Predation efficiency of copepods against the new invasive mosquito species Aedes koreicus (Diptera: Culicidae) in Italy

Abstract

Aedes koreicus (Edwards) (Diptera: Culicidae) is an invasive mosquito species and potential vector of pathogens which has recently colonised a large part of northeastern Italy and other European countries. Several species of cyclopoid copepods are natural predators of mosquito larvae and can be useful biological control agents in artificial containers used as breeding sites by Aedes mosquitoes. However, to ensure behavioural efficiency of these agents, and to avoid the introduction of non-native species, predatory copepods should be selected from the local fauna. In this study, we evaluated the predation efficiency under laboratory conditions of two locally bred populations of cyclopoid copepod species, Macrocyclops albidus (Jurine, 1820) and Mesocyclops leuckarti (Claus, 1857) (Copepoda: Cyclopoida), which are two of the most common European species of cyclopoid copepods, against Ae. koreicus larvae. Predation experiments were also conducted with Aedes (Stegomyia) albopictus (Skuse) as a “reference”. In each predation test, one adult female copepod was placed with 50 first instar larvae of a single mosquito species in a Petri dish filled with 10 mL of water. After 24 hours, the mean number (± standard error) of first instar larvae killed by one M. albidus female was 18.6 ± 1.3 Ae. koreicus and 20.9 ± 1.3 Ae. albopictus, and the mean number killed by one M. leuckarti female was 25.8 ± 2.8 Ae. koreicus and 36.1 ± 4.2 Ae. albopictus. In addition, M. leuckarti was slighly less effective against Ae. koreicus than against Ae. albopictus after 48 hours, probably because first instar larvae of Ae. koreicus were larger than first instar larvae of Ae. albopictus. Our findings indicate for the first time that copepods are effective predators of first instar larvae of Ae. koreicus.