Invasive Ants

Tapinoma melanocephalum.jpgTapinoma melanocephalum is an introduced ant found in Galapagos (photo: H. Herrera)

To date, 36 ant species are known to have been introduced to the Galápagos Islands. Two of these are fire ants, which are impacting biodiversity and the livelihoods of Galapagos residents. At least two other species are showing signs of becoming highly invasive, and there may be more. Invasive ants prey on invertebrates and small vertebrates, while their mutualistic relationship with invasive plant-feeding insects such as the cottony cushion scale and aphids can seriously affect endemic and agricultural plants. These ants are disrupting Galapagos conservation efforts such as the tortoise restoration program. Invasive ants cause loss of diversity and consequently degradation of terrestrial ecosystems as well as affect agricultural activities, domestic animals and produce allergic reactions in humans. 

Henri usando Winkler707jpg.jpgCDF scientist taking Winkler samples of ants for research (Photo H.Herrera) In 2012, CDF scientists working alongside the Galapagos National Park Directorate and with input from the Galapagos Biosecurity Agency, conducted an in-depth analysis of invasive ant management programs in Galapagos. The end result was a five-year strategic plan that identifies research and management activities required to prevent new introductions of invasive ants and reduce the impact of those that have already reached the Galapagos Islands.

To support management efforts, CDF scientists and collaborators are researching control methods for highly invasive ants. One of the highest priorities is finding a control solution for the tropical fire ant (Solenopsis geminata).  Research is urgent because Solenopsis uses nuptial flights as a dispersal strategy and is able to spread quickly between islands. Moreover, the tropical fire ant has a powerful sting and is known to attack bird hatchlings and juvenile tortoises in large numbers. It is also seriously affecting farming practices. CDF are currently working with colleagues at USDA-ARS, Gainesville, Florida, to evaluate the possibility of introducing natural enemies of the fire ant from its native range to keep ant numbers below damaging levels – a technique known as classical biological control. Several species of phorid flies, otherwise known as ant-decapitating flies, are known to attack the tropical fire ant and could be candidates.  

P_bifidus rearing.jpgLaboratory set up at USDA-ARS for rearing potential biological control agents of Solenopsis geminata (photo: Sanford Porter, USDA-ARS)

Considerable effort is also being invested to understand how many introduced ant species are found in the Galapagos and how far they have spread. Recent studies show a steady increase in the number of introduced ants as well as an increase in the number of islands invaded. These include several species of pest ants associated with human settlements.  Increasing our knowledge of what species are found in Galapagos and building local capacity in ant identification will help reduce the risks of introducing other invasive ant species on the Galapagos Islands' doorstep.  

Click here to read the Invasive Ants Strategic Plan (Spanish) (511.3 KB)

Collaborators: Galapagos National Park Directorate, Galapagos Biosecurity Agency (ABG), Conservation International, USDA-ARS, Gainesville, Florida, CSIRO, Ghent University, RBINS, the Entomology Department of the Royal Belgian Institute of Natural Sciences (RBINS) and the Belgian Global Taxonomy Initiative National Focal Point (GTI)

Project funders: Galapagos Conservancy, Conservation International

Champion Island: under siege from the tropical fire ant (Galapagos Conservancy Newsroom)

Links to publications