Control of the cowpea aphid, Aphis craccivora Koch (Homoptera: Aphididae), in cowpea, Vigna unguiculata (L.) Walp.

Cowpea, Vigna unguiculata (L.) Walpers, is a major dietary staple in tropical Africa where it is most often cultivated. The production is, however, greatly hampered by severe infestation and damage by insect pests including the cowpea aphid, Aphis craccivora Koch. The damage and bionomics of the aphid are briefly introduced. Chemical, cultural, physical and biological methods, and use of plant resistance for A. craccivora control in cowpea are reviewed. Finally, prospects for integrated pest management are discussed     

A review of the potential for competitive cereal cultivars as a tool in integrated weed management

Competitive crop cultivars offer a potentially cheap option to include in integrated weed management strategies (IWM). Although cultivars with high competitive potential have been identified amongst cereal crops, competitiveness has not traditionally been considered a priority for breeding or farmer cultivar choice. The challenge of managing herbicide‐resistant weed populations has, however, renewed interest in cultural weed control options, including competitive cultivars. We evaluated the current understanding of the traits that explain variability in competitive ability between cultivars, the relationship between suppression of weed neighbours and tolerance of their presence and the existence of trade‐offs between competitive ability and yield in weed‐free scenarios. A large number of relationships between competitive ability and plant traits have been reported in the literature, including plant height, speed of development, canopy architecture and partitioning of resources. There is uncertainty over the relationship between suppressive ability and tolerance, although tolerance is a less stable trait over seasons and locations. To realise the potential of competitive crop cultivars as a tool in IWM, a quick and simple‐to‐use protocol for assessing the competitive potential of new cultivars is required; it is likely that this will not be based on a single trait, but will need to capture the combined effect of multiple traits. A way needs to be found to make this information accessible to farmers, so that competitive cultivars can be better integrated into their weed control programmes.     

Comparative analysis of neonicotinoid binding to insect membranes: II. An unusual high affinity site for [3H]thiamethoxam in Myzus persicae and Aphis craccivora

Neonicotinoids represent a class of insect-selective ligands of nicotinic acetylcholine receptors. Imidacloprid, the first commercially used neonicotinoid insecticide, has been studied on neuronal preparations from many insects to date. Here we report first intrinsic binding data of thiamethoxam, using membranes from Myzus persicae Sulzer and Aphis craccivora Koch. In both aphids, specific binding of [3H]thiamethoxam was sensitive to temperature, while the absolute level of non-specific binding was not affected. In M persicae, binding capacity (Bmax) for [3H]thiamethoxam was ca 450 fmol mg(-1) of protein at 22 degrees C and ca 700 fmol mg(-1) of protein at 2 degrees C. The negative effect of increased temperature was reversible and hence not due to some destructive process. The affinity for [3H]thiamethoxam was less affected by temperature: Kd was ca 11 nM at 2 degrees C and ca 15 nM at 22 degrees C. The membranes also lost binding sites for [3H]thiamethoxam during prolonged storage at room temperature, and upon freezing and thawing. In A craccivora, [3H]thiamethoxam was bound with a capacity of ca 1000 fmol mg(-1) protein and an affinity of ca 90 nM, as measured at 2 degrees C. Overall, the in vitro temperature sensitivity of [3H]thiamethoxam binding was in obvious contrast to the behaviour of [3H]imidacloprid studied in parallel. Moreover, the binding of [3H]thiamethoxam was inhibited by imidacloprid in a non-competitive mode, as shown with M persicae. In our view, these differences demonstrate that thiamethoxam and imidacloprid, which represent different structural sub-classes of neonicotinoids, do not share the same binding site or mode. This holds also for other neonicotinoids, as we report in a companion article.     

