Desenvolvimento de Thyrinteina arnobia Stoll (Lepidoptera: Geometridae) em folhas de Eucalyptus urophylla e Psidium guajava

Abstract

Development of Thyrinteina arnobia Stoll (Lepidoptera: Geometridae) on leaves of Eucalyptus urophylla and Psidium guajava ABSTRACT -The development of Thyrinteina arnobia Stoll (Lepidoptera: Geometridae) caterpillars fed either on Eucalyptus urophylla or Psidium guajava (Myrtaceae) leaves was studied in laboratory. The first instar was the most critical for survival of this insect in both diets. Shortest larval period (27 days) was obtained for males on guava leaves, with the longest one for caterpillars which originated females or males with E. urophylla leaves (37 days). No insects feeding on guava leaves which originated males reached six instar while the sexual ratio with this diet was 0.6. With E. urophylla leaves, 58.3% of males presented six instars with a sexual ratio of 0.3. The width of head capsules of the caterpillars, for both sexes, was significantly different in both diets, being bigger for those fed with guava leaves, with rates of 4.3; 6.2; 10.0 and 13.0%, from the second to the fifth instar, respectively. This rate reached 28.0% in the sixth instar, corresponding to an increase of 113.0% in relation to the previous instar, indicating that individuals fed on guava leaves are stronger and more vigorous than those fed on E. urophylla. Largest width of the head capsule was associated to high viability and short duration of the larval period for individuals fed on guava leaves what suggests that this diet is more suitable for rearing this insect. T. arnobia is a native pest of guava and probably it is not adapted to feed on Eucalyptus yet.

Development and reproduction of Podisus nigrispinus (Hemiptera: Pentatomidae) fed with Thyrinteina arnobia (Lepidoptera: Geometridae) reared on guava leaves

“…However, Holtz et al (2003) evaluated the effect of these substances on T. arnobia and found that these compounds did not affect the development of this caterpillar on eucalyptus, but others substances that come from guava could affect their development. Santos et al (2000) and Oliveira et al (2005) found that T. arnobia had better development on guava leaves, which could be considered as the best host for it, while eucalyptus leaves had poor digestibility and nutritional quality which reduced the development of this caterpillar. For this reason, when T. arnobia was reared with eucalyptus leaves, probably the larvae had a lower quality and therefore affected the development of the predator.…”

Adaptação de Thyrinteina arnobia em novo hospedeiro e defesa induzida por herbívoros em eucalipto

“…Resultados contrários aos obtidos no presente trabalho foram encontrados por Santos et al (2000). Segundo esses autores, o hospedeiro de origem (goiaba) seria o melhor hospedeiro para desenvolvimento e manutenção da população de T. arnobia.…”

“…Deste modo, houve, simultaneamente, indução do sistema de defesa das plantas e adaptação das lagartas, que foram retiradas de plantios de eucalipto e criadas em plantas de goiaba. Entretanto, no trabalho de Santos et al (2000), esse método não foi executado, pois os insetos foram coletados de eucalipto e os testes, feitos com a primeira geração em goiaba.…”

“…A adaptação dessas pragas às espécies do gênero Eucalyptus fica evidenciada porque, mesmo possuindo em sua composição grande quantidade de compostos de defesa, principalmente óleos essenciais (Fox & Macauley, 1977), essas plantas sofrem desfolhas periódicas causadas por esses insetos (Santos et al, 2000).…”

Ocorrência de Compsosoma perpulchrum em eucalipto, no estado de Minas Gerais, Brasil

“…Em 2010, o país contava com, aproximadamente, 4,7 milhões de hectares de eucaliptais, sendo 29,4% desta área no Estado de Minas Gerais (Associação Brasileira de Produtores de Florestas Plantadas, 2011). A eucaliptocultura brasileira é responsável pelo abastecimento de matéria prima para as indústrias de papel, celulose e siderurgia, entretanto, essa cultura enfrenta graves problemas com relação a pragas (Santos et al, 2000).…”