Species richness in natural and disturbed habitats: Asteraceae and Flower-head insects (Tephritidae: Diptera)

Anthropogenic changes in the landscape result in an environmental mosaic with serious consequences for biodiversity. The aim of the present study was to assess the effects of the anthropogenic changes on Asteraceae richness and abundance, and to evaluate the consequences for the richness of Tephritidae assemblages in five sampling sites, with three sampled habitats in each: cerrado (Brazilian savanna), eucalyptus stands and pasture. Sampling was carried out in 15 random transects (cerrados and one pasture) and in 30 transects (eucalyptus stands and the remaining pastures). Composition, species richness and insect abundance in each habitat type was estimated by sampling the flower heads for each species of host plant, collected by four people for 1h. Differences in mean abundance of plant population between habitats and sites were tested by two-way ANOVA. Differences in plant species richness between habitats and sites and effects of habitat, site and host plant richness on insect richness were tested using a generalized linear model with Poisson errors. Within each sampling site, cerrados showed higher species richness of Asteraceae than pastures and eucalyptus stands. There were also significant differences in plant richness among sites. Mean population abundance values were significantly different among habitats, but not among sites. Increased host plant richness led to significant insect species richness. There were no additional significant effects of habitat on insect richness. Therefore, anthropogenic alterations in landscape determined the impoverishment of plant assemblages and therefore of insect assemblages, because of the positive relationship between host plant richness and insect richness.

Assemblages of endophagous insects on Asteraceae in São Paulo Cerrados

A survey of the endophagous insects fauna associated to Asteraceae capitula was carried out from 2000 to 2002 in eight cerrado sensu stricto sites located in the Brazilian state of São Paulo. Sixty-four endophagous species of Diptera and Lepidoptera were recorded from 49 asteracean host plants. Approximately half of the species were obtained from a single locality, with a large proportion emerging from a single sample (unicates). Thirty percent of the species were singletons (i.e. only one individual was recorded). The large proportion of rare species suggests a high species turnover among localities. Lepidopteran species were recorded on more host species than dipterans, confirming their more polyphagous food habit, also observed in other Brazilian biomes and in Europe. We conclude that the studied cerrado localities, all within São Paulo State, are isolated with its invertebrate fauna composed of many rare and exclusive species. We suggest that the maintenance of Asteraceae biodiversity and their endophagous insects depend on the conservation of all cerrado remnants in the state.

No presente estudo foi realizado um levantamento da fauna de insetos endófagos de capítulos de Asteraceae (Compostas), de 2000 a 2002, em oito localidades de cerrados sensu stricto no estado de São Paulo. Foram obtidas 64 espécies de endófagos (dípteros e lepidópteros) de 49 espécies de hospedeiras. Aproximadamente metade das espécies foi obtida de apenas uma área, e destas uma grande proporção ocorreu em apenas uma amostra (unicatas). Trinta por cento das espécies foram consideradas "singletons" (apenas um indivíduo foi obtido). A grande quantidade de espécies raras sugere uma forte troca de espécies entre diferentes áreas. Lepidópteros foram registrados em mais espécies hospedeiras que dípteros, confirmando o já observado para o mesmo sistema de insetos e plantas em outros ambientes no Brasil e Europa. As áreas de cerrado sensu stricto estudadas no estado de São Paulo encontram-se isoladas, com uma grande parte da fauna de invertebrados composta por muitas espécies raras e exclusivas. Diante deste quadro, sugere-se que a manutenção da biodiversidade de Asteraceae e seus endófagos em seus níveis atuais depende da conservação de todo o conjunto de remanescentes de cerrado do estado.

New species of Tomoplagia Coquillett (Diptera: Tephritidae) from capitula of Asteraceae in Brazil / Novas espécies de Tomoplagia Coquillett (Diptera: Tephritidae) de capítulos de Asteraceae no Brasil

Twelve new species of Tomoplagia reared from capitula of Asteraceae collected in southern and southeastern Brazil are described (T. achromoptera n. sp., T. aczeli n. sp., T. bicolor n. sp., T. brasiliensis n. sp., T. cipoensis n. sp., T. dimorphica n. sp., T. grandis n. sp., T. interrupta n. sp., T. matzenbacheri n. sp., T. rupestris n. sp., T. variabilis n. sp., and T. voluta n. sp.). Five of these species have highly atypical wing markings, differing from the usual pattern for the genus, which includes five oblique yellow bands. Aberrant wing patterns were previously known in only three species. All the new species were reared from capitula of Vernonieae, confirming this Asteraceae tribe as the main host group of Tomoplagia species. Of these new species, five are specialists on the Lychnophorinae, a Vernonieae subtribe endemic to campo rupestre vegetation, which occurs on tops of mountain chains in central and southeastern Brazil. These species of Tomoplagia are probably restricted to the small ranges of these host plants. An addedum to the most recent key to species (Aczél 1955a) is provided, including couplets to all of the species with modified wing patterns

São descritas doze novas espécies de Tomoplagia criadas de capítulos de asteráceas, coletados no Sul e Sudeste do Brasil (T. aczeli n. sp., T. achromoptera n. sp., T. bicolor n. sp., T. brasiliensis n. sp., T. cipoensis n. sp., T. dimorphica n. sp., T. grandis n. sp., T. interrupta n. sp., T. matzenbacheri n. sp., T. rupestris n. sp., T. variabilis n. sp., e T. voluta n. sp.). Cinco espécies têm ornamentações atípicas das asas, derivadas do padrão normal para o gênero, que é de cinco faixas amarelas oblíquas. Padrões atípicos foram descritos anteriormente apenas para três espécies. Todas as espécies descritas foram criadas de capítulos de Vernonieae, o que confirma as plantas desta tribo de asteráceas como as principais hospedeiras das espécies de Tomoplagia. Entre as espécies de Tomoplagia descritas, cinco são especialistas de Lychnophorinae, uma sub-tribo das Vernonieae endêmica da vegetação de campo rupestre, que ocorre nos topos de cadeias montanhosas do Brasil central e sudeste. Estas espécies de Tomoplagia são, provavelmente, restritas à pequena distribuição geográfica de suas plantas hospedeiras. Um adendo à chave para espécies mais recente (Aczél 1955a) é apresentado, incluindo entradas para todas as espécies com ornamentações atípicas das asas