Search

Significance Changes in land use, climate, and agricultural technologies affect pest severity and management. We analyzed long-term longitudinal data (1991–2015) on three major cotton pests for 51 Chinese counties. Bacillus thuringiensis (Bt) insect-resistant cotton had pervasive effects on the whole pest complex and its management. Adoption resulted in major reductions in insecticide use against bollworm. The resulting restoration of aphid biocontrol decreased aphid severity. Mirid bug severity increased, aided by higher May temperatures and reduced insecticide sprays against bollworm. Landscape effects on pest severity varied between species. Farmers sprayed at nondamaging infestation levels. Findings support Bt-based plant resistance as a component of integrated pest management (IPM) but highlight the potential for unintended outcomes for the whole pest complex and the importance of climate change., Long-term changes in land use, climate, and agricultural technologies may affect pest severity and management. The influences of these major drivers can only be identified by analyzing long-term data. This study examines panel data on land use, adoption of genetically modified Bacillus thuringiensis (Bt) insect-resistant cotton, weather, pest severity, and insecticide use on three major cotton pests for 51 counties in China during 1991–2015. Bt cotton had pervasive effects on the whole pest complex in cotton and its management. Adoption resulted in major reductions in insecticide use for bollworm control. The resulting restoration of aphid biological control decreased aphid severity. However, mirid bugs, which have few effective natural enemies in cotton, increased in severity with warming May and reduced insecticide spraying against bollworm. The effects of landscape on pest severity were pest specific. The severity of cotton aphid and mirid bugs decreased with higher land use diversity, but the severity of highly polyphagous cotton bollworm was unrelated to land use diversity. Shares of forest, water body, and unused land area were negatively associated with the severity of mirid bugs, whereas cotton bollworm responded positively to the shares of water body and unused land area. Farmers sprayed insecticides at mild infestation levels and responded aggressively to severe bollworm outbreaks. Findings support the usefulness of Bt-based plant resistance as a component of integrated pest management (IPM) but highlight the potential for unexpected outcomes resulting from agro-ecosystem feedback loops as well as the importance of climate.

Made available in DSpace on 2022-04-28T18:59:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-12-01 Shannon-Wiener's diversity index (SWI) was used under untreated conditions of a cotton field during the 2006/2007 crop season in the Cerrado region, Brazil. Comparison was carried out between the transgenic NuOpal® (Bollgard®)(Cry1Ac) and the non-transgenic isogenic variety DeltaOpal®. SWI was calculated for target pests, non-target herbivores and predators groups. Two sampling methods were used: whole plant observation and beat sheet. As expected, the mean number of target pests, especially Pectinophora gossypiella (Saund.) and Alabama argillacea (Hübner), was significantly smaller in Bt cotton. In the whole plant method sampling the SWI for non-tar-get herbivores was significantly higher in Bt-cotton. The mean number of Anthonomus grandis (Boh.) and Edessa meditabunda (Fabr.) adults were significantly higher in NuOpal® with the whole plant sampling method. However, such differences were not observed with the beat sheet method. For the natural enemies, SWI and mean number of larvae and adults of the dominant predators did not show any significant difference between Bt and non-Bt cotton. These results confrm the conservation of some tritrophic interactions inside the Bt (untreated) cotton and contributes to a better sustainable management of nontarget pests by enhancement of their natural biological control. Universidade Federal de Grande Dourados (UFGD) Instituto Mato-grossense do Algodão (IMAmt), Rodovia BR 070, Campo Experimental, Primavera do Leste, MT, 78850-000 Universidade Estadual Paulista Júlio de Mesquita Filho Universidade Estadual de Mato Grosso do Sul Centre de Cooperation Internationale en Recherche Agronomique Pour le Development (CIRAD), Montpellier Universidade Estadual Paulista Júlio de Mesquita Filho

Available at http://www.agbioforum.org/v14n2/v14n2a02-fok.htm; International audience; In China, Bt-cotton varieties have been marketed since 1997 to help control attacks of some cotton pests, notably Helicoverpa armigera. It is estimated that Bt-cotton is currently grown on about 70% of the total Chinese cotton-growing area. Most studies have explained this broad distribution by the specific advantages of Bt-cotton, particularly the reduction in pesticide use but this has been put into question in more recent papers, which also raised the issue of seed prices. In our study based on datasets seldom used in earlier analyses, we argue that Bt-cotton use in China is related to the development of the cotton variety market through a two-phase phenomenon. Bt-cotton use has resulted from the development of the variety market facilitated by a favourable legal framework since the mid-1990s, but the current stiff competition is responsible for quality uncertainty and possibly for high seed pricing, thereby threatening the profitability and continued use of Bt-cotton, in addition to the development of the variety market. The quality seed subsidy policy was launched in 2007 to rectify the disorder in the variety and seed market, but the effectiveness of this regulation measure is debatable.

