Form Of Biological Control Research Articles

Exploring the nematicidal mechanisms and control efficiencies of oxalic acid producing Aspergillus tubingensis WF01 against root-knot nematodes.

Root-knot nematodes (RKN; Meloidogyne spp.) are among the highly prevalent and significantly detrimental pathogens that cause severe economic and yield losses in crops. Currently, control of RKN primarily relies on the application of chemical nematicides but it has environmental and public health concerns, which open new doors for alternative methods in the form of biological control. In this study, we investigated the nematicidal and attractive activities of an endophytic strain WF01 against Meloidogyne incognita in concentration-dependent experiments. The active nematicidal metabolite was extracted in the WF01 crude extract through the Sephadex column, and its structure was identified by nuclear magnetic resonance and mass spectrometry data. The strain WF01 was identified as Aspergillus tubingensis based on morphological and molecular characteristics. The nematicidal and attractive metabolite of A. tubingensis WF01 was identified as oxalic acid (OA), which showed solid nematicidal activity against M. incognita, having LC50 of 27.48 μg ml-1. The Nsy-1 of AWC and Odr-7 of AWA were the primary neuron genes for Caenorhabditis elegans to detect OA. Under greenhouse, WF01 broth and 200 μg ml-1 OA could effectively suppress the disease caused by M. incognita on tomatoes respectively with control efficiency (CE) of 62.5% and 70.83%, and promote plant growth. In the field, WF01-WP and 8% OA-WP formulations showed moderate CEs of 51.25%-61.47% against RKN in tomato and tobacco. The combined application of WF01 and OA resulted in excellent CEs of 66.83% and 69.34% toward RKN in tomato and tobacco, respectively. Furthermore, the application of WF01 broth or OA significantly suppressed the infection of J2s in tomatoes by upregulating the expression levels of the genes (PAL, C4H, HCT, and F5H) related to lignin synthesis, and strengthened root lignification. Altogether, our results demonstrated that A. tubingensis WF01 exhibited multiple weapons to control RKN mediated by producing OA to lure and kill RKN in a concentration-dependent manner and strengthen root lignification. This fungus could serve as an environmental bio-nematicide for managing the diseases caused by RKN.

Life as Aftermath: Social Theory for an Age of Anthropogenic Biology

Anthropogenic pressures now shape the development, interrelations, and evolution of microbes, plants, animals, and humans. In an age of oxidative stress and failures of DNA repair, cytokine storms and microbial dysbiosis, social scientific theory stutters in the face of biological consequences of forces it masterfully detailed, from biopower to looping kinds. Concepts of the fallibility of knowledge from the unanticipated consequence to the wicked problem are too generic to fathom the nature of the living within reconfigured biotic-abiotic relations in the aftermath of industrialization. Working through examples—genetic modification in weed control, and solvents in cryobiology—this paper offers a novel analytic for anthropogenic biology specific to the relations between knowledge and life in the wake of the industrial twentieth century: a novel patterning of living matter and process from the molecular to the ecological arising with forms of biological control. Changes in pathogens and hosts, targets and bystanders are specific to the form of control but not anticipated by it, illegible within its originating logics. Hubris gone moldy, anthropogenic biology grows from forms of power that overestimate the comprehensiveness of their own efficacy, mistaking the ability to temporarily control living things for full knowledge of them.

Native Trichoderma Induced the Defense-Related Enzymes and Genes in Rice against Xanthomonas oryzae pv. oryzae (Xoo).

The application of Trichoderma is a form of biological control that has been effective in combating Xanthomonas oryzae pv. oryzae, the causative agent of the devastating disease known as bacterial blight of rice. In this present study, four strains of Trichoderma, viz., T. paraviridescens (BDISOF67), T. erinaceum (BDISOF91), T. asperellum (BDISOF08), and T. asperellum (BDISOF09), were collected from the rice rhizosphere and used to test their potentiality in reducing bacterial blight. The expression patterns of several core defense-related enzymes and genes related to SA and JA pathways were studied to explore the mechanism of induced resistance by those Trichoderma strains. The results primarily indicated that all Trichoderma were significantly efficient in reducing the lesion length of the leaf over rice check variety (IR24) through enhancing the expression of core defense-related enzymes, such as PAL, PPO, CAT, and POD activities by 4.27, 1.77, 3.53, and 1.57-fold, respectively, over control. Moreover, the results of qRT-PCR exhibited an upregulation of genes OsPR1, OsPR10, OsWRKY45, OsWRKY62, OsWRKY71, OsHI-LOX, and OsACS2 after 24 h of inoculation with all tested Trichoderma strains. However, in the case of RT-PCR, no major changes in OsPR1 and OsPR10 expression were observed in plants treated with different Trichoderma strains during different courses of time. Collectively, Trichoderma induced resistance in rice against X. oryzae pv. oryzae by triggering these core defense-related enzymes and genes associated with SA and JA pathways.

