The establishment of agricultural matrices generally involves deforestation, which leads to fragmentation of the remaining forest. This fragmentation can affect forest dynamics both positively and ...negatively. Since most animal species are affected, certain groups can be used to measure the impact of such fragmentation. This study aimed to measure the impacts of agricultural crops (matrices) on ant communities of adjacent lower montane Atlantic rainforest fragments. We sampled nine forest fragments at locations surrounded by different agricultural matrices, namely: coffee (3 replicates); sugarcane (3); and pasture (3). At each site we installed pitfall traps along a 500 m transect from the interior of the matrix to the interior of the fragment (20 pitfall traps ~25 m apart). Each transect was partitioned into four categories: interior of the matrix; edge of the matrix; edge of the fragment; and interior of the fragment. For each sample site, we measured ant species richness and ant community composition within each transect category. Ant richness and composition differed between fragments and matrices. Each sample location had a specific composition of ants, probably because of the influence of the nature and management of the agricultural matrices. Species composition in the coffee matrix had the highest similarity to its corresponding fragment. The variability in species composition within forest fragments surrounded by pasture was greatest when compared with forest fragments surrounded by sugarcane or, to a lesser extent, coffee. Functional guild composition differed between locations, but the most representative guild was 'generalist' both in the agricultural matrices and forest fragments. Our results are important for understanding how agricultural matrices act on ant communities, and also, how these isolated forest fragments could act as an island of biodiversity in an 'ocean of crops'.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Some effort had been made concerning the social biodiversity of wasps in Brazil; however, few approaches have been made relating to how this taxa have adapted their nesting behavior to anthropic ...mixed environments. Thus, the present work aimed to survey the occurrence of social wasps in an anthropic area and their relationship with different types of nesting substrates. Increasing the knowledge of social wasps in anthropic areas would allow us to develop strategies for their conservation and management. Twenty long-term surveys were made at the Universidade de São Paulo, Ribeirão Preto campus, São Paulo State. During the searches, we collected information about wasp species and nesting substrate. A total of 20 species of 8 genera were identified, and a total of 431 active colonies were registered. Epiponini was the richest in terms of species richness. On the other hand, Mischocyttarini was represented by more active colonies. Mischocyttarus cerberus had a remarkably greater number of colonies, which agreed with the idea of preference of anthropic environments by independent founding wasps. Nesting behavior was associated with eight substrate categories. We observed that some species might express certain plasticity regarding their nesting substrate usage, whereas some expressed certain specificity. Facing the increase in the actual urbanization process and, consequently, habitat loss, this type of study might contribute towards better understanding how these insects are affected by altered environment.
Mischocyttarus cerberus stands out among the most investigated species of the eusocial paper wasp, in Brazil. While the adult characteristics were relatively well reported in the earlier studies, ...very meager information was available regarding their immature stages. This study provides a description of the immature morphology of the general brood of M. cerberus, by studying the number of instars and analyzing the degree of influence exerted by some of the environmental factors on the individuals in the immature phases. This work involves a detailed study of 72 wasp colonies from Rio Claro and Ribeirão Preto. Using the larvae drawn from 41 nests, the number of instars was calculated; besides, the degree to which a few environmental factors could affect the immature brood development was assessed in 31 nests. Eggs showed patterns similar in terms of form and size to that of the species described earlier. The two ventral lobes, characteristic of the Mischocyttarus larvae, were fully developed only in the fifth instar. The measurements of the larval heads in the five instars found concurred with the earlier reports for most of the social wasps. Furthermore, the larval stages took longer to develop, which could be related to the greater susceptibility of the larvae to the prevailing environmental factors. From the results of our study, we concluded that the M. cerberus showed the typical developmental pattern in the immature stages of its genus.
The reuse of nests by the same or different species can save a colony energy and resources. Furthermore, it can increase colony growth and the production of brood. The queenless ant Dinoponera ...quadriceps builds deep nests in Caatinga to escape from the dry and hot environment. The reuse of deep nests from other species can provide D. quadriceps with protection from high temperature, whilst saving on the energy required to build new nests. Here, we present the first finding of D. quadriceps reusing the nest of Atta sexdens species.
A new species of casque-headed tree frog of the genus Aparasphenodon is described from the municipality of Cataguases (21°20'S, 42°45'W; 288 m a.s.l.) in the Atlantic Rain Forest of Minas Gerais ...State, southeastern Brazil. Aparasphenodon pomba sp. nov. is characterized by medium size (males, snout-vent length, SVL 51.6-60.5 mm; females, SVL 58.7-62.1 mm); snout almost round in dorsal view; dorsum and limbs with cream-colored reticulation on dark-brown background; spots on ventral surface cream-colored; lips white; cream-colored dorsolateral stripe originating on the snout, crossing the upper eyelid and extending posteriorly to the axilla level; and red iris.
In recent years, there has been increasing interest in matrix-type influence on forest fragments. Terrestrial amphibians are good bioindicators for this kind of research because of low vagility and ...high philopatry. This study compared richness, abundance, and species composition of terrestrial amphibians through pitfall traps in two sets of semideciduous seasonal forest fragments in southeastern Brazil, according to the predominant surrounding matrix (sugar cane and pasture). There were no differences in richness, but fragments surrounded by sugar cane had the lowest abundance of amphibians, whereas fragments surrounded by pastures had greater abundance. The most abundant species, Rhinella ornata, showed no biometric differences between fragment groups but like many other amphibians sampled showed very low numbers of individuals in fragments dominated by sugar cane fields. Our data indicate that the sugar cane matrix negatively influences the community of amphibians present in fragments surrounded by this type of land use.
Pheidole oxyops Forel (Hymenoptera: Formicidae) is a generalist ant that can display passive and active forage strategies. Moreover, this species can forage actively for a variety of food resources ...from plant debris to dead arthropods. In this study we tested whether abiotic factors (e.g., daytime, temperature, and residual soil accumulation), as well as neighboring colonies, could influence the patterns of foraging activity. Forage activity was observed in morning, afternoon, and evening sessions. Also, we recorded the frequency of individuals, direction, and ground surface temperature during foraging events. Our results showed that forage direction was not affected by residual soil accumulation and neighboring P. oxyops colonies. The rate of departures from nests decreased as ground surface temperature increased, but nest exits increased significantly with the occurrence of nearby P. oxyops colonies. We observed also that P. oxyops appeared to maximize forage activities during the evening period that would reduce their exposure to potential predators, competitors, and any adverse effects associated with direct solar radiation.
This study presents a list of anurans associated to bromeliads in Parque Estadual da Serra do Brigadeiro, state of Minas Gerais, southeastern Brazil. It also brings information regarding the type of ...association between these anurans and plants. We recorded eight species belonging to five genera and two families, Cycloramphidae and Hylidae. The most abundant species was Scinax gr. perpusillus, followed by Scinax aff. perereca, Dendropsophus minutus, Bokermannohyla circumdata, Hypsiboas faber, Thoropa miliaris, Hypsiboas polytaenius and Dendropsophus elegans. Most species observed occupying bromeliads uses these microhabitats only as diurnal shelter. Scinax gr. perpusillus was the only classified as bromeligenous, depending upon the plants to complete its reproductive cycle.
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