Search

Leaf-cutting ants are distributed exclusively in the Americas. For this study, we sampled different areas of native vegetation and monocultures to survey the leaf-cutting ants that occur in the State of Goiás, and to what environments they are associated. We recorded six species of leaf-cutting ants: Atta sexdens, Atta laevigata, Acromyrmex subterraneus, Acromyrmex disciger, Acromyrmex ambiguus, and Acromyrmex hispidus. The last four were registered for the first time for the State of Goiás.

Made available in DSpace on 2020-12-10T19:50:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-02-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Toxic baits are the most efficient method to control leaf-cutter ants in eucalyptus forests for paper and cellulose production. For the proper use of these baits, insecticide compounds must reach workers and contaminate them. Thus, understanding how these baits are processed inside the nests is vital for a successful control, especially when it comes to genus Acromyrmex. Lack of information on toxic baits and on contamination of Acromyrmex workers raises the question: do workers from subspecies Acromyrmex subterraneus (Forel) prepare leaves and toxic baits in similar ways for their fungus garden? To answer it, this study described and analyzed the behavioral repertoire executed by A. subterraneus workers during the preparation of leaf disks and baits and their incorporation into the fungus garden. Results show that the act of licking the substrate was the most frequently executed behavior, regardless of subspecies or size categories. Moreover, additional behaviors have been observed when workers processed the baits, such as licking and scraping their jaws on the surface of the bait pellet, as well as licking and biting fragments of bait pellets, moistening them. Thus, it is concluded that the preparation of baits is different from that of leaves; baits are more processed and can therefore contribute to contaminating workers via insecticides. Sao Paulo State Univ, Sch Agr Sciences,Vegetal Protect Dept, Lab Social Insects,Pests, Botucatu, SP, Brazil Sao Paulo State Univ, Expt Campus Itapeva, Sao Paulo, SP, Brazil Univ w Sao Paulo, Coll Agr Sciences, Agron Dept, Lab Agr Entomol, Presidente Prudente, SP, Brazil Sao Paulo State Univ, Sch Agr Sciences,Vegetal Protect Dept, Lab Social Insects,Pests, Botucatu, SP, Brazil Sao Paulo State Univ, Expt Campus Itapeva, Sao Paulo, SP, Brazil CNPq: . 301167/2003-6 CAPES: Finance Code 001

The present study was developed in order to evaluate the effect of five essential oils on the workers of the leaf-cutting ants; Atta sexdens rubropilosa and Acromyrmex subterraneus molestans by contact with a treated surface and ingestion with a treated leaves.. The essential oils of cinnamon, clove and mustard had generally more effective with 5, 10 and 15% concentrations after 24, 48, 72 and 96 h against workers of A. sexdens rubropilosa and A. subterraneus molestans in contact bioassay, but mustard was the most effective in ingestion bioassay on both species. On the other hand, there was no significant difference among the essential oils with 1% concentration and control after 24, 48 and 72 h of treatment in contact and ingestion bioassays against workers of A. sexdens rubropilosa . However, Andiroba oil had less efficiency values in all concentrations been used. Therefore, the essential oils of mustard, cinnamon and clove have contact and ingestion effects on workers of A. sexdens rubropilosa and A. subterraneus molestans, and may be promising on the leaf-cutting ant control.

BACKGROUND Attractive toxic baits are the prevailing method for managing leaf-cutting ants in the eucalypt forests planted for the production of pulp, paper, timber and charcoal. For successful use in these baits, the insecticidal compounds need to circumvent the typical defences of the eusocial leaf-cutting ants. The challenge is to have an insecticide in the bait that will not directly harm and/or compromise foraging workers, but that will eventually suppress the colony. These underlying mechanisms are poorly known, and here the potential mechanism of fipronil activity in toxic baits for leaf-cutting ants was assessed using colonies of the representative Neotropical Acromyrmex subterraneus subterraneus (Forel, 1893). RESULTS Although forager activity was not directly impaired by fipronil, the insecticide affected forager nestmate interactions (auto- and allogrooming) and waste removal and, more importantly, greatly affected the minor workers, impairing their activities of fungus garden cultivation and progeny handling. The fast decay of the fungus garden compromised the sustainability of the colonies, ultimately leading to their demise within 8 days. CONCLUSION The behavioural effects of sublethal insecticide exposure towards minor workers are the main determinants of insecticide activity as ant baits and should be targeted in developing such compounds. © 2016 Society of Chemical Industry