Plant training for induced defense against insect pests: a promising tool for integrated pest management in cotton

Enhancing cotton pest management using plant natural defenses has been described as a promising way to improve the management of crop pests. We here reviewed various studies on cotton growing systems to illustrate how an ancient technique called plant training, which includes plant topping and pruning, may contribute to this goal. Using examples from cotton crops, we show how trained plants can be brought to a state of enhanced defense that causes faster and more robust activation of their defense responses. We revisit the agricultural benefits associated with this technique in cotton crops, with a focus on its potential as a supplementary tool for integrated pest management (IPM). In particular, we examine its role in mediating plant interactions with conspecific neighboring plants, pests and associated natural enemies. We propose a new IPM tool, plant training for induced defense, which involves inducing plant defense through artificial injury. Experimental evidence from various studies shows that cotton training is a promising technique, particularly for smallholders, which can be used as part of an IPM program to significantly reduce insecticide use and to improve productivity in cotton farming. © 2018 Society of Chemical Industry     

棉蚜抗药性现状及治理策略

棉蚜Aphis gossypii Glover是农业生产上最重要的害虫之一。化学杀虫剂一直以来都是棉蚜综合防治体系中的重要组成部分, 但化学杀虫剂的不合理使用导致棉蚜对多种杀虫剂均产生了高水平抗性。现有研究表明, 靶标位点突变、解毒酶基因的过表达以及某些肠道共生菌丰度的变化是导致棉蚜对杀虫剂产生抗性的主要机制。针对棉蚜抗性发展现状及其抗药性机制, 制定科学合理的抗性治理策略, 是充分发挥化学防治的优势、实现棉蚜可持续治理的关键。本文主要从棉蚜的抗药性现状、抗性机制和抗性治理策略3个方面对近10多年的主要进展进行了综述, 旨在为棉蚜抗药性长效治理和科学施策提供理论依据。     

Plant stalks as oviposition traps for Apolygus lucorum (Hemiptera: Miridae) under field conditions

Apolygus lucorum (Meyer-Dür) (Hemiptera: Miridae) is an important pest on cotton, fruit trees, tea and many other crops in China. Its small eggs are often laid inside plant tissues, making them difficult to detect and survey. In this study, the stalks of 20 plant species were assessed for use as oviposition traps for A. lucorum under field conditions in 2013, 2014 and 2017. During 2013–2014, A. lucorum adults laid eggs in the stalks of all plant species tested. When honey was added to bundles of stalks, the numbers of A. lucorum eggs laid in the stalks increased 1.79- to 44.00-fold compared with the stalks of the same plants without honey added. In general, the plant stalks of cotton Gossypium hirsutum L. and scandent hop Humulus scandens (Lour) Merr. attracted a great number of eggs among all plant species tested. In 2017, a positive correlation was found between the number of A. lucorum eggs laid in cotton plant stalks and A. lucorum adults in the corresponding field plots. Oviposition traps using cotton plant stalks provide a simple and practical method for monitoring the egg-laying dynamics of A. lucorum under field conditions.     

Mulched cover crops as an alternative to conventional weed management systems in vineyards

Conventional methods of weed management in vineyards rely primarily on herbicides and tillage. The desire to adopt alternatives to these methods is driven by environmental and economic reasons. Weed suppression and grape yield under mulched cover crop systems at two rainfed northern California vineyards were similar to, and at times exceeded, those under conventional tillage or herbicide management. Cover crop productivity was positively correlated with weed suppression and mulch decomposition rates and seemed to be determined primarily by location and then by cover crop type. The mulch from mowed cover crops averaged 603(± 94) gm⁻² at the two sites. Weed suppression was linked to light interception by the mulch cover for most weed species. Subterranean clover planted directly in the vine row significantly reduced weed cover where it established. The increased dominance of the perennial Convolvulus arvensis and reduction of certain annual species was indicative of species compositional changes in all treatments. Profits under the cover cropping systems exceeded those under conventional tillage and herbicide systems by €  794 ha⁻¹ averaged over the duration of the experiment at both locations.     

