and nontransgenic cotton plants

The effects of pesticide applications on pests (aphids and acarid mites) and predators (ladybeetles and spiders) were investigated in transgenicBt cotton and nontransgenic cotton agroecosystems in 1999, 2000 and 2001. Transgenic cotton did not cause changes in populations of acarids and did not reduce numbers of predators considerably; its effects on aphids were inconsistent. Although insecticides were not applied against the main pest — cotton bollworm — on transgenic cotton, the total number of insecticide applications in 3 years was no less than the total applied on nontransgenic cotton, because additional applications were required against sucking pests on transgenicBt cotton. Pesticide applications decreased numbers of aphids, acarids and predatory spiders significantly on both transgenic and nontransgenic cottons. The results suggest that the use ofBt cotton should be evaluated carefully in China. http://www.phytoparasitica.org posting April 30, 2004.     

Note: Toxicity of some insecticides onBracon hebetor under laboratory conditions

Insecticides which were environmentally friendly and the least toxic, were screened against a laboratory strain ofBracon hebetor (Say) (Hymenoptera: Braconidae) for their suitability for release in IPM of cotton. Concentrations ranging from 1 to 1000 ppm of the formulated insecticides in acetone were applied in glass vials and also by a leaf method, whereby cotton leaves were dipped in aqueous solutions of the same concentrations of insecticides. Adult parasitoids were exposed in both methods. According to the LC₅₀ at 24 h exposure, Λ-cyhalothrin and spinosad were the most (7 and 5 ppm) and least (263 and 225 ppm) toxic in the vial and the leaf method, respectively, toB. hebetor. The possible use of the parasitoid for IPM of cotton is discussed. http://www.phytoparasitica.org posting July 20, 2006.     

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.     

转Bt基因抗虫棉对根际土壤Bt蛋白 残留和速效养分含量的影响

以4个品种转Bt基因抗虫棉及其对照常规棉为研究对象,采用ELISA试剂盒法检测其在不同生育期根际土壤Bt蛋白残留,同时比较速效养分含量的变化。结果表明：（1）棉花根际土壤中Bt蛋白的残留量在蕾期达到最大;在整个生育期4个品种转基因抗虫棉根际土壤中Bt蛋白的含量均显著高于对照常规棉（P＜0.05）,其中鲁棉研28号在蕾期显著高于对照常规棉1 029.66%,鲁棉研36号在蕾期显著高于对照常规棉2 573.45%,山农棉8号在苗期显著高于对照常规棉1 208.89%,鑫秋4号在花铃期显著高于对照常规棉793.18%。（2）棉花根际土壤中硝态氮含量在苗期最高,吐絮期最低,且在部分生育期转基因抗虫棉与对照常规棉差异显著;铵态氮含量在苗期最高,吐絮期最低,4个品种转基因抗虫棉在蕾期、花铃期均与对照常规棉差异显著;速效磷含量在苗期最低,吐絮期最高,其中鲁棉研28号在蕾期显著高于对照常规棉10.29%,鲁棉研36号在苗期显著高于对照常规棉6.77%。研究表明,转基因抗虫棉的种植和生育期是影响棉花根际Bt蛋白残留量、速效养分含量的主要因子。     

Evaluation of food sprays and relay strip crops for enhancing biological control of bollworms and cotton aphids in cotton

Studies were conducted at the Texas Agricultural Experiment Station research farms located at Munday (1996 test) and Chillicothe (1997 test) to evaluate relay strip crops in combination with a food spray to enhance biological control of bollworms, Helicoverpa zea (Boddie), and cotton aphids, Aphis gossypii Glover, in cotton. The relay crops included fall plantings of hairy vetch, Vicia villosa Roth, and canola, Brassica napus L., and a spring planting of grain sorghum, Sorghum bicolor L. Cotton, Gossypium hirsutum L., was planted between the relay crops or was isolated from the relay crops. Treatments within the two cotton systems included an untreated check plot, a plot sprayed with sugar+yeast (food spray) during summer to attract and hold predator insects, a plot sprayed with biological ('soft') insecticides for bollworm and cotton aphid control (Bacillus thuringiensis and pymetrozine, respectively), and a plot sprayed with harsh insecticides for bollworm and cotton aphid control (zeta cypermethrin and dicrotophos or profonofos, respectively). A split-plot experimental design, with three replications, was used where whole plots included relay and isolated cotton systems and subplots were the four food/chemical treatments. Predator numbers were monitored with a vacuum sampler once a week in relay crops and cotton. Bollworms and cotton aphids were monitored visually once a week in cotton during July and August. Total predator numbers were higher in cotton adjacent to relay crops in 1996, but not in 1997. The food spray did not enhance attraction and retention of predators either year. Bollworm larval numbers were significantly higher in relay cotton, food spray plots in 1996. Bollworm larval numbers were similar in relay and isolated cotton, and larval numbers were significantly reduced only in the plot where zeta cypermethrin (harsh insecticide plot) was used. In 1996, cotton aphid numbers in the relay cotton system were significantly higher in the untreated check plots in relation to numbers in the food spray, soft insecticide, and harsh insecticide plots, which were statistically similar. In the isolated cotton system, aphid numbers were highest in untreated plots, intermediate in food spray and soft insecticide plots, and lowest in the harsh insecticide plots. Aphid numbers increased more rapidly in the harsh insecticide plots that had been treated previously for bollworm control. The food spray and pymetrozine treatments reduced cotton aphids more effectively in the relay cropping system than in the isolated cotton system. Bollworms and cotton aphids did not reach pest status in 1997. The combination of a relay cropping system with a food spray did not enhance predator numbers and did not aid in retention of predators in cotton during August. Sucrose in the food spray attracted high numbers of bollworms in 1996.     