Made available in DSpace on 2018-12-11T17:22:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-12-01 During foraging, thousands of leaf-cutting ant workers travel along high traffic foraging trails which, when narrow, reduce the leaf delivery rate due to the reduction in workers’ travel-speed. On the other hand, high worker traffic promotes head-on encounters which are supposed to mediate worker task allocation and so could constitute a cue which induces traffic reduction. Very small workers along trails, for example, could change their task between marking the trail chemically to hitchhiking. Since they assume the hitchhiker function even in the absence of phorid parasitoids, one can suppose that hitchhiker behavior could be a strategy mediated by head-on encounters to avoid the high density of workers. Thus, we studied how the variation of worker density on the trail influences the hitchhiker frequency, testing the hypothesis that very small workers climb on the transported leaves to reduce trail traffic. Therefore, five Acromyrmex subterraneus colonies were linked to a foraging area by trails of different width (1.5 or 3 cm). We counted the number of hitchhikers and the outbound worker flow. The frequency of hitchhikers increased along narrow trails, and also due to outbound workers in both trail widths. Regardless of outbound foraging flow being comparable in both trail widths, the narrower ones had high density of workers leading to a presumed increase in head-on encounters. Head-on encounter rates cause a reduction in travel speed and, furthermore, are regulatory factors of task-allocation. Thus, high density trails lead to an increase in the rate of head-on encounters which could constitute as a stimulus to task-allocation of very small workers to the function of hitchhiker to avoid traffic jams. Programa de Pós-Graduação em Ecologia Universidade Federal de Juiz de For a, Rua José Lourenço Kelmer, s/n. Campus Universitário, Bairro São Pedro Laboratório de Insetos Sociais-Praga Departamento de Produção Vegetal Setor Defesa Fitossanitária FCA/UNESP, PO Box 237 Programa de Pós-Graduação em Ciências Biológicas Comportamento e Biologia Animal Universidade Federal de Juiz de Fora, Rua José Lourenço Kelmer, s/n. Campus Universitário, Bairro São Pedro Laboratório de Insetos Sociais-Praga Departamento de Produção Vegetal Setor Defesa Fitossanitária FCA/UNESP, PO Box 237

The original version of this article unfortunately contained some mistakes for the greek letter “Ɵ” in the proof manuscript.

International audience; Associations with symbiotic organisms can serve as a strategy for social insects to resist pathogens. Antibiotics produced by attine ectosymbionts (Actinobacteria) suppress the growth of Escovopsis spp., the specialized parasite of attine fungus gardens. Our objective was to evaluate whether the presence or absence of symbiotic actinobacteria covering the whole ant cuticle is related to differential immunocompetence, respiratory rate and cuticular hydrocarbons (CHs). We evaluated these parameters in three worker groups of Acromyrmex subterraneus subterraneus: External workers (EXT), internal workers with actinobacteria covering the whole body (INB) and internal workers without actinobacteria covering the whole body (INØ). We also eliminated the actinobacteria by antibiotic treatment and examined worker encapsulation response. INB ants showed lower rates of encapsulation and respiration than did the EXT and INØ ants. The lower encapsulation rate did not seem to be a cost imposed by actinomycetes because the elimination of the actinomycetes did not increase the encapsulation rate. Instead, we propose that actinobacteria confer protection to young workers until the maturation of their immune system. Actinobacteria do not seem to change nestmate recognition in these colonies. Although it is known that actinobacteria have a specific action against Escovopsis spp., our studies, along with other independent studies, indicate that actinomycetes may also be important for the individual health of the workers.

Made available in DSpace on 2018-11-26T17:21:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-01-01 This study investigated the stimuli that trigger digging behavior inAcromyrmex subterraneus during nest building. The hypothesis was that the presence of the fungus garden and/or brood triggers the excavation of tunnels and chambers. For the experiment, the excavation rate of individually marked workers kept in plastic cylinders filled with soil was recorded. Four treatments were applied: (1) 30 medium-sized workers, 5 g fungus garden and 30 brood items (larvae and pupae); (2) 30 medium-sized workers and 5g fungus garden; (3) 30 medium-sized workers and 30 brood items; (4) 30 medium-sized workers without fungus and brood. After 24 h, morphological parameters of nest structure (length and width of the chambers and tunnels in cm) and the volume of excavated soil were recorded. In contrast to the expected findings, no change in morphological structure, rate of excavation by workers, or volume of excavated soil was observed between treatments, except for tunnel width, which was greater, when no brood or fungus garden was present. Thus, the results do not support the hypothesis that the fungus garden and/or brood are local stimuli for nest excavation or that they mold the internal architecture of the nest. Although this hypothesis was confirmed for Acromyrmex lundii and Atta sexdens rubropilosa, the same does not apply to A. subterraneus. The digging behavior of workers is probably the result of adaptation during nest building in different habitats. (C) 2016 Sociedade Brasileira de Entomologia. Published by Elsevier Editora Ltda. Univ Fed Juiz de Fora, Inst Ciencias Biol, Programa Posgrad Comportamento & Biol Anim, Juiz De Fora, MG, Brazil Univ Estadual Paulista, Fac Ciencias Agron, Dept Prod Vegetal, Botucatu, SP, Brazil Univ Fed Juiz de Fora, Inst Ciencias Biol, Programa Posgrad Ecol, Juiz De Fora, MG, Brazil Univ Estadual Paulista, Fac Ciencias Agron, Dept Prod Vegetal, Botucatu, SP, Brazil

