Biological Control Mechanisms Research Articles

Role of egg-laying behavior, virulence and local adaptation in a parasitoid’s chances of reproducing in a new host

Understanding the ability of parasitoid insects to succeed in new host populations is a relevant question for biological control and adaptive mechanisms. Cotesia typhae is an African parasitoid specialized on the moth Sesamiae nonagrioides, also called the Mediterranean corn borer. Two Kenyan strains of C. typhae differ in their virulence against a new host population from France. We explored behavioral and physiological hypotheses about this differentiation. Cotesia genus belongs to a group of Hymenoptera in which females inject a domesticated virus in their host to overcome its resistance. Since viral particles are injected along with eggs and since the strain with the higher virulence injects more eggs, we hypothesized that virulence could be explained by the quantity of virus injected. To test this assumption, we measured the injected quantities of eggs and viral particles (estimated by viral DNA segments) of each parasitoid strain along several ovipositions, to vary these quantities. Unexpectedly, results showed that virulence against the French host was not correlated to the injected quantities of eggs or viral segments, indicating that virulence differentiation is explained by other causes. The virulence against the respective natural hosts of the two C. typhae strains was also measured, and results suggest that local adaptation to a more resistant natural host may explain the pre-adaptation of one strain to the new host population. We also identified a differentiation of oviposition strategy and subsequent offspring number between the parasitoid strains, which is important in a biocontrol perspective.

ESTRATEGIAS DE CONTROL BIOLÓGICO UTILIZADAS PARA EL MANEJO DE LA ANTRACNOSIS CAUSADA POR Colletotrichum gloeosporioides EN FRUTOS DE MANGO: UNA REVISIÓN SISTEMÁTICA

<p>The mango (<em>Mangifera indica</em> L.) is one of the most produced tropical fruits in the world, however, during post-harvest it is affected by pathogens such as <em>Colletotrichum gloeosporioides</em>, which causes mango anthracnose. Synthetic fungicides are generally used to control this disease, but prolonged use can cause health and environmental effects; Therefore, biological control emerges as an alternative for the management of this disease, given that it is considered an effective and safe technique. The objective of this study was to describe the biological control strategies used for the management of anthracnose caused by <em>C. gloeosporioides</em> in mango fruits from a systematic review of the scientific literature. The ScienceDirect, Scopus and Scholar Google databases were used. It was found that the largest number of publications were made in 2013 and 2017, with Ataúlfo and Tommy Atkins as the most studied mango varieties and Mexico was the country with the highest number of articles reported. The most studied biological control mechanism was the effect of functional groups of microorganisms on mycelial growth and the highest percentages of inhibition were reported for this mechanism, although the greatest number of reports on control mechanisms were of the category of antagonistic microorganisms. It is concluded that knowledge about the mechanisms used to control anthracnose will allow adopting more effective, practical and reliable measures; thus, managing to maintain mango quality during the storage, distribution and marketing period.</p>

STUDY OF A PREDATOR–PREY MODEL WITH PEST MANAGEMENT PERSPECTIVE

Recently, pest control has become a very interesting research topic because it is closely associated with agricultural and economic loss. Empirical evidence shows that pest insects are responsible for lower crop production and many other adverse effects on the farming sector. There are several biological, physical and chemical control mechanisms. However, the biological control of pest populations by using natural enemies is one of the most important ecosystem services adopted in agriculture around the world. In the present study, we consider an ecological model consisting of prey (pest) and its natural enemy as the predator. Different system equilibria are obtained, their stability is analyzed, and Hopf bifurcation of the system around the interior equilibrium is discussed. The sufficient permanence criteria of the system are also derived. Moreover, we perform bifurcation analysis to explore the existence of limit cycle. We also investigate the stability property of the positive periodic solution when the interior equilibrium loses its stability. Our analytical results are further verified through numerical simulations. Our findings suggest that, in the absence of a super predator, pest and natural enemy show stable coexistence. However, in the presence of super predator, if the natural enemy is killed at a lower rate, both pest and natural enemy coexist. Finally, above a threshold value, the natural enemy is eradicated from the system and pest outbreak occurs.

Valinomycin, produced by Streptomyces sp. S8, a key antifungal metabolite in large patch disease suppressiveness

Large patch disease, caused by Rhizoctonia solani AG2-2, is the most devastating disease in Zoysiagrass (Zoysia japonica). Current large patch disease control strategies rely primarily upon the use of chemical pesticides. Streptomyces sp. S8 is known to possess exceptional antagonistic properties that could potentially suppress the large patch pathogen found at turfgrass plantations. This study aims to demonstrate the feasibility of using the strain as a biological control mechanism. Sequencing of the S8 strain genome revealed a valinomycin biosynthesis gene cluster. This cluster is composed of the vlm1 and vlm2 genes, which are known to produce antifungal compounds. In order to verify this finding for the large patch pathogen, a valinomycin biosynthesis knockout mutant was created via the CRISPR/Cas9 system. The mutant lost antifungal activity against the large patch pathogen. Consequently, it is anticipated that eco-friendly microbial preparations derived from the S8 strain can be utilized to biologically control large patch disease.

