Insecticide resistance is the quieter, lesser-known relative of antibiotic resistance. Anyone who has been to a hospital recently knows about antibiotic resistant bacteria. But how many people think about insecticide resistance when they spray their home garden with insecticides?
A research group has published the first directed-discovery research program for a new, environmentally-friendly insecticide from the venom of a native Australian tarantula.
Check out this scary video on milking Tarantula venom
On my recent visit to Narrabri I was lucky enough to join Sophie Davidson and the Cotton Young Farming Champions’ Richie Quigley, Ben Egan and Martin Murray on a tour of the Australian Cotton Research Institute
Our tour guide was Trudy Staines who is the Science Educational Officer Primary Industries Centre for Science Education (PICSE).
Trudy also undertakes research at the centre with her focus being identifying and management of Bt Cotton boll worm resistance
Use of the Sterile Insect Technique (SIT) together with transgenic cotton expressing the Bt transgene suppresses the growth of the pink bollworm population and facilitates management of resistance to Bt toxin.
Pink bollworm feeds only on cotton bolls and does not damage other tissues.
(a) Sustainable use of Bt cotton to control pink bollworm populations is threatened by the emergence of resistance.
(b) Although costly, repeated release of sterile pink bollworm moths (red) in vast excess to the number of wild moths (brown) can suppress the growth of pink bollworm populations.
(c) Combined use of Bt cotton and SIT ensures that the release of fewer sterile moths can suppress the growth of pink bollworm populations while preventing the emergence of resistance to Bt toxin.
The development of insecticide resistance is a major limitation to successful
pest control in crop production in Australia. Resistance at the field level
results in reduced efficacy of insecticide applications, leading to increased spraying
and reduced chemical options. Insecticide resistance represents a significant economic
cost to growers particularly when more expensive chemistries and mixtures
become necessary for control. Increased spraying also represents an environmental
threat, and has social implications, particularly in areas close to towns.
The Australian cotton industry has been supporting insecticide resistance monitoring
and associated research for over 25 years in an effort to manage insecticide
use and maintain the efficacy of all available chemistries. Helicoverpa (boll worm) is also a major pest of grain and pulse crops
Testing for Helicoverpa insecticide resistance at the ACRI, Narrabri.
The Young Farming Champions had fun testing their skills sexing boll worms. I was hopeless at it but Richie had obviously done this before and had picked the boys from the girls in no time
Field collections of Helicoverpa eggs are reared in the laboratory and larvae are
tested with doses of insecticide that are known to kill susceptible insects. Survivors
are considered to be resistant. Eggs are collected from all available hosts including
sorghum, maize, chickpeas and other pulses, sunflowers and cotton. This data
is used to determine regional resistance frequencies to identify any changes in resistance.
There are many methods used to control insects to ensure high yields and good quality cotton is produced. Using a combination of these methods is known as Integrated Pest Management (IPM), a widely recognised best practice in agricultural insect control.
Some of the methods used to control insect pests include:
- Encouraging beneficial insects into the crop, such as ladybirds, spiders, wasps and ants, to eat the pests
- Regular monitoring of insect populations and crop damage
- Use of transgenic cotton such as Bt cotton (Bollgard II) that is resistant to heliothis
- Alternating pesticides to reduce the chance of pesticide resistance
- Crop rotation to kill the Heliothis pupae living in the soil
- Ploughing the field after harvesting to destroy the Heliothis pupae (pupae
- Biological sprays containing viruses or the naturally occurring soil bacterium Bacillus thuringiensis (Bt) that produces proteins toxic to heliothis
- Management of crops to promote early maturity.
- Keeping non-crop areas free from weeds, volunteer cotton and other crops
As an example this is the treatment of cotton stubble
After picking the cotton is slashed to break up the quite woody plant. Because it is machine picked, there is some left over cotton on the ground. It looks a lot more than it is and it is not economic to pick up the last bits Once the cotton is slashed it is then mulched into the soil. This is done for 2 reasons.
Firstly to break the resistance cycle of insects. If an insect is resistant to the GM technology it will survive and climb down to the ground to pupate over the winter. In the summer it will fly out as a moth and then breed more resistant larvae. The soil is worked to incorporate the cotton trash and the breaking the cycle and any remote possibility that the insects may be resistant to the GM (or other) technologies.
The second reason the cotton stubble is mulched back into the soil is to increase the organic matter.
A combination of all of these things has seen a reduction in insecticide use of 87% since 2003, with some cotton crops not sprayed at all these days.
Pest control is a major focus of the cotton industry’s environmental program called myBMP, which sets out the latest research and best practice guidelines for controlling insects.
The cotton industry very innovative as you can see and I learnt a lot and it. Thanks Trudy for showing us around