Insecticide Resistance and Ecotoxicology
Insecticide Composition
Insecticide = Active Ingredient + Additives
Formulations
• Solutions• Emulsion concentrates• Water dispersible
powders• Suspension
concentrates• Baits
• Dusts• Granules and pellets• Fumigants• Controlled release
formulations• Spray adjuvants
Solutions• DDT used to be applied in this way.• Now solution are used only for ultra
low-volume applications.
Emulsion concentrates
• If insoluble in water… then use an emulsifying agent.
A what ?!
Emulsion concentrates
• Emulsifying agent: Substance used to facilitate the dispersion of an immiscible material in a solvent.
Dissolve insecticide on: organic solvent + emulsifier
Dissolve mix on water
Water dispersible powders
• Insoluble • Dispersed in water. • Insecticide can be a solid or a liquid.
Suspension concentrates
• Solid held in suspension
Baits
• Insect attractant + insecticide
• Attractant:
- Food source
- Pheromone
Dust
• Inert carrier + insecticide
- Seed dressing
- Foliage
Granules and Pellets• Inert carrier + insecticide
0.1-2.5 mm
• Safe• Easy to handle• Precise targeting• Slow release
> 2.5 mm
Fumigants• Used in soil or
enclosed spaces
• Stored products pests
• Gas proof spaces
• Costly
• Supervised
• Gases
• Diffuse well
• Absorbed through cuticule or resp. syst.
• All are toxic to humans.
Controlled release formulations
• Less active ingredient
• Slow release
Spray adjuvants
• Dispersants
• Emulsifiers
• Surfactans• Spreaders• Penetrants• Stickers• Humectants
It is not that simple…
LD50
• Lethal dose
• Dose at which 50% of the test insects are killed
Insecticide Concentration
Insecticide efficiency depends on…
• Insect behavior
• Insect size
• Insect instar
• Insect habitat
Insecticide efficiency depends onalso…
The user also has a saying
• Ease of use
• Safety
• Price
Insecticide inconveniences
• Moving large volumes
• Time invested in spraying
• Safety concerns
• Cost
Insecticide Resistance
Directional selection
How does it work?
Recognized since 1911
It became a concern in 1940s
After the 1950s several cases observed
1%
99%
EcotoxicologyEcotoxicology
Non-target
What have insecticide companies done to help?
• Increase power of active ingredients
• Improve selectivity
• Decreased residual life of insecticide
• Safety checks have improved
• Improved application methods
The IPM proposal