Despite recent progress in understanding mechanisms of tree species coexistence in tropical forests, a simple explanation for the even more extensive diversity of insects feeding on these plants has been missing. We compared folivorous insects from temperate and tropical trees to test the hypothesis that herbivore species coexistence in more diverse communities could reflect narrow host specificity relative to less diverse communities. Temperate and tropical tree species of comparable phylogenetic distribution supported similar numbers of folivorous insect species, 29.0 ± 2.2 and 23.5 ± 1.8 per 100 square meters of foliage, respectively. Host specificity did not differ significantly between community samples, indicating that food resources are not more finely partitioned among folivorous insects in tropical than in temperate forests. These findings suggest that the latitudinal gradient in insect species richness could be a direct function of plant diversity, which increased sevenfold from our temperate to tropical study sites.

Norton and Didham suggest that differences in plant abundance between tropical and temperate forests may influence the host specificity of herbivores in these forests. We agree in principle but show that this is likely only for very rare plant species in tropical forests. Studies of herbivores hosted by rare plant species would help our understanding of tropical plant-insect interactions.

Between 2000-2002, the structure of communities of lepidopteran larvae was studied in leaf bearing crowns of Quercus cerris in the central and northern part of the Malé Karpaty Mts (SW Slovakia). Caterpillars were collected using the beating method in four study plots. In total, 58 species were found. The families Geometridae, Noctuidae and Tortricidae comprised the highest number of species found. The family Geometridae comprised the highest number of pests. The most abundant species for individual plots were Lymantria dispar, Operophtera brumata, Ypsolopha alpella and Cyclophora ruficiliaria. Most of the recorded species belonged to the trophic group of generalists (39 species). ShannonWiener's diversity index and Pielou's equitability (evenness) value indicated there were marked differences between the Horný háj study plot (an insular forest with ants as the predators of caterpillars) and other plots. The main ecological gradient along DCA-1 related to the host specificity of caterpillars and consisted of three groups: (a) polyphagous species; (b) specialist species feeding chiefly on oaks or exclusively on oaks and (c) species preferring some oak species, mainly Q. cerris. The fragmentation of growth was identified along DCA-2.

AbsTrAcT:The differences between oak lepidopteran communities were studied in Slovakia in 1993 and 1994. Sampling was undertaken between April and October on 3 oak species (Quercus robur, Q. petraea, Q. rubra). Biological traits of larvae were examined in order to explain differences in seasonal guilds among oaks. Communities varied in structure and abundance. Species richness in four seasonal guilds (flush, late spring, summer and autumn feeders) had a similar pattern on each of the studied oak species. The guild of flush feeders had the richest species assemblage, followed by the late spring feeder guild and both guilds were significantly richer than the summer feeder guild and autumn feeder guild. 579Tischeria spp. and also some smaller free feeders like Cyclophora spp.). Some larger species from the first guild like L. dispar, Orthosia spp. or Biston stratarius often complete their development at this time. The third guild occurs in August-September. It consists partially of the second generation of the first guild for example Pandemis spp., Cyclophora spp. and Pseudoips prasinanus. Finally, the fourth guild (October-November) consists of the second flight period of leaf miners in the genera Stigmella, Tischeria and Phyllonorycter and the mostly univoltine genus Ectoedemia. Recent studies of Kulfan et al. (1997) and Kulfan and Degma (1999) showed that species diversity and evenness differed significantly between oak species and time of the year.Our effort was focused on understanding the mechanisms that explain variance in lepidopteran communities in various seasonal guilds on different oaks. The main study goals were: (1) To investigate patterns of lepidopteran communities on three oak species across a year;(2) To analyze the similarity of seasonal guilds at various sites represented by different oaks. sTudy siTes And MeTHodsA dataset was collected during May to October in 1993 and 1994. Samples were taken every 20 days (nine times per season, the last sampling was excluded from statistical assessment due to the zero number of larvae in almost all samples) using a beating tray (25 beatings per sample). There were nine sample intervals each year. Sampling started on 30 April, 7-10 days after budburst, and finished on 7 October in both years. Branches at eye height, about 1 m in length, were beaten during each sampling period. Approximately 99.5% of 1,518 collected larvae were identified in situ to the species level; others were identified after rearing in a laboratory to the adult stage. Gerasimov (1952) and Patočka (1954Patočka ( , 1980 were used as identification references. A systematic list of species includ- ing selected life history traits can be found in the Appendix (Table 1A). The study area in Western Slovakia was between 48°25' and 48°30'N and 17°09' and 17°11'E (Fig. 1 Leaf-mining Lepidoptera were excluded from this study as only free-living species sensitive to sampling using a beating tray were collected.In statistical analyses we summarized the number of individuals in each family to deter...

A current checklist of Lepidoptera that utilize Robinia pseudoacacia as a hostplant in Slovakia (Central Europe) is provided. The inventory is based on a bibliographic review and new unreported data from southwest Slovakia. The list includes 35 Lepidoptera species belonging to 10 families. Most species are polyphagous and belong to Euro-Siberian faunal community. Two monophagous species, the leaf miners Macrosaccus robiniella and Parectopa robiniella, and the polyphagous pest Hyphantria cunea have subsequently been introduced to Slovakia.