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

Abstract

-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 fi ve 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 fl ower 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 signifi cant differences in plant richness among sites. Mean population abundance values were signifi cantly different among habitats, but not among sites. Increased host plant richness led to signifi cant insect species richness. There were no additional signifi cant 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.

Comparing assemblages of Asteraceae and their insect herbivores under different land‐use regimens

“…Plant assemblages in Eucalyptus stands were subsets of cerrado sites. Otherwise, pasture assemblages included 12 species that were exclusive to them and these assemblages were only partially subsets of cerrado sites (see also Diniz et al . 2010).…”

“…2009). Therefore, pasture management may well contribute to reducing isolation effects on insect populations in the cerrado (Diniz et al . 2010).…”

“…According to this rationale, pastures may be potentially suitable areas for colonization and establishment of new populations of plants and insects. Thus, depending on the management regime of these new areas, regeneration of the cerrado with a native floral/faunal composition might be practical (Diniz et al . 2010).…”

The relative roles of habitat heterogeneity and disturbance in drosophilid assemblages (Diptera, Drosophilidae) in the Cerrado

“…But, it remains uncertain how the insect communities of the Cerrado respond to the strong heterogeneity of the biome, as well as to the increasing levels of anthropogenic disturbance. Previous studies have indicated that the effects of seasonality (Morais et al ., ; Pinheiro et al ., ; Scherrer et al ., ; Silva et al ., ), vegetation diversity (Diniz et al ., ; Morais et al ., ), and vegetation heterogeneity (Pacheco & Vasconcelos, ), as well as those of fire (Vasconcelos et al ., ; Louzada et al ., ; Diniz et al ., ), fragmentation (Brandão et al ., ), afforestation (Gries et al ., ), and the introduction of exotic grasses (Almeida et al ., ; Almeida‐Neto et al ., ), can be reflected by insect communities in the Cerrado. But, this emerging body of knowledge is focused on the most studied insect taxa, such as butterflies, ants and beetles.…”

Tefritídeos endófagos (Diptera: Tephritidae) associados à Asteraceae em Chapecó, Santa Catarina doi:10.5007/2175-7925.2011v24n1p15

“…Existe pouca informação sobre biologia e taxonomia de grande número de espécies de tefritídeos associados à Asteraceae (FOOTE et al, 1993). No Brasil, os principais estudos realizados sobre a interação entre tefritídeos e Asteraceae são os realizados por: Lewinsohn (1991); Prado et al (2002); Prado e Lewinsohn (2004); Almeida et al (2006), Diniz et al (2010), Fávero et al (2010) havendo pouquíssimas informações até o momento sobre tal assunto em Santa Catarina.…”