BIOLOGICAL CONTROL OF TOMATO PHYTOPATHOGENS AS AN ALTERNATIVE TO AGRICULTURAL DEFENSIVES AND ANTIBIOTICS

The tomato ( Solanum lycopersicum L.) is one of the most cultivated vegetable in the world. China represents about 25 % of all world production, so there is a dependence and constant use of agricultural defensives in tomato crops. The application of chemical products banned in many parts of the world has as a side effect a major impact on human health and the ecosystem, therefore necessary to adopt other disease prevention strategies. Another method of combating tomato diseases is the use of microorganisms as a form of biological control, which is considered an alternative to agricultural defensives and antibiotics offering better sustainability and less toxicity. In this work, the agricultural defensives most used by producers were, Pyraclostrobin, Mancozebe, Copper oxychloride, and derivatives of DDT. For the antibiotics, Streptomycin and Oxytetracycline were the most used, whereas Bacillus spp. and Lactic Acid Bacteria (LAB) was the microorganisms most cited as a form of biological control. Lastly the main phytopathogens of tomato were Xanthomonas spp., Clavibac t er michiganensis subsp. michiganensis and Ralstonia solanacearum . The objectives of this work were to identify the main types of agricultural defensives, antibiotics, and genera of microorganisms used to control tomato diseases and to compare their impact on human health and the environment.

A Review of Research and Developments with Insect Agents Used for Biological Control of Australian Acacia Species (Caesalpinioideae) in South Africa

There are 14 species of Australian Acacia now known to be invasive in South Africa, ten of which are under some form of biological control (biocontrol). The biocontrol agents introduced against this group include a fungal pathogen, Uromycladium morrisii Doungsa-ard, McTaggart, Geering & R.G. Shivas (Pucciniales: Raveneliaceae) for Acacia saligna (Labill.) H.L.Wendl., and ten insect species, including two bud-galling wasps, five seed-feeding weevils and three flower-galling fly species, all of which supress reproductive output of their hosts. There are also two native fungal pathogens that have become associated with the introduced acacias, and which have been developed for potential mycoherbicide use. Screening and importation of new agents has seen limited activity in the ten-year period reviewed here (i.e., 2011–2020). Most attention has been focussed on efforts to evaluate the effectiveness of the established agents and, importantly, to gain an understanding of the role of seeds in the population dynamics of the host plants.

Current understanding of biological identity at the nanoscale and future prospects.

Nanoscale objects are processed by living organisms using highly evolved and sophisticated endogenous cellular networks, specifically designed to manage objects of this size. While these processes potentially allow nanostructures unique access to and control over key biological machineries, they are also highly protected by cell or host defence mechanisms at all levels. A thorough understanding of bionanoscale recognition events, including the molecules involved in the cell recognition machinery, the nature of information transferred during recognition processes and the coupled downstream cellular processing, would allow us to achieve a qualitatively novel form of biological control and advanced therapeutics. Here we discuss evolving fundamental microscopic and mechanistic understanding of biological nanoscale recognition. We consider the interface between a nanostructure and a target cell membrane, outlining the categories of nanostructure properties that are recognized, and the associated nanoscale signal transduction and cellular programming mechanisms that constitute biological recognition.

