LABORATORY BIOLOGIES OF BAGOUS-AFFINIS AND B-LAEVIGATUS (COLEOPTERA, CURCULIONIDAE) ATTACKING TUBERS OF HYDRILLA-VERTICILLATA (HYDROCHARITACEAE)

Adults of Bagous affinis Hustache imported into quarantine from India fed on all parts of the submersed aquatic weed Hydrilla verticillata (L.f.) Royle that were exposed to air. The preferred oviposition site was moist, waterlogged wood, although eggs were also laid in soil and hydrilla stems. Mean fecundity was 231.7 eggs per female. A larvae usually developed in one tuber, but often tubers were attacked by more than one larva. Pupae were found inside tubers and in soil. Total developmental period at 27-degrees-C was 18-29 d, with a mean of 21.9 d. B. affinis was released in Florida in 1987. The biology of Bagous laevigatus O'Brien & Pajni was similar to that of B. affinis, but mean fecundity was only 70.4 eggs per female. In addition to developing on hydrilla tubers, larvae of this species readily developed on tubers of sago pondweed, Potamogeton pectinatus L. B. laevigatus was destroyed in quarantine.