Parasitoid associated with Liriomyza huidobrensis (Diptera: Agromyzidae) outbreaks in tomato fields in Brazil

1. The knowledge of natural factors that affect pest populations is essential in predicting the occurrence of pest outbreaks and in developing integrated pest management programmes. Natural enemies, climatic elements and host plants are among the most important factors affecting pest dynamics.
2. Tomato (Solanum lycopersicum) is the second most consumed vegetable worldwide. The pea leaf miner Liriomyza huidobrensis (Diptera: Agromyzidae) is a major pest to the tomato in Brazil.
3. This study aimed to determine the main natural factors that regulate L. huidobrensis populations in tomato fields in Brazil.
4. Liriomyza huidobrensis densities were evaluated by directly counting the number of active mines on the basal leaf of the middle section of the plant canopy, and predators and parasitoids were assessed using the leaf‐beating‐against‐a‐tray technique. Eight commercial tomato fields were assessed over two years. The phenological growth stages of the tomato plants (vegetative and reproductive) were noted during the assessments.
5. Liriomyza huidobrensis populations peaked between the middle and end of the planting season.
6. Opius sp. (Hymenoptera: Braconidae) was the main natural enemy of L. huidobrensis.
7. Our results suggest that phenological growth stage and Opius sp. are associated with population dynamics of L. huidobrensis in tomato fields.
8. Therefore, integrated pest management programmes should aim to preserve populations of the parasitoid Opius sp.

     

麻竹山地笋用林水文过程及养分动态

在福建省南靖国有林场的小山城工区设置试验地,进行了麻竹林生态系统水文特征和养分动态研究.实验表明在一定降雨量级范围内,林冠截留量随着降水量的增加而增加,且较小雨量级时增加较快,较大雨量级时增加较慢,并趋于一定值;林冠截留量与一次性降雨量的关系可以用Richards函数较好地拟合.由于雨季降雨量大,林冠截留、穿透水和茎流量都具有明显的季节性,穿透水和茎流量明显多于旱季,林冠截留率则明显小于旱季.全年林冠截留、穿透水和竹秆茎流量分别是283.10、1720.45和99.09 mm.年均林冠截留率、穿透率和竹秆茎流率分别为13.47%,81.82%和4.71%.在养分动态方面,在实验地分别实施全翻、带翻及扩穴(即按农户常规土壤管理,每年3月扩穴,不深翻)3 种不同的土壤垦复措施,结果显示全翻垦复措施地表径流的N,P,K的流失量最大,其中又以中K的流失量最大(3.84 kg/hm2),N,P,K的年流失量大小顺序为全翻>带翻>扩穴.就林地养分利用率而言,带翻是3 种措施中最高的为21.22%,其次为全翻为20.46%,最小为扩穴19.61%,且N、P和K的年盈余量也是3 种措施中最少的,分别为783.18 kg/hm2,120.68kg/hm2和184 .50kg/hm2,所以带翻的经营方式,在带来最好的经济效益的同时,不至于显著提高水土流失,是值得推广的一种麻竹林经营方式.     

Seasonal decline of the tomato leafminer,Tuta absoluta,in the shifting landscape of a vegetable‐growing area

Insect pest populations exhibit seasonal dynamics in response to changes in resource availability or other environmental factors such as climatic conditions, natural enemies, and intra‐ or interspecific competition. Understanding such dynamics is critical for developing effective integrated pest management strategies. The objective of the present study was to identify factors driving the seasonal decline of the tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), in the shifting landscape of a vegetable‐growing area in Senegal. A set of 42 tomato fields was monitored for the number of T. absoluta adults caught in pheromone traps and for the incidence of larvae, during 5 months from June to November 2016 in the Niayes area (Senegal). The surface of solanaceous host crops, climatic conditions, and abundance of natural enemies were also monitored. A drastic decline in T. absoluta abundance was observed during the rainy season. The decrease in resource availability, especially tomato crops, in the surrounding landscape of monitored fields was the main factor affecting the population dynamics during the rainy season. However, alternative host crops such as eggplant and Ethiopian eggplant, can provide ‘reservoirs’ for residual populations of the pest. For applied purpose, it would be interesting to focus the management efforts on residual populations during the rainy season, to make more difficult the reconstitution of populations during the dry season.     

