1. The temporal dynamics of plant phenology and pollinator abundance across seasons should influence the structure of plant-pollinator interaction networks.Nevertheless, such dynamics are seldom considered, especially for diverse tropical networks.2. Here, we evaluated the temporal variation of four plant-pollinator networks in two seasonal ecosystems in Central Brazil (Cerrado and Pantanal). Data were gathered on a monthly basis over 1 year for each network. We characterized seasonal and temporal shifts in plant-pollinator interactions, using temporally discrete networks. We predicted that the greater floral availability in the rainy season would allow for finer partitioning of the floral niche by the pollinators, i.e. higher specialization patterns as previously described across large spatial gradients.Finally, we also evaluated how sampling restricted to peak flowering period may affect the characterization of the networks.3. Contrary to our expectations, we found that dry season networks, although characterized by lower floral resource richness and abundance, showed higher levels of network-wide interaction partitioning (complementary specialization and modularity). For nestedness, though, this between-seasons difference was not consistent. Reduced resource availability in the dry season may promote higher interspecific competition among pollinators leading to reduced niche overlap, thus explaining the increase in specialization. There were no consistent differences between seasons in species-level indices,indicating that higher network level specialization is an emergent property only seen when considering the entire network. However, bees presented higher values of specialization and species strength in relation to other groups such as flies and wasps, suggesting that some plant species frequently associated with bees are used only by this group.5. Our study also indicates that targeted data collection during peak flowering generates higher estimates of network specialization, possibly because species activity spans longer periods than the targeted time frame. Hence, depending on the period of data collection, different structural values for the networks of interactions may be found.6. Synthesis. Plant-pollinator networks from tropical environments have structural properties that vary according to seasons, which should be taken into account in the description of the complex systems of interactions between plants and their pollinators in these areas. K E Y W O R D SCerrado, functional diversity, modularity, nestedness, network sampling, Pantanal, resource availability, seasonality | 2411Journal of Ecology SOUZA et Al.

Differences in species richness and species composition of spiders associated with aquatic macrophytes of different structural complexities were examined in the Pantanal floodplain of Mato Grosso do Sul, Brazil. The plants studied were Nymphaea amazonum (Nymphaeaceae), Salvinia auriculata (Salviniaceae), Echinodorus paniculatus (Alismataceae) and Eichhornia azurea (Pontederiaceae), whose classes of complexity were determined based on their leaf and branch densities, vertical structure, and height. Data were collected from 62 monospecific plant patches in temporary lentic environments. A total of 235 spiders of 33 species in 13 families was collected. Nymphaea amazonum, the plant with the lowest complexity class, did not provide adequate sites for the establishment of spiders, and only four individuals of four spider species were found on its patches. Salvinia auriculata and E. paniculatus shared the intermediate class of complexity, but showed statistically significant differences in composition and richness of spider species. In E. paniculatus, greater height and lower leaf and branch densities favored the establishment of web weavers, whereas the smaller height and higher density of S. auriculata promoted the occurrence of wandering spiders. Eichhornia azurea, the plant with the highest complexity class, presented the greatest number of unique spider species, differing from the other plants in spider species composition. Results indicate that richness and composition of spider species associated with aquatic macrophytes in the study site are influenced by the structural complexity of these plants.

To understand the geographic distribution of visceral leishmaniasis (VL) in the state of Mato Grosso do Sul (MS), Brazil, both the climatic niches of Lutzomyia longipalpis and VL cases were analysed. Distributional data were obtained from 55 of the 79 counties of MS between 2003-2012. Ecological niche models (ENM) of Lu. longipalpis and VL cases were produced using the maximum entropy algorithm based on eight climatic variables. Lu. longipalpis showed a wide distribution in MS. The highest climatic suitability for Lu. longipalpis was observed in southern MS. Temperature seasonality and annual mean precipitation were the variables that most influenced these models. Two areas of high climatic suitability for the occurrence of VL cases were predicted: one near Aquidauana and another encompassing several municipalities in the southeast region of MS. As expected, a large overlap between the models for Lu. longipalpis and VL cases was detected. Northern and northwestern areas of MS were suitable for the occurrence of cases, but did not show high climatic suitability for Lu. longipalpis . ENM of vectors and human cases provided a greater understanding of the geographic distribution of VL in MS, which can be applied to the development of future surveillance strategies.

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1. Recent reports on bee health suggest that sublethal doses of pesticides have negative effects on wild bee reproduction and ultimately on their population growth.2. Females of the solitary horned mason bee Osmia cornuta, evaluate thoracic vibrations and odours of males to assess male quality. When certain criteria are met, the female accepts the male and copulates. However, these signals were found to be modified by sublethal doses of pesticides in other hymenopterans. Here, we tested whether sublethal doses of a commonly used fungicide (Fenbuconazole) impact male quality signals and mating success in O. cornuta. Males exposed to fenbuconazole exhibited reduced thoracic vibrations and an al-tered cuticular hydrocarbon profile compared to the control bees. Moreover, males exposed to the fungicide were less successful in mating than control males. Synthesis and applications.Our results indicate that a low toxicity fungicide can negatively affect male reproductive success by altering behavioural and chemical cues. This could explain the decreasing pollinator populations in a pesticidepolluted environment. This study highlights the need for a more comprehensive approach, including behaviour and chemical cues, when testing new pesticides and a more cautionary approach to the pesticides already used on crops.