Pest Control Technology Research Articles

RNA intereference (ENAi): a novel technology with potential for pest insect management

RNA Interference (RNAi) is a biological mechanism widely distributed in eukaryotes that allows silencing of genes in the presence of double-stranded RNA (dsRNA) molecules. This mechanism was discovered more than 15 years ago, since then a lot of research projects have been performed in order to obtain a better understanding of how this mechanism works, its function in different organisms, utility for specific gene function description and its potential in the technologic development of other areas. Gene silencing occurs by the interaction between enzymatic complexes in the cytoplasm, with small interference RNA molecules (siRNA), which act on the endogenous messenger RNA (mRNA), therefore preventing their translation to proteins. It is a fact that RNAi could be used as an alternative technology for pest control, through silencing essential genes for the target species. The implementation of this technology involve many necessary studies, ranging from the identification of target genes including dsRNA sequence design, development of bioassays and field tests that show the real effects of dsRNA on gene silencing, and the evaluation of associated factors that could produce variability during the process. Due to this, is necessary more research studies for a marketing establishing of this technology. This paper presents the theory behind the RNAi mechanism, current achievements of this technology, as well as the potential of this technology for insect pest control.

Foraging behavior and virulence of some entomopathogenic nematodes

At present the biological control as a pest control technology is becoming more desirable. Biological formulations on basis of entomopathogenic nematodes are one of the effective means for the protection of agricultural and forest plants from harmful insects. Nowadays, the use of entomopathogenic nematodes as biological control agents is a key component in IPM system. The foraging strategies of entomopathogenic nematodes (EPNs) vary between species. This variation is consistent with use of different foraging strategies between ambush, cruise and intermediate to find their host insects. In order to ambush prey, some species of EPNs nictate, or raise their bodies of the soil surface so they are better poised to attach passing insects, other species adopt a cruising strategy and rarely nictate. Some species adopt an intermediate strategy between ambush and cruise. We compared in laboratory the foraging strategies of the entomopathogenic nematode species: Steinernema carpocapsae, Heterorhabditis bacteriophora and the recently described species Steinernema tbilisiensis and assessed their virulence against mealworm beetle, Tenebrio molitor L. (Coleoptera: Tenebrionidae). The tests showed that S. tbilisiensis adopts both foraging strategies.

Targeting insect mitochondrial complex I for plant protection.

SummaryPlant engineered to express double‐stranded RNA (dsRNA) can target the herbivorous insect gene for silencing. Although mounting evidence has emerged to support feasibility of this new pest control technology, field application is slow largely due to lack of potent targets. Here, we show that suppression of the gene encoding NDUFV2, a subunit of mitochondrial complex I that catalyses NADH dehydrogenation in respiratory chain, was highly lethal to insects. Feeding cotton bollworm (Helicoverpa armigera) larvae with transgenic cotton tissues expressing NDUFV2 dsRNA led to mortality up to 80% within 5 days, and almost no larvae survived after 7 days of feeding, due to the altered mitochondrial structure and activity. Transcriptome comparisons showed a drastic repression of dopa decarboxylase genes. Reciprocal assays with Asian corn borer (Ostrinia furnacalis), another lepidopteran species, revealed the sequence‐specific effect of NDUFV2 suppression. Furthermore, the hemipteran lugus Apolygus lucorum was also liable to NDUFV2 repression. These data demonstrate that the mitochondrial complex I is a promising target with both sequence specificity and wide applicability for the development of new‐generation insect‐proof crops.

Accelerating research on Spotted Wing Drosophila management using genomic technologies

Spotted Wing Drosophila (Drosophila suzukii) is an invasive species and a serious pest of berry and soft-skinned fruit crops. The close genetic relationship between D. suzukii and other well-studied Drosophila species has provided researchers with an already extensive genetic toolkit. The reference genome and transcriptome of this insect have been annotated and made publicly available since 2013, and facilitate basic and applied research. In this review, we present a synthesis of recent research that implements next-generation sequencing and genomic technologies to better understand biological questions concerning this important pest. Much of the work performed is directly applicable to improving agricultural management practices, and includes topics such as insecticide response and resistance, invasion demographics, seasonal biology, and RNA interference technologies for pest control.