Impact of ploughing on soil seed bank dynamics in temporary pools

We examined the impact of ploughing on soil seed banks of plant communities living in temporary marshes located in agricultural fields. The quantity, quality and vertical distribution of seeds were quantified under ploughed or unploughed treatment at community level. We also focussed on a typical semi-aquatic species, Damasonium alisma, to investigate the impact of ploughing at population level. We used two complementary techniques to study seed banks: hand sorting and seedling emergence. We found that species richness of seeds, seed abundance and germination ability were strongly affected by ploughing at community level. Concerning D. alisma, most of the seeds (56%) were stored in the two deepest soil layers among the four considered in ploughed pools. Moreover, the germination rate was higher for buried seeds (84%) than for seeds collected at the surface (33.6%). These patterns were almost inverted in unploughed pools. Our results agree with the temporal storage effect generally suggested to describe the seed bank property of plant communities. But in addition, we showed that ploughing induces a spatial storage effect in accumulating species and individuals in the seed banks that favourably influence community dynamics. We conclude that, in contrast to what is usually thought, ploughing disturbance can be of benefit for such ephemeral wetland vegetation.     

The potential of crop management practices to reduce pollen beetle damage in oilseed rape

A major problem associated with agricultural intensification over recent decades has been the development of insecticide resistance in crop pest populations. This has been a particular issue for control of the pollen beetle (Brassicogethes aeneus syn. Meligethes aeneus), a major pest of oilseed rape throughout Europe. Sustained and often prophylactic use of pyrethroid insecticides has led to the development of insecticide-resistant beetle populations, and alternatively, more environmentally benign integrated pest management strategies are sought for the pest. The population dynamics of pollen beetles and their natural enemies, and the damage caused by the pest, are influenced by processes acting at multiple scales, from the regional or landscape scale down to the local field or within-field scale. In this review, we focus on the within-field scale, and how crop management factors, including tillage, crop plant density, crop nutrition and crop rotations may be optimised and incorporated into integrated pest management strategies for more sustainable and effective control of the pest.     

Current status and future perspectives on natural enemies for pest control in Taiwan

ABSTRACT

In Taiwan, the agricultural policy, ‘Reduce the consumption of pesticide to half in the next 10 years’, was launched in 2017. Pesticide application, which results in contamination of food by chemical residues, pest resistance, and other adverse ecological effects, is a growing public and environmental concern. Pest control by natural predators is, thus, the best alternative. Biological control methods implemented based on insights obtained from studies on pest behaviour, rearing, and various crop management modes, increase the possibility of controlling pests in modern organic agricultural systems. More than a decade has passed since the first introduction of a predatory insect in Taiwan for pest control (in the 1990s). Predatory and parasitic natural enemies, including lacewing, predatory stink bugs, Orius, and parasitic wasps, were initially used for controlling thrips, aphids, spider mites, whiteflies, and lepidopteran pests. At present, there exists a wide range of integrated pest management (IPM) methods incorporating other non-chemical, biological, and agricultural methods. However, recently, there has been an increase in research and development on the utilisation of natural enemies of insects and the associated food safety issues. Mass production and release, storage, and handling techniques of insect predators and parasitoids have been successful in recent years. The final goal of present day research is to develop natural enemy products and provide an IPM-based model to farmers for using natural enemies in agricultural production systems, thereby reducing pesticide application and ensuring food security.     

