The venom apparatus and other morphological characters of the ant Martialis heureka (Hymenoptera, Formicidae, Martialinae)

We describe and illustrate the venom apparatus and other morphological characters of the recently described Martialis heureka ant worker, a supposedly specialized subterranean predator which could be the sole surviving representative of a highly divergent lineage that arose near the dawn of ant diversification. M. heureka was described as the single species of a genus in the subfamily, Martialinae Rabeling and Verhaagh, known from a single worker. However because the authors had available a unique specimen, dissections and scanning electron microscopy from coated specimens were not possible. We base our study on two worker individuals collected in Manaus, AM, Brazil in 1998 and maintained in 70% alcohol since then; the ants were partially destroyed because of desiccation during transport to São Paulo and subsequent efforts to rescue them from the vial. We were able to recover two left mandibles, two pronota, one dismembered fore coxa, one meso-metapropodeal complex with the median and hind coxae and trochanters still attached, one postpetiole, two gastric tergites, the pygidium and the almost complete venom apparatus (lacking the gonostylus and anal plate). We illustrate and describe the pieces, and compare M. heureka worker morphology with other basal ant subfamilies, concluding it does merit subfamilial status.

Rediscovery of the putatively extinct ant species Simopelta minima (Brandão) (Hymenoptera, Formicidae), with a discussion on rarity and conservation status of ant species

Simopelta minima (Brandão, 1989) was originally described based on four workers collected in soil samples from a small cocoa plantation in Ilhéus, state of Bahia, northeastern Brazil. In the subsequent years after the description, this cocoa plantation was eliminated and the species was then considered extinct by the Brazilian environmental institutions. The recent rediscovery of S. minima workers in subterranean pitfall trap samples from Viçosa, state of Minas Gerais, southeastern Brazil, over 1.000 km distant from type locality, suggests that the rarity and vulnerability status of some ant species may be explained by insufficient sampling of adequate microhabitats, in time and space.

A new species of the fungus-farming ant genus Mycetagroicus Brandão & Mayhé-Nunes (Hymenoptera, Formicidae, Attini)

The fungus-farming ant genus Mycetagroicus Brandão & Mayhé-Nunes was proposed based on three species from the Brazilian "Cerrado": M. cerradensis, M. triangularis and M. urbanus. Here we describe a new species of Attini ant of the genus Mycetagroicus, M. inflatus n. sp., based on two workers collected in eastern Pará State, Brazil. A new key for species identification, comments on differences among species and new geographical distribution data are furnished.

A mixed colony of Scaptotrigona depilis and Nannotrigona testaceicornis (Hymenoptera, Apidae, Meliponina)

We describe a case of a spontaneously established mixed colony of two species of stingless bees. The host colony of Scaptotrigona depilis, an aggressive bee that forms large colonies, was invaded by workers of Nannotrigona testaceicornis, a smaller bee that forms small colonies. The host colony and the invading species colony were maintained in next boxes about 1.5 m apart. The N. testaceicornis colony had been recently divided. Observations were made daily for 10 min, and every two weeks the colony was opened for observations within the nest. Initially the host colony bees repulsed the invading species, but as their numbers built up, they were no longer able to defend the entrance. An estimated 60-90 N. testaceicornis workers lived integrated into the colony of S. depilis for 58 days. During this period, they reconstructed and maintained the entrance tube, changing it to an entrance typical of N. testaceicornis. They also collected food and building material for the host colony. Nannotrigona testaceicornis tolerated transit of S. depilis through the entrance, but did not allow the host species to remain within the tube, though the attacks never resulted in bee mortality. Aggression was limited to biting the wings; when the bees fell to the ground they immediately separated and flew back. There have been very few reports of spontaneously occurring mixed stingless bee colonies. It is difficult to determine what caused the association that we found; probably workers of N. testaceicornis got lost when we split their colony, and then they invaded the colony of S. depilis.

