Test 3 Flashcards
describe insecticide resistance
a heritable change in the sensitivity of an insect pop to insecticides reflected in the failure of that insecticide to achieve the expected level or control
insecticide resistance is _______ driven by _______
population evolution driven by natural selection
can resistance evolve to any management tactic that causes high mortality and/or reduced natality
yes
describe cross-resistance
development of resistance to one insecticide confers resistance to another insecticide
what does the rate of resistance depends on
-frequency of application
-level of insecticide-induced mortality
-genetics (monogenic vs. polygenic)
-reproductive and development rate
does increase pop isolation lead to higher or lower insecticide resistance
increased rate of insecticide resistance
does insecticide resistance evolve faster in monogenic or polygenic genes
polygenic will take longer to evolve because resistance involves multiple genes
describe metabolic resistance
resistant insects can destroy or excrete the toxic compound faster than susceptible ones
describe target-site resistance
a change in structure of the target protein that decreases herbicide binding to its usual site of action
describe penetration resistance
the insect will absorb insecticide slower and therefore will receive a smaller dose
describe behavioural resistance
insect will stop feeding or leave an area when it comes across an insecticide
-behavior needs to have a genetic basis
Name 4 resistance mechanisms
- metabolic resistance
- target-site resistance
- penetration resistance
- behavioral resistance
why is the colorade potato beetle so bad?
its resistant to at least 56 insecticides and has every type of resistance mechanism
why is the Colorado potato beetle so insecticide resistance
it feeds on solanaceous plants which have compounds that are like insecticides so its adapted to deal with insecticides
name 6 ways we can manage resistance
- practice IPM
- follow economic thresholds
- target most susceptible life stage
- apply according to the label
- rotate different MOAs
- preserve susceptible genotypes (field refuges)
describe toxicology
study of adverse effect associated with exposures to substances
describe toxicity
the inherent poisonous potency of a substance (relative to other stuff)
what is a fundamental concept of toxicology (paracelsus)
the dose makes the poison
what’s the difference between acute, subchronic, and chronic toxicity
acute: very short term exposure (24-48h)
subchronic: short term exposure (3-6m)
chronic: long-term exposure (2-4 yrs or more)
what is an LD50
does that will kill 50% of the pop you are testing on
does a lower LD50 mean the substance is more or less toxic
lower number means it takes less of it to kill you or cause an effect
what is ED50
dose that would produce the effect of interest in 50%
what is EC50
concentration that would produce the effect of interest in 50%
what is LC50
concentration that would kill 50%
what is LT50
time required to kill 50%
name 6 things that influence toxicity
- exposure route (touch, inhale)
- metabolism
- excretion
- species
- age
- nutrition/ state of health/ genetics
what makes up the exposure of a substance
how you come in contact and the duration
describe concentration vs. dose
conc: amount of substance per unit of solution
dose: amount of substance received by the organism
describe the meaning of dose
amount that gets in via exposure
= conc. of substance x amount of substance received
describe effect/response
physiological or behavioral change resulting from exposure to a substance (change in structure, function, or mortality)
name 4 sub-lethal effects
-growth and development (slowed growth)
-sexual characteristics (fertility)
-physiology (respiration)
-behavior (feeding, learning)
describe hormesis
where a low dose of a potentially harmful stressor can actually stimulate beneficial adaptive responses in an organism
what are some sub-lethal effect on pops.