Integration of partial resistance,plant density and use of fungicide for management of white mould in common bean

In-row plant densities have not been studied for common beans with type II growth habit and contrasting reactions to white mould. Advanced breeding lines with partial resistance or susceptibility to white mould were combined with 4, 7, 10 or 13 plants m⁻¹ and with or without fungicide at a constant between-row spacing of 0.5 m in five sprinkler-irrigated field trials conducted during the autumn–winter season in Brazil. White mould pressures in the trials covered the whole range from zero to moderate/high (46–60% of white mould severity index). In all trials, means of white mould incidence, severity and yield did not vary significantly between 7 and 13 plants m⁻¹ for the partially resistant line, regardless of the fungicide levels. For the susceptible line, 13 plants m⁻¹ increased white mould incidence and severity under moderate disease, regardless of the fungicide levels, and decreased yield compared with 10 plants m⁻¹ when fungicide was applied twice under moderate/high disease pressure. For the susceptible line, 7 or 10 plants m⁻¹ maximized yield in all trials, with or without fungicide applications. The results suggest that the current recommendation of 11–13 plants m⁻¹ could be used for type II beans with partial resistance to white mould in either a conventional or organic system. For susceptible genotypes, 7–10 plants m⁻¹ seems to be the most appropriate in-row plant density. This study may improve the recommendation of in-row plant density for type II beans cultivated under white mould pressure.     

The consequences of late outbreaks of the aphid Aphis gossypii in cotton growing in central Africa: Towards a possible method for the prevention of cotton stickiness

'Sticky cotton' causes substantial economic loss in central Africa. The phenomenon is the result of honeydew excreted by sapsucking insects, mainly the aphid Aphis gossypii Glover. The chemical protection currently available to farmers does not limit this type of damage effectively. From exhaustive counting of infested leaves and quantitative measurement of stickiness with a thermodetector, a positive relationship can be established between the seriousness of fibre stickiness and aphid outbreaks at the end of the season. A control method involving the topping of plants after boll opening reduces the number of leaves on which aphids feed and thus the abundance of the aphids.     

Plant growth inhibitory activity of Lycoris radiata Herb. and the possible involvement of lycorine as an allelochemical

Lycoris radiata Herb., a common medicinal plant of Far East Asia, was examined for its potential use in paddy weed control. The preliminary screening in greenhouse conditions indicated growth inhibitory activities. The emergence, root and shoot growth, and root dry weight of the bioassay species were reduced when grown in soil mixed with the leaves of L. radiata . Aqueous extracts of the fresh leaves at various concentrations inhibited the root and shoot growth of all tested plant species. To identify the active components, L. radiata ethanolic extract was subjected to bioassay-guided fractionation, purification, and spectroscopic analysis. This process led to the isolation of lycorine as a potential allelochemical. The concentration of lycorine in the dry leaves of L. radiata is estimated to be 0.08%. It is possible that lycorine is exuded from the roots or leaches from the living or decomposing leaves, along with other numerous inhibitors, and inhibits the growth of neighboring or successional plants. These results suggest that L. radiata has the potential to inhibit plant growth and lycorine acts as one of the most important plant growth inhibitors. This plant can be grown as a ground cover plant and its dead leaves could be applied as cover mulch.     

植物精油应用于害虫防治研究进展

从植物精油对害虫的生物活性(驱避、拒食、引诱、触杀、熏蒸、抑制生长发育)、植物精油的增效研究,以及植物精油对害虫的作用机理方面综述了植物精油用于植物保护领域防治害虫的研究进展,并展望了植物精油在植物保护中的应用前景。     

高寒地区芸豆氮肥与密度优化组合模式研究

以黑龙江省北部主栽芸豆品种英国红为试验材料,分析了氮肥和密度对生育期、形态特征、产量、产量构成因素、商品与营养品质等方面的影响。结果表明:N肥会显著增加各个生育时期和生育期的天数,低密度时差异不显著,超过20万株·hm-2差异显著。单株荚数、单荚粒数和百粒重随着密度的增加而降低,各氮肥处理间差异不显著;芸豆的商品率随着密度的增大而降低;N肥45 kg·hm-2和密度10万株·hm-2的组合脂肪含量最大为1.51%,各处理间差异显著;蛋白质最大值出现在N肥60 kg·hm-2和10万株·hm-2的密度与氮肥组合上,最大值为14.55%,与N肥45 kg·hm-2和10万株·hm-2组合差异不显著,与其它组合间差异显著;N30 kg·hm-2和20万株·hm-2组合产量最高,为3 418.56 kg·hm-2,与N肥45 kg·hm-2和15万株·hm-2组合产量(3 417.46 kg·hm-2)相当,与其他组合间差异显著。综合种植的经济效益和品质分析,最为理想栽培模式为N肥45 kg·hm-2和15万株·hm-2组合。     

