Interspecific variation in the defensive responses of obligate plant-ants: experimental tests and consequences for herbivory

The aggressive behavior of ants that protect plants from herbivores in exchange for rewards such as shelter or food is thought to be an important form of biotic defense against herbivory, particularly in tropical systems. To date, however, no one has compared the defensive responses of different ant taxa associated with the same plant species, and attempted to relate these differences to longer-term efficacy of ant defense. We used experimental cues associated with herbivory-physical damage and extracts of chemical volatiles from leaf tissue-to compare the aggressive responses of two ant species obligately associated with the Amazonian myrmecophyte Tococa bullifera (Melastomataceae). We also conducted a colony removal experiment to quantify the level of resistance from herbivores provided to plants by each ant species. Our experiments demonstrate that some cues eliciting a strong response from one ant species elicited no response by the other. For cues that do elicit responses, the magnitude of these responses can vary interspecifically. These patterns were consistent with the level of resistance provided from herbivores to plants. The colony removal experiment showed that both ant species defend plants from herbivores: however, herbivory was higher on plants colonized by the less aggressive ant species. Our results add to the growing body of literature indicating defensive ant responses are stimulated by cues associated with herbivory. However, they also suggest the local and regional variation in the composition of potential partner taxa could influence the ecology and evolution of defensive mutualisms in ways that have previously remained unexplored.

Foraging Behavior and Mortality of Ectatomma brunneum (Hymenoptera, Formicidae) in Simultaneous Exposure to Ant Baits and Conventional Diet in Laboratory

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Proventriculus of Cephalotes ants: A structural and comparative analysis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Foraging behavior of tyrant flycatchers (Aves, Tyrannidae) in Brazil

Este trabalho apresenta dados acerca do comportamento de forrageamento e substratos usados para a captura de presas por 28 espécies de tiranídeos (Tyrannidae) no Brasil. Para seis espécies: Arundinicola leucocephala Linnaeus, 1764, Fluvicola nengeta Linnaeus, 1766, Machetornis rixosa Vieillot, 1819, Myiozetetes similis Spix, 1825, Pitangus sulphuratus Linnaeus, 1766 e Tyrannus melancholicus Vieillot, 1819 -, também são apresentados dados sobre a altura do poleiro usado para caça, tempo de procura por presas, distância e ângulo de ataque. Com raras exceções, manobras do tipo sally strike foram as mais freqüentes, enquanto folhas vivas e o ar foram os substratos mais comumente usados para capturar presas. Para as seis espécies acima citadas três grupos de altura de forrageamento puderam ser discernidos: F. nengeta e M. rixosa forrageiam no chão, A. leucocephala e P. sulphuratus ocupam um estrato médio e T. melancholicus e M. similis formam um terceiro grupo e geralmente atacam suas presas a partir de poleiros situados a 3 m ou mais do chão. Com exceção de P. sulphuratus, que apresentou o tempo de procura mais longo, as outras cinco espécies não diferiram nesse aspecto. Três grupos foram também discernidos em relação à distância de ataque: F. nengeta e M. rixosa atacam presas próximas (< 2 m) a eles, A. leucocephala, P. sulphuratus e M. similis formam um grupo de média distância (3-4 m) e T. melancholicus apresentou as mais longas distâncias de ataque (até 12 m). As aves diferiram em alguns aspectos do ângulo de ataque que, juntamente com diferenças sutis em outros aspectos do comportamento de forrageamento podem levar a diferenças importantes na seleção de presas.

Anting behavior by the White-bearded Manakin (Manacus manacus, Pipridae): an example of functional interaction in a frugivorous lekking bird

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Brood Care Behavior in Ectatomma brunneum (Hymenoptera, Formicidae, Ectatomminae) Under Laboratory Conditions

The objective of this work was to make an ethogram based on the brood care behavior of two nests of the ant Ectatomma brunneum under laboratory conditions, in order to determine the behavioral acts performed and their frequencies, comparing the results obtained with those of other species of poneromorph ants. Using the sample scanning method, activities of brood care behavior performed by workers were monitored for 150 hours, from February to August 2007. A total of 18 different behavioral acts were observed (n = 12,494). More than half of the brood care behaviors by E brunneum (52.07%) were related to care for larvae, and the same was observed by other researchers in ethograms of species of Ectatomminae and Ponerinae ants. This may be related to specific needs in this immature stage, since rills is the period when the brood receives all the food necessary to complete their development to the adult stage.

Colony defense behavior of the primitively eusocial wasp, Mischocyttarus cerberus is related to age

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Habitat selection and potential antiherbivore effects of Peucetia flava (Oxyopidae) on Solanum thomasiifolium (Solanaceae)

Several spider species use plants as shelter and foraging sites, but the relationships among these organisms are still poorly known. Lynx spiders of the genus Peucetia do not build webs, and many species live strictly in plants bearing glandular trichomes. Peucetia flava Keyserling 1877 inhabits Solanum thomasifolium in southeastern Brazil and usually preys on herbivores and other small insects adhered to the glandular trichomes of its host plant. To evaluate the potential anti-herbivore protection. of this spider species for S. thomasifolium, we glued termites used as herbivore models oil trichomes of S. thomasifolium and on neighboring plants lacking glandular trichomes. leaf miner damage and spider density were recorded for S. thomasifolium plants in July 1997. There was a positive relationship between plant size and spider density. The removal or termites in S. thomasifolium by P. flava was higher than ill plants without glandular trichomes. The leaf miner damage was negatively related to spider density. Our results Suggest that P. flava may be all important plant bodyguard in the defense of S. thomasifolium from its natural herbivores.

