Sobre um novo Nicoletiidae (Zygentoma: Insecta) do Brasil vivendo com formigas lava-pés (Hymenoptera: Formicidae)

Descreve-se um novo Zygentoma (Nicoletiidae: Subnicoletiinae), mirmecófilo da formiga lava-pés Solenopsis saevissima (Formicidae: Myrmicinae) no Estado do Rio de Janeiro, Brasil: Allotrichotriura saevissima gen. nov. sp. nov. que é comparado com os géneros e subgéneros conhecidos na subfamília. As principais características diagnósticas respeitam a combinação da forma do corpo, quetotaxia cefálica e do corpo, morfologia do prétarso e número de estilos e vesículas abdominais. Embora prospecções recentes tenham sido levadas a cabo na localidade típica, apenas se conhece a amostra original, que integra exclusivamente fêmeas.

Microdon tigrinus (Diptera, Syrphidae): Populational fluctuations and specificity to the nest of Acromyrmex coronatus (Hymenoptera: Formicidae)

This study was performed in the southern and southeastern regions of Brazil, visiting numerous municipalities, over a period of 25 years, excavating nests of 12 species of leaf-cutting ants of the Acromyrmex genus. Larvae and pupae of Microdon tigrinus were found only in nests of the leaf-cutting ant Acromyrmex coronatus, indicating high specificity. Observation showed that larvae and pupae were well accepted in the nests and the adults, immediately after puparia eclosion and prior to wing distension, were not attacked by the workers, suggesting that they produce semiochemicals for a short time period until they arrive outside the Acromyrmex coronatus nest. It was postulated that these larvae feed on the organic detritus of the nest, as shown for Microdon larvae of other species.

Natural history of an ant-plant-butterfly interaction in a Neotropical savanna

Non-myrmecophilous lepidopteran larvae using plants bearing ant attractants such as extrafloral nectaries are good models for studying morphological and behavioural mechanisms against ant predation. Udranomia spitzi (Hesperiidae) is a butterfly whose larvae feed on leaves of Ouratea spectabilis (Ochnaceae), a plant with extrafloral nectaries. We described the early stages of U. spitzi, and used field observations and experiments to investigate the defensive strategies of caterpillars against predatory ants. Larvae pass through five instars and pupation occurs inside larval leaf shelters. Ant-exclusion experiments revealed that the presence of ants did not affect significantly caterpillar survival. Predation experiments showed that vulnerability to ant predation decreased with increase in larval size. The present study showed that predatory ants are not as relevant as demonstrated for other systems, and also illustrates how observational data and field experiments can contribute to a better understanding of the biology and ecology of a species of interest.