Evaluation of natural foci of Panstrongylus megistus in a forest fragment in Porto Alegre, State of Rio Grande do Sul, Brazil

Introduction Panstrongylus megistus is commonly found in wild environments of the State of Rio Grande do Sul, Brazil. The aim of this study was to characterize the network of refuges used by triatomine in a forest fragment of Porto Alegre and to identify Trypanosoma cruzi infection, associated hosts and the epidemiological importance of both hosts and triatomines. Methods Techniques including the spool-and-line method and active searching (transects) were used to identify natural foci. Results The food source for each triatomine was determined using the precipitin test, and the infection of marsupials was determined by xenodiagnosis. A total of 33 adults (domestic environment) and 27 nymphs (wild environment) of P. megistus were found in addition to 43 Didelphis albiventris specimens. The infection rates of triatomine adults, triatomine nymphs and opossums with T. cruzi I were 64%, 73% and 69%, respectively. Birds, rodents and opossums were the main resources used by triatomine. Conclusions This work presents the first characterization of a natural focus of P. megistus in Rio Grande do Sul. The natural characteristics of this focus and its implication in the transmission of T. cruzi are discussed

Sustainable bioproducts in Brazil: disputes and agreements on a common ground agenda for agriculture and nature protection

A key question for food, biofuels, and bioproducts production is how agriculture affects the environment, and social and economic development. In Brazil, a large agricultural producer and among the biologically wealthiest of nations, this question is challenging and opinions often clash. The Brazilian parliament and several stakeholders have recently debated the revision of the Forest Act, the most important legal framework for conservation of natural vegetation on Brazilian private agricultural lands. Past decades have shown improvements in the agricultural sector with respect to productivity and efficiency, along with great reductions in deforestation and growth of environmentally certified production. However, the opposing sides in the debate have ignored this progress and instead continue to entrench their respective combative positions. A structured exchange involving nine experts associated with major producer interests (livestock, crops, planted forest, and charcoal) and environmental NGOs was moderated based on a framework that sorted viewpoints into four categories: (i) common ground - compatible interests considered to be high priority for Brazilian sustainable agricultural development; (ii) serving exclusive nature conservation interest; (iii) serving exclusive agricultural production interest; and (iv) mainly serving the purpose of sustaining dispute. We conclude that the majority of actions and expected future trends reflect achievements and ambitions to balance production and conservation, but much public opinion - and in turn decisions in the parliament and government for agriculture and conservation - is shaped by a perceived conflict between these objectives and a debate that has become, at least to some extent, an end in itself

Casteless sociality in an allodapine bee and evolutionary losses of social hierarchies

Communal behaviour is a form of social behaviour where two or more females nest together and have no reproductive hierarchies. Communal behaviour has often been regarded as an evolutionary ‘stepping stone’ to more complex forms of sociality involving castes, as well as a social form derived from solitary behaviour with no further evolution towards eusociality. However, recent phylogenetic studies on halictine bees suggest that some instances of communal behaviour are derived from eusociality. Here, we describe social nesting in an allodapine bee, Braunsapis puangensis, which has been introduced to Fiji from southern Asia. We show that this bee has a casteless form of sociality similar to communal organization, but which has been derived from an ancestrally hierarchical social system. This is likely due to a combination of small benefits for social nesting that rapidly saturate as colonies become larger, along with low costs for dispersal. We suggest that casteless forms of sociality have frequently evolved from hierarchical societies across many insect groups, but the analyses required for recognizing such societies are often undeveloped and hampers comparative approaches. Transitions from hierarchical to casteless societies challenge the notion that eusociality is an evolutionary ‘end point’ and we argue that eusociality can, in some cases, be regarded as an evolutionary step towards egalitarian societies. We also suggest that evolutionary periods involving reproductive hierarchies could select for traits that allow individuals to better assess their social environment and subsequently enable lower reproductive skew.C. R. B. da Silva, M. I. Stevens, M. P. Schwar