CRSS 3500 Quiz 2 Questions and
Answers All Correct
Mechanisms of antibiosis - Answer- - physical = cuticular waxes, trichomes (hairs), plant
thickness
- chemical = toxins, digestibility reducers
Positive effects of antibiosis on natural enemies - Answer- - slows development of
hosts/prey: prolongs exposure while small
- may reduce movement of hosts/prey: makes them easier to attack
EXAMPLES of positive effects of antibiosis - Answer- - Spined soldier bug is more
effective against Velvetbean caterpillar in resistant soybeans because prey stay small
longer
- Parasitism of aphid increases on plants with glandular trichomes, which are sticky and
slow aphid movement
Negative effects of antibiosis on natural enemies - Answer- - may make hosts/prey toxic
(reduce suitability)
- physical mechanisms may trap and kill natural enemies or allow hosts/prey to escape
attack
EXAMPLES of negative effects of antibiosis - Answer- - Increased nicotine levels in
tobacco cultivars were toxic to the parasitoid Cotesia congregata, but had much less
effect on the hornworm, leading to greater hornworm problems
- High densities of glandular trichomes on resistant potatoes trap the egg of parasitoid
Edovum puttleri
HPR and natural enemies - Answer- - may have positive and/or negative effects on
natural enemies
- can actually lead to greater pest problems, if important natural enemies are deterred
- a lot of potential to be effective together, especially with the development of target
transgenics
Insecticide History - Answer- 1946: first report of resistance to DDT
1950s&1960s: widespread resistance to DDT and related products
1965: first Carbamates
1972: first B.t. (HD-1)
1973-75: first pyrethroids
Inorganic compounds - Answer- - first products used as insecticides
- minimal use today (sulfur as a miticide & cryolite for chewing insects)
Organic compounds - Answer- - oils and soaps: primarily physical action, potential for
phytotoxicity, insecticidal soap
- botanicals: pyrethrum, nicotine, rotenone, neem
- microbial: bacillus thuringiensis (used on mosquitos), entomopathogens (NPV)
General MOA EXAMPLES - Answer- - nervous system
- growth regulators
- feeding inhibition
- metabolic processes
- nerve and muscle action
Insect Growth - Answer- - exoskeleton = prevents dehydration, periodically shed for
growth and development
Speed of Activity - Answer- - nerve toxins are fastest
- growth regulators generally active at next molt (mortality is generally slow)
- interference with metabolic processes generally slow death
- disruption of midgut (slow death)
- feeding blockers (slow death)
T/F - European honeybees (which are not native) are in danger - Answer- FALSE -
European honeybees are not in danger
T/F - Native pollinators are most at risk and most important to us - Answer- TRUE
Neonicotinoid insecticides DEFINITION - Answer- - group of insecticides with a
chemical structure that is similar to nicotine
- nerve poison that affects the nicotinic acetylcholine receptor
Chronic / Sub-Lethal = ? - Answer- long term affects
Acute = ? - Answer- die on the spot
Two basic types of application - Answer- 1. Liquid Spray: easier to calibrate, very
precise, subject to drift and runoff
2. Broadcast granules: less precise, little residue on flowers/foliage, no drift bit it can
runoff
Best Management Practices of Landscape - Answer- - apply pesticide only when
needed
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