Nest architecture development of grass-cutting ants

ABSTRACT Atta bisphaerica is a species of grass-cutting ants commonly found in the Cerrado biome. The Brazilian Cerrado (savanna) biome covers 2 million km representing 23% of the area of the country. It is an ancient biome with rich biodiversity, estimated at 160,000 species of plants, fungi and animals. However, little is known about their nest architecture development. This study investigated the architecture of fourteen A. bisphaerica nests from Botucatu, São Paulo, Brazil. Molds were made of the nests by filling them with cement to allow better visualization of internal structures such as chambers and tunnels. After excavation, the depth and dimensions (length, width, and height) of the chambers were measured. As expected, there was a lateral development in the nests and increase in the number of chambers over time. Results showed that in nests with an estimated age of 14 months, the average depth was 1.6 ± 0.4 m; for those with 18 months it was 2.2 ± 0.7 m and at 28 months it was 2.5 ± 0.7 m. The number of chambers varied from 4 to 7 in 28-month nests, 2 to 4 in 18-month nests, and from 2 to 3 in 14-month nests. With respect to the dimensions of the internal tunnels, there were variations in their average width, increasing with time. The fungus chambers were located beneath the largest mound of loose soil. This study contributes to a better understanding of the so far unknown nest architecture development of A. bisphaerica grass-cutting ants.

Record and foraging behavior of ants (Hymenoptera, Formicidae) in vertebrate carcasses / Registro de forrageio de formigas (Hymenoptera, Formicidae) em carcaças de vertebrados

Knowing the importance of participation by insects at cadaverous decomposition processes, and the limited use of the family Formicidae in criminal investigations, this study aims to record the foraging activity of four genera of ants in carcasses of birds and mammals. Observations occurred accidentally in two locations in the State of Minas Gerais, Brazil. In total, seven species of ants foraging in eight vertebrate carcasses were recorded. In addition, the study reported for the first time the presence of Wasmannia in carcasses in Brazil.

Sabendo da importância da participação dos insetos em processos de decomposição cadavérica e do uso limitado da família Formicidae em investigações criminais, o objetivo do presente estudo foi registrar a atividade de forrageio de quatro gêneros de formigas em carcaças de aves e mamíferos. As observações ocorreram de forma acidental em duas localidades do Estado de Minas Gerais, Brasil. No total, foram registradas sete espécies de formigas forrageando em oito carcaças de vertebrados. O trabalho registrou ainda pela primeira vez a presença do gênero Wasmannia em carcaças no Brasil.

Dynamics of the restoration of physical trails in the grass-cutting ant Atta capiguara (Hymenoptera, Formicidae)

ABSTRACT Dynamics of the restoration of physical trails in the grass-cutting ant Atta capiguara. Leaf-cutting ants of the genus Atta build long physical trails by cutting the vegetation growing on the soil surface and removing the small objects they find across their path. Little is known on the dynamics of trail construction in these ants. How much time do they need to build a trail? To answer this question we selected six trails belonging to two different nests of A. capiguara and removed on each trail a block of soil of 20 cm × 15 cm that included a portion of the physical trail. This block was then replaced by a new block of the same size that was removed in the pasture near the trail and that was uniformly covered by the same type of vegetation as that found on the block of soil that was removed. The time required to restore the trail was then evaluated by the length of the grass blades found along the former location of the trail. The results show that ants rapidly restore the portion of the physical trail that was interrupted, which suggests that they could also do the same after their trails have been recolonized by the vegetation.

Nesting of social wasps (Hymenoptera: Vespidae) in a riparian forest of rio das Mortes in southeastern Brazil / Nidificação de vespas sociais (Hymenoptera: Vespidae) em floresta ripária do rio das Mortes no Sudeste do Brasil

The survival of social wasp species depends on the success in founding new nests. These species can use plant species with different specific characteristics for nesting, with nest architecture varying according to the habits of those plant species. The nesting of social wasps in natural environments was studied in the period from October 2005 to September 2007 in the rio das Mortes riparian forest, municipal district of Barroso, Minas Gerais State, Brazil, with the objective of evaluating the different types of plant substrate used by social wasps for nesting, and to investigate whether there is a relationship between nest construction type and the habits of plant species. A total of 171 colonies of social wasps belonging to 29 species were recorded, which used 78 plant species as nesting substrate (76 Angiosperms and two Pteridophytes) of arbustive, herbaceous, arboreal, epiphyte and liana habits. Species with phragmocyttarus and gymnodomous nests were observed nesting, with higher incidence, in arboreal plants and their deciduousness did not affect the nesting. The preservation of natural areas is suggested in order to guarantee a higher availability of nesting places for the social wasp species, ensuring their higher efficiency in the environmental services and biological control of agricultural pests.

A sobrevivência das espécies de vespas sociais depende do sucesso na fundação de novos ninhos. Essas espécies podem utilizar para nidificação de diferentes espécies vegetais com características específicas, com a arquitetura dos ninhos que variam em relação aos hábitos dessas espécies vegetais. A nidificação de vespas sociais em ambiente natural foi estudada no período de outubro de 2005 a setembro de 2007 em uma floresta ripária do rio das Mortes, município de Barroso, Estado de Minas Gerais, Brasil, com o objetivo de avaliar os diferentes tipos de substratos vegetais utilizados por vespas sociais para nidificação, e investigar se há relação entre o tipo de construção dos ninhos com os hábitos das espécies vegetais. Foram registradas 171 colônias de vespas sociais pertencentes a 29 espécies, que utilizaram como substrato de nidificação 78 espécies vegetais (76 Angiospermas e 2 Pteridófitas) de hábitos arbustivo, herbácea, arbóreo, epífita e liana. Espécies com ninhos fragmocítaros e giminódomos nidificaram, com maior incidência, em plantas arbóreas e a deciduidade das mesmas não afetou a nidificação. Sugere-se a preservação das áreas naturais de modo a garantir maior disponibilidade de locais de nidificação para as espécies de vespas sociais, assegurando maior eficiência nos serviços ambientais e no controle biológico de pragas na agricultura.

