[Differential survival of Euselasia apisaon Dahman (lepidoptera: riodinidae) pupae at understorey plants in the Eucalyptus plantations of Belo Oriente, MG, Brazil]. / Sobrevivência diferencial de pupas de Euselasia apisaon Dahman (Lepidoptera: Riodinidae) em plantas de sub-bosque nos plantios de Eucalyptus de Belo Oriente, MG.

Herbivorous insects may attack eucalyptus causing economic losses. One of these pests is the moth Euselasia apisaon Dahman, a key pest in the basin of middle Rio Doce. Here we studied the survival of pupae of this moth in Eucalyptus and in understorey plants and tested the hypotheses: i) live pupae are more abundant in plants of the understorey than in eucalyptus, ii) there is no difference between the abundance of pupae in different plants of the understorey. We sampled three areas cultivated with eucalyptus in Belo Oriente, MG, and samples were taken in five plots each area, getting five branches of each plant and of five eucalyptus trees that bordered the plot. The proportion of live and dead pupae and the mortality rate were estimated. The abundance of live pupae was higher in the understorey and the mortality rate of pupae was the same among different families of plants of the understorey. It is possible the larger available leaf area of understorey plants justify the greater abundance of live pupae in this habitat, however, avoidance of feeding habitat to finish the life cycle is also a possible explanation. Mortality rate in plants of the understorey points to an equal pressure of natural enemies on the pupae. These appointments help us to understand the dynamics of pests in eucalyptus plantations, providing important information to support actions against pests in natural environments.

Sobrevivência diferencial de pupas de Euselasia apisaon Dahman (Lepidoptera: Riodinidae) em plantas de sub-bosque nos plantios de Eucalyptus de Belo Oriente, MG / Differential survival of Euselasia apisaon Dahman (lepidoptera: riodinidae) pupae at understorey plants in the Eucalyptus plantations of Belo Oriente, MG, Brazil

Herbivorous insects may attack eucalyptus causing economic losses. One of these pests is the moth Euselasia apisaon Dahman, a key pest in the basin of middle Rio Doce. Here we studied the survival of pupae of this moth in Eucalypts and in understorey plants and tested the hypotheses: i) live pupae are more abundant in plants of the understorey than in eucalyptus, ii) there is no difference between the abundance of pupae in different plants of the understorey. We sampled three areas cultivated with eucalyptus in Belo Oriente, MG, and samples were taken in five plots each area, getting five branches of each plant and of five eucalyptus trees that bordered the plot. The proportion of live and dead pupae and the mortality rate were estimated. The abundance of live pupae was higher in the understorey and the mortality rate of pupae was the same among different families of plants of the understorey. It is possible the larger available leaf area of understorey plants justify the greater abundance of live pupae in this habitat, however, avoidance of feeding habitat to finish the life cycle is also a possible explanation. Mortality rate in plants of the understorey points to an equal pressure of natural enemies on the pupae. These appointments help us to understand the dynamics of pests in eucalyptus plantations, providing important information to support actions against pests in natural environments.

Thermoregulatory constraints on behavior: patterns in a neotropical dragonfly assemblage

Odonate species are classified in terms of their thermoregulatory behavior into flier and percher categories. Larger perchers could be more efficient thermoregulators in sunny sites and smaller perchers depend more on air temperature. In this paper, an analysis of the behavioral temporal budget of an odonate neotropical assemblage was performed to determine the role of body size on territorial defense and general behavioral strategies. This analysis revealed three groups based on time budget. The first and second groups contained the species that remained perched for most of the activity time, but species of the first group differ from the second group by the larger proportion of transition flights. The third group contained species which were usually observed patrolling or in reproductive activities. The larger species spent more time in patrol and territorial defense activities, while smaller species remained perched. Larger dragonflies, with better thermoregulatory abilities could spend more time in reproductive activities. The behavioral classification of fliers and perchers is considered extremely useful but could oversimplify the behavioral patterns among species that have a wide body size variation. It is proposed that a behavioral continuum associated with the body size variation in perchers could explain some patterns of species interactions in odonate communities.

As libélulas são classificadas comportamentalmente em voadoras e pousadoras com relação a sua capacidade de termoregulação. Libélulas de grande tamanho corporal devem termoregular de forma mais eficiente em locais com elevada irradiação solar, ao passo que libélulas menores dependem da temperatura ambiente. Neste estudo, foram realizadas análises de orçamento temporal de uma assembléia de libélulas para determinar como o tamanho corporal pode restringir a defesa de territórios e outros comportamentos. Baseado no orçamento temporal, foram observados três grupos de espécies. O primeiro e o segundo grupos abrangem espécies que permaneceram pousadas grande parte do tempo de atividade, entretanto espécies do primeiro grupo realizaram vôos de transição mais freqüentemente. O terceiro grupo conteve as espécies que foram observadas freqüentemente patrulhando seus territórios ou executando atividades reprodutivas. As espécies maiores permaneceram mais tempo em atividades de patrulha e defesa de seus territórios enquanto as espécies menores ficaram mais tempo pousadas. Libélulas maiores com maior habilidade de termoregulação puderam gastar mais tempo em atividades reprodutivas. A classificação das libélulas em voadoras e pousadoras é considerada extremamente útil, mas simplifica os padrões comportamentais observados entre espécies que têm grande variação de tamanho corporal. É provável que o contínuo comportamental associado com a variação de tamanho corporal, nos pousadores, possa explicar os padrões de interações entre espécies em comunidades de libélulas.