Scientists Exploit Ash Tree Pest's Chemical Communication....

A newly identified chemical sex attractant, or pheromone, of the emerald ash borer could mean improved traps for monitoring and controlling the tree-killing beetle. That's the goal of U.S. Department of Agriculture (USDA) entomologist Allard Cossé and his colleagues. 

More recently, the team discovered a macrocyclic lactone (3z-dodecan-12-olide -see structure), a compound that female borers release while feeding. Large-scale field tests conducted in Canada and the United States showed that the compound attracts male borers and has potential for use in traps either alone or combined with ash-tree-based attractants, reports Cossé, at the ARS National Center for Agricultural Utilization Research in Peoria, Ill........

ARS : News

Details in a book 

Predator-released hydrocarbons repel oviposition by a mosquito - nature's insect repellents ?

                                                                   N-Heneicosane 

                                                                    N-Tricosane

Many animals use chemicals to communicate with each other. Pheromones (most of us are familiar with these class of semi-synthetic compounds-used mainly as insect repellents) which influence social and reproductive behaviors within a particular species, are probably the best known and studied. Kairomones are produced by an individual of one species and received by an individual of a different species, with the receiving species often benefiting at the expense of the donor.

Cohen and his Israeli colleagues focused on the interaction between two insect species found in temporary pools of the Mediterranean and the Middle East: larvae of the mosquito C. longiareolata and its predator, the backswimmer N. maculata. When the arriving female mosquitoes detect a chemical emitted by the backswimmer, they are less likely to lay eggs in that pool.

To reproduce conditions of temporary pools in the field, the researchers used aged tap water with fish food added as a source of nutrients. Individual backswimmers were then placed in vials containing samples of the temporary pools, and air samples were collected from the headspace within the vials. The researchers used gas chromatography-mass spectrometry to analyze the chemicals emitted by the backswimmers.

Cohen and his colleagues identified two chemicals, hydrocarbons called n-heneicosane and n-tricosane (see structures), which repelled egg-laying by mosquitoes at the concentrations of those compounds found in nature. Together, the two chemicals had an additive effect.

Since the mosquitoes can detect the backswimmer's kairomones from above the water's surface, predator-released kairomones can reduce the mosquito's immediate risk of predation, says Cohen. But they also increase the female mosquito's chance of dying from other causes before she finds a pool safe for her to lay her eggs in.

Researchers conclude that, these newly identified compounds, and others that remain to be discovered, might be effective in controlling populations of disease-carrying insects. It's far too soon to say, but there's the possibility of an advance in the battle against infectious disease.

http://www3.interscience.wiley.com/journal/123572945/abstract?CRETRY=1&SRETRY=0

Alternates to pheromones ?

I studied about the pheromones when I was doing my post graduation and the professor, who taught us has worked with Dr. H.C. Brown (Nobel Laureate, for his contribution to the field of Organo Boranes) made us understand what are pheromones, how they are prepared and how actually they attract the insects. I think the field has been widely accepted. As for as my knowledge goes the preparation of pheromones is a costly affair (via , organo boranes). Recently I found this interesting article, where in the researchers claim that with the help of alternate chemicals (other than pheromones) one can send insects off the scent of crops.

Dr. Antony Hooper of Rothamsted Research, an institute of BBSRC said, one way in which insects find each other and their hosts is by smell, or more accurately: the detection of chemical signals – pheromones, for example. Insects smell chemicals with their antennae; the chemical actually gets into the antennae of the insect and then attaches to a protein called an odorant-binding protein, or OBP. This then leads to the insect changing its behavior in some way in response to the smell, for example, flying towards a plant or congregating with other insects (that is what we were taught..) But the more interesting part of the research is .....studying an OBP found in the silkworm moth Bombyx mori, Dr Hooper and his team were able to look at how the OBP and a relevant pheromone interact. They also tested the interaction between OBP and other molecules (that are similar to, but not the same as, the pheromone). They actually found that there are other compounds that bind to the OBP much more strongly than the pheromone.

The researchers could potentially apply these compounds, in some way to block the insects’ ability to detect chemical signals – the smell would be overwhelmed by the one they introduced. and by doing so the researchers expect the insects to be less likely to orientate themselves towards the crop plants, or find mates in this case, and therefore could reduce the damage. Though still lot of work has to be done, its a good beginning.

Hope this new and innovative way to prevent and control pests and diseases will be a success in the days to come. I wish every success in their endeavor...

Congrats Dr. Antony Hooper and co-workers..

Ref :
http://www.bbsrc.ac.uk/media/releases/2009/090924_scientists_discover_how_to_send_insects_of_the_scent.html