Enhancing Soil Organic Matter as a Route to the Ecological Intensification of European Arable Systems

Soil organic matter (SOM) is declining in most agricultural ecosystems, impacting multiple ecosystem services including erosion and flood prevention, climate and greenhouse gas regulation as well as other services that underpin crop production, such as nutrient cycling and pest control. Ecological intensification aims to enhance crop productivity by including regulating and supporting ecosystem service management into agricultural practices. We investigate the potential for increased SOM to support the ecological intensification of arable systems by reducing the need for nitrogen fertiliser application and pest control. Using a large-scale European field trial implemented across 84 fields in 5 countries, we tested whether increased SOM (using soil organic carbon as a proxy) helps recover yield in the absence of conventional nitrogen fertiliser and whether this also supports crops less favourable to key aphid pests. Greater SOM increased yield by 10%, but did not offset nitrogen fertiliser application entirely, which improved yield by 30%. Crop pest responses depended on species: Metopolophium dirhodum were more abundant in fertilised plots with high crop biomass, and although population growth rates of Sitobion avenae were enhanced by nitrogen fertiliser application in a cage trial, field populations were not affected. We conclude that under increased SOM and reduced fertiliser application, pest pressure can be reduced, while partially compensating for yield deficits linked to fertiliser reduction. If the benefits of reduced fertiliser application and increased SOM are considered in a wider environmental context, then a yield cost may become acceptable. Maintaining or increasing SOM is critical for achieving ecological intensification of European cereal production.     

Efficacy of the entomopathogenic nematode, Steinernema feltiae, against sweetpotato whitefly Bemisia tabaci (Homoptera: Aleyrodidae) under laboratory and glasshouse conditions

The potential of using the entomopathogenic nematode Steinernema feltiae to control the sweetpotato whitefly Bemisia tabaci (Gennadius) has been established in previous laboratory studies. However, laboratory studies can overestimate the level of control achieved by biocontrol agents in the glasshouse. Glasshouse trials are therefore required to confirm laboratory results before full-scale commercial development is considered. Under both controlled laboratory and glasshouse conditions high mortality of second instar B. tabaci (>90% and >80%, respectively) was recorded after application of S. feltiae. The efficacy of the biocontrol agent at various application rates was also investigated, where halving the rate of S. feltiae application caused no significant reduction in B. tabaci mortality on tomato foliage. Steinernema feltiae has shown much potential for incorporation into integrated pest management strategies for the control of B. tabaci.     

Incidence of resistance to neonicotinoid insecticides in greenhouse populations of the whitefly, Trialeurodes vaporariorum (Hemiptera: Aleyrodidae) from Greece

The greenhouse whitefly, Trialeurodes vaporariorum Westwood, is an important pest of field and greenhouse crops of horticultural and ornamental plants. In integrated pest management programs its control is mainly based on the release of biological control agents and application of chemical insecticides. Neonicotinoids are relatively new chemicals currently applied for the chemical control of T. vaporariorum. However, cases of development of insecticide resistance to neonicotinoids have already been reported. The state of resistance to neonicotinoid insecticides for populations of the greenhouse whitefly in Greece is currently unknown. The objective of our study was to screen a number of whitefly populations for resistance to the neonicotinoids imidacloprid and thiacloprid. Seven whitefly populations were collected from tomato greenhouse crops from different areas of central and northern Greece. LC₅₀ values were estimated for all populations following the method proposed by the Insecticide Resistance Action Committee (IRAC). The development of resistance to both neonicotinoids was confirmed for all tested populations with resistance ratios ranging from 1.5 to 4.4-fold and from 1.4 to 12.2-fold for imidacloprid and thiacloprid, respectively. We discuss our results with regard to the development of neonicotinoid resistance in T. vaporariorum populations and its implications for whitefly control.     

