Inter‐individual variation in colour patterns in noctuid moths characterizes long‐distance dispersers and agricultural pests

A high capacity for long‐distance dispersal is a key to success for species confronted with environmental heterogeneity, habitat modification, fragmentation and loss. However, dispersal capacity is difficult to quantify and therefore poorly known in most taxa. Here, we report on a test for an association of variation in dispersal capacity with variable colouration of noctuid moths. First, using data from 12 experienced lepidopterologists, we showed that despite variation among experts in average assessments, different species are consistently classified as having non‐variable, variable or highly variable colour patterns when assessed by different experts. We then compared the incidence of non‐resident species with high inter‐individual variation in colour patterns recorded on the isolated island Utklippan (n = 47), with that in a species pool of potential long‐distance dispersers from the nearest mainland (n = 295). Species with high inter‐individual colour pattern variation were over‐represented on the island compared with species having non‐variable colouration. This finding constitutes rare evidence from the wild of long‐distance dispersal, measured on a spatial scale relevant for moths when tracking habitats in fragmented and changing landscapes or when keeping pace with environmental challenges associated with climate change. Finally, we showed that Swedish noctuid moths classified as agricultural pests (n = 28) had more variable colour patterns compared with non‐pests (n = 368). The majority of agricultural pests were also recorded on the isolated island, an outcome that is indicative of pest species having high dispersal capacity. Data on colour pattern variation may thus offer a simple and cost‐effective proxy to estimate dispersal capacity and can also help identify potential pest species. Our findings are potentially useful when modelling and predicting population and range dynamics of species in spatiotemporally heterogeneous environments, with direct implications for conservation biology and pest management.     

Soil‐dwelling insect pests of tree crops in Sub‐Saharan Africa,problems and management strategies—A review

This review aims to draw the attention of researchers, ecologists and farmers to the threats of soil‐dwelling insect pests on important tree crops in sub‐Saharan Africa, with a special focus on termites. It synthesizes the information on the effects of various factors affecting soil pest occurrence and damage, suggesting that the resultant undesirable effects of soil pests in this region are largely as a result of indiscriminate tree cutting, slash‐and‐burn agriculture and indiscriminate use of pesticides. Major insect orders, their host ranges and the nature of damage on selected tree crops are described. This study further critiques existing soil pest management practices, showing that majority of soil pest management practices are ineffective. Thus, management strategies like “attract and kill” approach based on entomopathogenic fungi need to be studied, developed and emphasized for the management of soil insect pests in sub‐Saharan Africa. A conclusion section attempts to offer suggestions for ways in which future work on soil pests in sub‐Saharan Africa could proceed.     

A meta‐analysis of insect pest behavioral manipulation with plant volatiles

Many insect pests utilize plant volatiles for host location and untangling the mechanisms of this process can provide tools for pest management. Numerous experimental results have been published on the effect of plant volatiles on insect pests. We used a meta‐analysis to summarize this knowledge and to look for patterns. Our goal was to identify herbivore and plant traits that might explain the herbivores’ behavioral response to plant volatiles in field applications. We scored a total of 374 unique plant volatile‐insect herbivore interactions obtained from 34 published studies investigating 50 herbivore pest species. Attractants had a significant effect on insect herbivore abundance but repellents did not; this latter result could be a result of the comparatively small number of field studies that tested plant volatiles as repellents (3%). Females were significantly more attracted to plant volatile baits than males. The diet breadth of herbivores was independent of a behavioral response to plant volatiles, but more case studies show effects of volatiles on chewers, followed by wood‐borers and sap‐feeders. There are more demonstrations of attraction to plant volatiles in Lepidoptera than in Thysanoptera. The method of plant volatile application had a significant effect on herbivore abundance and increasing the number of chemicals in individual baits attracted more herbivores. The magnitude of the response of herbivores to plant volatiles in forest and agricultural habitats was similar. We explore consistent patterns and highlight areas needing research in using plant volatiles to manage insect pests.     

Endophyte–grass complexes and the relationship between feeding preference and performance in a grass herbivore

Overseeding non‐endophytic turfgrass lawns with endophytic turfgrass is considered promising for the development of integrated pest management programs in urban landscapes. In this context, a better understanding of the variability in the preference–performance response of insect herbivores exposed to endophytic grasses could be useful to develop efficient practices. Specifically, while endophytic varieties that are strongly toxic and avoided could provide good control of mobile pests, varieties that are toxic but not avoided could be more suitable for the control of sedentary pests. In this laboratory study, we investigated how the infection of 10 grass varieties by Neotyphodium endophytes affected the feeding performance and preference of newly hatched nymphs of the hairy chinch bug, Blissus leucopterus hirtus Montandon (Heteroptera: Lygaeidae), a common turfgrass pest in north‐eastern USA. We found that endophytes generally induced a strong relationship between feeding performance and preference in this herbivore. However, two endophytic varieties did not conform to this relationship, with one variety being highly toxic but not avoided and the other less toxic but highly avoided. These results provide a solid basis to further explore the impacts of endophytic grasses on the dispersal and survival of insect pests in mixed stands of endophytic and non‐endophytic plants.     

