Evaluación de la factibilidad de usar el inhibidor de crecimiento de insectos, cyromazina, para tratar nidos con las tecnicas de autofumigación o rociador

• Methods are urgently required to protect endangered Galapagos birds from the invasive nest parasitic fly, Philornis downsi;
• An option under evaluation is the application to nests of an insect growth inhibitor,Cyromazine. The use of half the recommended dose (0.2 g/l) of this insecticide moderately increased reproductive success of birds in nests treated in 2017-2019;
• In 2020, we tested the application of a full dose (0.4 g/l) in 13 bird nests against 19 control nests;
• The application of Cyromazine on top of the nest material was effective in interrupting the development of P. downsi larvae and significantly increased bird-breeding success. Chick growth was marginally greater in insecticide-treated nests, though not significant;
• To deliver Cyromazine to the nest, one of the options being considered is the selffumigation technique where birds take insecticide-treated material to the nest. Studies were conducted on Floreana and Santa Cruz islands to determine whether two threatened species, the Medium Tree-finch and the Little Vermilion Flycatcher, would use materials that were offered to them for nest building;
• The Little Vermilion Flycatcher readily took feathers from the ground and incorporated them into the nest. On Floreana Island, tree finches were not attracted to the cotton provided in dispensers;
• In the event that a risk analysis shows that Cyromazine is safe to use in bird nests, other materials and techniques should be tested to encourage threatened birds to collect insecticide-treated material and take it to their nests.