Galapagos Invasive Species:
Noxious weeds invasion

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Taking advantage of natures tactics: Biological control of weeds

Lantana camera biocontrolIf it is not feasible to eradicate an invasive plant or contain it in a limited area, because it is already too common and widespread, and it is also difficult to control even in high-priority conservation sites. One option that could bring about control over the whole range of the species in the islands is biological control. This has not yet been attempted for any invasive plant in Galapagos, but is becoming more common worldwide, as safe methods for selecting highly specific agents that will kill or weaken only the target species, without affecting native or endemic species, are developed. The Botany Department of the Charles Darwin Foundation is therefore working with CAB International, the world leaders in biocontrol, to develop projects to investigate the possibilities of controlling some of our worst invaders by this means. Possible targets include quinine Cinchona pubescens, blackberry Rubus niveus and the invasive ornamental Lantana camara.

We have begun with Lantana because it has a history of having been controlled by fungal pathogens in several countries, with much research having identified several fungal agents that attack different varieties of the species. Many of these are so specific as to attack only a single variety. This high specificity is important in Galapagos, where we have an endemic Lantana, L. peduncularis. However, CABI scientists have already identified a fungus that attacks the variety of L. camara which we have in Galapagos but does not appear to attack our endemic species. The pictures to the right show levels of infection of Puccinia lantanae as a result of different periods of exposure to moisture: A. eight hours, B. fourteen hours, and C. twenty hours in the dew chamber.

The next step is to carry out more specificity testing with these species, and with related species in the same family (Verbenaceae) and other endemics, so as to be sure that the fungus will not attack any of them. This work is being undertaken by research student Jorge Luís Rentería. For safety reasons, the experiments are done by sending our plants to Britain, rather than bringing the fungus to Galapagos. We are still at least two years away from testing on the islands, and before we even consider that, we have to be convinced that the project will not pose any danger to the native flora of Galapagos.

Source: Charles Darwin Foundation.

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This website was created on 25 October 2004 by PT and JK