Ebook "STABILITY OF TERRESTRIAL ECOSYSTEMS TO PLANT PESTS: AN AXIOMATIC APPROACH"
Gleb I.Vasechko,
Cand.Sc.(Biology)
© Gleb Vasechko, 2005 All rights reserved.
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Created 20.03.2005
Last modification 15.06.2021
Gleb Vasechko.
PART I. A LIST OF THE AXIOMS. Continuation.
AXIOM 2. THE NATURE of ECOSYSTEM STABILITY to PLANT PESTS and its COMPONENTS. Continuation.
Table 1. The classification of the components of ecosystem stability to plant pests (CESPPs) 2.1. "Plant resistance to PPs"
| Codes and names of subcategories of CESPPs 2.1. in a sequence of orders | ||||
| 1 | 2 | 3 | 4 | 5 |
2.1.1. Plant resistance to plant pests operating on the level of individual plants |
2.1.1.1. Nonpreference |
2.1.1.1.1. Nonpreference to herbivores |
2.1.1.1.1.1. Visual or tactile |
- |
2.1.1.1.1.2. Olphact-oral or hustatoral |
- | |||
2.1.1.1.1.3. Of unknown nature |
- | |||
2.1.1.1.2. Nonpreference to phytopathogens |
2.1.1.1.2.1. Of unknown nature |
- | ||
2.1.1.2. Antibiosis |
2.1.1.2.1. Antibiosis to herbivores |
2.1.1.2.1.1. Structural |
2.1.1.2.1.1.1. Permanent | |
2.1.1.2.1.2. Physiological (biochemical) |
2.1.1.2.1.2.1. Permanent | |||
2.1.1.2.1.2.2. Delayed | ||||
2.1.1.2.1.2.3. Induced | ||||
2.1.1.2. Antibiosis |
2.1.1.2.1. Antibiosis to herbivores |
2.1.1.2.1.3. Symbiosis with fungi toxic for herbivores |
- | |
2.1.1.2.1.4. Symbiosis with natural enemies of plant pests |
2.1.1.2.1.4.1. Providing of parasites and predators of PPs by feeding and pairing | |||
2.1.1.2.1.4.2. Producing of structures for nesting of predators of PPs or promotion to them at building of nests. | ||||
2.1.1.2.1.5. Nutrient inadequacy of host-plant tissues |
2.1.1.2.1.5.1. Permanent | |||
2.1.1.2.1.5.2. Induced | ||||
2.1.1.2. Antibiosis |
2.1.1.2.2. Antibiosis to phytopathogens |
2.1.1.2.2.1. Structural |
2.1.1.2.2.1.1. Permanent | |
2.1.1.2.2.2. Physiological (biochemical) |
2.1.1.2.2.2.1. Permanent | |||
2.1.1.2.2.2.2. Induced | ||||
2.1.1.3. Tolerance |
2.1.1.3.1. Tolerance to herbivores |
2.1.1.3.1.1. Deactivation of arthropod digestive juices |
- | |
2.1.1.3.1.2. Repair or compensation of losses of host-plant tissues |
||||
2.1.1.3.1.3. Indifference to losses of host-plant tissues |
- | |||
2.1.1.3.1.4. Tolerance to gall-forming arthropods |
- | |||
2.1.1.3.2. Tolerance to phytopathogens |
2.1.1.3.2.1. Limited compatibility |
- | ||
2.1.1.3.2.2. Symbiosis with former parasites |
2.1.1.3.2.2.1. Compatibility | |||
2.1.1.3.2.2.2. Mutualism | ||||
2.1.1.3.2.2.3. Compatibility and cooperation with natural enemies of parasites | ||||
2.1.1.3.2.3. Demarcation of affected tissues |
- | |||
2.1.1.3. Tolerance |
2.1.1.3.2. Tolerance to phytopathogens |
2.1.1.3.2.4. Indifference to losses of host-plant tissues |
- | |
2.1.1.3.2.5. Permissible susceptibility |
- | |||
2.1.1.4. Evasion |
2.1.1.4.1. Evasion from herbivores |
2.1.1.4.1.1. Mortality due to starvation, i.e. Exposition to 2.1.1.2.1.1.1. |
- | |
2.1.1.4. 1.2., i.e. Exposition to 2.2.1. |
- | |||
2.1.1.4.1.3., i.e. Exposition to 2.1.1.2.1.2.1. |
- | |||
2.1.1.4.1.4., i.e. Decrease of the period of damage |
- | |||
2.1.1.4.2. Evasion from phytopathogens |
2.1.1.4.2.1. Starvation (exposition to 2.1.1.2.2.1.1.) |
- | ||
2.1.2. Plant resistance to plant pests operating on the level of a plant community |
2.1.2.1. Superevasion |
2.1.2.1.1. Superevasion from herbivores |
2.1.2.1.1.1. Starvation (exposition to 2.1.1.2.1.1.1.) 2.1.2.1.1.2. Exposition to 2.2.1. |
- |
2.1.2.1.1.3. Exposition to 2.1.1.2.1.2.1. |
- | |||
2.1.2.1.1.4. Protection of vulnerable plant stages |
- | |||
2.1.2.1.2. Superevasion from phytopathogens |
2.1.2.1.2.1. Protection of vulnerable plant stages by early maturation |
- | ||
2.1.2.2. Disappearance |