New host association: Polybia scutellaris (Hymenoptera, Vespidae) parasitized by Melaloncha (Diptera, Phoridae)

New host association: Polybia scutellaris (Hymenoptera, Vespidae) parasitized by Melaloncha (Diptera, Phoridae). The genus Melaloncha Brues is a large assemblage of New World, parasitoid phorid flies. They are parasitoids of Apoidea bees. However, here we present the first record of a wasp parasitized by Melaloncha sp. The new host is Polybia scutellaris (White), a neotropical eusocial wasp. The parasitized wasp was found in an urban park near the city of La Plata, Buenos Aires, Argentina. It appears that the genus Melaloncha parasitizes a wider range of social Hymenoptera than currently known.

Does body size of neotropical ant species influence their recruitment speed? / O tamanho corpóreo de espécies de formigas neotropicais influencia na velocidade de recrutamento?

Ants are one of the most important animal groups in tropical forests because of its abundance and number of species. An important characteristic of the group is the eusociality, which allows the occurrence of a recruitment behavior when food resource is found. However, there are two main questions regarding this behavior: (i) the recruitment is a product of environmental or phylogenetic pressures, and (ii) the recruitment speed is related to the body size of the ant species. In this work we addressed these two questions using 17 species of neotropical ants, in the Amazonic lowland dense rain forest. According to results, recruitment behavior is related to ant size, where smaller species exhibit this trait when finding a protein resource. However, species size is not important in recruitment speed, which suggests that speed can be best explained by the type of food resources needed in the ant colony.

Formigas são um dos mais importantes grupos animais nas florestas tropicais devido a sua abundância e seu número de espécies. Uma característica importante do grupo é a eusocialidade, que permite a ocorrência do comportamento de recrutamento quando um recurso alimentar é encontrado. Entretanto, existem duas questões principais acerca desse comportamento: (i) o recrutamento é um produto de pressões ambientais ou filogenéticas, e (ii) a velocidade de recrutamento é relacionada ao tamanho corpóreo das espécies de formigas. Neste trabalho nós analisamos essas duas questões em 17 espécies de formigas neotropicais, na floresta Amazônica densa de terras baixas. De acordo com os resultados, o recrutamento é fortemente relacionado com o tamanho da formiga, sendo que espécies menores exibem essa característica quando encontram uma fonte protéica. Entretanto, o tamanho das espécies não é importante na velocidade de recrutamento, o que sugere que a velocidade de recrutamento pode ser melhor explicado pelo tipo de recursos alimentares necessários à colônia.

Hymenoptera marking technique

In true social hymenopterans, such as many species of bees, wasps and all species of ants, the main characteristics are the overlapping of generations, the care with the offspring and the division of labor among the members of the colony. The first biological feature means that in a same moment there are groups of individuals, with variable ages, that execute different activities in the colony. In order to study the division of labor among the members of the colony, or to estimate the life span of these insects, or even to analyze any kind of behavior in non-social insects, it is necessary to know the exact age of each individual. For this reason, the insects must be identified soon after emergence. The identification of insects with numbers is an important technological improvement in behavioral studies, mainly in honeybee colonies. The aim of this scientific note is to describe an easy and cheaper technique for marking hymenopterans.

The mitochondrial genome of the stingless bee Melipona bicolor (Hymenoptera, Apidae, Meliponini): sequence, gene organization and a unique tRNA translocation event conserved across the tribe Meliponini

At present a complete mtDNA sequence has been reported for only two hymenopterans, the Old World honey bee, Apis mellifera and the sawfly Perga condei. Among the bee group, the tribe Meliponini (stingless bees) has some distinction due to its Pantropical distribution, great number of species and large importance as main pollinators in several ecosystems, including the Brazilian rain forest. However few molecular studies have been conducted on this group of bees and few sequence data from mitochondrial genomes have been described. In this project, we PCR amplified and sequenced 78 percent of the mitochondrial genome of the stingless bee Melipona bicolor (Apidae, Meliponini). The sequenced region contains all of the 13 mitochondrial protein-coding genes, 18 of 22 tRNA genes, and both rRNA genes (one of them was partially sequenced). We also report the genome organization (gene content and order), gene translation, genetic code, and other molecular features, such as base frequencies, codon usage, gene initiation and termination. We compare these characteristics of M. bicolor to those of the mitochondrial genome of A. mellifera and other insects. A highly biased A+T content is a typical characteristic of the A. mellifera mitochondrial genome and it was even more extreme in that of M. bicolor. Length and compositional differences between M. bicolor and A. mellifera genes were detected and the gene order was compared. Eleven tRNA gene translocations were observed between these two species. This latter finding was surprising, considering the taxonomic proximity of these two bee tribes. The tRNA Lys gene translocation was investigated within Meliponini and showed high conservation across the Pantropical range of the tribe.

Social insects and social amoebae.

The evolution of social groupings in insects, especially wasps, is compared to that of social amoebae (cellular slime moulds). They both show a gamut of colony sizes, from solitary forms to complex colonies with a division of labour. The various ideas as to how there might have been an evolution of complexity within insect societies, such as the role of genetic relatedness, the role of mutualism, the origin of sterility, the manipulation and exploitation of some individuals by others within a colony, are discussed, and then applied to social amoebae. The result is both interesting and instructive: despite some differences, there are many striking parallels, which suggests that there are some common denominators in the formation and evolution of a social existence among organisms.