-decreased size
-demographic changes
-pop genetic changes
what determines if the exposure will cause an effect
the dose
describe a hazard
anything that has the potential to cause harm
-related to the toxicity of a substance and exposure
describe risk
potential/probability that a hazard will cause harm or have adverse effects
describe risk assesment
process of quantifying risk based on info about a hazard and the amount of exposure to that hazard
how to you calculate risk
risk = hazard X probability of exposure
describe pest resurgence
insecticide kills pest and natural enemies but the pest rebounds to a higher density than before insecticide application
describe a secondary pest outbreak after applying insecticides
insecticide used to kill pest A also kills natural enemies of pest B and then the density of pest B increases
-you reduce the target pest but now have a new problem
when designing a non-target effects study what is important to consider
the experimental design should reflect the biology of the test insect and the properties and intended use of the insecticide
-exposure route
-exposure duration
- test concs
-life stage
-residual life
what are the types of studies for a non-target effects study
-lab
-semi-field
-field/greenhouse
is insecticide exposure in lab studies lower or higher than what would be in real life
higher
what does it mean if the insecticide is toxic or not toxic in lab
not toxic in lab = prob not toxic in field
toxic in lab = may or may not be toxic in the field
why can semi-field studies be unrealistic
insects are confined to a treated plot
what field study is non-target effects most realistic
field studies
what are pros and cons of doing a study in a lab
pros: low expense. low difficulty, high control
cons: over exposure
what are pros and cons of doing a study in a field
pros: realistic
cons: high expense, high difficulty and low control
what is the goal of biological and chemical control
to reduce or minimize toxic effects and/or insecticide exposure to natural enemies
what are 4 ways to minimize toxic effects and/or insecticide exposure to natural enemies
- choose less toxic/ more selective products
- target pest hot spots
- time insecticide apps differently
- provide untreated refugia (reservoir to keep natural enemies)
what is an ecologically significant trait or Spotted wing drosophila
they have a serrated ovipositor that penetrates the surface barrier of soft-skinned fruit to lay eggs
why do the Spotted wing drosophila have rapid dispersal
-cryptic nature
-global fresh fruit trade
-lack or regulation
-rapid development
-multiple hosts facilitate establishment
what fruit is at most risk from Spotted wing drosophila
strawberries (but has many hosts)
whats the threshold for fruit infested by Spotted wing drosophila
0 tolerance threshold for invested fruit
-ripening fruit + SWD activity = spray
why is the Spotted wing drosophila such a bad pest
-highly fecund
-large host range
-multiple generation
-able to disperse
-no native natural enemies
how can you monitor the larvae activity of SWD
-examine fruit weekly for eggs and larvae
-place fruits in a salt solution
-place fruit in a bag and leave in a sunny location
does susceptibility to SWD decrease or increase as fruit ripens
increases
how can you predict if it will be a bad year for SWD
if there is a warm winter and warm spring there is a high prob or early emergence
what temps do SWD prefer
moderate temps and dont like it when its dry
where do female SWD prefer to lay their eggs in the canopy
where there are lower temps and higher humidity so in shaded fruits and more dense areas of the canopy
name 4 factors that affect SWD environment suitability
- irrigation type (want drip system)
- presence of weed mat (good)
- pruning intensity (more=better)
- surrounding veg (don’t want?)
what are ways to manipulation SWD habitat in field
-pruning to open the canopy
-sanitation (remove infested fruit)
-ground cover management (want bare ground)
what life cycle f SWD is most important to target
adults before the eggs are laid because all other life stages are protected
what are 3 postharvest practices for reducing SWD
- refrigeration
- chemical treatments
- irradiation
how are growers coping with SWD
-better traps
-exclusion netting
-biocontrol
-sterile insect release
-collaboration
-modifying behavior (gum)
what are semiochemicals
chemicals that mediate interactions between organisms
-pheromones (intraspecific communication) –allelochemicals (interspecific communication)
describe a sex pheromone
produced by one sex and attracts the opposite sex (usually produced by females)
describe an aggregation pheromone
attracts both sexes and usually is produced by males
what do kairomones do
favour the recipient (attract insect to a plant they want to eat)
what do allomones do (produced by plant to repel herbivore
favour the emitter
what do synomones do
favour the recipient and emitter
how are semiochemicals used in IPM
-trapping (monitoring, mass trapping)
-mating disruption
-push/pull
how is mass trapping used on SWD
they are attracted to VOCs released by gum-like substance which disrupts their behaviour
describe how mating disruption works
synthetic sex pheromone is released into crop to prevent mating
describe push-pull
pest is simultaneously pulled from the crop and pushed towards a trap or trap crop
what are the problems with ECB being in corn
-yield loss
-stalk and ear rots
-mycotoxins in grain
-harvestability
what was the response to Cry1Fa resistance from ECB
