Helicoverpa armigera - why it is difficult to manage?

The insecticides developed so far by various companies has failed to manage the population of Helicoverpa armigera on global bases. The transgenic crops developed against them also showing failure in different parts of world. Unlocking of genome of H. armigera is carrying out by CSIRO Entomology. How the molecular techniques helps to find a solution to Helicoverpa menace.

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  • Your comments are well-received.  I apologize if I caused any confusion with my terminology, healthy vs. unhealthy.  I usually talk to farmers and the terms tolerance, antibiosis, and antixenosis are not part of the lexicon but are more academic terms.

    Resistance to Bt crops is growing, even amongst the target insects, Lepidopterous pests.  This is causing many farmers to wonder why they are planting Bt crops if they have to spray insecticide at all.  Initially, decreases in insecticide use is the norm, but over time, insecticide use increases among Bt crops.  We are at that stage with many farmers.  Either resistance is achieved among the caterpillars, and/or new insects begin to feast on the crop plant.  These new insects are attracted to Bt crops (cotton or otherwise) due to the inherent weakness attributed to Bt crops.  As you know, the Bt toxin is produced in all cells of the cotton plant thus taxing its energy reserves.  The crop is weakened and is objectively "unhealthy" thus my use of this term.  New insecticides are brought in to combat the resistant pests and/or to combat the new insects who may have arrived on the scene only after conditions attracted it.  We are working hard to "health up" plants so that farmers may successfully grow healthy crops.  Once doing so, H. armigera, or any insect pest will move on to another field where conditions are more suitable for it.  I hope that you too are able to succeed in this endeavor.  All the best.

    • thank you for clarifying the terms. you have explained the things in nice way... Bt crops though posses genes of foreign origin producing toxins, weak in their defense mechanisms of its own. So various pest management strategies should be work together to combat the pest harbouring in them...

  • thank you for your comment. I am not agreeing with the term that you have used in the comment such as unhealthy and healthy plants. The terminology in Host Plant resistance such as tolerance, antibiosis and antixenosis is suited for the context.

    H. armigera even showing resistance to newer generation of insecticides which is having entirely different mode of action in insects. So the pest is changing its mechanism of defense  against chemicals according to situations.

    Moreover I have worked on Bt cotton and assess the incidence of bollworms in it. It is not 100 per cent effective against bollworms though it is helping the farmers by reducing the frequency of insecticides sprays the followed before introduction of bt cotton...

    considering the above facts, it is quite evident that the pest is trying to modifying its behavior according to the situation..which will be reflected in different mechanisms and ultimately have genetic bases. 


  • Insects, including H. armigera, are only attracted to unhealthy plants.  Insecticides tax the immune systems and detoxification systems of plants, and soil microbes, thus reducing a plant's overall health.  Transgenic crops are notoriously unhealthy and often result in increased insecticide use as they are more attractive to insects.  Healthy crops are not attacked and enjoy immunity from H. armigera as well as other insect pests.  Hope this helps and all the best to you.

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