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Insects > Lecture 16 > Flashcards

Lecture 16 Flashcards

1
Q

what are the direct effects of pests?

A

vectors of human diseases (ex: mosquitos, ticks, fleas)

allergic rxns (ex: ladybeetles)

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2
Q

what are the indirect effects of pests?

A

Domestic animals (ex: cattle flies)

Crops (ex: aphids, locusts, armyworms, leafhoppers etc.)

Timber species (ex: bark beetles)

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3
Q

what costs are involved in applying control measures of pests?

A

economic costs & envr costs

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4
Q

economic injury level (EIL)

A

“min number of pests that reduce yield equal to the gain threshold”
or
“lowest number of pests that cause economic damage”

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5
Q

central concept in integrated pest management (IPM)

A

“a comprehensive pest technology that uses combined means to reduce the status of pests to tolerable levels while maintaining a quality envr”

attempt to maintain envr quality

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6
Q

what are the 2 considerations when applying pest control

A

how much it costs per unit area to apply an insecticide

how much money you are getting out of each yield

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7
Q

injury

A

any damage detected on the crop

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8
Q

incres in injury =

A

decres in yield

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9
Q

what occurs when you reach the gain threshold?

A

necessary to apply a controlled measure or you will lose money

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10
Q

economic damage & what is necessary when you reach this point?

A

when you can save some yield by applying a controlled measure

invest money in a control measure when you pass this point

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11
Q

what happens when you cross the damage boundary?

A

yield reduction

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12
Q

when is it necessary to apply a control measure?

A

when crossing economic injury level (EIL)

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13
Q

where does noneconomic losses occur?

A

b/w EIL & Damage boundary

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14
Q

what occurs when applying control in noneconomic losses?

A

lose money, but if you apply at the damage boundary then you can save money

doesn’t make sense to apply here b/c insects might be controlled naturally

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15
Q

economic threshold (ET)

A

“number of insects that should trigger a management action” = “action threshold”

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16
Q

the economic threshold is always lower than _____

A

economic entry level

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17
Q

management activity

A

where the population passes economic threshold & where insecticide was applied

where you should apply an insecticide

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18
Q

what are the 2 kinds of insecticides?

A

natural products & synthetic products

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19
Q

natural products

A

plants produce for defense

but it’s expensive to extract form plants so synthetic products have been used as an alternative

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20
Q

what are exs of natrual products? (4)

A

alkaloids [nicotine]

rotenone

pyrethrins

neem

21
Q

synthetic products

A

same effect as natural products (not the same chemical composition)

22
Q

what are exs of synthetic products?

A

nictotinoids or neonicotinoids, pyrethroids, carbamates, organophosphates, organochlorides

23
Q

what are the advantages of synthetic insecticides?

A

Can be produced in massive amounts & are cheap

24
Q

what are the disadvantages of synthetic insecticides?

A

No natural ways to break them down

25
Q

what are the issues with insecticides? (5)

A
  1. Toxicity to humans
  2. Biomagnification
  3. Disruption of regulation by natural enemies
  4. Secondary pests
  5. Selection for resistant pests
26
Q

where do deaths from insecticides mostly occur? & why?

A

developing countries

toxicity of products: use older & banned pesticides in undeveloped countries (tend to be lethal)

protection of application: manually apply, no equipment

  • -> no $ to buy
  • -> no enforcement
27
Q

biomagnification

A

concentration of pesticides on higher trophic levels

28
Q

how does biomagnification effect higher trophic levels?

A

higher mortality

29
Q

why does increased use of insecticides lead to larger areas affected by brown hoppers?

A

disruption of natural enemies

30
Q

describe the cycle occurring when using bbroad-spectrumpesticides

A

When you spray, you kill both the pests & the natural enemies

Leads to increase resistance of pests

Can kill natural enemies

Leads to the need to apply more & continues the cycle

31
Q

secondary pests

A

Pest species, usually at low levels, that increase due to pesticides affecting their natural enemies

Originally, aren’t a pest but become one when exposed to insecticides b/c the insecticides kill the natural enemies

32
Q

what is an ex of a secondary pest?

A

mites - not a prob until you spray for aphids

leads to resistant mites

33
Q

what is the result of applying insecticides?

A

selecting for resistant pests

34
Q

How do you delay resistance of insecticides?

A

rotate pesticides

use diff types of modes of action so you don’t continually select for this type of resistance

35
Q

biological control (BC)

A

Use of a living organism to suppress pop density or impact of pest pops

36
Q

classical BC

A

importation & est of exotic natural enemies

37
Q

when is classic BC used?

A

with an introduced pest

38
Q

augmentation BC

A

periodic release of natural enemies

39
Q

when is augmentation BC used?

A

Works well in small areas or for greenhouse protection b/c you know they will remain in the same area

doesn’t require further intervening or management

40
Q

conservation BC

A

enhance pops or impact of natural enemies already present

done by making the habitat more favourable for the natural enemies

41
Q

what are the ecosystem services provided by insects?

A

Predators control the pops of the pests

Provide support to any of our activities

42
Q

what effect do insecticides have on ecosystems?

A

lead to a loss of ecosystem functions which then leads to more $$ to replace the function

43
Q

what are the functions that humans would need to replace if insects weren’t there to fulfill the role?

A

dung burial

pollination wild insects

pest control of native herbivores

food for wildlife

44
Q

soybean aphid in NA (4)

A

invasive species

40-50% yield losses

potential virus vector

economic control is consistent

45
Q

what are the natural enemies of soybean aphids? (2)

A

Multicoloured Asian ladybeetle & Minute Pirate Bug control

46
Q

are predators effective at reducing soybean aphids?

A

yes

47
Q

what are other control methods besides chemicals & BC? (5)

A

Host plant resistance

Physical control

Cultural control (ex: tillage or crop rotation)
	Disrupts lifecycle of pests

Pheromone & other insect attractants
Disrupts mating – pop won’t reach high levels

Genetic manipulation of insect pests
Replace insects with those that don’t carry disease vectors

48
Q

do parasitoids have an effect in pop control of soybean aphids?

A

NO

49
Q

How is resistance of the orange whet midge managed?

A

controlled by Sm1 resistance gene (in plants)

–> mix resistant with non-resistant to delay resistance in pest

Insects (33 decks)

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