What Is A Biological System
Although it sounds redundant, the only possible definition that adequately describes the term that concerns us today is “a complex network of biologically relevant entities”.
On the other hand, the Royal Academy of Engineering describes a biological system as a set of relevant organs and structures that work together to fulfill some physiological function in a living being, such as the cardiovascular, circulatory, arterial, and adrenal systems and many others. This last meaning may be valid, but several very interesting concepts are left behind.
A biological system, on the other hand, should not be confused in any case as a living system / organism per se. The set of systems allows life, but a system alone is not alive.
Approaches To The Biological Control Of Insect Pests
EN004
Approaches to the Biological Control of Insect Pests
Kimberly Stoner
E-mail: Introduction
Biological control is the use of living organisms to suppress pest populations, making them less damaging than they would otherwise be. Biological control can be used against all types of pests, including vertebrates, plant pathogens, and weeds as well as insects, but the methods and agents used are different each type of pest. This publication will focus on the biological control of insects and related organisms.
Recognizing the role of natural enemies of pest insects
Pests are those species that attack some resource we human beings want to protect, and do it successfully enough to become either economically important or just a major annoyance. They are only a tiny fraction of the insect species around us. Even many of the species we would recognize as important pests only occasionally do significant damage to us or our resources.
The three categories of natural enemies of insect pests are: predators, parasitoids, and pathogens.
Using biological control in the field
There are three primary methods of using biological control in the field: 1) conservation of existing natural enemies, 2) introducing new natural enemies and establishing a permanent population , and 3) mass rearing and periodic release, either on a seasonal basis or inundatively.
1. Conservation of existing natural enemies
Selecting and using pesticides to minimize the effect on natural enemies
For young people:
Semiochemicals Released By Living Agents
Many living organisms release semiochemicals that can affect the behavior of pest organisms . These processes can be utilized as mechanisms of biological control if they lead to lower pest populations or reductions in damage to focal crops. Such effects can be achieved if, for example, a semiochemical has a manipulative effect on pest behavior, such as repellence or oviposition deterrence. Formally, an active semiochemical must be produced and released in situ by a living organism for this to qualify as a mechanism of biological control. In addition to microorganisms, companion plants can be used to produce semiochemicals for various purposes, e.g., to make crop plantations less attractive to herbivorous pests .
Recommended Reading: What Is Method Of Loci In Psychology
Predation Parasitism Pathogenicity And Herbivory
Direct consumption of pests, phytopathogens, and weeds leading to trophic cascades has traditionally been viewed as the most important process reducing damage to plants in natural ecosystems . It is also often regarded as the most important type of biological control in cultivated plantations, and encompasses several mechanisms. For example, predators kill and consume their prey while insect parasitoids oviposit their eggs on or into their hosts, which are subsequently consumed by the immature offspring. Similarly, some entomopathogenic living agents may penetrate insects external cuticle, causing systemic infection, while others cause infection and death of the host following ingestion. In other examples of a direct interference mechanism of biological control, mycoparasitic fungi enfold and attack the hyphae of other fungi then absorb and digest their contents . Furthermore, the pathogenic mechanisms of phytopathogenic fungi, bacteria, and viruses can be exploited in biological control of invasive plants and agricultural weeds . Finally, herbivores can also act as biocontrol agents if they suppress unwanted vegetation . All of these modes of attack either kill targeted pests, pathogens, or weeds or reduce their ability to cause damage.
The Last Step: The Biological Network At The Ecosystem Level
As you can imagine a biological network is a system based on subunits connected to each other within a whole, for example, food webs in an ecosystem. Each of the living beings that make up a food web are composed of multiple biological systems but, in turn, they are only a small point in the largest biological system of all: the one that allows the flow of energy and permanence of the ecosystems that make up our planet.
Not everything is about predations, as there are also biological networks based on intra and interspecific competition without the need for the death of living beings, for example, the indirect struggle for a resource or the search for a mate. An ecosystem is like a tower made of metal: if one of the fundamental pillars is removed, everything that is above collapses.