Sexual selection and social hierarchy in fishes.

Sexual selection is a crucial element to understand behavioral evolution. Teleost fish have been considered as good models for research on sexual selection in the last decades due to their variety of sexual behavior. Female fish can choose males based on body and behavioral traits, such as body size, body color, ornaments, territorial quality, nest size and courtship behavior. Choices are based upon several types of sensorial inputs, such as visual, chemical, sonorous and electrical signals. Intrasexual selection also acts on females because they can mate with a dominant individual in male-male competitions. For both approaches, there is an expectation regarding the benefits of sexual selection by means of female choice. However, in several cases females do not choose the dominant male. In this mini-review, we present and discuss both intersexual and intrasexual mechanisms of sexual selection in fish and point out that females do not always choose a male for mating.

NONLEPTONIC ANNIHILATION DECAYS of B MESON WITH A NATURAL INFRARED CUTOFF

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Reaction of tangerines genotypes to Elsinoe fawcettii under natural infection conditions

A verrugose dos citros, causada pelo fungo Elsinoe fawcettii, encontra-se presente em todas as áreas citrícolas do Brasil. Dada sua importância, o comportamento de acessos e híbridos de tangerinas foi avaliado sob condições naturais de infecção. O estudo envolveu plantas não irrigadas, com 15 anos de cultivo, sendo coletados 100 frutos de três plantas por genótipo, na fase de colheita. Mediante o emprego de escala de notas que variaram de 0 (ausência de sintomas) a 6 (sintomas severos), procedeu-se a avaliação do nível de severidade da doença. Dentre genótipos que mostraram-se resistentes incluem-se Citrus deliciosa, C. tangerina, C. nobilis; um híbrido de mandarina (C. nobilis x C. deliciosa) e um híbrido de satsuma (C. unshiu x C. sinensis). Nos demais genótipos foram encontrados sintomas, cujos níveis de severidade variaram de 1 a 3, enquadrando-os como de moderada resistência.

Field methods for the study of ants in sugarcane plantations in Southeastern Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Evaluation of Ir, Ru, and W as permanent modifiers for the simultaneous determination of As, Bi, Pb, Sb, and Se in natural water by electrothermal atomic absorption spectrometry

Iridium-, Ru-, and W-coated platforms were prepared by thermal treatment of the transversely heated graphite atomizer and investigated for the simultaneous determination of As, Bi, Pb, Sb, and Se in tap water by electrothermal atomic absorption spectrometry. The maximum pyrolysis temperature for As and Bi increased in a modifier sequence W < Ru < Ir. For Pb, Sb, and Se, this sequence was W < Ru, It. Calculated characteristic masses in the presence of It, Ru, and W were 35, 33, and 35 pg for As; 63, 51, and 52 pg for Bi; 50, 32, and 34 pg for Pb; 40, 35, and 31 pg for Sb; and 39, 39, and 93 pg for Se, respectively. Ruthenium was elected as the optimum modifier.Repeatability of the measurements was typically < 6%. Recoveries of As, Bi, Pb, Sb, and Se added to tap water samples varied from 79 to 109%. Accuracy was also checked by analysis of five certified reference materials (CRMs) from the National Institute of Standards and Technology (NIST1640 - Trace Elements in Natural Water; NIST 1643d Trace Elements in Water) and High Purity Standards (Trace Metals in Drinking Water Standards, lots #812708, #591107, and #710710). A paired t-test showed that the results for the CRMs were in agreement at the 95% confidence level with the certified values. The graphite tube lifetime was about 650 firings. multi-element determination is particularly challenging due to the necessity of carefully optimizing compromise conditions.Based on the considerations listed above, the aim of this paper was to evaluate the behavior of Ir, Ru, and W as permanent modifiers for the simultaneous determination of As, Bi, Pb, Sb, and Se. The performance of the proposed procedure was also verified after the ETAAS analysis of tap waters and reference materials.

PHEIDOLE ANTS AS POTENTIAL BIOLOGICAL-CONTROL AGENTS OF THE BOLL-WEEVIL, ANTHONOMUS-GRANDIS (COL, CURCULIONIDAE), IN SOUTHEAST BRAZIL

This study evaluates the potential of ants as natural biological control agents of the boil weevil (Anthonomus grandis), during the between-season period, in South-east Brazil. Active adults of Anthonomus were experimentally distributed on the ground of the cotton field. Results show that 20% of the adult Anthonomus are attacked and removed by foraging ants. The native ant Pheidole oliveirai was by far the most efficient predator, accounting for 94% of the predation on Anthonomus. Recruited workers of P. oliveirai were usually very fast at transporting the weevils to their nests. The potential benefit of suppressing overwintering adult Anthonomus during the between-season period is mainly that of reducing the risk of high level infestations during the next cropping cycle.

STUDY OF AMNONIFYING BACTERIA BEHAVIOR IN THE LAKES CARIOCA AND D-HELVECIO (RIO-DOCE-VALLEY-MG)

The study of the amnonifying bacteria behavior in the lakes Carioca and D. Helvecio, which belong to the natural lacustrine system of the Rio Doce Valley - Minas Gerais - Brazil, during the period from March to November, showed a similar seasonal variation in both lakes, with higher population density in March and November (raining period) and lower density in May, July and September (dry period). The vertical variation was also relatively similar for both lakes, were during the thermal stratification the distribution was regular along the water column, while during the period of thermal stratification the populational density was remarkably different at different depths. The characterized ammonifying types to the genera Acinetobacter, Moraxella and Proteus, which in culture reveal high amnonifying activity with values which have reached 30,8 mug/l of ammonia per population unity (105 bacteria/ml).