Phosphine and protectant insecticides resistance gallery

The images in this gallery relate to resistance of insects to phosphine and protectant insecticides in stored grain.

Please click on an image to view a larger version.

Sites maps showing resistance to Phosphine

  • A map of Australia showing areas of strong resistance to phosphine
    Sites within Australia showing strong resistance to phosphine. © DAFF.
  • A map of eastern Australia where strong resistance to phosphine has been identified
    Sites within eastern Australia showing strong resistance to phosphine. © DAFF.
  • A map of eastern Australia where strong resistance to protectant insecticides has been identified
    Sites within eastern Australia showing strong resistance to protectant insecticides. © DAFF.

Silos

  • Photograph of a modern sealable silo
    A modern sealable silo equipped with a pressure relief valve and aeration. © DAFF.

A modern sealable silo, equipped with pressure relief valve and aeration - the pressure relief valve can be used to periodically test the integrity of the silo´s seals (i.e. its gas-tightness).

It is impossible to kill phosphine-resistant insect pests when phosphine is used in stored grains in unsealed silos.

Figure 1 - Phosphine fumigation in unsealed silo

  • Diagram of unsealed silos
    A figure showing weevils in stored grain in unsealed silos, and the treatment by phosphine fumigation. © DAFF.

Phosphine fumigation in an unsealed silo:

  1. application of phosphine tablets in a silo with live weevils and immature weevils (eggs, larvae, pupae) inside the grains
  2. during the first few days, tablets react to release phosphine gas that kills susceptible adult weevils (grey) quickly, but not the eggs and pupae nor resistant adults (black), and the gas leaks out of the silo
  3. after 7 days little phosphine remains, and the eggs, pupae and resistant adult weevils survive.

Figure 2 - Phosphine fumigation in sealed silo

  • Diagram of sealed silos
    A figure showing weevils in stored grain in sealed silos, and their treatment by phosphine fumigation. © DAFF.

Phosphine fumigation in a sealed silo:

  1. application of phosphine tablets in a silo with live weevils and immature weevils (eggs, larvae, pupae) inside the grains
  2. during the first few days, tablets react to release phosphine gas that kills susceptible adult weevils (grey) quickly, but not the eggs and pupae nor resistant adults (black)
  3. after 7 days, phosphine remains in the silo at a high enough concentration to kill the eggs, pupae and resistant adults.

Last updated 17 October 2013