Bioecologia de Oncideres ocularis Thomson (Col.: Cerambycidae)

• Autor(a) principal: Alves, Pedro Guilherme Lemes
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/3930
• topic: Entomologia florestal; Bioecologia; Besouros desfolhadores; Serradores; Forest entomology; Bioecology; Beetles defoliators; Sawyers; CNPQ::CIENCIAS AGRARIAS::RECURSOS FLORESTAIS E ENGENHARIA FLORESTAL::SILVICULTURA::PROTECAO FLORESTAL

The work was performed to expand the knowledge about the biology of Oncideres ocularis Thomson, 1868 (Col.: Cerambycidae), during the period of September/2009 to March/2011. Girdled twigs and adult insects of this species were collected from three commercial plantations of Acacia mangium Willd. located in the Coimbra county, Minas Gerais State, and from one silvipastoral system of Eucalyptus urophylla S.T. Blake x E. grandis W. Hill ex Maiden, A. mangium and Brachiaria spp. located at Viçosa county, Minas Gerais State, Brazil. The egg, when recently laid, was white, show an elongated ellipsoid shape, 2,44 ± 0,02 mm average length and 0,58 ± 0,12 mm width. The eggs incubation period was 12,1 ± 0,2 days and the eggs viability was 60,78%. The first instar larvae were yellowish-white, had no legs, body covered with tiny hairs, mainly, on the last abdomen segments. Larvae were 1,90 ± 0,03 mm long, 0,61 ± 0,01 mm wide, with head capsule measuring 0,35 ± 0,01 mm wide. The occurrence period adults was from December to March. Females made 17,27 ± 1,0 incisions per girdled branch, laying just one egg per incision. Incisions were more concentrated at the lower-medium and medium section of the girdled branches, and less concentrated at the upper section. Males and females adults can be distinguished by the last antennal segment length; it was seven times longer than it pedicel on males and around two times and a half longer on females. They also can be distinguished by the shape of the last abdominal segment; it had a inverted “v” shape on males, and a rounded shape on females. Girdles twigs were 9,88 ± 0,18 mm in diameter and 99,21 ± 2,23 cm in length. A girdle made by one O. ocularis can cause an average loss of 4.233,05 ± 726,75 cm² of foliar area, per tree. Females were upside down while girdling the branches, and spent from one to two days to girdle one twig, and adults fed upon twig bark. Other cerambycids also emerged from twigs girdled by O. ocularis: Engyum quadrinotatum (Thomson, 1864), Orthostema abdominale (Gyllenhal, 1817), Nesozineus bucki (Breuning, 1954) and Lepturges sp., and beetles in the Buprestidae, Scolytidae and Bostrichidae families. Such insects co-inhabiting the branches were token in account as very important competitors for space and food against O. ocularis. Variables as twig diameter, girdled area, twig length, foliar mass, twig mass, number of secondary branches, twig volume, twig superficial area, number of incisions and number of larvae hatched, evaluated on 100 girdled branches were used to search for patterns on the twig morphology that affect the reproduction of this insect . The best models had included the twig superficial area and twig volume. So biological stages of the twig girdler O. ocularis were characterized, and become clear that only the twig morphology is insufficient to explain variations on the reproduction of this insect.