Influence of pesticides and application methods on pest and predatory arthropods associated with cotton

Incidence of sucking pests was studied in a transgenic (Bt) and non-transgenic cotton (non-Bt) agro ecosystem in 2008 and 2009. Simultaneously, the influence of different pesticides applied in two different methods on sucking pests and generalist predators was investigated on transgenic cotton. In stem application, the insecticides solutions prepared were painted directly on the middle portion of the plant stem but in foliar application the recommended dosages of the insecticides were sprayed on the cotton plant. The transgenic and non-transgenic cotton did not differ significantly in the population of sucking pests. The different pesticides when applied by foliar sprays reduced significantly more sucking pests than stem application. Among the different insecticides used, imidacloprid caused the maximum reduction of the leaf hopper population, acetamiprid caused the maximum whitefly reduction, and clothianidin caused the maximum thrips reduction under foliar application. Via stem application, acetamiprid and thiomethoxam were found better in suppression of the sucking pests?? population, but the population of predators was significantly less disrupted by the stem application method. The foliar application was in general more effective; stem application may be more applicable early in the season when its efficacy was higher and when foliar sprays were particularly destructive to beneficial pests. In foliar application, all the systemic neonicotinoids like imidacloprid, clothianidin, admire, thiamethoxam and acetamiprid were found highly toxic to natural enemies in comparison with spirotetramat, buprofezin and fipronil.     

Integrated pest-management approaches in orchard,cereal and potato protection in Poland1

With its total area of 312,683 km² and a population of about 39 million people, the area of agricultural land per person in Poland is about 0.47 ha. The yields of basic crops are rather low and the losses due to pathogens, animal pests and weeds are high. The use of pesticides is about 1.0–1.3 kg a.i. per ha and this gives a good starting point for integrated pest management (IPM) in the production system of various crops. IPM in glasshouse crops reached the level of 500 ha per year. An IPM approach against codling moth (Cydia pomonella) in orchards allowed a reduction by 70% in the number of insecticide treatments. In the case of apple scab (Venturia haequalis), the IPM approach allowed a reduction in the number of fungicide treatments by 30% on an area of 100,000 ha. In respect to small grains, the IPM approach concerns rational use of fungicides and herbicides in winter wheat and barley. In potato protection, the IPM approach mainly concerns Colorado beetle (Leptinotarsa decemlineata), which at present is controlled by chemical insecticides on 77% of the potato area. Special research and demonstration IPM programmes sponsored by USDA/AID in Central and Eastern Europe will be operational during 1992/1995 and will concern orchards (apple, pear), small grains (wheat, barley) and potatoes.     

Effect of pest management systems on foliage- and grass-dwelling spider communities in an apple orchard in Hungary

