Temporal and spatial variation of Stenoma cathosiota Meyrick (Lepidoptera: Elachistidae) caterpillar abundance in the cerrado of Brasilia, Brazil

Abstract

Variação Temporal e Espacial na Abundância das Lagartas de Stenoma cathosiota Meyrick (Lepidoptera: Elachistidae) no Cerrado de Brasilia, DF RESUMO -As lagartas da mariposa Stenoma cathosiota Meyrick alimentam-se de folhas de Roupala montana Aubl. (Proteaceae) em áreas de cerrado do Distrito Federal. Elas constroem abrigos juntando folhas da planta onde se alimentam e empupam. São parasitadas por uma vespa (Hymenoptera: Braconidae) que emerge da pupa. A abundância de lagartas de S. cathosiota e a freqüência do parasitismo foram comparadas em duas áreas de estudo: uma com queimadas freqüentes (bienal) e a outra com queimadas esporádicas (1987 e 1994). Na área com baixa freqüência de queimada, a variação na abundância das lagartas entre anos foi signifi cativamente diferente (χ² = 24,06; gl. = 1; P = 0,000). No entanto, a variação na abundância de lagartas entre áreas, para o mesmo período de tempo, não diferiu estatisticamente (χ² = 3,45; gl. = 1; P = 0,063). A freqüência do parasitismo foi alta, ocorrendo em 29% das lagartas coletadas e não diferiu entre as áreas. A grande variação temporal na abundância de lagartas no cerrado difi culta a determinação dos efeitos do fogo sobre essa fauna.PALAVRAS-CHAVE: Braconidae, Stenomatinae, fogo, parasitismo, planta hospedeira ABSTRACT -The caterpillars of Stenoma cathosiota Meyrick feed on Roupala montana Aubl.(Proteaceae) in the cerrado of the Distrito Federal, Brazil. They construct shelters by joining leaves of the plant where they feed and pupate. The caterpillars are parasitized by a wasp (Hymenoptera: Brachonidae), which emerges from the pupae. Caterpillar abundance and parasitism frequency were associated in an area of frequently burned cerrado (biennial fi re) and in another area that burns sporadically (1987 and 1994). For S. cathosiota, the variation among years in a single area, with sporadic fi res, was greater than the variation among areas with different fi re regimes. Caterpillar abundance among years was signifi cantly different in the area that burns sporadically (χ² = 24.06; df. = 1; P = 0.000). However, there were no signifi cant differences on caterpillar abundance between areas for the same period (χ² = 3.45; df. = 1; P = 0.063). Parasitism frequency was high, reaching 29% of the collected caterpillars, and did not differ among areas. The great temporal variation in abundance of lepidopteran caterpillars in the cerrado makes it diffi cult to determine the effects that fi re exerts over this fauna.KEY WORDS: Braconidae, Stenomatinae, fi re, host plant, parasitismKnowledge of the effects of fi re over cerrado vegetation has grown quickly in recent years (Hoffman 1998;Miranda et al. 2002Miranda et al. , 2004. However, its effects on the fauna are still poorly understood. In accidentally burned, protected areas, there has been a tendency for greater herbivory and greater abundance of some herbivorous insects during the fi rst regrowth after the fi re (Prada et al. 1995, pers. obs.). For example, the frequency of a gall insect was greater and they had hig...

Abundance of epigaeic arthropods in a Brazilian savanna under different fire frequencies

“…Despite the great diversity and functional importance of savanna arthropods, they have received little attention by researchers working in the cerrado (see OLIVEIRA & MARQUIS 2004) and other tropical savannas (ANDERSEN et al 2003). Of the few studies conducted in the cerrado so far, most have dealt with one or a few taxonomic groups and have reached different conclusions about fire effects (e.g., MORAIS & BENSON 1988, PRADA et al 1995, SEYFFARTH et al 1996, VIEIRA et al 1996, MARINI-FILHO 2000, MARTINS et al 2004, MORAIS et al 2007, KNOECHELMANN & MORAIS 2008. Therefore, understanding the general responses of arthropods to different fire regimes remains a challenge.…”