RNAi technology: a new platform for crop pest control

The insect pests are big threat in meeting the food demands for future generation. The present pest control strategies, including the existing transgenic approaches show certain limitations and are not completely successful in limiting the insect pests. However, the sequence-specific gene silencing via RNA interference (RNAi) holds a great promise for effective management of agricultural pests. RNAi is naturally occurring conserved process responsible for gene regulation and defense against pathogens. The efficacy of RNAi varies among different insect orders and also depends upon various factors, including the target gene selection, method of dsRNAs delivery, expression of dsRNAs and presence of off-target effects. RNAi-mediated silencing of different insect genes involved in various physiological processes was found to be detrimental to insects growth, development and survival. In this article, we have reviewed the potential of RNAi-based strategies for effective management of insect pests. We have also discussed the various parameters, which are to be considered for host-induced RNAi-mediated control of insect pests without producing any effect on non-target organisms and environment.     

Population Genetics of Ceratitis capitata in South Africa: Implications for Dispersal and Pest Management

The invasive Mediterranean fruit fly (medfly), Ceratitis capitata, is one of the major agricultural and economical pests globally. Understanding invasion risk and mitigation of medfly in agricultural landscapes requires knowledge of its population structure and dispersal patterns. Here, estimates of dispersal ability are provided in medfly from South Africa at three spatial scales using molecular approaches. Individuals were genotyped at 11 polymorphic microsatellite loci and a subset of individuals were also sequenced for the mitochondrial cytochrome oxidase subunit I gene. Our results show that South African medfly populations are generally characterized by high levels of genetic diversity and limited population differentiation at all spatial scales. This suggests high levels of gene flow among sampling locations. However, natural dispersal in C. capitata has been shown to rarely exceed 10 km. Therefore, documented levels of high gene flow in the present study, even between distant populations (>1600 km), are likely the result of human-mediated dispersal or at least some form of long-distance jump dispersal. These findings may have broad applicability to other global fruit production areas and have significant implications for ongoing pest management practices, such as the sterile insect technique.     

Habitat manipulation to mitigate the impacts of invasive arthropod pests

Exotic invaders are some of the most serious insect pests of agricultural crops around the globe. Increasingly, the structure of landscape and habitat is recognized as having a major influence on both insect pests and their natural enemies. Habitat manipulation that aims at conserving natural enemies can potentially contribute to safer and more effective control of invasive pests. In this paper, we review habitat management experiments, published during the last 10 years, which have aimed to improve biological control of invasive pests. We then discuss during what conditions habitat management to conserve natural enemies is likely to be effective and how the likelihood of success of such methods can be improved. We finally suggest an ecologically driven research agenda for habitat management programmes.     

Epidemiological landscape models reproduce cyclic insect outbreaks

Forest insect outbreaks can have large impacts on ecosystems and understanding the underlying ecological processes is critical for their management. Current process-based modeling approaches of insect outbreaks are often based on population processes operating at small spatial scales (i.e. within individual forest stands). As such, they are difficult to parameterize and offer limited applicability when modeling and predicting outbreaks at the landscape level where management actions take place. In this paper, we propose a new process-based landscape model of forest insect outbreaks that is based on stand defoliation, the Forest-Infected-Recovering-Forest (FIRF) model. We explore both spatially-implicit (mean field equations with global dispersal) and spatially-explicit (cellular automata with limited dispersal between neighboring stands) versions of this model to assess the role of dispersal in the landscape dynamics of outbreaks. We show that density-dependent dispersal is necessary to generate cyclic outbreaks in the spatially-implicit version of the model. The spatially-explicit FIRF model with local and stochastic dispersal displays cyclic outbreaks at the landscape scale and patchy outbreaks in space, even without density-dependence. Our simple, process-based FIRF model reproduces large scale outbreaks and can provide an innovative approach to model and manage forest pests at the landscape scale.     