Ants Can Learn to Forage on One-Way Trails

The trails formed by many ant species between nest and food source are two-way roads on which outgoing and returning workers meet and touch each other all along. The way to get back home, after grasping a food load, is to take the same route on which they have arrived from the nest. In many species such trails are chemically marked by pheromones providing orientation cues for the ants to find their way. Other species rely on their vision and use landmarks as cues. We have developed a method to stop foraging ants from shuttling on two-way trails. The only way to forage is to take two separate roads, as they cannot go back on their steps after arriving at the food or at the nest. The condition qualifies as a problem because all their orientation cues-chemical, visual or any other - are disrupted, as all of them cannot but lead the ants back to the route on which they arrived. We have found that workers of the leaf-cutting ant Atta sexdens rubropilosa can solve the problem. They could not only find the alternative way, but also used the unidirectional traffic system to forage effectively. We suggest that their ability is an evolutionary consequence of the need to deal with environmental irregularities that cannot be negotiated by means of excessively stereotyped behavior, and that it is but an example of a widespread phenomenon. We also suggest that our method can be adapted to other species, invertebrate and vertebrate, in the study of orientation, memory, perception, learning and communication.

Description of the immatures of Linepithema humile Mayr (Hymenoptera: Formicidae)

Linepithema humile Mayr is an ant species originally native to South America that has been spread accidently throughout the globe through international trade. It is a serious urban and crop pest. Despite its economic importance, little is known about the larvae of this species apart from a brief description based on a few specimens. The present investigation is aimed at describing every immature stage of L. humile. Three larval instars were determined through the frequency distribution of the maximum width of head capsules from a sample of 525 larvae. The morphological descriptions were based on 150 eggs, 70 larvae, and 90 pupae examined by light and scanning electron microscopy. Some morphological characteristics reported to be typical of Linepithema Mayr larvae were confirmed - dolichoderoid body shape, presence of dorsal protuberance, sparse simple body hairs, presence of nine pairs of spiracles and dolichoderoid mandibles. We concluded that an earlier published description was based on queen larvae, and that the protuberance is only present in worker larvae. The information provided in this study may aid ant systematics and phylogenetics, as well provide a better understanding of the biology of this species.

Description of the Immatures of Workers of the Weaver Ant, Camponotus textor (Hymenoptera: Formicidae)

The weaver ants Camponotus textor (Forel) (Hymenoptera: Formicidae) are native to Central and South America, where they use their larvae to build silken nests by sewing tree leaves together. Few Studies have been conducted with this species, and little is known about the morphology of their larvae. Tie present paper estimated the number of larval instars of C. textor and presents a detailed morphological description of each immature stage based on light and electron microscopic observations. The number of larval in stars was estimated as four based oil the frequency distribution of larval head widths. Tic larvae of this species presented some typical characteristics of Camponotus (Mayr) larvae: body shape `pogonomyrmecoid`, ten pairs of spiracles, antennae with three sensilla, conspicuous `chiloscleres` on the labrum, and mature larvae with pronounced labial pseudopalps. Unprecedented characteristics would include: great diversity of body hair types, and `camponotoid` mandibles but with four medial denticles. This information can aid biological and taxonomic studies with these ants, and may be useful for ant systematics.

Isolation and characterization of actinobacteria ectosymbionts from Acromyrmex subterraneus brunneus (Hymenoptera, Formicidae)

The ectosymbiont actinobacterium Pseudonocardia was isolated from the integument of Acromyrmex leaf-cutter ants and seems to play a crucial role in maintaining asepsis of the nest. Currently, there has been an intensive search for Pseudonocardia associated with several attine species, but few studies have indicated that other actinobacteria may be associated with these ants as well. We therefore characterized the culturable actinobacteria community associated with the integument of the fungus-growing ant Acromyrmex subterraneus brunneus Forel, 1893 (Hymenoptera: Formicidae). Ectosymbionts were isolated using four different media and characterized by morphological and molecular (16S rDNA) methods. A total of 20 strains were isolated, of which 17 were characterized as Streptomyces spp., and one isolate each as Pseudonocardia, Kitassatospora and Propionicimonas. Unlike other Acromyrmex species, A. subterraneus brunneus is associated with a diversity of actinobacteria. Even though Pseudonocardia is present on this leaf-cutting ant`s integument, the number and diversity of Streptomyces spp. found differs from those of previous studies with other attine ants and suggest that different culturing approaches are needed to characterize the true diversity of microbes colonizing the integument of attine ants. Moreover, understanding the diversity of the culturable actinobacteria associated with A. subterraneus brunneus should increase our knowledge of the evolutionary relationship of this intricate symbiotic association. (C) 2010 Elsevier GmbH. All rights reserved.

