19 December 2011
The rules of attraction
It's the end of the year and, as such, I get to combine two things that I like and dislike the most. It's cricket season with representative tournaments all over the place. I am fortunate to have three boys with good cricket ability and I have a real passion for coaching the game. One thing about cricket is that it needs a lot of gear. And it ain't cheap! It is also Christmas time and that means shopping. I do not have a real passion for this. However, my sons' and my interest in cricket does make it easier to think of presents... (And, no, they don't read this blog so they are not getting a hint before the big day). But where to go to get the gear? Actually, it's an easy decision for us as one shop with a good name in cricket gives a discount for players in my district. Why would they want to get paid less for their products by me? Well they want to attract me into their shop so that I buy stuff (and hopefully more than I intended). They reward my behaviour by giving me a bargin. As it turned out we did spend considerably more than we planned... So this store uses an 'attract and reward' system so that they will gain benefits of their own. Seems like a good idea for humans but also something that might be useful in nature. Afterall, there are many opportunities to attract species of some benefit to you.
A group of researchers, including Steve Wratten and Sophie Orre-Gordon from the Bioprotection Centre at Lincoln University, looked at the role of 'attract and reward' systems in crops, such as wine-grapes, broccoli and sweetcorn. These researchers provided artificial attractants modelled on herbivore-induced plant volatiles (HIPV). When plants are damaged by herbivores they produce HIPVs to let natural enemies of the herbivores know that their next meal is available on that particular plant. It saves these predators from having to spend so much time searching. The researchers, who published in Journal of Applied Ecology, used artificial HIPVs to bring natural enemies into a crop (attract) and planted buckwheat as a food source (reward). Insect numbers were monitored using yellow sticky traps over several weeks. Were these attempts to get more predators into crops successful? Certainly,there were more beneficial insects found in the crops. The 'attract and reward' system seemed to work for this. Of course, this system is only useful to the plants if these beneficial predator and parasitoid insects species actually reduce pest herbivore numbers. Significantly fewer pest larvae were found in the crops which had higher number of beneficial insects and this translated to significantly less damage on the fruit. So this seems like a win-win-win situation where the plants, growers and beneficial insects are all working together and getting good results. Now I'd better head off and finish my gift buying, there's a loyalty card deal going on at the mall.