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)