(Novas perspectivas sobre a ocorrência do comportamento de caroneira). Durante o forrageamento de formigas cortadeiras pode-se observar operárias mínimas sobre os fragmentos de folha transportados até o ninho, comportamento denominado de caroneira. São citadas várias funções relacionadas a este comportamento, como defesa contra forídeos parasitoides, limpeza dos fragmentos de folhas, economia de energia de retono ao ninho, além de ingestão de seiva que exsuda do corte. Sendo assim, o presente estudo se apresenta como uma forma de elucidar questões ecológico-comportamentais de caroneira em Acromyrmex subterraneus, tendo por objetivos avaliar i) se as caroneiras ocorrem de forma aleatória ou dependente do fragmento vegetal transportado, ii) se a carga microbiana influencia a frequência de caroneiras e iii) como as caroneiras respondem a variações no tráfego de forrageamento. Para tanto, foram feitas manipulações nos fragmentos vegetais oferecidos e nas trilhas de forrageamento. No primeiro experimento verificou-se que caroneiras podem ocorrer em qualquer tamanho de fragmento ou espécie vegetal, mas há variação do tamanho da caroneira em função do fragmento. Tal fato demonstra alta plasticidade deste comportamento, de forma a ocorrer sobre os mais diversos substratos. No segundo experimento a presença de fungo entomopatogênico e antibióticos diminuiu a ocorrência de caroneiras, não sendo possível relacionar a frequência de caroneiras com a remoção de carga microbiana. Sugere-se que as caroneiras tenham evitado contato com os conídios fúngicos e com as soluções antimicrobianas porque eram substâncias desconhecidas pelas operárias. Já no terceiro experimento observou-se incremento da frequência de caroneiras em trilha estreita, com alta densidade de operárias. De fato, a frequência de caroneiras se correlacionou positivamente com o fluxo de operárias que deixavam o ninho nos três experimentos. Devido à alta frequência de encontros promovida pelo aumento do fluxo de operárias que saem do ninho e da densidade de operárias na trilha estreita sugere-se que o comportamento de caroneira é estimulado por esta taxa de encontros, que é agente regulatório de alocação de tarefas. O comportamento de caroneira pode ser considerado uma estratégia comportamental para redução do tráfego de operárias nas trilhas. (New perspectives of hitchhiking behavior occurrence). During foraging of leafcutting ants, it can be observed minimal workers over leaf fragments, called hitchhikers. Many functions are cited as related with hitchhiking behavior, as defense against parasitoids, leaf cleaning, energy saving and sap feeding. Here, the objectives were to evaluate i) if hitchhiker occurrence is plant-size-species-dependent, ii) if microbial load influences hitchhiker frequency and iii) how hitchhiker frequency is influenced by high density of foraging traffic. It has been manipulated leaf fragments and foraging trails. In first experiment, it has been verified that hitchhikers could occur over any fragment size or plant species, but hitchhiker masses varied among plant species. In the second experiment, the entomopathogenic fungus and antibiotics reduced hitchhiker occurrence. Thus, it was not possible to relate hitchhiker frequency with microbial load removal. It has been suggested that hitchhikers avoid the conidia fungal and the antibiotic solutions due to these materials are unknown by workers. In the third experiment, hitchhiker frequency has been higher at narrow trails, which has greater worker density. Actually, hitchhiker frequency has been positively correlated with the outbound worker flow in the three experiments. Due to high head-on encounters promoted by the increased outbound worker flow and by the greater worker density in narrow trails, it has been suggested that hitchhiker behavior is stimulated by these encounters, which are regulatory agents of task allocation. The hitchhiker behavior could be considered a behavioral strategy to reduce worker traffic along foraging trails.

Leaf-cutting ants are well-known insects due to their remarkable activity as herbivores and the considerable economic damage they cause to many crops. The identification of season and time of day when leaf-cutting ants are most active is an important tool, not just to understand the foraging ecology of these ants, but also to optimize their control in plantation areas where they were pests. Thus, the aims of this study are to evaluate the daily foraging activity of leaf-cutting ant species of the genus Acromyrmex, which occur in forest plantations in Southern Brazil. Foraging activity of Acromyrmex crassispinus (Forel) and Acromyrmex subterraneus subterraneus (Forel) were correlated with weather conditions, and it was more intense during spring and summer. Workers that forage at night are significantly heavier than workers that forage during the day. This study showed that A. crassispinus and A. subterraneus subterraneus did not forage at temperatures below 10-11°C. Then, the use of granulated baits to control these leaf-cutting ants species where they were pests should be done just under favorable conditions of temperature for Acromyrmex foraging activity (over 12°C), to ensure maximum collection of baits by ants and the least left-over baits.

This study describes and quantifies the behavioural acts of two laboratory colonies of Acromyrmex subterraneus brunneus by investigating worker age polyethism. Twenty-nine behavioural acts were recorded during the 19-week observation period. Young individuals performed tasks inside the nest related to brood care and care for the fungus garden, whereas older individuals performed activities outside the nest such as foraging and activities in the waste chamber. The average longevity (±SD) was 108.21 ± 3.30, 109.15 ± 1.92 and 122.71 ± 1.55 days for large, medium and small workers, respectively. The small-sized workers presented a higher probability of reaching older age than large- and medium-sized workers. This study describes task switching according to age polyethism and the relationship of physical and temporal subcastes.

