The invasive fly threatening 21 Galapagos bird species

By Susana Madera

Galapagos, Ecuador, Jan 22 (EFE).- An inconspicuous and invasive parasitic fly threatens 21 bird species endemic to the Galapagos Islands, including 12 of the 17 finch breeds native to the archipelago’s delicately balanced ecosystem.

Philornis downsi, also known as the avian vampire fly, was first detected in the Galapagos in the 1960s and can now be found across the archipelago, save for far-flung islands such as Darwin, Wolf, Española and Genovesa.

“In all the rest (of the islands) the birds are being attacked and parasitized by this fly,” Paola Lahuatte, a researcher with the Charles Darwin Foundation, told Efe.

The fly lays its eggs in birds’ nests and its larvae feed on the blood of hatchlings, often to the point of death, Lahuatte added.

The larvae remain in the nest for around eight days, during which time it transforms into adult fly.

“The impact in recent years has been so considerable that there are species on the brink of extinction, such as the mangrove finch,” she said.

Others, such as the vermilion flycatcher, are also at risk of dying out because of the invasive fly.

Similar in appearance to a common fly, Philornis downsi averages around one centimeter in length.

Genetic analysis determined that the fly arrived in the Galapagos Islands from the mainland, most likely transported on boats or planes used by visitors in the 1960s before bio-security controls came into effect.

The fly lives for around six months and has thrived in the Galapagos.

Laboratory and field research in Ecuador, the University of Minnesota and the Escuela Superior Politécnica del Litoral has identified a very small wasp as a natural control to the population of the avian vampire fly.

“These micro wasps parasitize when the fly has encased itself to become an adult. They lay their eggs inside the capsule and its larvae eat the fly,” Lahuatte said.

However, scientists must first evaluate whether the wasp can be safely introduced to Galapagos Islands, where it is not native, without it posing a threat to other species.

According to Lahuatte, Ecuadorian authorities have approved experiments with one such wasp species, the Conura annulifera, which is found on mainland Ecuador.

In the meantime, conservationists are using low doses of insecticide in cotton material that the birds use to line their nests. EFE

sm/jt