Tritrophic interaction between the Mexican sunflower, the aphid Aphis gossypii and natural enemies in a greenhouse experiment

The establishment of invasive plants negatively affects natural environments. Invasive herbivores that attack weeds can be used as a form of biological control, but natural enemies of herbivores must be associated with this interaction to prevent the invasive phytophagous from become a local pest. We performed a greenhouse experiment to evaluate how the cotton aphid, Aphis gossypii, a ok and invasive herbivore, affects the performance of the weed Tithonia diversifolia, the Mexican sunflower. We also examined the relationship between the aphid and local natural enemies. Seedlings of T. diversifolia were divided in two groups: one infested by the aphid and another not infested. After 22 days, we assessed the relationship between aphid abundance and the presence of natural enemies (Coccinelidae and Aphidius platensis) on infested plants, and compared the vegetative performance of the two seedling groups. Both natural enemies were positively related to high aphid density on infested plants. Plants infested by the aphid presented foliar necrosis and senescence, and a reduction of around 50% in leaf number, foliar area, shoot length and shoot, root and total plant weight compared to non-infested plants. These results indicate potential biological control of Mexican sunflower seedlings by the cotton aphid, and control of this aphid by the studied natural enemies.

Bioprospecting of Bacillus thuringiensis in the control of Aedes aegypti larvae

Aedes aegypti (Diptera: Culicidae) is the main vector of Dengue, Zika and Chikungunya, diseases that have attracted the attention of scientific society and the population in general, due to epidemiological outbreaks and numerous health hazards and the imminent risk of death. Much has been discussed about more efficient forms of control for this mosquito, considering that the chemical control, currently used, has been causing impacts on the environment and the health of the population. Thus, alternative methods have been evaluated. Among them, biological control through products formulated from Bacillus thuringiensis has stood out, as biotechnological advances have allowed to improve and enhance the products already on the market, as well as to develop new bioinsecticides from the entomopathogenic proteins produced by these microorganisms, aiming to make the larvae control more and more effective. To this end, this study aimed to carry out a bibliographic survey on the use of Bacillus thuringiensis as a form of biological control of Aedes aegypti larvae, due to the need to use safer and more effective methods of control for disease vector insects.

Pesticides in agriculture

Pesticides in agriculture

Phylogeny and Molecular Study of Some Entomopathogenic Rhizobacteria Isolated from Two Regions in Algeria

The use of bacteria in the control of insect pests is a form of biological control whose practice is still not widespread. It is in this context that the present work falls. It concerns the isolation, characterization and identification of local bacterial strains for the purpose of their use in the control of certain pests. Indeed, 20 bacteria were isolated from soil cultivated in the region of Boumerdes (center of Algeria) with a total of 21 bacterial strains isolated from Adrar region (Desert Algerian). After carrying out the efficacy tests against 2 insect pests; Migratory locust (Locusta migratoria) and wax moth (Galleria mellonella), 8 potentially interesting strains were identified based on their genetic traits. Molecular characterization of these strains was performed by isolation of DNA, PCR and sequencing of the 16S rRNA gene, followed by phylogenetic analysis. The rDNA16S sequences of the 8 strains named B1, B2, B3, B4, B5, B6, H1 and H2 were recorded in the EMBL/EBI database and their phylogenetic analysis revealed that they belong to the genera Bacillus, Pseudomonas, Enterobacter and Delftia with a very high percentage of similarity with Bacillus thuringiensis strains (NR_043403) (99%) for isolate B1, Bacillus weihenstephanensis (NR_024697) (99%) for isolate B2, Pseudomonas fragi (JCM5420) (99%) for isolates B3 and B4, Bacillus thuringiensis (CMBLBT-5) (99%) for isolate B4, Enterobacter ludwigii (EN-119) for B5, Bacillus thuringiensis (4916) (99%) for isolate H1 and Delftia lacustris (R-54734) (100%) for isolate H2.

Biology ofTrichogramma pretiosum(Hymenoptera: Trichogrammatidae) Fed Transgenic Maize Pollen

Abstract Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) is an important natural egg parasitoids of pest insects in the agricultural environment, being used as a form of biological control, and it may be affected by the Bacillus thuringiensis (Bt) toxin present in transgenic plants widely used in Brazil. The aim of this study was to evaluate the effect of Bt maize pollen fed to adults of the parasitoid T. pretiosum Riley (Hymenoptera: Trichogrammatidae) reared in the eggs of the alternate host Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). Three treatments (diets) were compared: pollen from Bt maize, pollen from non-Bt maize, and 10% honey solution (control). Each treatment consisted of 50 T. pretiosum females that were freshly emerged and mated (between 24 and 36 h old). Biological characteristics indicative of the efficiency of T. pretiosum as a biological control agent were evaluated for 4 generations. The results suggest that the consumption of pollen did not affect the evaluated b...