During foraging, leaf-cutting ant workers of different size classes perform various tasks along foraging trails. Commonly, small workers called hitchhikers climb on leaf fragments imposing an extra transport cost, so their presence is thought to reduce the individual foraging performance. There are four main hypotheses which may explain the occurrence of hitchhikers and a different behavioral act related to their role can be predicted for each. Hitchhiker behavior was observed considering these hypotheses and the effect of the hitchhikers on the walking speed and transport rate of foragers was evaluated. The behavioral registers were obtained from 1371 hitchhikers on foraging trails of Acromyrmex subterraneus subterraneus nests in the field. To verify the influence of hitchhikers on walking speed and transport rate, 239 foragers with hitchhikers and 250 foragers transporting only leaf fragments were analyzed. The walking speed, burden and transport rate of each forager were calculated. Data indicated not only that hitchhikers are vigilant but that they remain motionless on the leaf fragment probably in order to reduce the impact of their presence for the loaded forager. The impact of their presence is verified through walking speed reduction but as they ride preferentially on larger workers who transport larger leaf fragments, there are no losses in the individual transport rate. The transporter selection made by the hitchhiker ensures at the same time enhanced protection against phorid parasitoids and the maintenance of the leaf transport rate.

Aggressive behavior is important for social insects because it makes possible for the colony to defend itself and the offspring from the action of invasive species. We studied the recognition and aggressiveness of the leaf-cutting ant Acromyrmex subterraneus subterraneus (Forel) to co-specific workers from other nest and heterospecific workers of Acromyrmex subterraneus molestans Santschi, Acromyrmex subterraneus brunneus (Forel) and Acromyrmex niger (Smith); and queens of their social parasite Acromyrmex ameliae De Souza, Soares and Della Lucia. Workers of other species were placed in contact with those of A. subterraneus subterraneus for three minutes and during this period the behavioral interactions were quantified. The aggressiveness index (AI) for each agonistic encounter was obtained. Acromyrmex subterraneus subterraneus workers exhibited greater aggressiveness against heterospecific than against conspecific competitors. Aggressiveness is connected to differences in the chemical profiles, which are larger in heterospecifics colonies.

Adult leaf-cutting ants of the subspecies Acromyrmex subterraneus subterraneus were fed with an Evans Blue dye solution, which allowed the investigation of subsequent exchange of liquids between ants by oral trophallaxis. Trophallactic behavior was filmed and the antennation patterns of donor and recipient ants were described. The ants’ crop capacity was measured following ad libitum feeding on dye solution. Ants previously fed on the dye solution (donors) were placed individually with unfed ants of the same caste (recipients) and the amount of dye solution passed from the donor to the recipient by oral trophallaxis was measured after one hour. The volume received was 0.26 ± 0.15μL (mean ± SD) and the residual volume of dye in the crop of the donors was 0.49 ± 0.23μL. There were 38 trophallactic events recorded for 50 pairs of ants. Trophallaxis was observed from 2.3 min to 21.5 min after initial exposure, with a mean latency of 8.4 ± 5.6 min. The mean duration of a trophallatic event was 2.3 ± 1.3 min. As far as we know, this is the first time that trophallaxis in leaf-cutting ants has been described and quantified.

Behavioral assays were conducted with individuals from monogynous and polygynous colonies of Acromyrmex subterraneus molestans to evaluate the discriminatory ability of ant workers. These bioassays showed that this subspecies could not discriminate among non-nestmates or nestmate workers. However, nestmates of these same colonies did discriminate among workers of another subspecies Ac. subterraneus subterraneus. When discrimation occurred there were no differences in the response of workers from either monogynous or polygynous colonies. Similarities or differences in the chemical profile of both subspecies explained the absence or occurence of aggressiveness among workers. The chemical profile of colonies of the same subspecies was very similar among them, although distinct among subspecies. The number of queens did not influence the cuticular chemical composition of the workers or their behavior.Ensaios comportamentais foram conduzidos com indivíduos de colônias monogínicas e poligínicas de Acromyrmex subterraneus molestans a fim de avaliar a habilidade discriminatória de suas operárias. Estes bioensaios mostraram que esta subespécie não é capaz de discriminar entre não companheiras e companheiras de ninho. Entretanto, companheiras de mesma colônia discriminam operárias pertencentes à outra subespécie, Ac. subterraneus subterraneus. Nesta situação, não houve diferença na resposta de operárias oriundas de colônias monogínicas e poligínicas. Similaridades ou diferenças no perfil químico de ambas as subespécies podem explicar a ausência ou presença de agressividade entre operárias. O perfil químico de colônias de mesma subespécie foi muito similar entre si e muito distinto entre subespécies. O número de rainhas não influenciou a composição química cuticular das operárias e nem o seu comportamento discriminatório.

Leaf-cutting ant workers care for larvae with an elaborate behavioural repertoire to satisfy the needs of the offspring. In order to investigate worker discrimination ability in the leaf-cutting ant Acromyrmex subterraneus brunneus, we compared the behavioural responses of workers towards worker-produced male larvae and queen- produced worker larvae, including the following behavioural acts: licking the larval body, transporting larvae, feeding larvae with hyphae, scraping larval mouth parts, ingesting faecal fluid excreted by the larva, and inserting hyphae of the symbiontic fungus on the larval body. We verified that workers behaved differently depending on larval origin, i.e. licking the larval body, transporting larvae and inserting hyphae of the symbiontic fungus on the larval body. Observed differences denote the ability of workers in discriminating among larvae, probably because of their different individual needs.