CURRENT STATUS OF ORCHID PRODUCTION IN THAILAND

Thailand is a natural habitat for about 1,129 species and 178 genera of orchids. For about 100 years, orchid growing was considered a hobby for the rich, but the introduction of Dendrobium Pompadour proved to be a landmark that also brought popularity of orchid cultivation in Thailand. In 1966, only a small amount of orchid cut flowers were exported from Thailand to some European countries, but with a decade, the country attained the status of the world’s leading producer and exporter of orchids where it continues to hold the primary orchid exporter in the world. In 2012, the total Thai growing areas of production was 7,420 acres with yields of 2,403 kilograms per acre and cut-flower exports of 2.1 billion 63.6 billion US$ to 148 countries and plant export to 160 countries (17.8 million US$) where. Also in 2012, it is estimated that 46% of the orchid production were consumed locally and 54% were exported. Newly developed technology to increase the production and reduce costs, such as greenhouses, planting materials and containers, pest control, production, plant breeding, tissue culture, postharvest and packaging technology, replaced traditional growing, which imitated natural growing. These improved practices have resulted in higher yields and quality of flowers and plants, as well as reductions in production costs. Orchids will continue to dominate other ornamental crops in Thailand due to better technology know-how, suitable climatic conditions, experienced and skillful growers and exporters, as well as their nationwide popularity and the country’s pride.

Pollution of soils and ecosystems by a permanent toxic organochlorine pesticide: chlordecone—numerical simulation of allophane nanoclay microstructure and calculation of its transport properties

Pest control technology was introduced into the tropics without considering the specificity of their ecosystems and the risk of pollution was underestimated. Some volcanic soils (andosols) contain nanoclay (allophane) with a unique structure and porous properties compared to crystalline clays. Andosols are characterized by large pore volume and pore size distribution, a high specific surface area, and a fractal structure. These soils are more polluted than the other kinds of tropical soils but release less pollutants (chlordecone) to water and plants. The literature shows that the allophane microstructure favors accumulation and sequestration of chlordecone, an organochlorine pesticide, in andosols. We used a numerical model to simulate the structure of allophane aggregates. The algorithm is based on a cluster-cluster aggregation model. From the simulated data, we derived the structural features, pore volume and tortuosity, and its transport properties, hydraulic conductivity and diffusion. We show that transport properties decrease because of the presence of allophane. We propose that low hydraulic conductivity and diffusion are important parameters to explain the high concentrations and trapping of pollutants in andosols.

Reconsideration of Farming methods in ZHOU(周) times from the perspective of the ecological environment

To re-examine the classical literatures and archaeological finds in the perspective of the ecological environment can find that the farming method had greatly developed in ZHOU(周) times: the land had evolved the distinction of “quan”(?) and “quan”(?), “me”(畝), during the course of land arrangement; sowing in drill has appeared; mature cultivation techniques and pest repellent and control technology had formed in farming practices. Influence by climate conditions, “quan”(?) is mainly used for drainage in Western ZHOU dynasty. The Zhou(周) people farming way was influenced, to a large extent, by the ecological environmental factors.

Should we internalise inter-temporal production spillovers in the case of pest resistance?

The efficiency of pesticides decreases with their global application by farmers. Within a strategic dynamic framework, this results in inter-temporal production spillovers. We analyse a dynamic fiscal scheme that can be implemented to correct these inefficiencies. We show that it is able to restore socially optimal paths but that the final time of pesticide use differs. With this scheme, farmers have a tendency to switch to a backstop pest-control technology earlier than is socially optimal. We also show that an additional exit fiscal scheme is necessary to obtain a switching time equal to the socially optimal one. We test our theoretical results on a stylised illustration, showing that the best policy strategy consists of implementing a lump-sum transfer in order to delete the revenue effect induced by the dynamic fiscal scheme.

Biological Parameters ofPodisus nigrispinus(Hemiptera: Pentatomidae) Fed with Different Soybean Insect Pests

AbstractBiological parameters of Podisus nigrispinus (Dallas) fed with third-instar Lepidoptera larvae of Spodoptera frugiperda J.E. Smith, Spodoptera cosmioides (Walker, 1858), and Anticarsiagemmatalis (Hübner, 1818), as well as eggs of Euschistus heros (F., 1798), the brown stink bug, were evaluated. Experiments were performed under controlled conditions (25 ± 1°C; 70 ± 10% relative humidity, and a photoperiod of 16:8 [L:D] h). P. nigrispinus had good nymphal development with >87% larval survival (viability), as well as high fecundity in adults, when fed with A. gemmatalis, S.frugiperda, and S. cosmioides larvae. Differently, adults of P. nigrispinus originating from nymphs fed with eggs of E. heros completed their life cycle; however, larval survival (viability) was reduced to 45.7%. Furthermore, these adults did not oviposit, and their body mass was from 50 to 73% lower than in individuals originating from nymphs fed with other tested prey. Taking into consideration that neither E. heros nor Spodoptera spp. are controlled by Bt soybean varieties expressing the Cry 1Ac protein, it can be assumed that the predator P. nigrispinus will still find prey species to feed in soybean fields even after the adoption of this pest control technology. This might help lower any potential negative impact of Bt soybean adoption above this insect predator. Moreover, the studied caterpillars proved to be potential prey for the predator's mass rearing, similarly to what is presently being done with coleopteran larvae.

