VL 10 Flashcards
Complex system (e.g. rainforest)
Many species interconnected through multiple trophic levels, which have reached and equilibrium over millions of years
Simple system (e.g. monoculture)
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
Greenhouse ecosystems
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)
Greenhouse-specific pests
Diptera: Fungus gnats
Thysanoptera: Thrips
Hemiptera: White flies
Diptera: Shore flies
Fungus gnats management
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
Whiteflies treatments
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
Thrips
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)
Examples of sanitation
Weed fabric barrier for floor
Sealed waste bins
Regular cleaning
Examples of physical barriers
Screened fan openings
Sticky tape as traps
Screened vents
Sticky tape at openings
Monitoring
Observation and determination as to weether the economic threshold has been passed
Sticky tapes (different colors)
Pheromone trap
Beat sheet
Contact insecticide
Kills insect that crawl on coated surfaces
Systemic insecticide
Chemical that is absorbed by the plant and systemically moves throughout the plant via the vascular system
Translaminar insecticide
Spray that is absorbed into surface tissues, generally no surface residue, doesn’t travel through tissues
Fumigants
Volatile insecticides that target the tracheal system
Broad-spectrum vs. narrow-spectrum
targets insects or arthropods in general (e.g. Neonicotinoids) or only specific pests
Issues to consider in context of insecticides
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.
Widely-used chemical pesticides
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
Neonicotinoids
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
Off target effects of neonicotinoids on pollinators
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
Bacillus thuringiensis (Bt)
Probably the most widely used anti-insect biocontrol
Produces Cry proteins that lead to gut destruction
different strains have alternate Cry proteins
Horitcultural oils
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)
Disadvantages of horticultural oils
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)
Physical barriers in the field
Floating row covers
Exclusion bags
Tilling
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
Pheromone trap
“Confusion trap”, high dose of female grapevine moth pheromone prevents males from finding their mates
Push-pull pest management
Using a repellent plant, the “push”
in conjunction with an attractive plant, the “pull”
Push pull slides
50 - 55