Genetically modified soybean expressing insecticidal protein (Cry1Ac): Management risk and perspectives

A Bt soybean has been recently developed, thus, efficiently regulating the populations of major lepidopteran pests. However, in other cases, these benefits have been reduced or lost because of the rapid evolution of pest resistance to the Bt toxins in transgenic crops. When pest populations are exposed to Bt crops and to refuges (non- Bt plants), the evolution of resistance is governed by the fitness of resistant individuals relative to susceptible individuals for both the presence and absence of Bt toxins. One major ecological concern regarding the biosafety of Bt crops on the environment is their potential effects on non-target organisms, especially predators and parasitoids that play an important role in pest control. This information is important for supporting insect resistance management (IRM) programs and for improving agricultural practices in a crop production system with Bt plants. Before the use of Bt plants for insect pest control in Brazil is adopted, IRM programs should be established to ensure the sustainability of this technology for integrated pest management (IPM). This review presents data on Bt soybean and lepidopteran pests as well as on the importance of natural enemies as a form of biological control, and applications for IPM and IRM.

Active bacteriophage biocontrol and therapy on sub-millimeter scales towards removal of unwanted bacteria from foods and microbiomes.

Bacteriophages can be used as antibacterial agents as a form of biological control, e.g., such as phage therapy. With active treatment, phages must “actively” produce new virions, in situ, to attain “inundative” densities, i.e., sufficient titers to eradicate bacteria over reasonable timeframes. Passive treatment, by contrast, can be accomplished using phages that are bactericidal but incapable of generating new phage virions in situ during their interaction with target bacteria. These ideas of active versus passive treatment come from theoretical considerations of phage therapy pharmacology, particularly as developed in terms of phage application to well-mixed cultures consisting of physically unassociated bacteria. Here I extend these concepts to bacteria which instead are physically associated. These are bacteria as found making up cellular arrangements or bacterial microcolonies—collectively, clonal bacterial “clumps”. I consider circumstances where active phage replication would be required to effect desired levels of bacterial clearance, but populations of bacteria nevertheless are insufficiently prevalent to support phage replication to bacteria-inundative densities across environments. Clumped bacteria, however, may still support active treatment at more local, i.e., sub-millimeter, within-clump spatial scales, and potential consequences of this are explored mathematically. Application is to the post-harvest biocontrol of foodborne pathogens, and potentially also to precise microbiome editing. Adequate infection performance by phages in terms of timely burst sizes, that is, other than just adsorption rates and bactericidal activity, thus could be important for treatment effectiveness even if bacterial densities overall are insufficient to support active treatment across environments. Poor phage replication during treatment of even low bacterial numbers, such as given food refrigeration during treatment, consequently could be problematic to biocontrol success. In practical terms, this means that the characterization of phages for such purposes should include their potential to generate new virions under realistic in situ conditions across a diversity of potential bacterial targets.

Genetics and insect pest management in agriculture.

Abstract Genetics has long played a role in the history of insect pest management, and changes in the genetic methods used reflect changes that have occurred in the field itself over time. Beginning from simple collections of mutations and the development of chromosome linkage maps, many of the early applications of genetic technology were focused on the development of new strains for the sterile insect technique as a form of biological control. Since that time, and as the field of genetics underwent a true merger with molecular biology, the focus shifted almost entirely to methods using molecular technology. These methods had the advantage of being more broadly applicable to control of a wide range of pest species, and this did much to move the field away from the frustrations often associated with attempts to transfer genetic tools developed in Drosophila directly to these species. The latest applications of molecular genetic technologies in the area of genetically based control methods now also include cutting-edge systems for genome editing and the use of RNA inhibition for selectively knocking out the expression of individual genes. Finally, as the field of genetics has shifted its focus from the analysis of individual genes to that of entire genomes, new and exciting prospects are opening up for improvements in use of genetic technology for the management of insect pests.