From Integrated to System-Wide Pest Management: Challenges for Sustainable Agriculture

Insect pests and vectors of animal and plant diseases are a major constraint to the improvement of agricultural productivity, and a continuous threat to food security and livelihoods, particularly in less developed countries. The excessive reliance on broad-spectrum insecticides as the prevailing strategy to control pest outbreaks for over 50 years worldwide has showed some limitations with the increasing number of documented cases of field-evolved resistance and re-emergence of pests or vector-borne diseases that had been previously placed under control. More widely, agriculture intensification has contributed to the erosion of crop and livestock genetic diversity and fragmentation or suppression of natural habitats supporting biodiversity-mediated ecosystem services such as insect pest regulation. These concerns are being exacerbated in a context of global change, including population growth, global warming, transboundary trade, on-farm loss of biodiversity, and societal demand for a safer environment and residue-free food, which foster increasingly stringent pesticide use in agriculture and livestock farming. Integrated pest management (IPM) is an ecosystem approach to crop production and protection that combines different management strategies and practices to grow healthy crops and minimize the use of pesticides. IPM thus requires science-based knowledge of the life cycle of pests and their interactions with the environment, including natural enemies and habitats. Field realities, however, show that IPM is often used in a reactive manner and at a local scale, as a simple toolbox. A fundamental shift to a system-wide approach is needed to achieve preventive and effective pest control, while enhancing crop yields, and reducing farmers' reliance on pesticide use and the associated environmental impacts. This shift should at least consider: (i) the functional area of the target pest populations; (ii) the complexity of ecological processes driving regulation; and (iii) the intelligent combination of pest control technologies. Area-wide integrated pest management is a promising way to improve conventional pest control by targeting pest populations within their functional area. This approach requires a better knowledge of target pests, especially regarding their life system (spatial distribution, habitats, dispersal ability over time and space, genetic structure, metapopulation dynamics and gene flow), ecological processes driving regulation (food web networks and natural enemy assemblages), and responses to farming practices at a field and landscape scale. In addition, the success of such an approach relies on a strong cooperation amongst stakeholders for the design, implementation and compliance of pest management programs, and requires farmer education and external coordination, either from governmental bodies or farmers associations. (Resume d'auteur)

The Role of TcdB and TccC Subunits in Secretion of the Photorhabdus Tcd Toxin Complex

The Toxin Complex (TC) is a large multi-subunit toxin encoded by a range of bacterial pathogens. The best-characterized examples are from the insect pathogens Photorhabdus, Xenorhabdus and Yersinia. They consist of three large protein subunits, designated A, B and C that assemble in a 5∶1∶1 stoichiometry. Oral toxicity to a range of insects means that some have the potential to be developed as pest control technology. The three subunit proteins do not encode any recognisable export sequences and as such little progress has been made in understanding their secretion. We have developed heterologous TC production and secretion models in E. coli and used them to ascribe functions to different domains of the crucial B+C sub-complex. We have determined that the B and C subunits use a secretion mechanism that is either encoded by the proteins themselves or employ an as yet undefined system common to laboratory strains of E. coli. We demonstrate that both the N-terminal domains of the B and C subunits are required for secretion of the whole complex. We propose a model whereby the N-terminus of the C-subunit toxin exports the B+C sub-complex across the inner membrane while that of the B-subunit allows passage across the outer membrane. We also demonstrate that even in the absence of the B-subunit, that the C-subunit can also facilitate secretion of the larger A-subunit. The recognition of this novel export system is likely to be of importance to future protein secretion studies. Finally, the identification of homologues of B and C subunits in diverse bacterial pathogens, including Burkholderia and Pseudomonas, suggests that these toxins are likely to be important in a range of different hosts, including man.

Identification of relevant non-target organisms exposed to weevil-resistant Bt sweetpotato in Uganda.