Biocontrol and Action Mechanism of Bacillus amyloliquefaciens and Bacillus subtilis in Soybean Phytophthora Blight.

With the improper application of fungicides, Phytophthora sojae begins to develop resistance to fungicides, and biological control is one of the potential ways to control it. We screened two strains of Bacillus; Bacillus amyloliquefaciens JDF3 and Bacillus subtilis RSS-1, which had an efficient inhibitory effect on P. sojae. They could inhibit mycelial growth, the germination of the cysts, and the swimming of the motile zoospores. To elucidate the response of P. sojae under the stress of B. amyloliquefaciens and B. subtilis, and the molecular mechanism of biological control, comparative transcriptome analysis was applied. Transcriptome analysis revealed that the expression gene of P. sojae showed significant changes, and a total of 1616 differentially expressed genes (DEGs) were detected. They participated in two major types of regulation, namely “specificity” regulation and “common” regulation. They might inhibit the growth of P. sojae mainly by inhibiting the activity of ribosome. A pot experiment indicated that B. amyloliquefaciens and B. subtilis enhanced the resistance of soybean to P. sojae, and their control effects of them were 70.7% and 65.5%, respectively. In addition, B. amyloliquefaciens fermentation broth could induce an active oxygen burst, NO production, callose deposition, and lignification. B. subtilis could also stimulate the systemic to develop the resistance of soybean by lignification, and phytoalexin.

Perception of Asian carp as a possible food source among Missouri anglers

ABSTRACTSilver and bighead carps were imported from China to the United States in the 1970s as a biological control mechanism for improving water quality. After escaping captivity, both species spread into the Mississippi River Basin and now threaten to enter the Great Lakes. Human consumption is one solution, but many Americans believe that carp is unsavory. A random sample of 2,000 licensed anglers in Missouri was asked to complete a mail-back questionnaire about Asian carp, yielding a 27% response rate (n = 465). Results indicated that knowledge and perception about carp were poor, and food neophobia (fear of new foods) scores were above average. Less than 15% of respondents had eaten carp, but nearly 53% were willing to try. Marketing should focus on the benefits of consumption while downplaying any possible concerns. Although education programs are worthwhile, taste might be more influential to change public attitudes toward Asian carp.

Mixtures of tritiated water, zinc and dissolved organic carbon: Assessing interactive bioaccumulation and genotoxic effects in marine mussels, Mytilus galloprovincialis

Release of tritium (3H) in the marine environment is of concern with respect to its potential bioaccumulation and detrimental impact on the biota. Previous studies have investigated the uptake and toxicity of this radionuclide in marine mussels, and the interaction of 3H with dissolved organic ligands and elevated temperature. However, despite the well-established view that toxicity is partly governed by chemical speciation, and that toxic effects of mixture of contaminants are not always additive, there have been no studies linking the prevailing chemistry of exposure waters with observed biological effects and tissue specific accumulation of 3H in combination with other constituents commonly found in natural waters. This study exposed the marine mussel Mytilus galloprovincialis for 14 days to mixtures of 3H (as tritiated water, HTO) and zinc (Zn) at 5 Mbq L−1, and 383, 1913 and 3825 nM Zn, respectively, to investigate (a) 3H and Zn partitioning in soft tissues of mussels, and (b) DNA damage in haemocytes, determined using the single cell gel electrophoresis or the comet assay. Additionally, the extent of association of 3H with dissolved organic carbon (DOC, added as humic acid) over the exposure period was investigated in order to aid the interpretation of biological uptake and effects. Results concluded a clear antagonistic effect of Zn on 3H-induced DNA damage at all Zn concentrations used, likely explained by the importance of Zn in DNA repair enzymes. The interaction of DOC with 3H was variable, with strong 3H-DOC associations observed in the first 3 d of the experiment. The secretion of 3H-binding ligands by the mussels is suggested as a possible mechanism for early biological control of 3H toxicity. The results suggest risk assessments for radionuclides in the environment require consideration of potential mixture effects.