It is also necessary to note that, although we have given you the most typical example of all, a biological network does not apply only to ecosystems and interactions between living things. For example, it is also a biological network according to the definition given, a metabolic network, although on a much smaller scale than the one previously named. In this case, each of the interconnected “points” are the chemical compounds, which are “united” by chemical reactions that give rise to one substance or another through the use of enzymes.
Don’t Miss: How To Find Biological Grandparents Uk
Editorial: Biological Control Systems And Disease Modeling
- 1Department of Chemical & Bimolecular Engineering, University of Delaware, Newark, NJ, United States
- 2Consejo Superior de Investigaciones Científicas , Madrid, Spain
- 3Department of Chemical Engineering, University College London, London, United Kingdom
- 4Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA, United States
Editorial on the Research TopicBiological Control Systems and Disease Modeling
How Much Sleep Do You Need
Your need for sleep and your sleep patterns change as you age, but this varies significantly across individuals of the same age. There is no magic number of sleep hours that works for everybody of the same age. Babies initially sleep as much as 16 to 18 hours per day, which may boost growth and development . School-age children and teens on average need about 9.5 hours of sleep per night. Most adults need 7-9 hours of sleep a night, but after age 60, nighttime sleep tends to be shorter, lighter, and interrupted by multiple awakenings. Older people are also more likely to take medications that interfere with sleep.
In general, people are getting less sleep than they need due to longer work hours and the availability of round-the-clock entertainment and other activities.
Many people feel they can “catch up” on missed sleep during the weekend but, depending on how sleep-deprived they are, sleeping longer on the weekends may not be adequate.
Read Also: What Does Abiotic Mean In Biology
Modern Approaches In Augmentation Of Natural Enemies
Because most augmentation involves mass-production and periodic colonization of natural enemies, this type of biological control has lent itself to commercial development. There are hundreds of biological control products available commercially for dozens of pest invertebrates, vertebrates, weeds, and plant pathogens .
The practice of augmentation differs from importation and conservation in that making permanent changes in a agroecosystem to improve biological control is not the primary goal. Rather, augmentation generally seeks to adapt natural enemies to fit into existing production systems. For example, cultures of the predatory mite, Metaseiulus occidentalis were laboratory-selected for resistance to pesticides commonly used in an integrated mite management program in California almond orchards . This program has saved growers $24 to $44 per acre per year in reduced pesticide use and yield loss . Genetic improvement of several predators and parasitoids has been accomplished with traditional selection methods , and appears possible with recombinant DNA technology.
Trichogramma brassicae
Cooperative research over the last 5 years has resulted in successful commercial-scale pilot testing of this method in North America on seed corn and field corn production systems . This strategy now has the potential for immediate commercial implementation in North America.
Landscape Ecology and the Conservation of Natural Enemies
Eriborus terebrans
Biotypes: Or A Taxon By Any Other Name
In classical biological control of arthropod pests, multiple geographic races of natural enemies are commonly introduced . Such an approach is justified by the successes achieved when new biological races have been introduced . However, it makes biotype determination a common problem in biological control programs. For arthropods introduced for weed biological control, biotypic differences in host-plant affinities are now well known and require careful elaboration of geographic and host-plant-related variation in candidate species . Diehl and Bush classify insect biotypes using a combination of genetic and geographic relationships. Given that some biological trait is variable , they suggest five categories into which biotypic variation falls: nongenetic polyphenisms, genetic polymorphisms, geographic variation, host races, and species. Each case must be examined in terms of how the insect’s life system may reinforce isolation among subpopulations or which promotes divergent selection.
