The Role of Resource Density on Energy Allocation in the Neotropical Termite Nasutitermes aff. coxipoensis (Termitidae: Nasutitermitinae).

Organisms acquire energy from environment and must allocate it among different life traits (growth, maintenance and reproduction). Social insects must manage the energy allocation to various levels such as colony growth and caste functions. Here, we addressed the question of whether resource density affects the energy allocation to the number of individuals and caste functions as well as nest's growth rate in the Neotropical termite Nasutitermes aff. coxipoensis (Homgren) (Termitidae: Nasutitermitinae). In a manipulative field experiment, colonies of N. aff. coxipoensis, with known volume, were maintained in plots with three different resource's density (0.32, 0.64 and 1.92 baits/m2) over 3 months. After this period, the number of individuals as well as the caste identity and nest volume were measured. Surprisingly, our results showed that colonies reared in the extremes of resource's density (0.32 and 1.92 baits/m2) produced a higher number of individuals compared with colonies reared with intermediate resource density (0. 64 baits/m2). The mean number of workers increased linearly with resource density; however, the average number of immature was higher in colonies reared with 0.32 baits/m2 compared with colonies reared with 0.64 and 1.92 baits/m2. No significant differences of resource density were observed in the mean number of soldiers, worker/soldier ratio as well as in the nest's growth rate. In conclusion, the resource's density seems to play an important role in determining the investment of energy in the number of individuals and caste in N. aff. coxipoensis colonies.

The impact of edge effect on termite community (Blattodea: Isoptera) in fragments of Brazilian Atlantic Rainforest / O impacto do efeito de borda na comunidade de cupins (Blattodea: Isoptera) em fragmentos de florestas da Mata Atlântica

Abstract Habitat fragmentation is considered to be one of the biggest threats to tropical ecosystem functioning. In this region, termites perform an important ecological role as decomposers and ecosystem engineers. In the present study, we tested whether termite community is negatively affected by edge effects on three fragments of Brazilian Atlantic Rainforest. Termite abundance and vegetation structure were sampled in 10 transects (15 × 2 m), while termite richness, activity, and soil litter biomass were measured in 16 quadrants (5 × 2 m) at forest edge and interior of each fragment. Habitat structure (i.e. number of tree, diameter at breast height and soil litter biomass) did not differ between forest edge and interior of fragments. Termite richness, abundance and activity were not affected by edge effect. However, differences were observed in the β diversity between forest edge and interior as well as in the fragments sampled. The β diversity partitioning indicates that species turnover is the determinant process of termite community composition under edge effect. Our results suggest that conservation strategies should be based on the selection of several distinct sites instead of few rich sites (e.g. nesting).

Resumo A fragmentação do habitat é considerada uma das maiores ameaças para o funcionamento do ecossistema tropical. Nesta região, os cupins desempenham um papel ecológico importante como decompositores e engenheiros do ecossistema. No presente estudo, testamos se comunidades de cupins são negativamente afetadas pelo efeito de borda em três fragmentos de Mata Atlântica. Para isso, foram amostrados a abundância de cupins e a estrutura da vegetação em 10 transectos (15 × 2 m), enquanto a riqueza, abundância de cupins e biomassa da serrapilheira foram amostrados em 16 parcelas (5 × 2 m) na borda e no interior de cada um dos três fragmentos. A estrutura do habitat (número de árvores, diâmetro à altura do peito e biomassa da serrapilheira) não diferiu entre a borda e o interior dos fragmentos. A riqueza, abundância e atividade dos cupins também não foram afetados pelo efeito de borda. No entanto, foram observadas diferenças na diversidade β entre borda e interior dos fragmentos, bem como nos fragmentos amostrados. O particionamento da diversidade β indicou que a substituição de espécies ("turnover") é o processo determinante da composição da comunidade de cupins sob efeito de borda. Nossos resultados sugerem que as estratégias de conservação devem ser baseadas na seleção de locais distintos em vez de poucos locais (via processo de aninhamento - "nesting").

The impact of edge effect on termite community (Blattodea: Isoptera) in fragments of Brazilian Atlantic Rainforest.

Habitat fragmentation is considered to be one of the biggest threats to tropical ecosystem functioning. In this region, termites perform an important ecological role as decomposers and ecosystem engineers. In the present study, we tested whether termite community is negatively affected by edge effects on three fragments of Brazilian Atlantic Rainforest. Termite abundance and vegetation structure were sampled in 10 transects (15 × 2 m), while termite richness, activity, and soil litter biomass were measured in 16 quadrants (5 × 2 m) at forest edge and interior of each fragment. Habitat structure (i.e. number of tree, diameter at breast height and soil litter biomass) did not differ between forest edge and interior of fragments. Termite richness, abundance and activity were not affected by edge effect. However, differences were observed in the ß diversity between forest edge and interior as well as in the fragments sampled. The ß diversity partitioning indicates that species turnover is the determinant process of termite community composition under edge effect. Our results suggest that conservation strategies should be based on the selection of several distinct sites instead of few rich sites (e.g. nesting).