Wolbachia versus dengue

A novel form of biological control is being applied to the dengue virus. The agent is the maternally transmitted bacterium Wolbachia, naturally absent from the main dengue vector, the mosquito Aedes aegypti. Three Wolbachia-based control strategies have been proposed. One is suppression of mosquito populations by large-scale releases of males incompatible with native females; this intervention requires ongoing releases. The other interventions transform wild mosquito populations with Wolbachia that spread via the frequency-dependent fitness advantage of Wolbachia-infected females; those interventions potentially require just a single, local release for area-wide disease control. One of these latter strategies uses Wolbachia that shortens mosquito life, indirectly preventing viral maturation/transmission. The other strategy uses Wolbachia that block viral transmission. All interventions can be undermined by viral, bacterial or mosquito evolution; viral virulence in humans may also evolve. We examine existing theory, experiments and comparative evidence to motivate predictions about evolutionary outcomes. (i) The life-shortening strategy seems the most likely to be thwarted by evolution. (ii) Mosquito suppression has a reasonable chance of working locally, at least in the short term, but long-term success over large areas is challenging. (iii) Dengue blocking faces strong selection for viral resistance but may well persist indefinitely at some level. Virulence evolution is not mathematically predictable, but comparative data provide no precedent for Wolbachia increasing dengue virulence. On balance, our analysis suggests that the considerable possible benefits of these technologies outweigh the known negatives, but the actual risk is largely unknown.

Benefits and Costs of Controlling Rangeland Grasshoppers (Orthoptera: Acrididae) with Exotic Organisms: Search for a Null Hypothesis and Regulatory Compromise

The rebuttal of Lockwood (1993, Environ. Entomol. 22:503–518) by Carruthers & Onsager (1993, Environ. Entomol. 22:[in press]) focuses on the elements of cost-benefit analysis and regulatory policy. I present the case that “native” has ecological, evolutionary, ethical, and legal meaning (hence the term neoclassical biological control is justified). In comparing the costs and benefits of grasshoppers (using only conditional values), the argument that costs of widespread damage and control exceed the benefits interms of sustained ecological and economic productivity is not supported by available data, whether we consider the interests of the rancher or the public. Moreover, when unconditional values are included, neoclassical control of rangeland grasshoppers becomes indefensible. Contrary to selected evidence presented by Carruthers & Onsager (1993), existing data show that native biological control agents are as or more effective in population regulation than the exotic agents. Host ranges of the exotic organisms are essentially unknown given the quality and quantity of available data, so ecological safety assurances are unfounded. A careful review of the data used to demonstrate the probability of success by the proposed exotic agents clearly demonstrates that these organisms have a very lowlikelihood of economic or ecological benefit. The essential ecological differences between various forms of biological control must be addressed in terms of regulatory policies and procedures. Existing federal laws may be sufficient to protect the agricultural and environmental interests of western rangeland, but only if these laws are interpreted and enforced from a sound ecological basis.

Mitotic stability and nuclear inheritance of integrated viral cDNA in engineered hypovirulent strains of the chestnut blight fungus.

Transmissible hypovirulence is a novel form of biological control in which virulence of a fungal pathogen is attenuated by an endogenous RNA virus. The feasibility of engineering hypovirulence was recently demonstrated by transformation of the chestnut blight fungus, Cryphonectria parasitica, with a full-length cDNA copy of a hypovirulence-associated viral RNA. Engineered hypovirulent transformants were found to contain both a chromsomally integrated cDNA copy of the viral genome and a resurrected cytoplasmically replicating double-stranded RNA form. We now report stable maintenance of integrated viral cDNA through repeated rounds of asexual sporulation and passages on host plant tissue. We also demonstrate stable nuclear inheritance of the integrated viral cDNA and resurrection of the cytoplasmic viral double-stranded RNA form in progeny resulting from the mating of an engineered hypovirulent C. parasitica strain and a vegetatively incompatible virulent strain. Mitotic stability of the viral cDNA ensures highly efficient transmission of the hypovirulence phenotype through conidia. Meiotic transmission, a mode not observed for natural hypovirulent strains, introduces virus into ascospore progeny representing a spectrum of vegetative compatibility groups, thereby circumventing barriers to anastomosis-mediated transmission imposed by the fungal vegetative incompatibility system. These transmission properties significantly enhance the potential of engineered hypovirulent C. parasitica strains as effective biocontrol agents.

