Thursday, September 27, 2012

Larva Thursday (3)

Quite a few families and species of beetles have larval forms that prefer to eat wood which often puts them at odds with us humans. Unfortunately wood boring beetles are commonly detected only a few years after new construction. The lumber supply may have contained wood infected with beetle eggs or larvae, and since beetle life cycles can last one or more years, several years may pass before the presence of beetles becomes noticeable. This also puts them on top of the list of  potential pest species. Lumber trade is a global business and as a result the beetle larvae become globetrotters. One of the worst examples of these days is the Emerald ash borer native to Asia but accidentally introduced to North America in the 1990s. It was detected as late as 2002 and has killed some 100 million ash trees so far and threatens to kill most of the 7.5 billion ash trees throughout North America.
Emerald Ash Borer
(Agrilus planipennis)

Therefore it is essential that biosecurity authorities have reliable species diagnostic tools available in order to detect incursions of these species early enough. However, taxonomic literature on relevant species is scattered and sparse, and the lack of molecular diagnostic methods means that identification of eggs and larvae has been impossible to date because the immature life stages are morphologically homogeneous. 

The great potential DNA Barcoding has been recognized by a few researchers and confirmed by studies that e.g. recorded other invaders to North America, emphasized the importance for the nut production, or simply investigated its applicability in a regulatory context. In one of the studies the prospects are nicely summarized:

Furthermore, while it is crucial that appropriate taxonomic specialists confirm the identity of specimens used to develop DNA barcodes, once developed such data provide a generic method of identification that easily could be adopted by a molecular diagnostician without the need for specialised taxonomic training. This could free taxonomists from routine identification duties allowing more time to concentrate on much needed taxonomic research.

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