Based on the seemingly counterintuitive finding, no one is about to suggest that pollutant levels in soils should be increased; however, the finding may prove useful in finding other means for trees to combat destructive pests. By pollutants, this refers to a build-up of chemical toxins in soil. Soil pollution is typically caused by industrial activity, agricultural chemicals, or improper disposal of waste. Examples include petroleum hydrocarbons and lead.
The finding caught researchers by surprise. The discovery came about when biologists were examining genetic information from various fungi and bacteria found on the trees. With this analysis, the scientists discovered evidence relating to a large amount of genetic material from a plant pathogen called the spider mite.
The spider mite (Tetranychus urticae) is known as either the red spider mite or the two-spotted spider mite. It feeds on plants and is regarded as a pest. It causes damage by laying eggs on plants, and the hatched insects then proceed to suck nutrients from leaves.
When detecting evidence of the presence of the spider mite, the researchers found that the highest levels were found in trees growing in soil that was not contaminated and, conversely, the presence of these insects was far lower in trees growing in polluted soils. This finding suggests that the defense mechanism of the tree is somehow boosted by surviving in contaminated soil. By protecting itself with chemical toxicity, the tree is better able to resist pests.
To explore this further the research group are planning to run studies in greenhouses, which will enable relatively controlled environments to be constructed.
The research has been led by Dr Frederic E. Pitre, who works at the University of Montreal. The information has been presented by the Society for Experimental Biology; however, the findings have yet to be published in an academic journal.
