RESUMO
Giant (Myrmecophaga tridactyla) and collared anteaters (Tamandua tetradactyla) are common mammals in the Cerrado biome. They are specialized in eating termites (Isoptera, Blattaria) and ants (Formicidae, Hymenoptera). This study tested the preference of the giant anteater for termites with different defense strategies: 1) soldier with chemical defense and a soft nest (Nasutitermes), and 2) soldier with mixed defenses - chemical and mechanical - and a hard nest (Cornitermes). Pieces of nests of both genera of termites were provided to captive giant anteaters, their behaviors were observed, and the time spent feeding in each termite nests was recorded. The anteaters exploited both termite species, although no significance difference was found, they spent more time feeding on Cornitermes than on Nasutitermes. The stomach contents of one road-killed giant anteater and one collared anteater were analyzed. The collared anteater fed on a wider diversity of termite species with different defense strategies, but showed a preference for Cornitermes. We argue that the preference of anteaters for a termite species that has a harder nest, and soldiers with mixed defense, may be due to the presence of terpenoids in the chemical apparatus of Nasutitermes, absent in Cornitermes. Also, the much higher proportion of soldiers in Nasutitermes may influence the anteaters' choice.
Tamanduá-bandeira (Myrmecophaga tridactyla) e Tamanduá-mirim (Tamandua tetradactyla) são mamíferos comuns no bioma Cerrado. São espécies especializadas em se alimentar de cupins (Isoptera, Blattaria) e de formigas (Formicidae, Hymenoptera). Este trabalho testou a preferência de tamanduás-bandeira por cupins com diferentes estratégias de defesa: 1) soldados com defesa química e ninho macio (Nasutitermes) e 2) soldados com defesa mista química e mecânica e ninho duro (Cornitermes). Pedaços de ninhos de ambos os gêneros de cupins foram fornecidos para tamanduás-bandeira em cativeiro, seu comportamento foi observado e o tempo gasto para se alimentar em cada ninho foi registrado. Os tamanduás exploraram os dois tipos de ninhos, apesar de não haver diferença significativa, eles permaneceram mais tempo se alimentando de Cornitermes do que de Nasutitermes. Os estômagos de um tamanduá bandeira e de um tamanduá-mirim atropelados em rodovias foram utilizados para analisar a dieta das espécies. O conteúdo estomacal do tamanduá-mirim revelou uma maior diversidade de espécies de cupins com diferentes estratégias de defesa, mas mostrou uma preferência por Cornitermes. Discutimos que a preferência de tamanduás por espécies de cupins com soldados de defesa mista e que constroem ninhos duros, pode ser devido à presença de terpenos no sistema de defesa de Nasutitermes, ausente em Cornitermes. Além disso, uma proporção superior de soldados em Nasutitermes pode influenciar a escolha dos tamanduás.
Assuntos
Formigas , Isópteros , Pradaria , XenarthraRESUMO
Abundace and body size distribution of invertebrates of leaf litter in Amazonian forest, Brazil. Based on 605 invertebrates sampled of the litter in an Amazonian Forest, some basic macroecological patterns for this assemblage were described. The relationship between abundance and body size, at logarithmic scale, was triangular, and the distribution of species was constrained in an asymmetric triangular envelope, that was tested using null model procedures in ECOSIM (P= 0,0002). The most abundant species were at an intermediated body size. The relationship between maximum abundance with different mean body size classes confirmed the Energetic Equivalent Rule (b = -1,069; t-0,75 = -2,13; P = 0.079). This way, species tend to consume energy from the community independent of their body size, since requirements are compensated by local population density