Efeito do extrato de Melia azedarach sobre a predação de alevinos de carpa comum (Cyprinus carpio) por larvas de Neuraeschna (Odonata: Aeshnidae)

The presence of larvae of predator insects in fish farming ponds is one of the factors that contribute to the reduction of the survival of fingerlings and consequently to the decrease of production profits. Dragonflies, which belong to the order Odonata and lay their eggs directly in the water, are among the insects that have a harmful effect on fish farming. The larvae are starving carnivore: they predate post-larvae fish and fingerlings and thus become economically relevant plagues. The objective of this work is to study the occurrence of odonata larvae in fish ponds and evaluate the effect of vegetal extracts adsorved in silica to control odonata larvae predation on common carp. A total of 126 larvae (INSECTA: ODONATA) of the suborder Anisoptera were registered in the monitored ponds. Of those, 80 belonged to the family Aeshnidae and 46 to the Libellulidae. The genera Neuraeschna was dominant in the three sampled ponds and was used in the biological tests. During the tests of predation of fingerlings of common carps (Cyprinus carpio) by the Neuraeschna larva, the daily consumption was of 5,2 and 7,2 fingerlings in the treatments with and without EEC, respectively.). The adoption of Good Practises in Aquaculture and the sustainability of fish farming request the adoption of natural products.