Mark G. Wright, in, 2014
Also Check: How To Get An 800 On Sat Chemistry
Elements Of A Control System
In a system where, the variations in the output quantity are continuously measured through feedback and compared by the input quantity, then such a system is called control system. The reference input is the excitation signal given to the system. It is also called as command signal excitation. The output quantity is the response obtained after the processing of the signal. It is also called as response controlled variable. The basic components of control system are,
Figure: Block Diagram of Components Connected
The functioning of the component of the system shown in figure is,
Plant
It is a unit where actual processing is performed. The input to the plant is the control signal generated by the controller. The plant performs the necessary action on this signal and generates the desired output which is called as controlled signal.
Feedback
Feedback is a controlled action in which the sampled output is given to the input for automatic correction of output due to any changes or disturbances occurring in the system. Generally negative feedback is employed for controlling of systems as it provides accuracy, better stability and reject disturbances. The feedback signal is fed to the error detector.
Error Detector
Controller
Definition And Scope Of Biological Control
Biological control is a form of pest control that uses living organisms to suppress a pests density to lower levels. There are four kinds of biological control, two of which classical biological control and augmentative biological control are discussed in this article and two others conservation biological control and biopesticides.
Classical biological control is the deliberate importation and release of new species of natural enemies with the intention of suppressing the densities of a target weed or insect permanently over the whole of its range in the country receiving the natural enemies. Target pests are typically invasive species and the introduced natural enemies are those specialized agents that attack it in its native range. Classical biological control is a major tool in reducing impacts of invasive species, both in crops and natural areas.
N. Moazami, in, 2019
Recommended Reading: College Algebra Final Exam Review Sheet
Biological Control With Composts
Biological control requires edaphic sources of organic nutrients to sustain the activities of the biological control agent. More consistent and sustained biological control of soil pathogens such as Pythium, Phytophthora, Rhizoctonia, and Fusarium has been achieved using compost-amended media, as long as variables such as consistency of parent material, salinity, C/N ratio, and other parameters of the composting process are controlled . Container production and floricultural industries have used compost-amended media successfully as an alternative to biocides and soil drenches with fungicides . Similar results have been obtained in field soil, although with less consistency. In practice, composts are not consistently or naturally colonized by the diversity of biological control agents required for suppression of a broad spectrum of pathogens. Three types of specificity for biological control in compost-amended substrates have been identified:
JOHN H. PERKINS, RICHARD GARCIA, in, 1999
Biological Control And Holistic Plant
R. James Cook
Key words: plant diseases, fungi, bacteria, viruses,nematodes, plant breeding, cultural practices, tillage, plantingdate, non-pathogens, biocontrol agents
Introduction
In considering the contributions of biological pest control toa sustainable agriculture, it may be useful first to examinebriefly some of the advantages and disadvantages of each of themajor methods by which pests can be controlled. The major methodsof pest control can be grouped into three categories of 1)physical control, 2) chemical control, and 3) biological control.These broad categories, in turn, can be combined into integratedpest management , integrated crop and pest management, or, as will be used in this article, holisticplant-health care or simply plant-health caret The equivalent forlivestock is integrated livestock management or animal healthcare.
Chemical control is used in this report to mean control ofpests with chemical pesticides. The problems of chemicalpesticides have been reviewed amply and need not be restatedhere. While some pesticides must be abandoned because of theirunacceptable nontarget effect, there will always be a need inagriculture for safe and selective chemicals to limit the effectsof pests. More significantly, it is becoming increasingly moredifficult and expensive to find new kinds of synthetic chemicalpesticides. The chemical pesticide industry has therefore beendescribed as a “maturing industry.”
Biological control as a concept
Systems of self defense
Recommended Reading: How To Solve Matrix Algebra
Combined Use Of Parasitoids And Pathogens
In cases of massive and severe infection of invasive pests, techniques of pest control are often used in combination. An example is the emerald ash borer, Agrilus planipennis, an invasive beetle from China, which has destroyed tens of millions of ash trees in its introduced range in North America. As part of the campaign against it, from 2003 American scientists and the Chinese Academy of Forestry searched for its natural enemies in the wild, leading to the discovery of several parasitoid wasps, namely Tetrastichus planipennisi, a gregarious larval endoparasitoid, Oobius agrili, a solitary, parthenogenic egg parasitoid, and Spathius agrili, a gregarious larval ectoparasitoid. These have been introduced and released into the United States of America as a possible biological control of the emerald ash borer. Initial results for Tetrastichus planipennisi have shown promise, and it is now being released along with Beauveria bassiana, a fungal pathogen with known insecticidal properties.