A morphometric study was performed on the sexual forms of Acromyrmex subterraneus brunneus in colonies kept under laboratory conditions. The males studied were obtained from queenright and queenless colonies, i.e. they were produced by either the queen or the workers. Cluster analysis revealed a wide distribution in the size of the sexual forms produced in queenless colonies compared with queenright colonies, and that some of the worker-produced males were significantly smaller than those produced in queenright colonies. However, we found no indication that the males produced in queenless colonies are unable to mate, as smaller and larger males had identical genitalia that varied only in size, and therefore probably represent an alternative route of reproduction in this species.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:45:47Z No. of bitstreams: 1 S0085-56262004000100011.pdf: 321734 bytes, checksum: d608f6f26c4620d0e99331549e314a6f (MD5) Made available in DSpace on 2013-08-22T18:45:47Z (GMT). No. of bitstreams: 1 S0085-56262004000100011.pdf: 321734 bytes, checksum: d608f6f26c4620d0e99331549e314a6f (MD5) Previous issue date: 2004-03-01 Made available in DSpace on 2013-09-30T17:45:26Z (GMT). No. of bitstreams: 2 S0085-56262004000100011.pdf: 321734 bytes, checksum: d608f6f26c4620d0e99331549e314a6f (MD5) S0085-56262004000100011.pdf.txt: 20143 bytes, checksum: 45d4baaff26d574ecd12735fd3dbae2f (MD5) Previous issue date: 2004-03-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:20:18Z No. of bitstreams: 2 S0085-56262004000100011.pdf: 321734 bytes, checksum: d608f6f26c4620d0e99331549e314a6f (MD5) S0085-56262004000100011.pdf.txt: 20143 bytes, checksum: 45d4baaff26d574ecd12735fd3dbae2f (MD5) Made available in DSpace on 2014-05-20T13:20:18Z (GMT). No. of bitstreams: 2 S0085-56262004000100011.pdf: 321734 bytes, checksum: d608f6f26c4620d0e99331549e314a6f (MD5) S0085-56262004000100011.pdf.txt: 20143 bytes, checksum: 45d4baaff26d574ecd12735fd3dbae2f (MD5) Previous issue date: 2004-03-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) As formigas cortadeiras apresentam uma sofisticada divisão de trabalho durante o forrageamento, cultivo do jardim de fungo e devolução dos materiais forrageados. Materiais com diferentes graus de hidratação e dureza (esponja floral, isopor, plástico e argila) foram oferecidos a duas colônias de laboratório de Acromyrmex subterraneus brunneus Forel, 1911. As diferentes categorias de tamanho de operárias foram observadas durante a execução de 14 subtarefas. Probabilidade relativa de desempenho e as curvas aloéticas foram usadas para verificar a flexibilidade comportamental e os padrões comportamentais estereotipados das operárias. Os padrões comportamentais possibilitaram estabelecer papeis dentro de prováveis subcastas. Leaf cutting-ants present a sophisticated division of labor during foraging, fungus-garden cultivation and devolution of foraged materials. Material with different degrees of moisture and hardness (floral sponge, polystyrene, plastic and clay) were offered to two Acromyrmex subterraneus brunneus Forel, 1911 laboratory colonies. The different size categories of workers were observed during the execution of 14 subtasks. Relative probability performance and alloethic curves were used to verify behavioral flexibility and behavioral stereotyped patterns in the workers. The behavioral patterns could establish roles within probable subcastes. Universidade Estadual Paulista Faculdade de Ciências Agronômicas Departamento de Produção Vegetal Universidade Estadual Paulista Faculdade de Ciências Agronômicas Departamento de Produção Vegetal

Neotropical “Fungus-growing” leaf-cutting ants (tribe Attini) live in obligatory symbiosis with a fungus, which they grow on fresh leaves harvested by workers. Colonial recognition is likely based on chemical cues provided by cuticular hydrocarbons that have been found to be partly influenced by environmental odor sources. The diet breadth of Acromyrmex subterraneus subterraneus enabled us to test the impact of different plant diets on colonial recognition. The intermediary of the fungus in the ants’ feeding habit adds a special angle to the question. From a queenright (QR) mother colony of A. s. subterraneus we formed several groups of queenless (QL) workers with fungus (approx. 700 ants). The QR colony and two of the QL-groups were fed with the same diet of fresh bramble leaves. Two other QL-groups were fed with privet leaves and two with rose flowers. After 4 months, QR workers were significantly more aggressive towards the QL-group fed with rose flowers or privet leaves than towards workers of the QL-groups fed with fresh bramble leaves. Rose-fed QL workers were aggressive towards privet-fed QL workers and vice versa, but never towards workers of their counterpart group that fed on the same diet. These results suggest that the absence of the queen or the separation time between groups played a minor role in shaping nestmate recognition cues as compared to the diet. The behavioral studies were supplemented by chemical analyses of cuticles, postpharyngeal glands (PPG) and plant-food extracts revealing profiles variations that were correlated with the dietary changes. However, although the plant extract contained several hydrocarbons there was no congruency between the plant profile and the respective diet-group ants. These results support the hypothesis that the diet influences indirectly the chemical profiles and consequently the recognition cues in A. s. subterraneus.