Sites of Defoliation by Atta sexdens rubropilosa (Hymenoptera, Formicidae) in Artificial Plants

This study aimed to achieve a better understanding about the foraging behavior of leaf-cutter ant (Atta sexdens rubropilosa Forel) workers with respect to defoliation sites in plants. To accomplish that, artificial plants 70 cm in height were prepared and divided into four levels (heights), having natural plant leaves attached to them. Evaluations during the bioassays included the number of leaves dropped by the ants, as well as the percentage of plant mass removed. In all replicates, it became evident that the most exploited plant site is the apical region, which significantly differed from other plant levels.

Interaction between forest fragments and adjacent coffee and pasture agroecosystems: responses of the ant communities (Hymenoptera, Formicidae)

The responses of the ant community to environmental change, from forest fragment to agroecosystems (coffee or pasture) were evaluated in the south of the state of Minas Gerais, Brazil. In this paper we analized the interactions between forest and the two most typical agroecosystem from southest Brazil: sun-growing coffee plantation and introduced pasture. We sampled the ant community from five of each agroecosystems, inside the adjacent forest fragment, and on the edge between them. In each site we removed the litter from fifteen 1m(2) plots and extracted the ants using a Winkler extractor. A total of 165 ant species, distributed in 48 genera and 10 subfamilies were recorded. The coffee plantation presented the lowest abundance and estimated species richness. The causes of the changes observed among the areas are discussed.

Hymenoptera.

We present the fi rst review of Hymenoptera alien to Europe. Our study revealed that nearly 300 species of Hymenoptera belonging to 30 families have been introduced to Europe. In terms of alien species diversity within invertebrate orders, this result ranks Hymenoptera third following Coleoptera and Hemiptera. Two third of alien Hymenoptera are parasitoids or hyperparasitoids that were mostly introduced for biological control purposes. Only 35 phytophagous species, 47 predator species and 3 species of pollinators have been introduced. Six families of wasps (Aphelinidae, Encyrtidae, Eulophidae, Braconidae, Torymidae, Pteromalidae) represent together with ants (Formicidae) about 80% of the alien Hymenoptera introduced to Europe. Th e three most diverse families are Aphelinidae (60 species representing 32% of the Aphelinid European fauna), Encyrtidae (55) and Formicidae (42) while the Chalcidoidea together represents 2/3 of the total Hymenoptera species introduced to Europe. Th e fi rst two families are associated with mealybugs, a group that also included numerous aliens to Europe. In addition, they are numerous cases of Hymenoptera introduced from one part of Europe to another, especially from continental Europe to British Islands. Th ese introductions mostly concerned phytophagous or gall- maker species (76 %), less frequently parasitoids. Th e number of new records of alien Hymenoptera per year has shown an exponential increase during the last 200 years. Th e number of alien species introduced by year reached a maximum of 5 species per year between 1975 and 2000. North America provided the greatest part of the hymenopteran species alien to Europe (96 species, 35.3%), followed by Asia (84 species, 30.9%) and Africa (49 species, 18%). Th ree Mediterranean countries (only continental parts) hosted the largest number of alien Hymenoptera: Italy (144 spp.), France (111 spp.) and Spain (90 spp.) but no correlation was found with the area of countries. Intentional introduction, mostly for biological control, has been the main pathway of introduction for Hymenoptera. Consequently, the most invaded habitats are agricultural and horticultural as well as greenhouses. To the contrary, Hymenoptera alien in Europe are mostly associated with woodland and forest habitats. Ecological and economic impacts of alien Hymenoptera have been poorly studied. Ants have probably displaced native species and this is also true for introduced parasitoids that are suspected to displace native parasitoids by competition, but reliable examples are still scarce. Th e cost of these impacts has never been estimated.

