Predação de sementes de Allagoptera arenaria (Gomes) O'Kuntze (Arecaceae) por Pachymerus nucleorum Fabricius (Coleoptera, Chrysomelidae, Bruchinae)

Abstract

Seed predation on Allagoptera arenaria (Gomes) O'Kuntze, 1891(Arecaceae) palm by Pachymerus nucleorum Fabricius, 1972 was evaluated from September 2003 to September 2005 at the Parque Nacional da Restinga de Jurubatiba (PNRJ), Rio de Janeiro, Brazil. The biology and behaviour of P. nucleorum on A. arenaria and predation rates were described. Fruits found beneath 50 palms were collected, monthly, for each one of the two sampled areas at PNRJ (ridge forest and Clusia Sclthdl (Clusiaceae) open shrubland formation). The evaluation of preyed fruits was done by counting exit holes of Bruchinae in the field, the emergence of these insects in the laboratory and from fruits dissected. It was verified that Pachymerus nucleorum oviposit on young developing infrutescences, different from literature records for other palm species, for which oviposition takes place on the fruit already on the ground. Fruit predation by P. nucleorum was 29.3% at ridge forest and 20.6% at Clusia open shrubland formation. The life cycle of P. nucleorum was long and with wide range of variation within samples, what suggests a possible diapause in some stage of life cycle.