Eficiencia de autofumigación para control de Philornis downsi en la Isla Santa Cruz, Galápagos.
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2021
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Facultad de Ciencias Naturales. Universidad de Guayaquil
Resumen
Las aves que habitan en Galápagos se encuentran actualmente afectadas por las larvas
de la mosca Philornis downsi, un ectoparásito obligado en su etapa larvaria que se
alimenta de los pichones de las aves, afectando la diversidad de las islas. Durante varios
años se han realizado estudios acerca de cómo P. downsi afecta a las aves locales, así
mismo se han buscado métodos a corto y largo plazo para poder disminuir el impacto
del ectoparásito en las aves. Esto puede llevar a la extinción de la avifauna endémica
del lugar, por lo que es fundamental investigar formas rentables y efectivas para
controlar la problemática. Actualmente el método más efectivo utilizado ha sido la
inyección del insecticida permacap en la base de los nidos. La dificultad de la
metodología aplicada es que hay especies que construyen sus nidos a altura poco
accesible, incluso se debe escalar para llegar a ellos, lo que implica un mayor esfuerzo.
Además de que el usar insecticida en los nidos podría presentar una consecuencia
negativa para las aves a largo plazo. Por esta razón en el presente estudio, se probó la
técnica de autofumigación. Esto consiste en ofrecer a las aves dos diseños distintos de
dispensadores (plano y redondo) con tres tipos de materiales (algodón, plumas, fibras
de coco) impregnados con ciromazina (inhibidor de crecimiento de dípteros) para que
construyan sus nidos. Las aves mostraron preferencia por el tipo de dispensador plano
en comparación al dispensador redondo (p<0.001). También demostraron el uso de los
tres tipos de materiales ofrecidos, los cuales, dependiendo de la especie hubo mayor
preferencia de uno respecto a otro. Lo que en consecuencia podría ser un opción
económica y factible para el control de la carga parasitaria de Philornis donwsi en nidos.
Galapagos birds are currently affected by the fly larvae of Philornis downsi, an obligate ectoparasite in its larval stage that feeds on bird chicks, affecting the diversity of the islands. For several years, studies have been conducted on how P. downsi affects native birds, and short- and long-term methods have been sought to reduce the impact of the ectoparasite on the birds. This can lead to the extinction of the local endemic avifauna, so it’s essential to investigate cost-effective and efficient ways to control the problem. Currently the most effective method used has been the injection of permacap insecticide at the base of the nests. The difficulty of the applied methodology is that there are species that build their nests at inaccessible heights, that in some cases, climbing is the way to reach them, which implies a greater effort. In addition, the use of insecticides in the nests could have negative consequences to the birds at long term. For this reason, in the present study, the self-fumigation technique was tested. This consists in offering birds two different designs of dispensers (flat and round) with three types of materials (cotton, feathers, coconut fibres) impregnated with cyromazine (dipteran growth inhibitor) to build their nests. Birds showed preference for the flat dispenser type compared to the round dispenser (p<0.001). They also demonstrated the use of all three types of materials offered, which, depending on the species, there was a greater preference for one over the other. Therefore, this could be an economical and feasible option for controlling the parasitic load of Philornis donwsi in nests.
Galapagos birds are currently affected by the fly larvae of Philornis downsi, an obligate ectoparasite in its larval stage that feeds on bird chicks, affecting the diversity of the islands. For several years, studies have been conducted on how P. downsi affects native birds, and short- and long-term methods have been sought to reduce the impact of the ectoparasite on the birds. This can lead to the extinction of the local endemic avifauna, so it’s essential to investigate cost-effective and efficient ways to control the problem. Currently the most effective method used has been the injection of permacap insecticide at the base of the nests. The difficulty of the applied methodology is that there are species that build their nests at inaccessible heights, that in some cases, climbing is the way to reach them, which implies a greater effort. In addition, the use of insecticides in the nests could have negative consequences to the birds at long term. For this reason, in the present study, the self-fumigation technique was tested. This consists in offering birds two different designs of dispensers (flat and round) with three types of materials (cotton, feathers, coconut fibres) impregnated with cyromazine (dipteran growth inhibitor) to build their nests. Birds showed preference for the flat dispenser type compared to the round dispenser (p<0.001). They also demonstrated the use of all three types of materials offered, which, depending on the species, there was a greater preference for one over the other. Therefore, this could be an economical and feasible option for controlling the parasitic load of Philornis donwsi in nests.
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PHILORNIS DOWNSI, PINZONES DE DARWIN, AUTOFUMIGACIÓN, ECTOPARASITISMO, CIROMAZINA, FOTOTRAMPEO