Insect conservation and pest management

The issue of insect conservation in pest management has many conflicting aspects. For instance, it is desirable to conserve a pest residue in order to maintain natural enemy population and it is imperative to conserve natural enemies. However, conservation of pest species is not relevant if the pest species is an exotic invader and a candidate for eradication, mainly because eradication, if successful, achieves only regional extinction. Conservation of native pests depends, to a large extent, on whether the species is a direct pest of a high value crop or an indirect pest with an acceptable economic injury level. In this paper, integrated pest management is defined in terms of sustainable agriculture and the conservation of biodiversity, and give five premises that stress the level of disturbance of agricultural communities and the dynamics of pest status for arthropod species in the community. The possible impacts of the main integrated pest management tactics on arthropod conservation are tabulated and the results reached stress that diversification of agricultural systems through maximum use of native plants should benefit both integrated pest management and regional arthropod conservation.     

Municipal solid waste compost amendment in agricultural soil: changes in soil microbial biomass

Agricultural application of Municipal Solid Waste (MSW), as nutrient source for plants and as soil conditioner, is the most cost-effective option of MSW management because of its advantages over traditional means such as landfilling or incineration. However, agricultural application of MSW can lead to a potential environmental threat due to the presence of pathogens and toxic pollutants. Composting is an attractive alternative of MSW recycling. Application of MSW compost (MSWC) in agricultural soils can directly alter soil physico-chemical properties as well as promote plant growth. The soil microbial biomass, considered as the living part of soil organic matter, is very closely related to the soil organic matter content in many arable agricultural soils. Numerous studies, with different MSWC amendment doses on different soil types and under different water regimes revealed no detrimental effect on soil microbial biomass. In this review, we show the state of art about the effects of MSWC amendment on soil microbial biomass.     

Deep ploughing increases agricultural soil organic matter stocks

Subsoils play an important role within the global C cycle, since they have high soil organic carbon (SOC) storage capacity due to generally low SOC concentrations. However, measures for enhancing SOC storage commonly focus on topsoils. This study assessed the long‐term storage and stability of SOC in topsoils buried in arable subsoils by deep ploughing, a globally applied method for breaking up hard pans and improving soil structure to optimize crop growing conditions. One effect of deep ploughing is translocation of SOC formed near the surface into the subsoil, with concomitant mixing of SOC‐poor subsoil material into the ‘new’ topsoil. Deep‐ploughed croplands represent unique long‐term in situ incubations of SOC‐rich material in subsoils. In this study, we sampled five loamy and five sandy soils that were ploughed to 55–90 cm depth 35–50 years ago. Adjacent, similarly managed but conventionally ploughed subplots were sampled as reference. The deep‐ploughed soils contained on average 42 ± 13% more SOC than the reference subplots. On average, 45 years after deep ploughing, the ‘new’ topsoil still contained 15% less SOC than the reference topsoil, indicating long‐term SOC accumulation potential in the topsoil. In vitro incubation experiments on the buried sandy soils revealed 63 ± 6% lower potential SOC mineralisation rates and also 67 ± 2% lower SOC mineralisation per unit SOC in the buried topsoils than in the reference topsoils. Wider C/N ratio in the buried sandy topsoils than in the reference topsoils indicates that deep ploughing preserved SOC. The SOC mineralisation per unit SOC in the buried loamy topsoils was not significantly different from that in the reference topsoils. However, 56 ± 4% of the initial SOC was preserved in the buried topsoils. It can be concluded that deep ploughing contributes to SOC sequestration by enlarging the storage space for SOC‐rich material.     

Biological control of nematodes: Soil amendments and microbial antagonists

Summary Organic matter amendments to soil can be used to manage phytoparasitic nematodes. The most effective amendments are those with narrow C:N ratios and high protein or amine-type N content. For soil with 1.0% (w/w) organic matter amendment there is a direct relation between extent of nematode control and the N content of amendments. A special group of amendments are those containing chitinous materials. Chitin addition to soil results in stimulation of a select microflora capable of degrading the polymer. Several microbial species are known to destroy the eggs of phytonematodes (Meloidogyne spp). Organic matter can be modified by addition of specific compounds or by inoculation with particular microbial species to produce an amendment that will induce suppressiveness.     