Made available in DSpace on 2022-04-28T20:42:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-01-01 Leaf-cutting ants forage on a wide variety of plant species using the physical and chemical characteristics of the plants as a selection criterion. In order to determine the influence of the physical factor on the selection of foraging material, inert materials such as floral sponge, polystyrene, plastic and clay, which possess different degrees of physical resistance to cutting, were offered simultaneously to five Acromyrmex subterraneus brunneus colonies, and assessed 12 and 24 h after foraging. No substrate selectivity was observed during foraging. Physical resistance was used as a decision criterion for the incorporation or return of the foraged material. This fact suggests the existence of a second time of selection of the foraged material inside the colony during cultivation of the symbiontic fungus. Dept. of Prod. Vegetal FCA/UNESP, Botucatu, São Paulo state Dept. Prod. Veg. - Defesa F. FCA/UNESP, PO Box 237, Botucatu, SP Dept. of Prod. Vegetal FCA/UNESP, Botucatu, São Paulo state Dept. Prod. Veg. - Defesa F. FCA/UNESP, PO Box 237, Botucatu, SP

The trail pheromone ofAcromyrmex subterraneus subterraneus consists simply of the heterocyclic ester methyl 4-methylpyrrole-2-carboxylate in the venom reservoir of workers at about 1.2 ng/ant. No pyrazines were detected, and no enhancement of trail-following was observed when pyrazines were added to the pyrrole compound.

The division of labor between the different worker castes of leaf-cutting ants may reflect in their capacity to exchange liquids by trophallaxis. The crop capacity of and trophallactic exchanges between different size classes of worker leaf-cutting ants of the sub-species Acromyrmex subterraneus subterraneus were investigated. Size classes were defined from head capsule widths and crop capacity of each class was determined following ad libitum feeding on dye solution. Experiments were carried out to investigate trophallactic exchanges between donor ants and recipient ants of each class size combination on a one to one basis. An experiment was also performed to investigate dye distribution within mini-colonies following introduction of three classes of donor ants. Worker ants were categorized into four size classes from their head capsule widths (C1 = 0.8–1.0 mm; C2 = 1.2–1.5 mm; C3 = 1.6–2.0 mm; C4 = 2.1–2.4 mm). C1 ants crop capacity was 0.13 μL; C2: 0.21 μL; C3: 0.52 μL; C4: 1.03 μL. Ants of each class previously fed on the dye solution (donors) were placed individually with an unfed ant of each class (recipients) and the presence of dye solution, passed from the donor to the recipient by oral trophallaxis was observed after 1 h. Results showed that all classes of donor ants performed trophallactic exchanges with all recipient classes. However, statistically fewer exchanges were seen for C2 donor ants when placed with C3 recipient ants. Ten donor ants of each of three classes (C2, C3 and C4) were introduced into mini-colonies without queen ants. It was observed that C1 and C2 ants were poor recipients, whilst C3 and C4 received the highest percentages of dye. Within 10 h of introducing the donor ants, 14 to 20% of their nest-mates had received dye solution, with 58 to 77% of dye passed to recipients. These studies show the altruistic nature of “food-laden” leaf-cutters and indicate that ants involved in garden maintenance activity are less likely to receive liquids from foraging workers.

Neotropical leaf-cutting ants (tribe Attini) live in obligate symbiosis with fungus they culture for food. To protect themselves and their fungus garden from pathogens, they minimize the entry of microorganisms through mechanical and chemical means. In this study, focusing on the species Acromyrmex subterraneus and A. octospinosus, (Hymeoptera: Formicidae). Self- and allo-grooming behavior were quantified and it was found that A. octospinosus workers spend less time in self-grooming than A. subterraneus. In the experimental absence of fungus in A. subterraneus, the times spent in these two behaviors are not affected; however workers spend significantly more time immobile. Hygienic and trophallaxis behaviors were examined as well as the possibility that workers exchange food, and the grooming behavior of foraging and non-foraging workers were compared. Behavioral observations revealed that large workers spent more time grooming than small workers, and more than 62% of replete foragers passed collected liquid food via trophallaxis to a nestmate. However, trophallaxis was rarely observed between non-forager workers. These results suggest that trophallaxis permits the exchange of alimentary liquid between colony members, but it is not important for spreading the colony odor signature.

subterraneus (Forel 1893a). Canindeyú, Central, Cordillera (ALWC, INBP, LACM, MHNG MZSP, USNM). Literature records: Alto Paraná, Caaguazú, Canindeyú, Concepción, Cordillera, Guairá, Paraguarí, “Paraguay” (s. loc.) (Emery 1906, Forel 1906h, Forel 1908b, Forel 1909, Fowler 1985, Santschi 1925a)., Published as part of Wild, A. L., 2007, A catalogue of the ants of Paraguay (Hymenoptera: Formicidae)., pp. 1-55 in Zootaxa 1622 on page 30

