Larval foodplant and other effects on troidine guild composition (Papilionidae) in southeastern Brazil

Abstract

In two neighboring forest sites (Amarais and Monjolinho) in Campinas, São Paulo, Brazil, with different Aristolochia host plants, two guilds of the same six troidine swallowtail butterflies showed major differences in their relative species proportions. Parides agavus represented over half the adults marked in Monjolinho but only 3% of those in Amarais; P. proneus included over half the adults in Amarais, versus 3% in Monjolinho. These contrasting proportions remained essentially unaltered during a major macroclimatic anomaly (El Niño-Southern Oscillation) in 1982-1983, which however signifi- cantly altered the proportions of three other species, and permitted the occasional P. neophilus to become established and common in both sites. Troidine juveniles (a total of 1802) were located and followed during two years in Monjolinho. Introduction of Aristolochia melastoma, abundant in Amarais, into Monjolinho caused larvae and adults of the melastoma-specialist P. proneus to become more common there. No hostplant effects could be clearly identified, however, to account for the contrasting abundances of P. agavus in the two sites, which seem better correlated with dense vegetation structure and reduced understory illumination, affecting the microclimate in Monjolinho.