Assessing Cross-disciplinary Efficiency of Soil Amendments for Agro-biologically, Economically, and Ecologically Integrated Soil Health Management

Preventive and/or manipulative practices will be needed to maintain soil's biological, physiochemical, nutritional, and structural health in natural, managed, and disturbed ecosystems as a foundation for food security and global ecosystem sustainability. While there is a substantial body of interdisciplinary science on understanding function and structure of soil ecosystems, key gaps must be bridged in assessing integrated agro-biological, ecological, economical, and environmental efficiency of soil manipulation practices in time and space across ecosystems. This presentation discusses the application of a fertilizer use efficiency (FUE) model for assessing agronomic, economic, ecological, environmental, and nematode (pest) management efficiency of soil amendments. FUE is defined as increase in host productivity and/or decrease in plant-parasitic nematode population density in response to a given fertilizer treatment. Using the effects of nutrient amendment on Heterodera glycines population density and normalized difference vegetative index (indicator of physiological activities) of a soybean cultivar 'CX 252', how the FUE model recognizes variable responses and separates nutrient deficiency and toxicity from nematode parasitism as well as suitability of treatments designed to achieve desired biological and physiochemical soil health conditions is demonstrated. As part of bridging gaps between agricultural and ecological approaches to integrated understanding and management of soil health, modifications of the FUE model for analyzing the relationships amongst nematode community structure, soil parameters (eg. pH, nutrients, %OM), and plant response to soil amendment is discussed.     

世界毁灭性检疫害虫番茄潜叶蛾的生物生态学及危害与控制

番茄潜叶蛾原产于南美洲的秘鲁,严重危害多种茄科作物,是最具毁灭性的世界检疫性害虫,严重发生地块番茄减产80%~100%。该虫主要借助农产品的贸易活动进行远距离传播扩散。截至2017年,番茄潜叶蛾已在全世界的85个国家和地区发生(以及在22个国家和地区疑似发生)。目前,我国尚没有该虫分布,然而其一旦入侵,将对我国的番茄和马铃薯产业构成巨大威胁。从番茄潜叶蛾寄主范围、危害特点及造成的经济损失、生物生态学习性、地理分布和传播扩散途径、防控措施等方面进行概述,以期为该虫的有效防范提供参考。     

Compatibility of early natural enemy introductions in commercial pepper and tomato greenhouses with repeated pesticide applications

Successful integrated pest management in protected crops implies an evaluation of the compatibility of pesticides and natural enemies (NE), as control strategies that only rely on one tactic can fail when pest populations exceed NE activity or pests become resistant to pesticides. Nowadays in Almería (Spain), growers release NE prior to transplanting or early in the crop cycle to favor their settlement before pest arrival because this improves biocontrol efficacy, although it extends pesticide exposure periods. The purpose of this research was to evaluate the compatibility of two applications of pesticides with key NE in 2‐year trials inside tomato and sweet pepper commercial greenhouses: Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae), Orius laevigatus (Say) (Hemiptera: Anthocoridae) and Amblyseius swirskii (Athias‐Henriot) (Acari: Phytoseiidae). In tomato, flubendiamide and chlorantraniliprole (IOBC category 1) were compatible with N. tenuis, but chlorpyrifos‐methyl and spinosad (IOBC categories 2–3), which effectively reduced Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) density, compromised its predatory activity. In sweet pepper, chlorantraniliprole (IOBC category 1) was the only pesticide compatible with O. laevigatus while chlorantraniliprole, emamectin benzoate, spirotetramat and pymetrozine were harmless (IOBC category 1) to Amblyseius swirskii, and sulfoxaflor slightly harmful (IOBC category 2) to this phytoseiid predator.     