Environmental Issues Involved in Biological Control of Rangeland Grasshoppers (Orthoptera: Acrididae) with Exotic Agents

Within the field of biological control, there is a strategy that involves the attempt to control a native pest species with an exotic biological control agent. This strategy has been termed neoclassical biological control, and its ecological foundation differs markedly from other forms of biological control. Neoclassical biological control with a parasitic wasp and an entomophagous fungus from Australia is now being applied to rangeland grasshoppers in the western United States. Available evidence suggests that the costs of such a strategy greatly exceed the benefits. Although the probability of successful establishment may be low, if such an agent is established there are a number of possible nontarget impacts. Adverse effects include competitive suppression or extinction of both native biological control agents and nontarget acridids, which comprise the vast majority of extant grasshopper species. Suppression of nontarget acridids may result in loss of biological diversity, existing control of weed species, release of otherwise innocuous acridid species from competitive regulation, disruption of plant community structure, suppression of essential organisms vectored by grasshoppers, and disruption of food chains and other nutrient cycling processes. These impacts are particularly serious given that an established exotic agent is essentially permanent and spatially unbounded. Given that the value of the rangeland resource depends upon the largely unknown ecological processes that underlie its sustainable productivity, there are a number of management techniques that offer a greater probability of success with a markedly lower likelihood of ecological and economic disruption than does neoclassical biological control.

Evolution of resistance with sequential application of insecticides in time and space

The effect, on the evolution of resistance, of alternating two unrelated insecticides in space or in time (or both) is studied. Transient polymorphism is shown to occur under certain conditions of mating, selection and migration. In some situations, the transient polymorphism can show a sharp decline before the alleles recover to fixation. Alternating a single insecticide in space, and in space and time, is also considered. Neither alternation in space nor in time shows any advantage with regard to delaying the onset of resistance. The most promising mode is to alternate the presence and absence of a single insecticide in both space and time, especially if it is applied at the larval stage and if some form of biological control is used in the regions where no insecticide is applied.

A comparison, by sweep sampling, of the insect fauna from corn and sweet potato monocultures and dicultures in Costa Rica.

The insect fauna of 80 day-old plots of corn and sweet potato monocultures and dicultures in Costa Rica were compared using sweep sampling. Six hundred sweeps were taken in each of the three habitats. There were 15% more total species in the diculture than either monoculture but approximately the same total number of individuals. There were 75% more species and approximately 100% more individuals of parasitic Hymenoptera in the diculture than the monocultures. The ratio of numbers of phytophagous individuals to predaceous/parasitic individuals was lowest in the diculture (2.5) and highest in the sweet potato monoculture (14.3). It is suggested that these patterns may be explained if phytophagous insects are limited basically by abundance and diversity of food so that a diculture is at best the sum of two monocultures. However if abundance and diversity of parasitic insects depends more on structural complexity, the result of putting together two monocultures would be synergistic in terms of numbers and species of insects.Two chrysomelid beetles and two leaf-hopper species that were extremely common in the monocultures were significantly less common or absent in the polyculture, and only one leaf-hopper that was rare in the monocultures was relatively more common in the diculture. Comparison of species similarity showed that the corn monoculture and the diculture were much more similar than the sweet potato monoculture and the diculture, and the two monocultures showed the least similarity.Statistically smoothed out species-subsample curves were constructed for each of the three habitats, the curves were fitted to a mathematical model, and they were then extended in order to predict the theoretical total number of species in all three communities sampled. Extrapolation of the curves suggests that approximately 33% of the total sweepable insect community was sampled in the three habitats.One year after the initial sweep samples were taken, the populations of two sweet potato pests, Diabrotica balteata and Diabrotica adelpha, were sampled ten times over a 120 day period in plots of corn and sweet potato monocultures and dicultures. Approximately 50 days after planting, the numbers of both beetles on sweet potato in monocultures were much higher than in dicultures. This trend continued the rest of the season, the difference reaching a maximum approximately 90 days after planting.These data suggest that indigenous agriculturalists are correct: increasing resource diversity in a cropping system may act as a form of biological control, by increasing the relative abundance and diversity of the predaceous parasitic fauna and decreasing the abundance of the major herbivores.