2.1.2.2.1. Disappearance from herbivores |
2.1.2.2.1.1. Suppression of herbivores by means of food deficiency |
- | |
2.1.2.3. Supertolerance |
2.1.2.3.1. Supertolerance to herbivores |
2.1.2.3.1.1. Compensation of losses in seed and seedling stages |
- | |
2.1.2.3.1.2. Compensation of losses at competition of plants within a stem stock | ||||
2.1.2.4. Heterogeneity of a stock of dominants within an ecosystem |
2.1.2.3.2. Supertolerance to phytopathogens |
2.1.2.3.2.1. Compensation of losses in seed and seedling stages |
- | |
2.1.2.3.2.2. Compensation of losses at competition of plants within a stem stock | ||||
2.1.2.4.1. Hereditary heterogeneity of a stock of host-plants |
- | - | ||
2.1.2.4.2. Heterogeneity of a species composition within a stock of dominants |
- | - | ||
2.1.2.5. Parasitic nonpreference and antibiosis |
2.1.2.5.1. Growth under protection of nonpreference and antibiosis of other plant species |
- | - | |
COMPONENTS of ECOSYSTEM STABILITY to PLANT PESTS
of the CATEGORY 2.2. NATURAL ENEMIES
A community of natural enemies of PPs includes parasites, predators and pathogens both herbivores and phytopathogens. To classify this community, the following categories are proposed:
2.2.1. Natural enemies of invertebrate herbivores.
2.2.1.1. Parasites.
2.2.1.2. Predators.
2.2.1.2.1. Vertebrate predators.
2.2.1.2.2. Invertebrate predators.
2.2.1.3. Pathogens.
2.2.2. Natural enemies of vertebrate herbivores.
2.2.2.1. Parasites.
2.2.2.2. Predators
2.2.2.3. Pathogens.
2.2.3. Natural enemies of phytopathogens.
2.2.3.1. Antagonists.
2.2.3.2. Parasites/pathogens.
2.2.3.3. Predators.
2.2.1. Natural enemies of invertebrate herbivores
2.2.1.1. are insects of the orders Hymenoptera and Diptera, whose development takes place into bodies of insect herbivores that leads to mortality of the latter.
2.2.1.2. are invertebrate and vertebrate species, which catch herbivores, kill them, and feed.
2.2.1.3. are contagious microorganisms, which consume tissues of herbivores and serve as a cause of direct or indirect mortality of them.
2.2.1. are CESPPs, which serve as cooperators of CESPPs 2.1.1.2.1. "Antibiosis to herbivores", CESPPs 2.1.1.3.1. "Tolerance to herbivores", and CESPPs 2.1.1.4.1. "Evasion from herbivores." In the cases, where it operates CESPPs 2.1.1.3.1. and 2.1.1.4.1., cooperation of CESPPs 2.2.1. is obligatory for efficacy of self-protection of plants. Exactly CESPPs 2.2.1. reduces mass of herbivores to the level, at which they are able to feed at Low or Intermediate densities. The losses of tissues at such values of density are tolerable for host-plants. As to the cases of CESPPs 2.1.1.2.1, a cooperation with CESPPs 2.2.1. allows to diminish pressure on the part of herbivores that is significant for self-protection of plants, when CESPPs 2.2.1. is moderate in its expression, and when density of a herbivore population occurred to be High.
The prerequisites of operation of invertebrate herbivores (they are marked by the letter "P") as CESPPs are as the following:
2.2.1.P.1. Adaptation of natural enemies of invertebrate herbivores to local climate.
2.2.1.P.2. Adaptation of parasites and pathogens to overcome resistance of their hosts.
2.2.1.P.3. The diversity of species composition of vegetation within an ecosystem.
2.2.1.P.4. Presence of microclimate appropriate for activity of parasites and pathogens.
2.2.1.P.5. Abundance of ecological niches within ecosystems.
2.2.1.P.5.1. Age and structural diversity of vegetation - a presence of several stories of woody vegetation, and undergrowth (in forest ecosystems).
2.2.1.P.5.2. The microrelief diversity within an ecosystem and the area-wide heterogeneity - a presence habitats necessary for temporary migrations of natural enemies, which are located within a reach by these species.
