Everyone takes refuge from something, just like I take refuge from the sun and heat by working nights the bugs take refuge from pesticides and GM cotton in a refuge crop such as pigeon peas. Refuge crops are crops that are not sprayed and provide a safe haven for both beneficial insects and pest insects such Helicoverpa, this forms part of Integrated Pest Management (IPM) program for cotton. So what is Helicoverpa and IMP and why do we need refuge crops?
Lets start with what Helicoverpa and IPM are, Helicoverpa is a moth that lays its eggs on the leaves of the cotton plant, the caterpillar then eats the leaves moving its way up the plant until the start to eat the cotton boll (the fruit of the plant which contains the cotton), the plant then discards the cotton boll and the yield suffers. An integrated pest management (IPM) program is a way to effectively control pests using a combination of controls such as biological, chemical and mechanical. Using a variety of controls prevents resistance building up and allows for more effective controls. So what does this have to do refuge crops?
With the introduction of GM cotton we have been able to reduce the use of pesticides by over 80% because the cotton plant has had a gene spiced into it that gives it a natural resistance to Helicoverpa. If the only control method used is the GM cotton than the Helicoverpa will build up resistance and it won’t be as effective, the same goes if only GM and pesticides are used, the resistance will build up to quickly. So if we allow populations of Helicoverpa to live in refuge crop unaffected by pesticides and GM they will mix and breed with resistant Helicoverpa and help to lower the overall level of resistance in the species, allowing our methods of control to work for a longer period of time.
I hope this helps to explain more about what we do and why GM is benefiting farmers. If you have any questions feel free to comment.