TEMPORAL VARIATIONS OF COLLECTED IN AN PLANTATION IN THE STATE OF GOIÁS, BRAZILT†

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JOSÉ COLA ZANUNCIO1 *, TERESINHA VINHA ZANUNCIO1, EFIGÊNIO TEIXEIRA LOPES2 and FRANCISCO S. RAMALHO3 (1Departamento de Biologia /Bioagro, Universidade Federal de Viçosa, 36571-000 Viçosa, Minas Gerais, Brazil. E-mail: [email protected] br; 2Departamento de Engenharia Florestal, Universidade Federal de Viçosa, 36571-000, Viçosa,Minas Gerais, Brazil; 3Empresa Brasileira de Pesquisa Agropecudria - EMBRAPA,Rua Oswaldo Cruz 1143. Caixa Postal 174. 58107-720- Campina Grande, Paraíba, Brazil)

ABSTRACT Lepidopterans are considered an important group of Eucalyptus pests in Brazil due to severe losses in wood production arising from defoliation. Biweekly collections were made in the State of Goiás, Brazil as part of a study of the population dynamics and the effects of temperature and rainfall on Lepidoptera pests of Eucalyptus. Lepidoptera were collected with five light traps installed at two meters high with black light and powered by a 12 volt battery. These were divided into groups according to their importance as pests of Eucalyptus: group 1: 11 primary pests; group 2: 10 secondary pests; group 3: 64 species without defined importance to Eucalyptus; and group 4: non-identified species. Among the primary pests, Thyrinteina arnobia (Geometridae), (Arctiidae) and Sarsina violascens (Lymantriidae) were the most frequent, the last two being constant (> 50% of collections) and the first one accessory (25-50%). Idalus admirabilis (Arctiidae) and Eacles imperialis magnifica (Saturniidae) were the most frequent secondary pests, the first being constant and the second accessory. Most of the Lepidoptera species were collected during the coldest and driest months, which indicates that these conditions could favour the occurrence of Lepidoptera outbreaks in plantations of Eucalyptus in this region of Brazil. For this reason, population monitoring of these species should be intensified during these periods. KEY WORDS:Lepidopteran defoliators, Eucalyptus, monitoring.

INTRODUCTION

The versatility of wood of Eucalyptus species and their adaptability to many regions in Brazil has increased demand for monoculture plantations t the Brazilian Research CAPES and FAPEMIG. * Supported by Agencies CNPq, To whom correspondence should be addressed. 436

of species of this in large areas of the country. Leaf-cutting ants and several species of Coleoptera are the major pests of Eucalyptus in Brazil. In many cases their outbreaks can cause serious damage because the plant- ing of monocultures favours the reproduction of these insects (ZANUNCIO et al., 1994). SANTOS et al. (1986) reported that as the area of Eucalyp- tus plantations increased in Brazil, attacks of lepidopteran defoliators also increased. According to ZANUNCIO et al. (1998a), the use of chemical insecticides against these pests can cause the appearance of new pests, previously recorded as secondary, increases environmental pollution and causes destruction of beneficial organisms which are important for bio- logical balance of these ecosystems (BRAGANQA et al., 1998a, b). Based on a Cooperative Program for Integrated Pest Management of Forest Pests (PCMIP), several forest companies in Brazil are develop- ing methodologies to identify and measure populations dynamics of lepi- dopteran pests in Eucalyptus, which can contribute to successful pest con- trol. Light traps are used to study phototropic species of Lepidoptera (SIL- VEIRA NETO, 1972). The objective of this study was to identify and to measure population dynamics of lepidopterans in an Eucalyptus plantation in the State of Goias, Brazil. Frequency and constancy were calculated and the effect of temperature and rainfall on populations of these insects was evaluated.

MATERIALS AND METHODS

Field work was done in the State of Goias, Brazil (fig. 1), in an Eucalyptus plantation, from May 1995 to April 1996. Lepidoptera were collected over two week intervals with five light traps, installed at two meters high, equipped with black light and powered by a 12 volt battery. A plastic bag with pieces of newspaper and a vial with ethyl acetate was fixed to the funnel of each trap aiming to reduce morphological damage to insects collected (FERREIRA & MARTINS, 1982). Lepidoptera collected were placed in entomological blankets labelled with place and collection date and were sent to the Forest Entomology Laboratory, at the Federal University of Viqosa (UFV), in Viqosa, State of Minas Gerais, Brazil, where they were separated, counted and identified. This identification was based on literature keys and comparisons to specimens of the entomological collection of the UFV and of other scientific centres in Brazil. As proposed by ZANUNCIO et al. (1990, 1994), the collected Lepi- doptera were divided in four groups, according to their importance as pests of Eucalyptus: group 1 - species considered to be primary pests