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Insects in Agroecosystems > VL 10 > Flashcards

VL 10 Flashcards

1
Q

Complex system (e.g. rainforest)

A

Many species interconnected through multiple trophic levels, which have reached and equilibrium over millions of years

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2
Q

Simple system (e.g. monoculture)

A

Cultivation of a single crop in a given area. Challenges that the crop will face are not the same as those faced in natural ecosystems

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3
Q

Greenhouse ecosystems

A

Maintain relatively stable ebiotic environment (light intensity, temperature and humidity, no winds, no drought etc)

Semi-closed to surrounding area (restricted access for most vertebrates, many insects etc)

Commercial soils and fertilizers provide high nutrient content

Expensive (high energy and maintenance costs)

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4
Q

Greenhouse-specific pests

A

Diptera: Fungus gnats
Thysanoptera: Thrips
Hemiptera: White flies
Diptera: Shore flies

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5
Q

Fungus gnats management

A

Top greenhous pest #1
Diptera (true flies)

general guideline: eliminate wet organic material

Avoid overwatering of soil

Immediately remove dead plants

Regular clean and dry floors

Maintaining clean and dry floors

Monitor with yellow sticky tape

Bacillus thuringiensis sub. israelensis treatment

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6
Q

Whiteflies treatments

A

Hemiptera (true bugs)
Family: Aleyrodidae
Can be vectors of viruses

Biocontrol via parasitic wasps, predatory mites, predatory beetles and entomopathogenic fungi

Insecticide, but needs multiple rounds as it is not effective against nymphs

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7
Q

Thrips

A

Thyanoptera
Families: 14

Monitoring by blue sticky paper
Treatment:
1. Biocontrol via predatory mites or minute pirate bug (Hemiptera)
2. Insecticide (problematic as THrips developed many resistances)

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8
Q

Examples of sanitation

A

Weed fabric barrier for floor

Sealed waste bins

Regular cleaning

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9
Q

Examples of physical barriers

A

Screened fan openings

Sticky tape as traps

Screened vents

Sticky tape at openings

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10
Q

Monitoring

A

Observation and determination as to weether the economic threshold has been passed

Sticky tapes (different colors)
Pheromone trap
Beat sheet

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11
Q

Contact insecticide

A

Kills insect that crawl on coated surfaces

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12
Q

Systemic insecticide

A

Chemical that is absorbed by the plant and systemically moves throughout the plant via the vascular system

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13
Q

Translaminar insecticide

A

Spray that is absorbed into surface tissues, generally no surface residue, doesn’t travel through tissues

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14
Q

Fumigants

A

Volatile insecticides that target the tracheal system

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15
Q

Broad-spectrum vs. narrow-spectrum

A

targets insects or arthropods in general (e.g. Neonicotinoids) or only specific pests

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16
Q

Issues to consider in context of insecticides

A

Temperature and humidity

Droplet size

Time of day with maximum insect activity

Insect life cycle

Many insecticides are sensitive to:
- UV
- Hydrolysis
- pH

Exposure of human workers

Impact on beneficial animals

Residues: in products, soil, water, etc.

17
Q

Widely-used chemical pesticides

A

Organochlorides:
- DDT opens sodium channels in neurons
- leads to quick death
Extremely toxic to ecosystems - banned globally in 2004

Pyrethroids
- Permethrin, bifenthrin etc.
- Derived from compounds isolated from Chrysanthemum
Harmless to humans but harmful to aquatic animals

Organophosphates
- interfere with acetylcholinesterase activity
- use has declined due to lack of specifity
50% of currently used pesticides globally - developing countries

Ryanoids
- Synthetic derivatives or naturally occurring insecticide from Tyania speciosa
Ryanodine: alkaloid, disrupts muscular function leading to paralysis

18
Q

Neonicotinoids

A

Systemic
first neonic was approved by EU in 2005

Much more toxic to invertebrates than they are to mammals, birds and other high organisms

Low degradation rate in soil

high solubility in water

95% of seed coating ends up in soil and soil water

From 2013 to 2020, clothianidin, thiacloprid, imidacloprid and thiamethoxam have been banned

several countries apply derogations (due to emergency)

They are still allowed for veterinary use in EU

19
Q

Off target effects of neonicotinoids on pollinators

A

Mostly detected by in vitro testing

Survival

Reproduction

Sublethal effects (activity, locomotion, metabolism, ontogenetic development, behavior, learning, memory)

Interaction with pathogens

Synergy with other pesticides

20
Q

Bacillus thuringiensis (Bt)

A

Probably the most widely used anti-insect biocontrol

Produces Cry proteins that lead to gut destruction

different strains have alternate Cry proteins

21
Q

Horitcultural oils

A

Can be petroleum or vegetable based

Applied as a diluted solution (with emulsifier)

Kill immediately (blocks spiracles and absorbs into body, interfering with
metabolism and disrupting developing membranes)

Generally safe for consumption and the environment (and no odor)

22
Q

Disadvantages of horticultural oils

A

Only works with a limited numbers of insects (commonly used against “soft and small” insects, e.g., scale insects, mealy bugs, aphids, spider mites, white flies)

Only effective at moment of application (but: no residual effect)

May cause phytotoxicity if applied on cold, humid days (prevents drying)

23
Q

Physical barriers in the field

A

Floating row covers
Exclusion bags

24
Q

Tilling

A

Destroys eggs, larvae, and pupae of Coleoptera and Lepidoptera. Recommended to prevent large infestations of European maize borer, cotton bollworm, and maize earworm.

However, can also attract insects to the large volatile release if done outside the fall/winter

Can reduce helpful organisms such as earthworms

25
Q

Pheromone trap

A

“Confusion trap”, high dose of female grapevine moth pheromone prevents males from finding their mates

26
Q

Push-pull pest management

A

Using a repellent plant, the “push”

in conjunction with an attractive plant, the “pull”

27
Q

Push pull slides

A

50 - 55

Insects in Agroecosystems (10 decks)

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