Boring Invaders

[This was written by Fran Siebrits and published online by Wild Magazine http://www.wildcard.co.za/, 2011]

 Previously, to get information about trees suffering an insect invasion, bits of the bark would have to be ripped from the trunk. But a new finding has revealed a less invasive way of obtaining such information.
Trees produce a fair amount of resin when under attack by boring insects. It is this resin that traps information for many years, acting as a permanent library for scientific research. It has been discovered that resin can store information from 90 million years ago.

The resin that is produced collects on the tree trunk once an insect starts boring. This form of attack might not seem aggressive, but it damages the tree in two ways. As the insect bores its way through the phloem layer under the bark, it cuts off the tree’s access to nutrients. When the insect reaches the inner xylem layer of the tree, it often spreads an external fungus which restricts water from reaching the leaves of the canopy.

Coping with an insect invasion, and on top of that not having sufficient water, the trees are unable to effectively absorb carbon dioxide from the atmosphere. Without this vital component, the tree cannot photosynthesise and therefore begins to die.

The research team pieced all this together by examining water stress levels in trees resulting from insect invasion. Trees that are currently being attacked by insects and trees as ancient as the dinosaurs have a common carbon marker when it comes to an insect invasion: they have an increased level carbon-13. This information is stored in both the resin of living trees and fossilized trees (where resin is referred to as amber) and is therefore extremely compatible.

All this information is available by simply picking the resin off the tree, without ripping bark from and damaging its trunk.

The oldest fossilized amber with elevated levels of this carbon date back to 90 million years ago. Not only is this fascinating for ecological history, bit is will serve to aid scientists in understanding insect infestations and their overall role in the planet’s ecosystems.

Source: R. C. McKellar, A. P. Wolfe, K. Muehlenbachs, R. Tappert, M. S. Engel, T. Cheng, G. A. Sanchez-Azofeifa. Insect outbreaks produce distinctive carbon isotope signatures in defensive resins and fossiliferous ambers. Proceedings of the Royal Society B: Biological Sciences, 2011; DOI: 10.1098/rspb.2011.0276

Viewed online [http://www.sciencedaily.com/releases/2011/03/110322224325.htm]