Changes in emergence phenology,fatty acid composition,and xenobiotic-metabolizing enzyme expression is associated with increased insecticide resistance in the Colorado potato beetle

The Colorado potato beetle (Leptinotarsa decemlineata) is a major agricultural pest of solanaceous crops. An effective management strategy employed by agricultural producers to control this pest species is the use of systemic insecticides. Recent emphasis has been placed on the use of neonicotinoid insecticides. Despite efforts to curb resistance development through integrated pest management approaches, resistance to neonicotinoids in L. decemlineata populations continues to increase. One contributing factor may be alterations in insect fatty acids, which have multiple metabolic functions and are associated with the synthesis of xenobiotic-metabolizing enzymes to mitigate the effects of insecticide exposure. In this study, we analyzed the fatty acid composition of L. decemlineata populations collected from an organic production field and from a commercially managed field to determine if fatty acid composition varied between the two populations. We demonstrate that a population of L. decemlineata that has a history of systemic neonicotinoid exposure (commercially managed) has a different lipid composition and differential expression of known metabolic detoxification mechanisms relative to a population that has not been exposed to neonicotinoids (organically managed). The fatty acid data indicated an upregulation of Δ⁶ desaturase in the commercially managed L. decemlineata population and suggest a role for eicosanoids and associated metabolic enzymes as potential modulators of insecticide resistance. We further observed a pattern of delayed emergence within the commercially managed population compared with the organically managed population. Variations in emergence timing together with specific fatty acid regulation may significantly influence the capacity of L. decemlineata to develop insecticide resistance.     

Efficacy of sulphur on Tuta absoluta and its side effects on the predator Nesidiocoris tenuis

The South American tomato pinworm, Tuta absoluta (Meyrick), is one of the major pests of tomato crop. Since its detection in the Mediterranean basin, it has been commonly controlled using chemical insecticides. However, inoculation and conservation of predatory mirids, integrated with sprays of selective insecticides, has been demonstrated to be a cost‐effective strategy for controlling this pest. In this work, we tested the efficacy of two sulphur formulations, dustable and wettable powder, for controlling T. absoluta on tomato under greenhouse and open‐field conditions. In addition, the side effects of both sulphur formulations on the predator, Nesidiocoris tenuis (Reuter), were evaluated under laboratory conditions. Dustable sulphur, applied weekly on tomato seedlings artificially infested with T. absoluta in greenhouse conditions, significantly reduced the infestation levels and was demonstrated to have a repellent effect on oviposition. Wettable sulphur was not effective for controlling T. absoluta populations in both greenhouse and open‐field experiments. In the side effect trials conducted with N. tenuis, only dustable sulphur resulted in being moderately harmful as a fresh residue and slightly harmful as a 7‐day‐old residue; no effects were recorded exposing the predator to 14‐day‐old sulphur residues. In contrast, wettable sulphur was classified as harmless to N. tenuis. Our results suggest that the use of sulphur, especially as dustable powder, could be considered as a tool in T. absoluta management strategies, although its side effects on N. tenuis should be taken into account. The implications of these results for the use of sulphur formulations in pest and disease management programmes in tomato crops are discussed.     

Field evaluation of entomopathogenic nematodes for biological control of striped flea beetle, Phyllotreta striolata (Coleoptera: Chrysomelidae)

The striped flea beetle, Phyllotreta striolata (F.) (Coleoptera: Chrysomelidae) is a key pest of crucifer vegetables in Southern China. The use of entomopathogenic nematodes (EPNs) within an integrated pest management approach may offer an effective and environmentally safe strategy to suppress outbreaks of this pest. In the present study, the efficacy of Steinernema carpocapsae All and Heterorhabditis indica LN2 for the control of P. striolata in the field was evaluated, as well as the combined application of EPNs and azadirachtin against the pest. Both nematode species were capable of reducing populations of the soil-dwelling stages of P. striolata, thus leading to a reduction of the adult populations and the associated shot-hole damage on the leaves. Nematode treatments also increased cabbage yields as compared to the control and azadirachtin treatments alone. Azadirachtin alone was not effective to prevent damage by P. striolata, but it could enhance the control effect of S. carpocapsae shortly after application. Osmotically treated infective juveniles (IJs) of S. carpocapsae All performed as well as untreated IJs.