Spider communities (Araneae) inhabiting the canopy, the herbaceous layer and the borders, as well as the populations overwintering on the tree trunks of different aged IPM and conventional apple orchards were investigated in Hungary. Abundance and species richness of entire spider communities in IPM plots were significantly higher than in conventional plots, probably owing to the lower toxicity of pesticides used and higher prey densities. In the case of abundance, similar tendencies were observed in web-building and hunting spider guilds. Age of plantations can significantly influence spider density in the canopy, acting through the prey density. In young plantations, where size of the canopy was smaller and density of the pear lace bug (Stephanitis pyri L.) higher, significantly higher numbers of hunting spider communities were present than in old plantations which had been similarly treated. This relationship was not observed for web-building spiders. Diversity of canopy-inhabiting spider communities was higher in old plots, regardless of the treatments. The effect of the border of the orchard on spider communities was investigated and it was found that when selective insecticides were used, migration of spiders into orchards was increased significantly. When broad-spectrum insecticides were applied, spider densities in the canopy did not differ between outer and inner rows of the orchards. The effect of the treatments and orchard age, both on abundance and species richness of overwintering spider communities on the trunk, showed the same result as for canopy spiders, namely significantly larger spider communities were found in IPM plots and in the young plantation than in conventionally-treated plots and in the old plantation. Broad-spectrum insecticides reduced abundance and species richness of spider communities in the herbaceous layer of the conventionally-treated plot. At the same time, the spider communities of the herbaceous layer of the IPM plot did not differ significantly from adjacent herbaceous plants. A significant overlap exists between spider communities of the canopy and herbaceous layer. Despite chemical treatments, migration from the herbaceous layer into the canopy occurs. The effects of chemical treatments on the dominant species are discussed. There were no significant differences between the differently treated plots in abundance of one of the dominant species Oxyopes heterophthalmus Latreille. However, the other dominant species, Cheiracanthium mildei L. Koch, was more abundant in the IPM plots.     

Aerial electrostatic‐charged sprays for deposition and efficacy against sweet potato whitefly (Bemisia tabaci) on cotton

Background: The efficacy of aerial electrostatic‐charged sprays was evaluated for spray deposit characteristics and season‐long control of sweet potato whitefly (SWF), Bemisia tabaci Genn. biotype B (aka B. argentifolii Bellows & Perring), in an irrigated 24 ha cotton field. Treatments included electrostatic‐charged sprays at full and half active ingredient (AI) label rate, uncharged sprays and conventional sprays applied with CP nozzles at full label rate with several different insecticides. Results: Spray droplet size was significantly smaller for electrostatic‐charged sprays than for conventional sprays in top‐ and mid‐canopy locations. The seasonal mean numbers of viable eggs and live large nymphs on cotton treated with electrostatic‐charged sprays were comparable with those on cotton treated with conventional applications. Lethal concentration (LC₅₀) for adults for electrostatic‐charged sprays was comparable with that for conventional sprays. Conclusion: The amenability of electrostatic‐charged sprays to a wide array of pesticides with different chemistries should be a useful tool in combating insect resistance. Results reported here suggest that the potential exists for obtaining increased efficacy against whiteflies using an electrostatic spray charging system, and that additional research will be required to improve charge‐to‐mass (Q/M) ratio in order to increase deposition of pest control materials to the lower surfaces of cotton leaves where the whiteflies reside. Copyright © 2009 Society of Chemical Industry     

Management of resistance in Bemisia in Arizona cotton

A whitefly (Bemisia argentifolii) resistance crisis climaxed in 1995 in Arizona cotton and prompted the development of an integrated resistance management strategy adapted from a program implemented in Israel in 1987. The strategy incorporated two new major elements: once-per-year use of the insect growth regulators (IGRs) pyriproxyfen and buprofezin, and measures to delay use of pyrethroids for as long into the growing season as possible. A three-stage chemical use recommendation was formulated comprising IGRs (Stage I), other non-pyrethroid insecticides (Stage II), and synergized pyrethroid insecticides (Stage III). Results from use of the strategy in the 1996 season were very promising. Insecticide use for control of whiteflies was reduced substantially. State-wide monitoring of whitefly susceptibility revealed significant reductions in resistance to synergized pyrethroids as well as increased susceptibility to amitraz. Susceptibility of Lygus bugs to key insecticides changed correspondingly with increases and decreases in whitefly resistance from 1994 through 1996. ©1997 SCI     

A Stable Synthetic Pyrethroid,NRDC 147, and the Control of Spodoptera littoralis

Abstract

Pyrethrins, the botanical insecticides and their synthetic analogues are well known for their power of producing very rapid paralysis (knockdown) in treated insects. The use of pyrethrins or synthetic analogues in agriculture to combat insect pests on field crops has been rather limited. The main reason for this is their non-persistence in field conditions. A recently developed synthetic pyrethroid NRDC 147, which is 10–100 times more stable in light than previous pyrethroids was tested in the laboratory and field against the Egyptian cotton leafworm Spodoptera littoralis (Boisd). Results indicate higher efficiency (LC₅₀ 320 ppm), compared with 460, 422, 1250, 180, 2150 and 265 ppm for cyolane, chlorpyrifos, leptophos, methomyl, monocrotophos and methamidophos respectively. The residual effect (LT₅₀) is more than 7 days in the field for NRDC 147, while it was 5.8, 6.8 and 4.2 for cyolane, leptophos and methamidophos.