-removal of single toxin Bt hybrids and Cry1F hybrids replaced with Cry1F + Cry1Ab
-increased resistance monitoring
-increased research on ECB phenology
what is the life cycle of ECB
overwinter in corn stalks, then emerge and mate outside corn fields, then lay eggs on corn so larvae can feed on plant
what is the best option for managing for ECB
transgenic corn
describe mating disruption
the release of synthetic pheromone into a crop system to disrupt mating activity thus reducing the pest pop
name 2 benefits of mating disruption
- few non-target effects
- hard to develop resistance
what are lepidopteran pheromones made of
straight chain fatty acids derived chemicals, alcohols, aldehydes and acetates
what is a plume
when females release pheromones in air
what 3 factors are male and female mating behaviors dependent on
- age
- temp
- photoperiod
what is the behaviour call when a female releases plume
calling
name 2 forms of competitive mating disruption
- competitive attraction (false trail following)
- induced allopatry (M drawn away from F)
describe competitive disruption
males being drawn to pheromone dispensers rather than females
describe competitive attraction
when dispensers are more attractive/numerous than females
describe induced allopatry
males hang around dispensers instead of around females
name 2 forms of non-competitive disruption
- desensitization (elevated response threshold, sensory blockage)
- suppressed calling/mating
describe non-competitive disruption
males are prevented from responding to an authentic pheromone signal but don’t orient towards a dispenser
describe desensitization
exposure to a high conc. of pheromones makes males unresponsive to pheromone for a period of time
describe suppressed calling/mating
females detect high level of pheromone and stop calling
what are the 2 theoretical approaches to mating disruption
- many dispensers but low conc per dispenser
- few dispensers but high conc per dispenser
what is an implication of using mating disruption in IPM
pheromone lures can be placed in traps and used to monitor pests
what happens to pheromone traps when implementing mating disruption
males cant find females or trap
-trap shutdown
how do you monitor under trap shutdown
employ different lures (pheromone +synergist, semiochemicals, trap for F)
monitor for females
describe acoustic mating disruption
using electronic devices that mimic calling males or mask the sound of males
what are the issues with western bean cutworm
-feeds on field corn and dry edible beans
-results in yield dec. and inc. disease susceptibility
-gibberella and DON toxin
what life stage of the western bean cutworm is best to target
egg masses bc they are hard to reach with insecticides once larvae burrow
what regions is the western bean cutworm the largest problem
sandy regions
what are the management strategies and what is effective and ineffective
-tillage (not E)
-biological (minor E)
-genetic, Bt (E)
-insecticides (E)
what are the monitoring strategies for western bean cutworm
-pheromone traps
-scouting for egg masses
-insecticide
what is the hypothesis for where western bean cutworm will be located
regions will lower plant density, convex, and sandy
describe strong migratory connectivity
there is no gene flow between pops of the same species during migration
describe weak migratory connectivity
pops may mix during the year during migration and may have gene flow
-events during one period of the annual cycle may impact the pop during subsequent periods
why is understanding the migratory connectivity of a species crucial
for developing year-round predictive pop models
what is the best way to track insect migrants
isotope analysis
what are 3 applications of isotope analysis
- tracking migratory pests to estimate where a pop originated
- determining where invasive pests originated
- determining the degree of connectivity between portions of a migratory pests annual cycle
what host does the spotted lanternfly prefer
grapevines
why does the spotted lanternfly spread so easily
-females indiscriminately lay egg masses
-adults have sticky feet
why is the invasion potential of SLF high in ON
-eggs are able to survive cold conditions
-many favourite hosts in ON
is tree of heaven a required host for SLF
preferred but NOT required
why are SLF a plant stressor
they are phloem feeders and produce lots of honeydew
name 4 cultural management strats for SLF
- exclusion netting
- egg removal
- tree of heaven removal
- backpack vacuums
name 5 reasons why SLF is a successful invader
- wide host range
- high fecundity
- cryptic life stages (eggs)
- introduced with no natural enemy
- human activities facilitate long-distance spread
where is IPM increasing
-developed nations
-high-value crops (orchard)
how many farmers are below the threshold of IPM
70%
vertical vs. horizontal integrations
vertical = one species
horizontal = management of several pest classes at once
what are barriers to IPM adoption
- weak grower knowledge base
- user preferences and risk aversion
- vested interests and corporate responsibility
- traditional practices and emerging tech
- hard and soft policy levers
what are 5 reasons IPM is losing popularity
- no universal definition
- barriers to adoption
- inconsistencies between concepts and practice
- continued reliance on insecticides
- inadequate research on IPM
what are the 6 IPM tactics
- biocontrol
- chemical control
- behavioral control
- genetic control
- cultural control
- physical control