2.2.1.P.6. Undisturbed state of the soil surface.
2.2.1.P.7. A size of area of an ecosystem sufficient for providing of 2.2.1. species with vital requirements.
2.2.1.P.9. Presence of effective vectors of pathogens.
The prerequisites of natural enemies of invertebrate herbivores as well as of ones as to natural enemies of other categories of PPs determine biodiversity of an ecosystem. The better state of the prerequisites, the greater biodiversity.
A presence of the prerequisites of natural enemies of invertebrate herbivores exert complex effects, which fundamentally enhance ESPPs. The effects are the following:
1.
Synergic effect at suppression of herbivores.2. Dumping out a sea-saw feed-back mechanism, including:
2.(i) Dumping out an unsheltering feed-back mechanism.
2.(ii) Dumping out the genetic feed-back mechanism.
1. Synergic effect at suppression of herbivores
A good state of all the prerequisites of CESPPs 2.2.1. results in a developing within an ecosystem a special subsystem, where parasites, predators and pathogens of herbivores operate in a cooperation increasing the suppressive effect of each other. A protective potential of this subsystem is so high that the most species of herbivores exist in the Low or Insignificant densities at any weather situation.
Only those species of defoliators, which exert insignificant effect on vitality of their host-plants are able to reach High density independently to operation of the synergism at suppression of herbivores.
2. Dumping out a sea-saw feed-back mechanism
The term a sea-saw feed-back mechanism embraces the phenomena of sharp fluctuations of density of herbivores and their enemies, which takes place in the situations, when a herbivore species has no shelters or it is endangered by potent selective pressure on the part of an enemy species. At the extreme expression, this leads to extinction of both counteracting partners in an ecosystem.
The situation, when shelters of a herbivore species are lack, is referred to as an "unsheltering feed-back mechanism", whereas the situation of potent selective pressure is characterized by the term the "genetic feed-back mechanism."
The effect 2.(i) "Dumping out an unsheltering feed-back mechanism" takes place at presence of all the prerequisites, which provide invertebrate herbivores by abundant shelters. This effect stabilizes density of herbivores, and it is determined by factors, which are unrelated to shelters.
The effect 2. (ii) "Dumping out the genetic feed-back mechanism" takes place in the conditions of rich fauna of openly-feeding arthropod herbivores and diversity species of entomophagous organisms. The effect predicts arising in herbivore populations of resistance to pathogens and parasites so that the resistance is maintained of the moderate level. Such a level is optimal, because it provides the survivorship a herbivore species, and does not allow it to reproduce to High density. The disturbance of the effect of 2.(ii) "Dumping out of the genetic feed-back mechanism" in simple ecosystems results in arising of regular outbreaks.
2.2.2. Natural enemies of vertebrate herbivores
They are predators, parasites (helminthes) and pathogens.
The prerequisites of operation of predators of vertebrate herbivores (they are marked by the letter "P") as CESPPs are the following:
2.2.2.2.P.1. Proper activity of the predators, which operates in cooperation with CESPPs of the category 2.4. "Periodic (bottle-neck) suppression."
2.2.2.2.P.2. A size of area of an ecosystem sufficient for providing of the predators with vital requirements.
The prerequisites of operation of parasites (helminthes) and pathogens of vertebrate herbivores as CESPPs are the following:
2.2.2.1.P.1. and 2.2.2.3.P.1. High density of their hosts and specific environmental conditions, in particular increased moisture of a habitat concerned a presence of vectors of pathogens and/or additional hosts of pathogens and parasites.
2.2.3. Natural enemies of phytopathogens
2.2.3.1. Epiphytic microflora on a surface of above-ground parts of plants and community of soil antagonistic organisms inhabiting rhizosphere; both of these groups produce substances (antibiotics) toxic for phytopathogens.
2.2.3.2. Hyperparasites (fungi, viruses and virus-like particles), which infest phytopathogens (fungi and bacteria) that reduces virulence of the latter for plants.
2.2.3.3. Predaceous fungi, which attack phytonematodes and, probably, other groups of phytopathogens.
Virulence of phytopathogens is suppressed in biocenoses that implies effectiveness of their natural enemies. It is possible on condition that an operation of advanced complex of prerequisites of their activity. Proper cultural practices give a possibility to establish of them in articenoses.
The prerequisites of operation of natural enemies of phytopathogens (they are marked by the letter "P") as CESPPs are the following:
2.2.3.P.1. Growing of plants in the environmental conditions, which favorable for maintenance of proper physiological state of them, provide thriving of epiphytic microflora on a surface of above-ground parts of plants and community of soil saprophagous organisms inhabiting rhizosphere. Growing of cultivars, which are able to keep proper physiological state in severe environmental conditions.
2.2.3.P.2. Adaptation of hyperparasites to suppress their phytopathogen hosts.