Comparative study of cocoa black ants temporal population distribution utilizing geospatial analysis

Cocoa plantation also subjected to diseases and pests infestation. Some pests not only reduced the yield but also inhibit the growth of trees. Therefore, the Malaysia Cocoa Board (MCB) has explored Cocoa Black Ants (CBA) as one of their biological control mechanism to reduce the pest infestation of the Cocoa Pod Borer (CPB). CPB is capable to cause damage to cocoa beans, and later on will reduce the quality of dried cocoa beans. This study tries to integrate the use of geospatial analysis in understanding population distribution pattern of CBA to enhance its capability in controlling CPB infestation. Two objectives of the study are i) to generate temporal CBA distribution of cocoa plantation for two different blocks, and ii) to compare visually the CBA population distribution pattern with the aid of geospatial technique. This study managed to find the CBA population pattern which indicated spatially modest amount of low pattern distribution in February of 2007 until reaching the highest levels of ant populations in September 2007 and decreasing by the end of the year in 2009 for two different blocks (i.e 10B and 18A). Therefore, the usage of GIS is important to explain the CBA pattern population in the mature cocoa field. This finding might to be used as an indicator to examine the optimum distribution of CBA, which needed as a biological control agent against the CPB in the future.

Construction as biological cells: an exploratory study

ABSTRACTPerfection in nature is inspiring. The near-flawless proliferation of biological cells to construct a functional structure based on an embedded design is impressive. Accordingly, biological cell theory is explored using simile and metaphor to draw further inspiration for developing new insights. It is shown through examples that cells similar to biological cells can indeed be identified in construction including embedded designs. Biological cell properties are reviewed, and three properties, namely embedded design, rate of cell proliferation, and biological cell control mechanism are explored synthesizing new insights for managing construction. A new model symbolized as Readiness–Growth–Rest (RGR) consisting of three main states has also been proposed for cell-based construction driven by the embedded design. It consists of a readiness gate to ensure the embedded design is flawless and its readiness to enter the Growth state with transient growth checks and a completion gate. Any cell abnormality during the Growth state including any instability in the rate of cell proliferation diverts the cell into a Transient Rest state for appropriate action before it is permitted to re-enter the Growth state. The suitability, acceptability, and feasibility of the RGR model needs to be ascertained further for cell-based construction to be a greater reality.

A PREDATOR-PEST MODEL WITH ALLEE EFFECT AND PEST CULLING AND ADDITIONAL FOOD PROVISION TO THE PREDATOR — APPLICATION TO PEST CONTROL

The harmful effects of insect pests on human health and agricultural output are a major global concern. Frequent use of chemical pesticides as a means of pest control can have detrimental effects on the environment, resulting in water and soil pollution, food toxicity, resistance to pesticides, etc. As a result, there is an urgent need to develop a biological pest-control approach that would mitigate these harmful effects. The main purpose of the present study is to explore the interaction between strong Allee effects in the pest with other biological control mechanisms, such as providing additional food to the predator and pest culling as a means of proposing an efficient pest-control policy. To achieve this goal, local stability analysis around the equilibria, possible bifurcation and some basic dynamical features of the system was performed. Our work focuses on the basin of stability in multiple stable regions of the model, which yields the probability of convergence of each equilibrium for a given set of different initial conditions. The system exhibits bi-stability and tri-stability of the equilibria. Our findings indicate that providing additional food to the predator can be an efficient stand-alone pest control strategy, which can, if needed, be combined with other methods.

Induced systemic resistance (ISR) in hot pepper against Phytophthora capsici infection triggered by cell wall oligosaccharide elicitors from Trichoderma species

Induced systemic resistance, one of the mechanisms of biological control is elicited either by oligosaccharides or glycoproteins released from cell wall of fungal bioagents like Trichoderma species. Oligosaccharide elicitors from 10 Trichoderma isolates having biocontrol potential were tested for their ability to elicit ISR in hot pepper against Phytophthora capsici infection. Treatment with elicitors from isolates Th10, Th9, Th33 and Th28 reduced P. capsici infection in hot pepper by 70–80% compared to 100% infection in pathogen inoculated control. Assays of peroxiase (PO), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL) and glucanase revealed that elicitor treatment significantly induced higher enzyme activity in elicitor treated plants compared to control. Induction of more number of isoforms of PO and PPO was also observed. Elicitors from Th10 and Th33 induced two fold increase in PPO and PAL and three-fold increase in PO, while Th28 and Th9 increased PPO and glucanase by two folds. Different enzymes (involved in phenyl propanoid metabolism or hydryolytic enzymes) contributed to ISR in different isolates.

Cloning of Autophagy-Related MicroRNAs.

