Larva of the moth Helicoverpa are one of the main insect pests of cotton.
Managing moth resistance to cottons
CSIRO scientists are studying the resistance of two moth species to the toxins in transgenic cottons to help prolong the life of these new cottons.
7 June 2005 | Updated 14 October 2011
The bacterium Bacillus thuringiensis (Bt) has been used in pest control for many years. There are many strains of Bt which each produce different toxins specific to certain insects.
Australian cotton growers have long sprayed a formulation of Bt to control two of the main insect pests, the moths:
CSIRO scientists are using their expertise in genetics to prolong the life of transgenic cottons
In 1996, the first transgenic cottons (Ingard) containing a single toxin from Bt (Cry1Ac) were released commercially in Australia. More recently, Bollgard II containing two toxins (Cry1Ac and Cry2Ab) has been made available to growers.
Where these transgenic cottons are grown, they have dramatically reduced the number of insecticide sprays used.
In the past, Helicoverpa armigera has evolved resistance to conventional insecticides. To retain the benefits of the new technology, a Resistance Management Strategy (RMS) is being used. The RMS aims to prevent, or at least slow down, the development of resistance to the toxins in the transgenic cottons.
We are investigating resistance to the Bt toxins in the two species of Helicoverpa with an emphasis on the recently deployed Cry2Ab. Our research is being used to design and improve the RMS.
Because Bt-resistance is commonly recessive, genetic tests are used to find out how commonly these Bt toxin-resistance genes appear.
Our research concentrates on three main aspects:
Monitoring levels of natural resistance present in field-collected populations of Helicoverpa armigera and H. punctigera. Moths have been collected throughout Australia’s cotton growing areas.
Studying the genetic basis of a form of resistance to the Cry toxin Cry2Ab already isolated from Australian H. armigera in the field.
Studying the characteristics, including fitness costs and mode of action, of the forms of resistance present in several laboratory colonies with resistance to Cry2Ab toxin. Three of the colonies were isolated from field-collected insects, and two others have been selected for resistance in the laboratory.
The laboratory-based research is being done at CSIRO's Black Mountain Laboratories in Canberra while the field research is done at the Australian Cotton Research Institute in Narrabri, New South Wales.
We are working with the Australian Cotton Cooperative Research Centre.
Dr David Heckel at the Max Planck Institute also brings his expertise to the research.
Find out more about the Australian Cotton Research Institute [external link]
Ingard and Bollgard II are registered trademarks of CSIRO Australia.