The Role Of Genes And Neurotransmitters
Chemical signals to sleep
Clusters of sleep-promoting neurons in many parts of the brain become more active as we get ready for bed. Nerve-signaling chemicals called neurotransmitters can switch off or dampen the activity of cells that signal arousal or relaxation. GABA is associated with sleep, muscle relaxation, and sedation. Norepinephrine and orexin keep some parts of the brain active while we are awake. Other neurotransmitters that shape sleep and wakefulness include acetylcholine, histamine, adrenaline, cortisol, and serotonin.
Genes and sleep
Sleep studies
Your health care provider may recommend a polysomnogram or other test to diagnose a sleep disorder. A polysomnogram typically involves spending the night at a sleep lab or sleep center. It records your breathing, oxygen levels, eye and limb movements, heart rate, and brain waves throughout the night. Your sleep is also video and audio recorded. The data can help a sleep specialist determine if you are reaching and proceeding properly through the various sleep stages. Results may be used to develop a treatment plan or determine if further tests are needed.
Don’t Miss: Prentice Hall Gold Geometry Chapter 6 Answers
What Is Biological Control
Biological control is the use by humans of beneficial insects such as predators and parasitoids, or pathogens such as fungi and viruses, to control unwanted insects, weeds, or diseases. Biological control dates back to 324 BC, when Chinese growers were recorded using ants to feed on citrus pests.
The State of New Jersey has long had the foresight to invest in biological control. Biological control offers tremendous social, environmental, as well as economic advantages. Biological control can become self-sustaining and integrated in the normal environment of the control area. Since such controls are expected to continue indefinitely, a high initial expense may prove to be a very low total cost. Biological control is particularly useful where chemical pesticides are not suitable or are impractical in environmentally sensitive areas, or on low-unit-value crops, such as alfalfa or soybeans, where complete control may not be required.
In 1965, the President’s Science Advisory Board concluded that for every $1 spent on biological control research and development, there were $30 in accrued benefits. In 1987, USDA calculated that nationally, biological controls against the alfalfa weevil netted savings of about $48 million annually research costs were $1 million – for a ratio of return on investment of about 50 to 1. Currently, total grower savings from biological control amount to $2 billion, largely as a result of reduced cost of pesticide applications.
Vectoring Of Biocontrol Agents
Microbial biocontrol agents can be applied by using living organisms as vectors, e.g., bumble bees . Similarly, even entomopathogenic nematodes can be viewed as vectors for biological control, as they carry symbiotic bacteria that contribute to infections in target insects, and thus control. Although use of living vectors opens new possibilities for high-precision application of biocontrol agents, it is important to separate the functions of the two organisms. The vectoring per se is not the direct or indirect mechanism of biological control, but merely a means for carrying the agent to the site of activity. However, the mechanism of the biocontrol intervention may be completely dependent on the vector. For instance, after vectoring entomopathogenic nematodes have invaded an insect host and released symbiotic bacteria that infect the insect, the nematodes also reproduce, thus providing an environment for new generations of bacterial biocontrol agents .
Don’t Miss: What Does Heterotroph Mean In Biology
Mechanisms That Do Not Constitute Bases Of Biological Control
Mechanisms that do not specifically target pests or pathogens, or do not involve living control agents, do not meet the requirements for biological control according to our definition . In many cases, the distinction is relatively clear , but two types of mechanisms that are often incorrectly regarded as biological control are discussed below to explain why they do not fulfill the criteria.