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