Autophagy is a cellular survival pathway that is necessary for the degradation of cellular constituents such as long-lived proteins and damaged organelles. Conditions resulting in cellular stress such as starvation or hypoxia might activate autophagy. Being at the crossroads of various cellular response pathways, dysregulation of autophagy might result in pathological states including cancer and neurodegenerative diseases. Autophagy has also been shown to participate in stemness. MicroRNAs were introduced as novel regulators of autophagy, and accumulating results underlined the fact that they constituted an important layer of biological control mechanism on the autophagic activity.MicroRNAs are protein noncoding small RNAs that control cellular levels of transcripts and proteins through posttrancriptional mechanisms. Novel miRNAs in human and mouse genomes are yet to be identified. Considering the emerging role of autophagy in health and disease, identification of novel autophagy-regulating miRNAs and determination of relations between miRNA expression and physiological and pathological conditions might contribute to a better understanding of mechanisms governing health and disease. High-throughput techniques were developed for miRNA profiling, yet for a thorough characterization and miRNA target determination, miRNA cloning remains as an important step. Here, we describe a modified miRNA cloning method for the characterization of novel autophagy-regulating miRNAs.

Understanding the mechanism of biological control of postharvest phytopathogenic moulds promoted by food isolated yeasts

Understanding the mechanism of biological control of postharvest phytopathogenic moulds promoted by food isolated yeasts

Cerebellar-inspired algorithm for adaptive control of nonlinear dielectric elastomer-based artificial muscle.

Electroactive polymer actuators are important for soft robotics, but can be difficult to control because of compliance, creep and nonlinearities. Because biological control mechanisms have evolved to deal with such problems, we investigated whether a control scheme based on the cerebellum would be useful for controlling a nonlinear dielectric elastomer actuator, a class of artificial muscle. The cerebellum was represented by the adaptive filter model, and acted in parallel with a brainstem, an approximate inverse plant model. The recurrent connections between the two allowed for direct use of sensory error to adjust motor commands. Accurate tracking of a displacement command in the actuator's nonlinear range was achieved by either semi-linear basis functions in the cerebellar model or semi-linear functions in the brainstem corresponding to recruitment in biological muscle. In addition, allowing transfer of training between cerebellum and brainstem as has been observed in the vestibulo-ocular reflex prevented the steady increase in cerebellar output otherwise required to deal with creep. The extensibility and relative simplicity of the cerebellar-based adaptive-inverse control scheme suggests that it is a plausible candidate for controlling this type of actuator. Moreover, its performance highlights important features of biological control, particularly nonlinear basis functions, recruitment and transfer of training.

Advancing vector biology research: a community survey for future directions, research applications and infrastructure requirements

Vector-borne pathogens impact public health, animal production, and animal welfare. Research on arthropod vectors such as mosquitoes, ticks, sandflies, and midges which transmit pathogens to humans and economically important animals is crucial for development of new control measures that target transmission by the vector. While insecticides are an important part of this arsenal, appearance of resistance mechanisms is increasingly common. Novel tools for genetic manipulation of vectors, use of Wolbachia endosymbiotic bacteria, and other biological control mechanisms to prevent pathogen transmission have led to promising new intervention strategies, adding to strong interest in vector biology and genetics as well as vector–pathogen interactions. Vector research is therefore at a crucial juncture, and strategic decisions on future research directions and research infrastructure investment should be informed by the research community. A survey initiated by the European Horizon 2020 INFRAVEC-2 consortium set out to canvass priorities in the vector biology research community and to determine key activities that are needed for researchers to efficiently study vectors, vector-pathogen interactions, as well as access the structures and services that allow such activities to be carried out. We summarize the most important findings of the survey which in particular reflect the priorities of researchers in European countries, and which will be of use to stakeholders that include researchers, government, and research organizations.

Consequence of Prey Refuge in a Tri-trophic Prey-dependent Food Chain Model with Intra-specific Competition

The present article deals with the influence of a constant proportion of prey refuge in presence of intra-specific competition among predator population of a prey-dependent three species food chain model. The behaviour of the system near the biologically feasible equilibria is thoroughly analyzed. The preliminary results such as boundedness and dissipativeness of the system are established. Stability analysis including local and global stability of the equilibria has been carried out in order to examine the behaviour of the system. The present system experiences Hopf-Andronov bifurcation for suitable choice of the parameter values. The influences of the prey refuge parameters on the dynamical behaviour of the system are exhibited through several plots and discussed at some equilibrium positions. It is worth-noting that prey refuge has stabilization effect in some selected situations and bears the potential to control chaotic dynamics of the system. Hence, prey refuge may be of some use for biological control mechanism. Numerical simulations are performed to validate the applicability of the model under consideration.