Assessment of the impact of transgenic crops on non-target organisms (NTO) is a prerequisite to their release into the target environment for commercial use. Transgenic sweetpotato varieties expressing Cry proteins (Bt sweetpotato) are under development to provide effective protection against sweetpotato weevils (Coleoptera) which cause severe economic losses in sub-Saharan Africa. Like any other pest control technologies, genetically engineered crops expressing insecticidal proteins need to be evaluated to assess potential negative effects on non-target organisms that provide important services to the ecosystem. Beneficial arthropods in sweetpotato production systems can include pollinators, decomposers, and predators and parasitoids of the target insect pest(s). Non-target arthropod species commonly found in sweetpotato fields that are related taxonomically to the target pests were identified through expert consultation and literature review in Uganda where Bt sweetpotato is expected to be initially evaluated. Results indicate the presence of few relevant non-target Coleopterans that could be affected by Coleopteran Bt sweetpotato varieties: ground, rove and ladybird beetles. These insects are important predators in sweetpotato fields. Additionally, honeybee (hymenoptera) is the main pollinator of sweetpotato and used for honey production. Numerous studies have shown that honeybees are unaffected by the Cry proteins currently deployed which are homologous to those of the weevil-resistant Bt sweetpotato. However, because of their feeding behaviour, Bt sweetpotato represents an extremely low hazard due to negligible exposure. Hence, we conclude that there is good evidence from literature and expert opinion that relevant NTOs in sweetpotato fields are unlikely to be affected by the introduction of Bt sweetpotato in Uganda.

Complete Genome Sequence of Burkholderia sp. Strain RPE64, Bacterial Symbiont of the Bean Bug Riptortus pedestris

We isolated Burkholderia symbiont strain RPE64 from the bean bug Riptortus pedestris. Analysis of the complete 6.96-Mb genome, which consists of three chromosomes and two plasmids, will facilitate further understanding of insect–microbe symbiosis and the development of pest-control technologies.

Pest Management in Food Systems: An Economic Perspective

Population and income growth in the coming half century will lead to a tremendous rise in the demand for food. To meet this projected growth without massive extensification of farmland, agricultural yields must increase significantly. Crop yields depend heavily on the pest pressures farmers face and on the pest control treatments available. Pest control, however, inevitably has a multitude of unintended effects on the environment, public and worker health, and the productivity of neighboring farms. The magnitudes of these effects differ widely across pest control technologies and the situations in which they are used. Optimal pest management balances the quantifiable benefits of yield improvement and risk reduction against these external costs, taking into account nonpecuniary characteristics that impact farmers' decisions and welfare. Such analysis should be the basis of government regulation of pest management.

EVOLUTIONAL AND FUNCTIONAL ANALYSIS OF A SERINE PROTEASE IN Spodoptera litura

Spodoptera litura is a threatening agricultural insect in tropical and subtropical areas and accounts for tremendous annual crop losses. As seen in virtually all insect species, serine proteases (SPs) are crucial to S. litura. The expression pattern of SPs from the midgut of S. litura was studied through expressed sequence tags (ESTs) analysis. One of SP (SlSP1) was chosen for detailed study, because the expression of the gene was midgut and larvae specific. SlSP1 was conducted as a model of its evolution, structure, and potential binding activity with corresponding substrates. SlSP1 is composed of 255 amino acids including a signal peptide at N-terminal followed by a putative activation peptide and the mature protein along with five putative phosphorylation sites, three disulphide bridges, and two N-glycosylation positions. At least nine conserved motifs were obtained in multiple sequence alignments. Some conserved residues, such as the catalytic triad His84, Asp127, and Ser229 as well as six cysteines at position 66, 82, 194, 211, 223, and 247, were examined. After homology modeling and molecular dynamics simulation, the resultant three-dimensional (3D) structure of SlSP1 was docked with the substrates 2PTC-Arg and 2PTC-Lys, respectively. Molecular Mechanic/Poisson-Boltzmann surface area analysis was applied to anticipate optimal binding mode and crucial active sites of this enzyme. The residues Trp28, Gly187, Aso188, Arg249, Ile250, Lys246, and Lys278 are crucial for the substrate binding and molecule process. This information can be used in logical design of SPs inhibitors. New inhibitors may be a basis for development of a new pest control technology.