O termo poliginia se refere à coexistência de duas ou mais rainhas férteis na colônia. Coletou-se no campus da Universidade Federal de Viçosa uma colônia de Acromyrmex subterraneus molestans Santschi contendo 14 rainhas, com o objetivo de verificar se todas elas eram ovipositoras e férteis. O volume do jardim de fungo no ninho era de 500 ml com grande número de larvas e pupas. Observações do desenvolvimento dos ovários e espermatecas indicaram que 13 rainhas tinham copulado e seus ovários não mostraram diferenças morfológicas. Isto indicaria que a poliginia não é acidental e pode representar uma estratégia adaptativa para otimizar o desenvolvimento inicial de colônias em A. subterraneus molestans. Polygyny denotes the coexistence of two or more mated and fertile queens in the colony. A colony of Acromyrmex subterraneus molestans Santschi containing 14 queens was collected on campus of the Universidade Federal de Viçosa, Brazil, aiming to verify if they were all egg-layers and fertile . The volume of the fungus garden in the nest was about 500 ml with a large number of larvae and pupae. Observation of the ovarian development and spermathecae indicates that 13 queens had copulated and ovary did not show morphological differences among them. This could indicate that polygyny is not accidental and may represent an adaptative strategy to optimize the development of the initial colony in A. subterraneus molestans.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:49:44Z No. of bitstreams: 1 S0100-67622004000200017.pdf: 170440 bytes, checksum: 6605f156a1639d69265da59fd792fd2a (MD5) Made available in DSpace on 2013-08-22T18:49:44Z (GMT). No. of bitstreams: 1 S0100-67622004000200017.pdf: 170440 bytes, checksum: 6605f156a1639d69265da59fd792fd2a (MD5) Previous issue date: 2004-04-01 Made available in DSpace on 2013-09-30T17:45:54Z (GMT). No. of bitstreams: 2 S0100-67622004000200017.pdf: 170440 bytes, checksum: 6605f156a1639d69265da59fd792fd2a (MD5) S0100-67622004000200017.pdf.txt: 8800 bytes, checksum: 9c00e4878f76cb63ef2883c515cf6d74 (MD5) Previous issue date: 2004-04-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:20:27Z No. of bitstreams: 2 S0100-67622004000200017.pdf: 170440 bytes, checksum: 6605f156a1639d69265da59fd792fd2a (MD5) S0100-67622004000200017.pdf.txt: 8800 bytes, checksum: 9c00e4878f76cb63ef2883c515cf6d74 (MD5) Made available in DSpace on 2014-05-20T13:20:27Z (GMT). No. of bitstreams: 2 S0100-67622004000200017.pdf: 170440 bytes, checksum: 6605f156a1639d69265da59fd792fd2a (MD5) S0100-67622004000200017.pdf.txt: 8800 bytes, checksum: 9c00e4878f76cb63ef2883c515cf6d74 (MD5) Previous issue date: 2004-04-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Ninhos jovens de Acromyrmex subterraneus brunneus caracterizam-se pela terra solta no exterior do ninho, por ter uma única câmara de fungo com profundidade de 11 a 20 cm em relação à superfície do solo e por ter volume interno variando de 0,3 a 1,5 litros. Estes padrões de nidificação são caracteres importantes para a identificação e o conhecimento das interações da espécie com o seu habitat. Young nests of Acromyrmex subterraneus brunneus are characterized by refuse soil in the exterior of the nest, a single fungus chamber 11 to 20 cm deep in relation to soil surface and internal volume ranging from 0.3 to 1.5 liters. These nidification patterns are important characteristics for identifying and understanding the interactions between species and their habitats. Universidade Estadual Paulista Faculdade de Ciências Agronômicas Departamento de Produção Vegetal Universidade Estadual Paulista Instituto de Biociências Departamento de Zoologia Universidade Estadual Paulista Faculdade de Ciências Agronômicas Departamento de Produção Vegetal Universidade Estadual Paulista Instituto de Biociências Departamento de Zoologia

Nests of Acromyrmrex subterraneus sub terraneus were excavated in two localities of Minas Gerais to estimate their population. All the nests had flve entrance holes which were destroyed by methyl bromide application. Twenty four hours after, the fungus culture and the ants present in the Chambers were collected and weighed. In the entomology laboratory at the Federal University of Viçosa Six samples of identical weight were taken from each nest and the number of eggs, larvae, pupae and adults was counted. Total weight of the nests ranged from 1,30og to 2,684 g. Egg percentage varied from 62% to 21.1%; larvae averaged between 0.6 to 5.4 % and pupae from 70% to 843% %. The total number of individuals varied from 10,248 to 20,872. In general, the number of minor workers that are involved in fungal and brood care was about 9,4 times lower than the number of foragers. A positive significant correlation ( r=0.896) was found between the number of pupae and that of adults.