N-Terminal Coiled-Coils in the Human Kinesin-5 and Kinesin-1 Stalk are Sufficient for Tetrameric Organization

Oligomerization is a key biological control mechanism in protein function. Homo-dimerization versus homo-tetramerization transforms cellular function for different members of a protein superfamily. Case in point, the homotetrameric organization of Kinesin-5 proteins, via a ∼500 amino acid coiled-coil stalk, underlies their ability to organize the mitotic spindle. Little is known about the rules that govern homo-oligomerization of Kinesin-5 proteins. Our goal is to uncover the trigger sequence, or the element indispensable for tetramer formation, in Kinesin-5. Herein, sequence profiling tools show that the first 150 - 200 residues of the stalk is the only region, common to Kinesin-5 and Kinesin-1 proteins, that is calculated to form coiled-coils; the remaining ∼350 residues in Kinesin-5 exhibit variability in expected coiled-coil formation and do not parallel predictions for the dimeric Kinesin-1 proteins. In two protein constructs containing the first 141 residues of the stalk, in vitro tetramerization of the coiled-coil peptide and the truncated form of the human Kinesin-5 protein was observable by size-exclusion chromatography, static light scattering, and macro-ion mobility spectrometry. We also determined that the human Kinesin-5 and a chimeric protein consisting of the Kinesin-5 motor domain and Kinesin-1 stalk can crosslink and move more than one microtubule in situ. Our data support that, for more than one kinesin family member, the N-terminal portion of the stalk permits tetramerization. Regulation of the dimer-to-tetramer transition may require the sequence of flanking necklinker and C-terminal stalk domains.

A Mechanism for Biological Control—Tempo-Spatial Synchronization of Natural Enemy and Insect Pest Population Dynamics at the Peak by Increase of Biodiversity

A Mechanism for Biological Control—Tempo-Spatial Synchronization of Natural Enemy and Insect Pest Population Dynamics at the Peak by Increase of Biodiversity

SpIDA Surveys the Intricate Web of Macromolecular Oligomerization In Situ

The analysis of the quaternary state of proteins continues to be of importance in biophysics (1). Oligomerization is a key biological control mechanism in the functioning of proteins at the cell membrane and throughout the cellular milieu. For example, receptors involved in cell signaling appear to trigger cellular responses after dimerization or oligomerization from external cues (i.e., after ligand binding) (2). Likewise, an increasing number of diseases have been found to be related to inappropriate aggregation or oligomerization leading to pathological states (3).

Unearthing the genomes of plant-beneficial Pseudomonas model strains WCS358, WCS374 and WCS417.

BackgroundPlant growth-promoting rhizobacteria (PGPR) can protect plants against pathogenic microbes through a diversity of mechanisms including competition for nutrients, production of antibiotics, and stimulation of the host immune system, a phenomenon called induced systemic resistance (ISR). In the past 30 years, the Pseudomonas spp. PGPR strains WCS358, WCS374 and WCS417 of the Willie Commelin Scholten (WCS) collection have been studied in detail in pioneering papers on the molecular basis of PGPR-mediated ISR and mechanisms of biological control of soil-borne pathogens via siderophore-mediated competition for iron.ResultsThe genomes of the model WCS PGPR strains were sequenced and analyzed to unearth genetic cues related to biological questions that surfaced during the past 30 years of functional studies on these plant-beneficial microbes. Whole genome comparisons revealed important novel insights into iron acquisition strategies with consequences for both bacterial ecology and plant protection, specifics of bacterial determinants involved in plant-PGPR recognition, and diversity of protein secretion systems involved in microbe-microbe and microbe-plant communication. Furthermore, multi-locus sequence alignment and whole genome comparison revealed the taxonomic position of the WCS model strains within the Pseudomonas genus. Despite the enormous diversity of Pseudomonas spp. in soils, several plant-associated Pseudomonas spp. strains that have been isolated from different hosts at different geographic regions appear to be nearly isogenic to WCS358, WCS374, or WCS417. Interestingly, all these WCS look-a-likes have been selected because of their plant protective or plant growth-promoting properties.ConclusionsThe genome sequences of the model WCS strains revealed that they can be considered representatives of universally-present plant-beneficial Pseudomonas spp. With their well-characterized functions in the promotion of plant growth and health, the fully sequenced genomes of the WCS strains provide a genetic framework that allows for detailed analysis of the biological mechanisms of the plant-beneficial traits of these PGPR. Considering the increasing focus on the role of the root microbiome in plant health, functional genomics of the WCS strains will enhance our understanding of the diversity of functions of the root microbiome.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1632-z) contains supplementary material, which is available to authorized users.