Local diversity of tropical and temperature ant faunas (Hymenoptera, Formicidae)

Qualitative and quantitative collections of ants made in the region of Manaus, Brazil (evergreen tropical humid forest), and in western North Carolina, USA (deciduous temperate/wet forest), were undertaken to investigate. latitudinal patterns of ant diversity and community organization on regional and local scales. We have found to date 307 ant species in the Municipality of Manaus. Totals ranging from 134 to 270+ species have been reported in the literature for other tropical regions of less than 10,000km2. In contrast, temperate ant surveys generally report only SO to 150 species in similar or larger areas. Sampling at sardine baits set 10m apart on square grids, we found forest ecosystems near Manaus to be much richer and more diverse in ants than those sampled in North Carolina: 28 species vs. 5-10 species in 50 collections and 16 vs. 3 previously unrecorded species discovered with each doubling of sample size. Room's (1975a) results from climatically simllar Papua New Guinea forest agree closely with those from Manaus. We suggest that one important factor contributing to the increased diversity of tropical, omnivorous ants may be greater variety of nest sites available for specialization.

Distribution of Atta (Hymenoptera - Formicidae) in "terra-firme" rain forest of Central Amazonia: density, species composition and preliminary results on effects of forest fragmentation

One hundred and fourteen hectares of a "terra-fiirme" rain forest 70 km north of Manaus, Amazonas, Brazil, were surveyed for leaf-cutting ant colonies (Atta spp). One half of this area was in isolated forest fragments (surrounded by pastures or second growth) of two sizes: 1 and 10 ha. The other half was in non-isolated fragments (connected to a large parch of forest) of the same sizes. Only two species occured in this forest: Atta sexdens sexdens L. and A. cepfhalotes L. The first was the most abundant species with a mean density of 0.35 colonies per ha. The mean density of A. cephalotes colonies was 0.03 per ha. The density of colonies was not significantly different between the isolated fragments and the continuous forest. Furthermore, the species composition did not change with isolation. However, pre-isolation data and long term monitoring are necessary to conclude that the isolation of a forest fragment has no effect upon Atta colonies. The non-uniform spatial distribution of Atta colonics within the "terra-firme" forest must be taken into account when selecting conservation areas in the Amazon, in order to preserve this important group of ants together with their native habitat.

Split sex ratios in the social Hymenoptera: a meta-analysis

The study of sex allocation in social Hymenoptera (ants, bees, and wasps) provides an excellent opportunity for testing kin-selection theory and studying conflict resolution. A queen-worker conflict over sex allocation is expected because workers are more related to sisters than to brothers, whereas queens are equally related to daughters and sons. If workers fully control sex allocation, split sex ratio theory predicts that colonies with relatively high or low relatedness asymmetry (the relatedness of workers to females divided by the relatedness of workers to males) should specialize in females or males, respectively. We performed a meta-analysis to assess the magnitude of adaptive sex allocation biasing by workers and degree of support for split sex ratio theory in the social Hymenoptera. Overall, variation in relatedness asymmetry (due to mate number or queen replacement) and variation in queen number (which also affects relatedness asymmetry in some conditions) explained 20.9% and 5% of the variance in sex allocation among colonies, respectively. These results show that workers often bias colony sex allocation in their favor as predicted by split sex ratio theory, even if their control is incomplete and a large part of the variation among colonies has other causes. The explanatory power of split sex ratio theory was close to that of local mate competition and local resource competition in the few species of social Hymenoptera where these factors apply. Hence, three of the most successful theories explaining quantitative variation in sex allocation are based on kin selection.

Distribution des fourmis des bois et espèces apprentées (Hymenoptera, Formicidae, genre Formica) dans le canton de Vaud

This article shows the current distribution of seven ant species of the genus Formica (Hymenoptera, Formicidae, Formicinae) in the canton Waadt. Five species of wood ants (Formica subgenus Formica s.str.: F. rufa, F. polyctena, F. pratensis, F. lugubris et F. paralugubris) and two close species F (Formica) truncorum) et F. (Raptiformica) snaguinea) were investigated. The records originate from different surveys between 1996 and 2009 and offer the opportunity of an up to date overview of the species distribution.