Feasibility, limitation and possible solutions of RNAi‐based technology for insect pest control

Numerous studies indicate that target gene silencing by RNA interference (RNAi) could lead to insect death. This phenomenon has been considered as a potential strategy for insect pest control, and it is termed RNAi-mediated crop protection. However, there are many limitations using RNAi-based technology for pest control, with the effectiveness target gene selection and reliable double-strand RNA (dsRNA) delivery being two of the major challenges. With respect to target gene selection, at present, the use of homologous genes and genome-scale high-throughput screening are the main strategies adopted by researchers. Once the target gene is identified, dsRNA can be delivered by micro-injection or by feeding as a dietary component. However, micro-injection, which is the most common method, can only be used in laboratory experiments. Expression of dsRNAs directed against insect genes in transgenic plants and spraying dsRNA reagents have been shown to induce RNAi effects on target insects. Hence, RNAi-mediated crop protection has been considered as a potential new-generation technology for pest control, or as a complementary method of existing pest control strategies; however, further development to improve the efficacy of protection and range of species affected is necessary. In this review, we have summarized current research on RNAi-based technology for pest insect management. Current progress has proven that RNAi technology has the potential to be a tool for designing a new generation of insect control measures. To accelerate its practical application in crop protection, further study on dsRNA uptake mechanisms based on the knowledge of insect physiology and biochemistry is needed.

Pdl1 Is a Putative Lipase that Enhances Photorhabdus Toxin Complex Secretion

The Toxin Complex (TC) is a large multi-subunit toxin first characterized in the insect pathogens Photorhabdus and Xenorhabdus, but now seen in a range of pathogens, including those of humans. These complexes comprise three protein subunits, A, B and C which in the Xenorhabdus toxin are found in a 4∶1∶1 stoichiometry. Some TCs have been demonstrated to exhibit oral toxicity to insects and have the potential to be developed as a pest control technology. The lack of recognisable signal sequences in the three large component proteins hinders an understanding of their mode of secretion. Nevertheless, we have shown the Photorhabdus luminescens (Pl) Tcd complex has been shown to associate with the bacteria's surface, although some strains can also release it into the surrounding milieu. The large number of tc gene homologues in Pl make study of the export process difficult and as such we have developed and validated a heterologous Escherichia coli expression model to study the release of these important toxins. In addition to this model, we have used comparative genomics between a strain that releases high levels of Tcd into the supernatant and one that retains the toxin on its surface, to identify a protein responsible for enhancing secretion and release of these toxins. This protein is a putative lipase (Pdl1) which is regulated by a small tightly linked antagonist protein (Orf53). The identification of homologues of these in other bacteria, linked to other virulence factor operons, such as type VI secretion systems, suggests that these genes represent a general and widespread mechanism for enhancing toxin release in Gram negative pathogens.

Disease and Insect Pest Control Technology of Plant Using Artificial Light(<Special Issue>Plant Production Applied by Lighting Technology)

Disease and Insect Pest Control Technology of Plant Using Artificial Light(<Special Issue>Plant Production Applied by Lighting Technology)

New Technologies and Worker Safety in Western Agriculture

ABSTRACT The New Paths: Health and Safety in Western Agriculture conference, November 11–13, 2008, highlighted the role of technological innovation in agricultural production. The tree fruit industry in the Pacific Northwest has adopted a “technology road map” to reduce production costs and improve efficiency. An agricultural tour provided field demonstrations and discussions on such topics as mobile work platforms in orchards, traumatic and musculoskeletal injuries, and new pest control technologies. Occupational safety and health research will need to adapt to and keep pace with rapid changes in agricultural production processes.

Glyphosate‐resistant crops: adoption, use and future considerations

Glyphosate-resistant crops (GRCs) were first introduced in the United States in soybeans in 1996. Adoption has been very rapid in soybeans and cotton since introduction and has grown significantly in maize in recent years. GRCs have grown to over 74 million hectares in five crop species in 13 countries. The intent of this paper is to update the hectares planted and the use patterns of GRC globally, and to discuss briefly future applications and uses of the technology. The largest land areas of GRCs are occupied by soybean (54.2 million ha), maize (13.2 million ha), cotton (5.1 million ha), canola (2.3 million ha) and alfalfa (0.1 million ha). Currently, the USA, Argentina, Brazil and Canada have the largest plantings of GRCs. Herbicide use patterns would indicate that over 50% of glyphosate-resistant (GR) maize hectares and 70% of GR cotton hectares receive alternative mode-of-action treatments, while approximately 25% of GR soybeans receive such a treatment in the USA. Alternative herbicide use is likely driven by both agronomic need and herbicide resistance limitations in certain GR crops such as current GR cotton. Tillage practices in the USA indicate that > 65% of GR maize hectares, 70% of GR cotton hectares and 50% of GR soybean hectares received some tillage in the production system. Tillage was likely used for multiple purposes ranging from seed-bed preparation to weed management. GRCs represent one of the more rapidly adopted weed management technologies in recent history. Current use patterns would indicate that GRCs will likely continue to be a popular weed management choice that may also include the use of other herbicides to complement glyphosate. Stacking with other biotechnology traits will also give farmers the benefits and convenience of multiple pest control and quality trait technologies within a single seed.