Entomology - midterm Flashcards
Major arthropod crop pests are
insects and mites
Insect defining characteristics
3 segments
3 pairs of legs
Most species have winged adults
highly modified mouth parts
Mites defining characteristics
2 segments
4 pairs of legs
simple mouth parts
Types of mouth parts
Chewing
Rasping-sucking
piercing-sucking
Non-Host Resistance - definition
The entire plant species is resistant to a specific pathogen, parasite or pest
(very common, under complex genetic control)
Host (cultivar) resistance
Some genotypes of the species are resistant, some are not.
usually pathogen/parasite/pest specific, often controlled by R genes
Immunity
No successful infection/infestable, no visible plant damage, not even HR
Hyper Sensitive Response
Necrotic flecks/ lesions ( may not be visible, only involve a few cells)
Manifestation of quantitative resistance
Fewer or smaller lesions
slower disease/damage progess
stay green longer
yield better
Tolerance - definition
Infected/infested host suffers less damage than susceptible plants under same degree of parasitism/infestation
Passive (Constitutive) Resistance - def
Based on compounds & structures present before pathogen/parasite/pest infects/infests
ie. cuticle waxes
many forms are fairly nonspecific
Active (induced) resistance
Based on induction of defenses after pathogen/parasite/pest attacks
- plant recognizes presence of pathogen/pest by detecting elcitors
- many are nonspecific
Pathogenic/Pestiferous
-def
capable of causing disease or pest damage to the host species
Virulent (on a particular host genotype)
-def
Not recognized by any host resistance genes, therefore does not trigger the resistance reaction
Avirulent -def
Triggers host resistance reaction
Aggressive -def
Causes more disease than another isolate, a quantative term for how much disease an isolate can cause
Isolate -def
Individual pathogen/pest speciman or culture
Race or Pathotype /Biotype -def
Isolate of a pathogen/pest with the same virulence spectrum
isolates of the same race/biotype are virulent and avirulent on the same cultivars
Pathovar
A group of bacterial strains that infect a specific host genus or species
Compatiable
Interaction where the pathogen/pest is virulent and the host is susceptible
Incompatible
Interaction where pathogen/pest is avirulent and the host is resistant
Antibiosis Category of plant resistance to arthropods
-def & examples
Negative effects of resistant plant defense on pest BIOLOGY
- Chemical or morphological
- reduced body size and weight, slowed development (of pest)
Antixenosis Category of plant resistance to arthropods
-def & examples
Negative effects of resistant plant defenses on pest BEHAVIOR
- plant serves as a poor host for the pest
- physical barriers
- lack of feeding or oviposition stiumlatants
- chemical or morphological defenses resulting in short term change in insect behavior that results in the selection of an alternate host.
Tolerance Category of plant resistance to arthropods
Ability of resistant plant to withstand or recover from pest damage (measure of plant growth, not insect behavior or biology)
Classes of Alleochemicals
Alkaloids (contain n, caffine, cocaine)
Terpenois (volatiles, indirect resistance)
Phenolics (aromatic compounds)
Types of plant physical/chemical defenses
Trichomes -simple, hooked, glandular Resins Rapidly growing tissues super-strong cell walls modificaiton of plant architecture
Jasmonic Acid
A signaling compound for flowering
also involved in growth and defensive pathways
Induced Resistance
Re-read this powerpoint
Insect host strains (def)
Genetically different populations of the same species exhibiting partial reproductive isolation & adapted to specific host plants
Importance of light quality for plants
plant may grow differently, not produce same levels of exudates in tricomes
Importance of light quantity forplants
Influences a plants level of resistance to pests
Abiotic factors affecting expression of a plant’s insect resistance
Light quantity & quality Temperature Soil Fertility Soil Moisture Humidity
Insect Variables Affecting Expression of Insect Resistance
Age
Pre-Assay Conditioning
Gender
Infestation level