Szelenyiopria talitae sp. nov. is described and illustrated. This species is shown to be a larval parasitoid of Acromyrmex subterraneus subterraneus (Forel). Fil: Loiacono, Marta Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina Fil: Margaría, Cecilia B.. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina Fil: Oliveira Moreira, Denise D.. Universidade Federal Fluminense; Brasil Fil: Aquino, Daniel Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina

Acromyrmex (A.) subterraneus For. eidmanni, n. var. Ouvri��re. Long. 3,5 �� 7 mm. D'un brun ferrugineux avec le lit du scape, le front, le contour des yeux d' um brun noir��tre. Diff��re de subterraneus type, autre la couleur de la t��te et des autres vari��t��s, par les ��pines pronotales inf��rieu- res plus fortement recourb��es en avant comme elles le sont chez molestans Sant. et muticinodus st. homalops Em. Les cr��tes du vertex sont form��es de dents spiniformes et espacees. Les autres ��pines semblables �� celles de subterraneus mais les ��pinotales sont moins divergentes, un peu plus longues et plus fines. Les yeux sont un peu plus petits que chez subterraneus mais plus bomb��s et un peu pyramidaux (plus pepetits chez molestans et homalops, plus grande et plus plats chez mixtus). Le p��tiole plus fortement dent��. - Diff��re de muticinodus For. s. str. et st. depressoculis For. par ses yeux plus grands et le p��tiole arm��. Femelle. - D'un rouge brun��tre fonc�� mais plus clair que chez brunneus. Dessus de la t��te et parfois les bandes parapsidales et une tache au milieu du gastre, d'un brun plus obscur. Dessus du m��sonotum rid�� en long. L'��pine pronotale inf��rieure est courte, assez fortement arqu��e en avant, correspondant �� une petite encoche sur la bord inf��rieur lat��ral de la t��te indiqu��e par l'��pine moyenne de ce bord (plus fine et moins recourb��e chez subterraneus). Les yeux sont presque aussi grands que chez cette derni��re. Ailes brunes, la ant��- rieure longue de 8 mm. Taille aussi grande que chez brunneus dont la couleur est plus uniform��ment ooscure. M��le. - Ocre terrne. T��te, deux ��troites et courtes taches parapsidales brunes. Pas d'impression longitudinale m��- diane sur le m��sonotum mais en revanche une forte goutti��re m��diane sur le gastre qui est faiblement luisant. Epine pronotale inf��rieure courte, dirig��e en avant. Epine epinotale fine, arqu��e et longue comme les trois quarts de leur intervalle basal. Cette forme est interm��diaire entre subterraneus, molestans et homalops. Molestans a ��t�� confondue par Emery avec homalops; elles se ressemblent bien �� premi��re vue, mais molestans se distingue par ses ��pines m��sonotales ant��rieu- res presque verticales et le p��tiole plus nettement dent�� ou sub��pineux, tandis que chez homalops, les premi��res sont tr��s divergentes et ce dernier mutique ou submutique. - Je ne sais pourquoi, dans son catalogue des Myrmicines, Emery a adjoint homalops comme vari��t�� �� A. coronatus F. Elle en diff��re nettement par ses ��pines de l'angle post��rieure de la t��te non horizontales mais relev��es comme chez muticinodus For. �� laquelle esp��ce elle doit se rattacher comme race., Published as part of Santschi, F., 1937, Note sur Acromyrmex subterraneus Forel (Hym. Formicidae)., pp. 230-233 in Revista de Entomologia, S��o Paulo 7 on page 232

Note sur Acromyrmex subterraneus Forel (Hym. Formicidae) par le Dr. F. Santschi, Kairouan, Tunisie (Avec 7 figures) Forel (1893) a d��crit tr��s sommairement cette forme qu'il a parfois confondu avec A. coronatus Fabr. et �� laquelle il adjoint trois vari��t��s; l'une de celles-ci, la var. depressoculis For. doit se rattacher �� A. muticinodus For. qui est une esp��ce tr��s voisine, distincte de subterraneus par ses yeux bien plus petits et le p��tiole plus au moins inerme dessus. Dans ma r��vision de Acromyrmex (Rev. Suisse Zool. vol. 31, pp. 355-398) j'ai ��tabli une cl�� analytique comprenant les vari��t��s de A. subterraneus. Une revue de ces vari��t��s et l'adjonction de deux nouvelles formes m'incite �� en ��tablir une cl�� plus ad��quate. A. subterraneus �� des affinit��s tr��s nettes avec A. coronatus F., hystrix Latr. et octospinosus Reich., mais la premiere a les ��pines pronoto-lat��rales tr��s longues et les autres n'ont pas d'��pine pronotale ant��ro-m��diane. A. subterraneus For. se distingue des autres Acromyrmex par l'ensemble des caract��res suivants: Mandibules longues, fortement courb��es sur le plan, leur bord lat��ral sinueux. Epines susoculaires d��velopp��es. Scape non lob�� �� la base. T��guments mats avec de tr��s fines rugosites et sans ponctuation r��ticul��e. Une pubescence dense au devant des ��pines ��pinotales. Cr��te denticul��e. Epines inf��rieu- res du pronotum assez longues, fines, pointues et dirig��es obliquement en avant et en dehors. Epines de l'angle occipital dirig��es obliquement en arri��re du plan du bord occipital. Dessus du p��tiole nettement ��pineux. Yeux assez bombes. Cr��tes du vertex r��duits �� des asp��rit��s ou des denticules espac��s mais ne faisant pas une bande continue et inerme. Le type est de Blumenau, Sta. Catharina, Br��sil (Moeller)., Published as part of Santschi, F., 1937, Note sur Acromyrmex subterraneus Forel (Hym. Formicidae)., pp. 230-233 in Revista de Entomologia, S��o Paulo 7 on pages 230-231