Resposta da saúva Atta capiguara Gonçalves, 1944 (Hymenoptera: Formicidae) a açúcares e edulcorantes artificiais

O uso de iscas tóxicas, formuladas à base de polpa cítrica desidratada, para o controle de formigas cortadeiras de gramíneas pode levar a resultados insatisfatórios devido à baixa atratividade do substrato às operárias. Este trabalho foi realizado com o objetivo de identificar substâncias atrativas e com potencial para incorporação em matrizes de iscas granuladas para formigas cortadeiras de gramíneas, dentre diversos tipos de açúcares e edulcorantes artificiais. Os experimentos foram realizados em ninhos adultos de Atta capiguara Gonçalves, em área de pastagem. Inicialmente, as substâncias estudadas foram: sacarose, frutose, amido solúvel, rafinose, maltose, lactose, sorbose, celobiose, arabinose, xilose, glicose, galactose, raminose, arabinose, melizitose, sacarina e ciclamato (5,0% p/v). Posteriormente, estudaram-se soluções de maltose, xilose, sacarose, frutose e glicose a 5,0%, 7,5%, 10,0% e 20,0% p/v. Retângulos de celulose foram usados como veículo. Avaliou-se o número de retângulos carregados para o interior das colônias. De modo geral, as taxas de carregamento foram muito baixas, com médias máximas de 9,6% para lactose e de 6,0% para arabinose e ciclamato, na concentração 5,0%, não diferindo da testemunha (água destilada). No esquema fatorial, não foram verificados efeitos de solução, de concentração e de interação entre esses fatores. Os açúcares e edulcorantes artificiais estudados não são atrativos às operárias de Atta capiguara, inviabilizando sua inclusão em iscas tóxicas, com a finalidade de melhorar sua atratividade.Using of toxic baits made of dehydrated citric pulp to control grass-cutting ants can lead to unsatisfactory results because of the low attractiveness of the substrate to worker ants. This work aimed to identify attractive substances, with potential for incorporation in a matrix of granulated baits for grass-cutting ants, among several kinds of sugars and substances used in artificial sweeteners. Experiments were carried out in mature nests of Atta capiguara (Hym.: Formicidae) set in pasture. Studied substances were sucrose, fructose, soluble starch, raffinose, maltose, lactose, sorbose, cellobiose, arabinose, xylose, glucose, galactose, rhamnose, arabinose, melezitose, saccharine and cyclamate (at 5.0% w/v). Later, on maltose, xylose, sucrose, fructose and glucose solutions were included at 5.0%, 7.5%, 10.0% and 20.0% w/v, respectively. Cellulose rectangles were used as vehicle and number of rectangles carried into the colonies was evaluated. Carrying rates were very low with maximum means of 9.6% for lactose and 6.0% for arabinose and cyclamate, at the 5.0% concentration. No differences (P >; 0.05) were observed relatively to the control (distilled water). No effects were detected for solution, concentration and for the interaction of these factors. Sugars and artificial sweeteners studied were not attractive to Atta capiguara workers, turning their inclusion as attractants in toxic ant baits not viable

Characterization of Acromyrmex subterraneus brunneus (Hymenoptera: Formicidae) young nests in a fragment of the Neotropical Forest

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.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Relationship Between Population Size and Symbiont Fungus Culture Volume in Colonies of Acromyrmex balzani (Hymenoptera: Formicidae)

In order to quantify the population of Acromyrmex balzani Emery, 1890 nests and to verify whether the population dynamic of the colony is correlated with the symbiont fungus volume, the principal energy source of the colony, five nests located in grassland areas were evaluated. The nests were sprayed with neutral talcum powder to improve visualization and digging. The symbiont fungus and the entire population existent in the chambers were collected. The mean fungus volume and total nest population in excavated nests were, respectively, 74.76 ml and 1,095 individuals. Simple linear correlation analysis verified that the fungus volume grew proportionally to the number of individuals. Despite the correlation between fungus volume and population dynamic of colonies, the factors that determine this relationship are little known since other microorganisms live in association with the colony

Comparação entre parâmetros externos e internos de ninhos de Atta bisphaerica Forel, 1908 (Hymenoptera, Formicidae)