农田非作物生境调控与害虫综合治理

就害虫综合治理的研究而言,农田生态系统可以区分出作物生境和邻近作物的非作物生境。昆虫从作物生境迁移到非作物生境,与作物生境缺乏食物或受人类栽培活动干扰而引起的自然迁移、转换寄主和寻求庇护场所有关。许多研究表明,与特定作物田块相联系的植被类型和结构可影响害虫及其天敌迁居的种类、数量和时间。因此,我们可以通过改变大田周围非作物生境的植被组成及特征来调控农业生态系统中害虫与天敌的相互关系,提高天敌对害虫的控制效能。由于景观的空间格局对节肢动物的生物学特性有直接或间接的影响,所以,以景观为单元要比以同类作物的田块为单元更加适于害虫综合治理的研究和实施。在现代农业景观区域内重新引入和相嵌一些非栽培植物或廊道,可为众多有益节肢动物的繁殖、取食和避害提供多种类型的非作物栖境。     

Role of nanotechnology in agriculture with special reference to management of insect pests

Nanotechnology is a promising field of interdisciplinary research. It opens up a wide array of opportunities in various fields like medicine, pharmaceuticals, electronics and agriculture. The potential uses and benefits of nanotechnology are enormous. These include insect pests management through the formulations of nanomaterials-based pesticides and insecticides, enhancement of agricultural productivity using bio-conjugated nanoparticles (encapsulation) for slow release of nutrients and water, nanoparticle-mediated gene or DNA transfer in plants for the development of insect pest-resistant varieties and use of nanomaterials for preparation of different kind of biosensors, which would be useful in remote sensing devices required for precision farming. Traditional strategies like integrated pest management used in agriculture are insufficient, and application of chemical pesticides like DDT have adverse effects on animals and human beings apart from the decline in soil fertility. Therefore, nanotechnology would provide green and efficient alternatives for the management of insect pests in agriculture without harming the nature. This review is focused on traditional strategies used for the management of insect pests, limitations of use of chemical pesticides and potential of nanomaterials in insect pest management as modern approaches of nanotechnology.     

Dispersal strategies of phytophagous insects at a local scale: adaptive potential of aphids in an agricultural environment

Background  

The spread of agriculture greatly modified the selective pressures exerted by plants on phytophagous insects, by providing these insects with a high-level resource, structured in time and space. The life history, behavioural and physiological traits of some insect species may have evolved in response to these changes, allowing them to crowd on crops and to become agricultural pests. Dispersal, which is one of these traits, is a key concept in evolutionary biology but has been over-simplified in most theoretical studies. We evaluated the impact of the local-scale dispersal strategy of phytophagous insects on their fitness, using an individual-based model to simulate population dynamics and dispersal between leaves and plants, by walking and flying, of the aphid Aphis gossypii, a major agricultural pest, in a melon field. We compared the optimal values for dispersal parameters in the model with the corresponding observed values in experimental trials.     

Microsatellite isolation and characterization in the beneficial parasitoid wasp Diaeretiella rapae (M’Intosh) (Hymenoptera: Braconidae: Aphidiinae)

The primary parasitoid wasp, Diaeretiella rapae (M’Intosh), is used as a biological control agent in insect pest management strategies to combat aphid pests, mainly on cruciferous plants. To investigate the spatial scales over which this beneficial parasitoid wasp moves within an agricultural landscape, we developed five polymorphic microsatellite markers. The number of alleles per locus ranged from 11 to 21. Cross‐species amplification indicated that these loci may be useful in some other members of the Aphidiinae.     

气流控制农业害虫的发展与利用

气流控制技术工作原理是利用流动的空气消灭农作物上的害虫。利用气流控制技术原理制造产生流动的空气清除、杀死和收集农作物上害虫的机械装置称捕虫机或称吸虫机。应用捕虫机防治马铃薯、甘薯、茄子、香葱、草莓、茶树等农作物上的害虫方法,具有不污染环境、无残留、对人体健康无伤害、对土壤微生物影响较小等优点。本文从气流控制农业害虫的基本原理、发展和利用、局限性以及展望四个方面出发,阐述了国内外昆虫学者利用气流控制农业害虫研究的进展,目的是为我国研发和利用其技术防治农业害虫提供参考。     

Landscape changes have greater effects than climate changes on six insect pests in China

In recent years, global changes are the major causes of frequent, widespread outbreaks of pests in mosaic landscapes, which have received substantial attention worldwide. We collected data on global changes(landscape and climate) and economic damage caused by six main insect pests during 1951–2010 in China. Landscape changes had significant effects on all six insect pests. Pest damage increased significantly with increasing arable land area in agricultural landscapes. However, climate changes had no effect on damage caused by pests, except for the rice leaf roller(Cnaphalocrocis medinalis Guenee) and armyworm(Mythimna separate(Walker)), which caused less damage to crops with increasing mean temperature. Our results indicate that there is slight evidence of possible offset effects of climate changes on the increasing damage from these two agricultural pests. Landscape changes have caused serious outbreaks of several species, which suggests the possibility of the use of landscape design for the control of pest populations through habitat rearrangement. Landscape manipulation may be used as a green method to achieve sustainable pest management with minimal use of insecticides and herbicides.     

