Aspectos da biologia de Buenoa platycnemis (Fieber) (Insecta, Heteroptera, Notonectidae) da Restinga de Maricá, Rio de Janeiro

Abstract

A monthly quantitative study on B. platycnemis (Fieber, 1851) was carried out in a sand dune marsh, on the littoral of Rio Janeiro State. The aims of this study were to correlate the life cycle of the species with the seasonal regime of the water body, defining steps of the annual cycle, age strueture, and to indicate oviposition sites and trophic relations. The species shows a marked seasonal tendency. The major steps of the life cycle obtained were an invernal (weak) with a predominance of imagines, followed by another of population expansion, characterized by the absence of adults, massive eclosions and predominance of low instar nymphs. Probably, B. platycnemis has a sensibility to water levei variation and might be intluenced by the concentration of Spirogyra sp. (Chlorophyceae) in the water column. In relation to oviposition, B. platycnemis has not shown preference for any macrophyte, since eggs were found in Rhynchosphora corymbosa (Linnaeus) Britton (Cyperaceae), Eleocharis sellowiana Kunth. (Cyperaceae) and Nymphoides indica (Linnaeus) O. Kuntze. (Menyanthaceae). The observed predators of B. platycnemis were Anax amazilli (Burmeister, 1839) (Aeshinidae), Eryihemis crédula (Hagen, 1861) (Libellulidae) and other Odonata, nymphs and adults of Belostoma candidulum Montandon, 1903 (Belostomatidae), Notonecta (Paranecta) disturbata Hungerford, 1926, Buenoa antigone antigone (Ki-rkaldy, 1899) (Notonectidae), besides Curicta cf. tibialis (Martin, 1898) and Ranatra horvalhi Montandon, 1910 (Nepidae). Larvae of Sayomyia sp. (Chaoboridae), Chiro-nomus spp. and Labrundinia sp. (Chironomidae), Callibaetis gutlatus Navás, 1915 (Baetidae), cladocerans and copepods are potential prey of B. platycnemis, while ostracodes were refused.