Six Atta bisphaerica, Forel, 1908 (Hymenoptera, Formicidae) nests were excavated with the aim of studying the relationship between area and volume of the mound, the total volume and total number of chambers in the nest. Prior to excavation, the area and the volume of refused soil in the nests were measured. During excavation, all data referring to chambers were recorded, such as: length, depth and width. The nests named A1, A2, A3, A4, A5 and A6 presented 31.16; 40.87, 67.08, 35.04, 73.48 and 18,73m2 of mound area, respectively. The mound area did not correlate either with the volume or with the total number of chambers. The mound volume correlated significantly with the mound area, total number and total volume of chambers. The total volume of chambers was correlated with the total number of chambers.Foram escavados seis ninhos adultos de Atta bisphaerica Forel, 1908, (Hymenoptera, Formicidae) com o objetivo de estudar a relação entre área e volume do monte de terra solta, volume total e número total de câmaras do ninho. Antes de se iniciar o processo de escavação, mediram-se a área e o volume de terra solta dos ninhos. Durante a escavação, foram anotados todos os dados referentes à altura, largura e profundidade das câmaras. Os ninhos, denominados A1, A2, A3, A4, A5 e A6, apresentaram áreas de terra solta de 31,16; 40,87; 67,08, 35,04; 73,48 e 18,73m2, respectivamente. A área de terra solta não apresentou correlação significativa com volume e número total de câmaras. O volume de terra solta apresentou correlação significativa com a área de terra solta e com o número e volume total de câmaras. O volume total de câmaras apresentou correlação significativa com o número total de câmaras

Selectivity of Workers of the Grass-Cutting Ants Atta bisphaerica and Atta capiguara (Hymenoptera: Formicidae) to Vegetable Oils

The grass-cutting ants Atta capiguara Goncalves, 1941 and Atta bisphaerica Forel, 1908, have great economic importance as regards pastures and various agricultural cultivations in Brazil. These are ants which are difficult control, generally rejecting toxic baits, the main control method, in the field. In this work the reactions of the workers of A. capiguara and A. bisphaerica to vegetable oils in neutral substrates were observed, aiming to select the most attractive for the formulation of bait matrixes. Three field experiments were conducted. In the first experiment conducted for A. capiguara, the following treatments were used: corn oil, soy oil, cotton oil, canola oil, sesame oil, sunflower oil and control (distilled water). For the other experiments, conducted for both species of ant, the following treatments were used: cotton oil, rice oil, canola oil, sesame oil, sunflower oil, corn oil, soy oil, bait pellets without active ingredient, distilled water and cellulose (not immersed in water or oil). The data presented in this work affirms that soy oil, present in commercial baits,probably contributes to its attractiveness. Corn and rice oil presented potential as substitutes for soy oil in relation to the development of new bait matrixes for A. capiguara.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Ocorrência de formigas-cortadeiras do gênero Atta (Hymenoptera: Attini) na região sudoeste da Bahia

The objective of the research was to develop knowledge about the occurrence of species in the genus Atta Region Southwest Bahia and relate the occurrence of species to the predominant vegetation. The survey was conducted in different scripts, in the months from July to December 2005, starting with Vitória da Conquista/BA and proceeding up collections of 50 by 50 km along the BR 116 and BAs 026, 030, 148, 262, 263, 265, 270, 420, 634 and 670 highways, totaling 36 cities. We collected the greatest workers into the holes above the nest and the foraging trails. In these collection points was recorded predominant vegetation. The collected material was fixed in 70% ethanol for later identification of species. The identification of taxa was made in Insetos Sociais-Praga Laboratory of Universidade Estadual Paulista, Botucatu/SP, by Dr. Ana Paula Andrade Cruciol Protti. In this region we found three species of leaf-cutting ants Atta sexdens, Atta laevigata and Atta opaciceps. The species that occurred most frequently was A. sexdens considered accessory (present in 41.7% of cities), while A. laevigata and A. opaciceps were considered accidental (present in less than 25% of samples). It was found that A. sexdens nests in diverse environments, while the species A. laevigata was found nesting in grasslands, Mata Cipó and eucalyptus forests. The A. opaciceps was found in grassland.O objetivo da pesquisa foi verificar a ocorrência de espécies do gênero Atta na Região Sudoeste da Bahia e relacionar com a vegetação predominante no local de nidificação. O levantamento foi realizado em diferentes roteiros, nos meses de julho a dezembro de 2005, partindo-se de Vitória da Conquista, BA e procedendo-se coletas a cada 50 km, ao longo das rodovias BR 116 e BA (026, 030, 148, 262, 263, 265, 270, 420, 634 e 670), totalizando 36 municípios da região. Foram coletadas as maiores operárias nos orifícios acima dos ninhos e nas trilhas de forrageamento e foi registrada a vegetação predominante nos pontos de coleta. O material coletado foi fixado em álcool 70% para posterior identificação das espécies. A identificação dos táxons foi realizada no Laboratório de Insetos Sociais-Praga da Universidade Estadual Paulista, Botucatu, SP pela Dra. Ana Paula Protti Andrade Cruciol. Na região estudada foram encontradas três espécies de formigas-cortadeiras: Atta sexdens, Atta laevigata e Atta opaciceps. A espécie de maior ocorrência foi A. sexdens, considerada acessória (presente em 41,7% dos municípios), enquanto A. laevigata e A. opaciceps foram acidentais (presentes em menos de 25% das coletas). Verificou-se que A. sexdens nidificou em ambientes diversificados, enquanto a espécie A. laevigata foi encontrada nidificando em pastagem, Mata de Cipó e eucalipto, e A. opaciceps foi encontrada em pastagem