Impact of common insecticides on beneficial insects

Note that the values provided here are generalisations and there may be exceptions (e.g. relating to specific species or time of application).

Pest resurgence is included as there may be an increase in non-targeted pests following application of insecticides. This is mainly due to the demise of beneficials that may keep pests in check.

Insecticide group*

Persistence

Overall ranking

Impact on beneficial insects

Predatory beetles

Predatory bugs

Parasitic wasps

Spiders

Bees

FOLIAR-APPLIED
Bio-pesticides
  Bt

Short

Low

L

L

L

L

L

  Helicoverpa NPV

Short

Low

L

L

L

L

L

  Metarhizium

Short

Low

L

L

L

L

L

Petroleum spray oils

Short

Low

L

L

L

L

L

Organophosphates
  omethoate

Medium

Moderate

M

M

M

L

H

  dimethoate (low rate)

Short

Moderate

M

M

M

L

H

  dimethoate (high rate)

Short

High

M

M

H

M

H

  methidathion

Short

High

H

H

H

H

H

Indoxacarb

Medium

Low

L

L

L

L

no data

Phenyl pyrazoles (fipronil)

Medium

Low

L

L

L

M

H

Carbamates
  pirimicarb

Short

Low

L

L

L

L

L

  thiodicarb

Long

High

H

M

M

M

M

  methomyl

Short

High

H

M

M

M

H

Avermectins (emamectin benzoate)

Medium

Moderate

L

H

M

M

H

Synthetic pyrethroids

Long

High

H

H

H

H

H

SEED DRESSINGS
  fipronil

Medium

Low

Limited data available. Seed dresings generally less disruptive than foliar-applied formulations.
  imidacloprid

Medium

Low

  imidacloprid + thiomethoxam

Medium

Low

Symbols used in the table:

L – Low toxicity – nil or low impact on beneficials
M — Moderate toxicity – activity is significantly reduced but beneficial populations are able to recover in a week or so
H — High toxicity – high proportion of beneficial population killed and re-establishment will not occur for several weeks

Persistence of pest control: 

  • Foliar applications: short = <3 days, medium = 3–7 days, long = >10 days
  • Seed treatments: short = 2–3 weeks, medium 3–4 weeks, long = 4–6 weeks

*Insecticides and the groups they belong to can be found in the insecticide groups table.

Information in this table has been derived from the Cotton Pest Management Guide (2014-15).

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