Cotton Seed Distributors article

We have just been in a seminar at the Trade Show in regards to the resistance management strategy.  Would you just like to give a run down of how things went and all the key messages there?

Yes it is a bit of a new project to bring the TIMMS Committee and particularly the resistance monitoring work that our researchers have been doing through the year for the Trade Show and it has been great to have that opportunity and to put it in front of growers at such an early point.  I suppose some of the real highlights from today have been firstly in terms of Louise Rossiter’s conventional chemistry resistance monitoring that we have had a steady drop in resistance to conventional chemistry over the last three or four seasons.  The reasons for that are many I suppose but the real message is that we have got resistance moving in the right direction for a change as far as conventional chemistry goes and we have been able to therefore reflect that in the new resistance management strategy for this coming 2006/07 cotton season.  It has been opened up quite substantially and hopefully a lot more usable and flexible.

Andrew, as you mentioned the resistance to a lot of the major chemical groups has been dropping since about 2001 – 2002, it seems to me that also that the stringent requirements in regards to the resistance management strategy has been relaxed a little bit as well.  Do you think growers now should find this strategy a little bit more user friendly?

I definitely hope so.  I certainly do, it shows also more flexibility.  There is a lot longer windows available for all chemistry groups.  So I think it will be a lot more usable for the growers and a lot more practical but the other thing that we really need to be aware of in that we have opened that strategy up so much is we need to continue to monitor exactly what does happen from here on in.  So if the egg collections can continue as the consultants do their checking and we can continue to monitor what influence the opening up of this strategy is actually having in terms of resistance we can continue to adjust the strategy over time to ensure that we have got the resistance management strategy right.

Louise we have just heard some data in regards to conventional chemistry and resistance levels in field populations.  They seem to have dropped since 2001 – 2002 this is as a great result?

It is definitely a very good result.

What do you think are the major causes for this decrease?

Essentially an awareness of resistance management to start with.  People actually knowing that resistance management is important and trying to follow the IRMS to try and reduce resistance.  IPM obviously has had a part to play in terms of greater reliance of beneficial insects to take out any resistant insects that may develop.  We have of course had the introduction of INGARD® but later on Bollgard® and larger areas of Bollgard® means smaller areas of conventional cotton less spraying you get resistance when you spray.  You select for resistance so if you are not spraying as much you are not going to get the resistance frequencies.  I think also the use of synergists has had a role to play in reduction in pyrethroid resistance.

Louise, in some cases you rely on collections from out side your own resources,  would it be fair to say that in the future even know that resistance levels are dropping these questions still need to be done and testing still needs to be continued.

Good data on insecticide resistance frequencies out in the field still remains very important.  As the TIMMS Committee have put forward a much, less restrictive IRMS for possible use in the future.  We really need to make sure that we are not jeopardising everything that we have achieved through good resistance management in the past by now dismissing it as not important.  So good collections are important so that we can get good data on resistance frequencies out there so we can maintain these chemistries, we don’t know what the future holds for cotton production, we may have a greater reliance on them in the future so it is still very much an important issue, insecticide resistance.

Rod, you were just giving a talk or a presentation in regards to the Resistance Management Strategy.  Your actual key area is in regards to Bollgard® or BT resistance, you have put up some figures in regards to the Cry 2ab protein and resistance levels you have found.  Can you just give us a rundown of those?

Sure, over the last four years we have found a small amount of resistance to the second genes in Bollgard II that is Cry 2ab.  We have found not case of resistance to one Cry 1ac, the gene that was in, or the proteins produced by INGARD® so surprisingly we have found the presence of resistance to Cry 2ab.  The work has been done in Canberra initially in the early years and now it is transferred and Sharon Downes is doing that in Narrabri.  So the frequency of this resistance gene is about four in 1000.  This is still not a major issue but it is a potential issue in the future.

Rod that percentage or the four in the 1000 that you are finding, it is a little bit higher than you first would have thought I would have imagined but can you give us an indication of what you think in regards to what’s happening with the field population?

First of all the four in 1000, it was pre-existing Bollgard®.  So we found the first resistance case before Bollgard® so it is not a response or it’s not the selection for resistance it was there in the populations of H. armigera before man started interfering by introducing the Cry 2Ab from Bollgard® II.  The implications, the frequency of four in 1000 resistance genes means that about fourteen in every million moths will carry two copies of this resistant gene and make them resistant.  So the vast majority 999,000 moths out there are still fully susceptible to all toxins.  That fourteen in a million that I mentioned earlier, those guys might be resistant to 2Ab but the frequency of resistance to Cry 1Ac is very rare so if these guys will still be fully susceptible to Cry 1Ac that’s the other toxin that is in Bollgard® and so at this stage all we can say is that Bollgard® is looking very safe into the future but we need to keep an eye on these levels of resistance.

So the resistance findings are still a key part and very important for the future?

I am afraid it is going to be an ongoing thing whenever we use an odd chemical or biological against an insect population they have a track record, particularly Helicoverpa, they have got a track record of evolving resistance and yes we have to keep our eye on this thing on going into the future.