Agricultural ornithology: an Indian perspective

Agricultural ornithology aims at obtaining scientific information on birds in relation to agriculture and using this information for their management. Most of bird species play a useful role in agriculture by having a potent check on insect and rodent pests. However, some granivorous bird species, having adapted to the agricultural habitats and increased in numbers, are conflicting with our goals of agricultural production by inflicting economic losses to crops, fruits and stored grains. Bird management involves both the conservation of useful species and control of pests. Agricultural ornithology is of special importance in predominantly agricultural countries like India. Although a good deal of work has been done in this discipline in India, a lot remains to be done and, in fact, the discipline is still in its infancy. This paper reviews the progress made in agricultural ornithology in India, points out important problems and gaps in knowledge, and suggests approaches for future research.     

Symbiotic microorganisms: untapped resources for insect pest control

Symbiotic microorganisms offer one route to meet the anticipated heightened demand for novel insect pest management strategies created by growing human populations and global climate change. Two approaches have particular potential: the disruption of microbial symbionts required by insect pests, and manipulation of microorganisms with major impacts on insect traits contributing to their pest status (e.g. capacity to vector diseases, natural enemy resistance). Specific research priorities addressed in this article include identification of molecular targets against which highly specific antagonists can be designed or discovered, and management strategies to manipulate the incidence and properties of facultative microorganisms that influence insect pest traits. Collaboration with practitioners in pest management will ensure that the research agenda is married to agricultural and public health needs.     

害虫的遗传与行为调控

本文综述了昆虫的行为遗传机制、昆虫的发育与变态、昆虫对主要环境因子变化的响应、害虫与寄主植物的化学通讯和多营养级信息网及其对昆虫行为调控等国内外研究进展,提出了害虫治理要从杀灭防治转变为行为调控的新思路和新理念,认为未来的研究将围绕害虫暴发成灾的遗传与行为机理等科学问题,通过深入研究害虫发育变态、行为遗传,及其对关键生态因子和食物网内信号物质适应机制,揭示影响害虫发生的内外关键因素,寻找基于基因和生态调控行为治理害虫的新技术和新方法,为有效开展害虫治理、减少化学农药做出贡献。     

昆虫的生物光电效应与虫害治理应用

农业虫害的治理需要依据为害昆虫的特性提出与环境适宜、生态兼容的技术体系和关键技术。为害昆虫表现了对敏感光源具有个体差异性和群体一贯性的趋光性行为特征,并通过视觉神经信号响应和生理光子能量需求的方式呈现出生物光电效应的作用本质。利用昆虫的这种趋性行为诱导增益特性,一些光电诱导杀虫灯技术以及害虫诱导捕集技术广泛地应用于农业虫害的防治,具有良好的应用前景。     

Insect pest management in the age of synthetic biology

Arthropod crop pests are responsible for 20% of global annual crop losses, a figure predicted to increase in a changing climate where the ranges of numerous species are projected to expand. At the same time, many insect species are beneficial, acting as pollinators and predators of pest species. For thousands of years, humans have used increasingly sophisticated chemical formulations to control insect pests but, as the scale of agriculture expanded to meet the needs of the global population, concerns about the negative impacts of agricultural practices on biodiversity have grown. While biological solutions, such as biological control agents and pheromones, have previously had relatively minor roles in pest management, biotechnology has opened the door to numerous new approaches for controlling insect pests. In this review, we look at how advances in synthetic biology and biotechnology are providing new options for pest control. We discuss emerging technologies for engineering resistant crops and insect populations and examine advances in biomanufacturing that are enabling the production of new products for pest control.     

Can microbial-based insecticides replace chemical pesticides in agricultural production?

Extensive use of chemical insecticides to control insect pests in agriculture has improved yields and production of high-quality food products. However, chemical insecticides have been shown to be harmful also to beneficial insects and many other organisms like vertebrates. Thus, there is a need to replace those chemical insecticides by other control methods in order to protect the environment. Insect pest pathogens, like bacteria, viruses or fungi, are interesting alternatives for production of microbial-based insecticides to replace the use of chemical products in agriculture. Organic farming, which does not use chemical pesticides for pest control, relies on integrated pest management techniques and in the use of microbial-based insecticides for pest control. Microbial-based insecticides require precise formulation and extensive monitoring of insect pests, since they are highly specific for certain insect pests and in general are more effective for larval young instars. Here, we analyse the possibility of using microbial-based insecticides to replace chemical pesticides in agricultural production.