Monday, December 16, 2013

Potato eaters

Flea beetles are small, jumping beetles of the leaf beetle family Chrysomelidae. Many major agricultural crops are attacked by flea beetles. Species of the genus Epitrix, for example, feed mostly on plants from the family Solanaceae (Nightshades) and some of them are major pests of potato crops. What makes pest management so difficult is the fact that Epitrix species are morphologically very similar. Species delineation usually requires dissection and study of genitalia and that in turn requires a high level of expertise (and time, and patience). 

It comes to no surprise that DNA Barcoding is proposed to help with the identification of at least all the economically important Epitrix species especially when considering all their developmental stages at which it is usually impossible to tell what species is which. There are five species of the genus that feed on potato in Europe and North America (Epitrix cucumeris, Epitrix similaris, Epitrix tuberis, Epitrix subcrinita and Epitrix hirtipennis) and they are considered major pests. 

A group of French researchers has tested not only the standard COI barcode region but also ITS2. The latter was used to test for potential ambigous results with the mitochondrial marker. They couldn't detect any mitochondrial introgression. Once the reliability of the DNA Barcode was confirmed the researchers developed an RFLP-based diagnostic method and showed that unambiguous species discrimination can be achieved by using the sole restriction enzyme TaqI on COI polymerase chain reaction products. Now that makes the identification rather simple and considerable cheaper. 

The concluding paragraph of the paper shows how timely this study was:
During the final stages of review of this manuscript, the European commission published a decision (212/270/EU) to prevent the introduction of E. tuberis and E. subcrinita in Europe and limit the spread of E. cucumeris and E. similaris (Official Journal of the European Union, 2012). By enabling the identification of Epitrix specimens at different periods of the life cycle, this diagnostics tool should help member states conducting survey for the presence of potato flea beetles on potato crops as well as other host plant species, as recommended by the European commission. Fast and accurate detection of Epitrix potato flea beetles would help study their potential spread and contribute to their management with minimal disruption to Solanaceae trade.

By they way, BOLD contains quite a few sequences of those species in question some of which actually collected by the School Malaise traps, e.g. this one.

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