Monophagous leaf-mining larvae of Stigmella (Lepidoptera: Nepticulidae) on birch: patterns and differentiation in exploitation of the host

Abstract

Patterns of larval coexistence, density and mortality of six birch feeding Stigmella leaf-miners were analysed in four field sites in the Netherlands. Larval feeding was further characterized by quantitative records on phenology, oviposition (per host, per tree and per leaf), larval growth rate and relative use of different mesenchyme layers. As the Stigmella guild on birch in western Europe is known to consist of three phylogenetically distinct species-groups, the specific feeding syndromes were primarily interpreted in this context. Ecological segregation among species groups tended to be larger than that within these groups. Among group segregation mainly involved differences in phenology, types of birch trees, mesenchyme layers used for feeding and larval body size and growth rate. Within group differentiation primarily concerned the distribution and clumping of eggs and the use of differently sized trees. A preliminary analysis of the frequency of mines per infested leaf produced a rather aggregated pattern, suggesting that only a limited number of the available birch leaves are considered as suitable by ovipositing females.