Evaluating ecological‐niche factor analysis as a modelling tool for environmental weed management in island systems

Management actions are essential for mitigating the potentially harmful changes in biodiversity, ecosystem function and crop/forest productivity caused by invasive species. Species distribution models, if reliable, could be used to design effective management strategies. Although several modelling methods well suited for studying invasive species have been developed for presence‐only data, often the size of available data sets for modelling is small and results are not validated with test samples. Moreover, the impact of such methods in practical applications has been overlooked. Here, we evaluated the reliability of the modelling approach based on ecological‐niche factor analysis (ENFA) implemented in Biomapper software when applied to environmental weed data in the Azores. Presence‐only data sets of two top invasive woody species (Pittosporum undulatum and Acacia melanoxylon) were used. The continuous Boyce curve was used for validation, calculated either in Biomapper (cross‐validation) or based on test samples. The species' most habitable areas that should be regarded as management targets were thus estimated from modelling and validation. By imposing size restrictions on the presence‐only data sets used in modelling and validation, other habitable areas were defined and compared. The ENFA proved to be a suitable method for modelling environmental weed distributions, regardless of the presence‐only dataset size. Moreover, the cross‐validation of Biomapper was reliable, although its results should be interpreted with caution as they could potentially lead to statistically different management target areas.     

青枯病植物疫苗对番茄根系土壤微生物群落结构的影响

为了探讨青枯雷尔氏菌无致病力菌株FJAT-1458作为青枯病植物疫苗菌株对番茄根系土壤微生物群接种处理后番茄根系土壤微生物PLFAs组成、含量、微生物群落结构及多样性的变化。结果表明,与清水对照相比,接种菌株FJAT-1458后,番茄根系土壤微生物脂肪酸组成及含量发生了明显变化,可分为减少型、无变化型和增加型。进一步分析表明,菌株FJAT-1458能促进番茄根系土壤微生物总量、细菌总量和真菌总量的增加,增加幅度分别为5.98%~47.36%、2.07%~58.07%和5.65%~74.42%,对放线菌生长起到先抑制后促进作用。此外,接种菌株FJAT-1458后番茄根系土壤微生物群落的Shannon-wiener指数显著增加,21 d增加量最高(13.32%)。聚类分析表明,菌株FJAT-1458处理组与对照组的番茄根系土壤微生物均划分为3个群落类型(兰氏距离分别为3.28和4.62),但它们各自群落组成及特征不同;同时主成分分析也将2种处理划分在2个不同类群中。上述结果说明菌株FJAT-1458处理能明显改变番茄根系土壤微生物群落结构,增加其多样性,从而提高土壤微生态系统的稳定性,增强土壤抑制病害能力。     

探索中前行-中药材病害研究概况与思考

中医药是我国医学的特色,中药资源是中医药事业发展的物质基础,在国务院颁布的《中药材保护和发展规划》(2015-2020年)中,中药材首次被确立为我国的战略性资源。大量的中药材在田间生产及加工贮藏过程中存在病害问题,严重影响了中药材的产量和质量。我国药用植物病害研究经历了几十年的历程,在2000年之前,由于中药行业整体不受重视,研究的药材及其病害种类均极为有限,发表的研究论文很少。近10年来,随着中药在国内外的认可度提升和需求量增加,中药材栽培种类和面积急速扩大,病害研究的队伍和研究水平均有所增强。在研究方向和内容上主要集中在病原鉴定和防治技术方面,研究思路延续植物病理学的一般规律,针对药用植物特色的研究比较薄弱。本文总结了近20年以来我国中药材病害的研究概况,针对存在的问题,提出在人力不足和经费投入有限的情况下,要针对中药材病害发生的重点难点问题以及行业的需求,重点加强病害与中药材质量与安全性相关的基础性研究,加快先进技术的引入,提高研究效率和深度,为中药材病害防治提供理论基础和技术指导。