About ten countries have adopted Bt-cotton since its commercial release in the USA in 1996. This release immediately has led to raise the concern of Monsanto's monopoly and loss of varietal diversity in adopting countries. There are very few studies addressing the actual state of the cotton variety markets in the adopting countries. This article proposes an analysis of these markets in China along what is observed in other countries where Bt-cotton is grown. Monsanto's monopoly in supplying Bt-genes, indeed encountered in all countries except China, must be distinguished from monopoly of Monsanto's varieties. This latter monopoly is not always confirmed, and surely not in China. In this country, very active competition has taken place, with a tendency for breeders to propose varieties integrating both Bt and hybrid F1 traits. Furthermore, competition has become excessive and implies negative effects to producers as well as to breeding and seed distribution companies, hence forcing the Chinese government to engage regulation policy, Depuis la commercialisation du coton-Bt en 1996 aux USA, l'utilisation de ce type de coton est effective dans une dizaine de pays. Cette commercialisation avait fait surgir les craintes d'un monopole de Monsanto et la perte de diversité variétale dans les pays utilisateurs du coton-Bt. Il existe très peu d'analyse sur l'état réel des marchés de variétés de coton-Bt dans le monde. L'article propose une présentation de l'état et de l'évolution du marché des variétés de coton-Bt en Chine, en la plaçant dans la perspective des autres pays utilisateurs. Il faut distinguer monopole des gènes Bt de Monsanto, monopole effectif dans tous les pays sauf en Chine, et monopole des variétés proposées par Monsanto. Ce dernier monopole n'est pas toujours confirmé, et en tout cas pas en Chine. Dans ce pays, une concurrence très active s'est instaurée, avec une tendance des obtenteurs à proposer des variétés présentant à la fois le trait Bt et la caractéristique hybride F1. Cette concurrence est même excessive, elle engendre des effets négatifs tant pour les producteurs que les entreprises de distribution de variétés et de semences, obligeant l'Etat chinois à engager une intervention de régulation.

Integrated pest management (IPM) has been introduced in India to reduce the serious impact of the use of highly toxic pesticides on people’s health and the environment. However, IPM diffusion has been slow, in part because of the inherent complexity of the approach based on decisions requiring knowledge of ecological principles and local ecological dynamics. Farmer field schools (FFSs) on IPM, conducted for cotton growers in Andhra Pradesh, India, is shown to be an effective educational approach for building the essential knowledge and decision-making skills among farmers for IPM adoption. FFS farmers (73) drastically reduced the use of highly toxic pesticides as a result of increased knowledge on biological control principles. Yield levels were not affected by this reduction, showing that part of the current use of pesticides in cotton cultivation is superfluous. IPM labour demand has been suggested also as limiting IPM diffusion. However, an analysis of the physical labour use, carried out on a sub-sample (43 FFS and 52 control farms), showed that the adoption of IPM in the studied farms did not lead to an increase in the overall physical labour requirement, nor in the total time spent on plant protection.

The large diffusion of Genetically Modified Cotton (GMC) in China, namely Bt-Cotton, has been well evidenced but recent report on its reduced profitability raises the issue of long term adoption. This paper targets to point out that the adoption of Bt-Cotton in China has not depended only on its specific advantages in controlling pests. It focuses on the specific case of Jiangsu Province, along the Yangtze River Valley, for which the use of GMC is little reported in publications accessible to most scientists of the international community. The paper synthesizes the recent analyses published in Chinese from people involved either in research or in extension activities and it exploits the results of a survey implemented in 2005 as well as the data of the network of multi-location experiments of cotton varieties in the Yangtze River Valley. It comes out that in Jiangsu Province, the diffusion of GMC has benefited a lot from the modernization of the seed sector which has integrated Bt trait into hybrid cultivars which are perfectly adapted and profitable to the transplanting technique. In spite of a rather limited reduction in the cost of pest control, farmers should not abandon using Bt-Cotton, because the evolution of Chinese farming does not push cotton growers to be so much vigilant in optimizing their production costs, unless seed prices keeps on tremendously increasing. The continuation of a profitable use of GMC should require some move to better regulate the seed sector., La grande diffusion du coton génétiquement modifié (CGM) en Chine, plus précisément du coton-Bt, est bien reconnue même si les craintes sur la durabilité de ce succès ont émergé récemment. Ce papier vise à indiquer que l'adoption du coton-Bt en Chine n'a pas dépendu seulement de ses avantages pour contrôler les ravageurs. Il évoque le cas spécifique de la Province du Jiangsu, dans la Vallée du Yangse, pour laquelle l'utilisation du CGM est peu rapportée dans les publications accessibles à la communauté internationale. Le papier synthétise les analyses récentes publiées en chinois par des auteurs relevant de la recherche ou du développement et il s'appuie sur les résultats d'une enquête réalisée en 2005 et sur ceux du réseau multi-local d'expérimentations variétales de la Vallée du Yangse. Il ressort que dans la Province du Jiangsu, la diffusion du CGM a beaucoup bénéficié d'une modernisation du secteur des semences qui a intégré le caractère Bt dans les variétés hybrides très adaptées à la technique de production par transplantation. En dépit d'une réduction plutôt limitée du coût de contrôle des ravageurs, les paysans ne devraient pas abandonner l'usage du coton-Bt car l'évolution de l'agriculture chinoise ne pousse plus les paysans à être aussi vigilants pour optimiser les coûts de production, à moins que les prix des semences continuent à croître de manière phénoménale. La poursuite d'une utilisation rentable du CGM requiert des initiatives pour mieux réguler le secteur des semences.