Removal of clay by stingless bees: load size and moisture selection

Some organisms disperse energy, associated with the transportation of resource, which is not necessarily food. Stingless bees of Central Amazonia (Melipona flavolineata and M. lateralis) collect clay in banks along streams for nest building. The moisture of the clay varies along the bank, and bees collect clay from specific location, indicating that there is some sort of preference regarding their selection. This study aims at identifying: if larger bees carry more clay; if there is a preference for moisture of substrates; and if bees are less efficient accumulating and transporting clay when it is wet. In order to do so, I measured the size of the bees and of the pellets of clay found in the corbicula. I set up a field experiment to test substrate preferences. The amount of clay transported, increased exponentially in accordance to the size of the bee, and the preferred substrate was the driest clay. The amount and the efficiency of removal of clay were not affected by the moisture of the substrate. Despite the wet clay being denser, it does not reduce the efficiency of exploitation of the resource, but suggests that bees spend more energy to carry the same quantity of wet clay, which may be the underlying mechanism explaining their preference for removing drier clay.Alguns organismos têm custos energéticos associados com o transporte de recursos, que não necessariamente são alimentos. Algumas abelhas sem ferrão da Amazônia Central (Melipona flavolineata e M. lateralis) coletam argila na margem de córregos para a construção do ninho. A umidade da argila varia ao longo do barranco e as abelhas coletam argila de pontos específicos, o que sugere que há preferência. Aqui testo se abelhas maiores transportam mais argila; se existe preferência pela umidade do substrato; e se abelhas são menos eficientes na coleta e transporte de argila com elevada umidade. Para isso, eu medi o tamanho das abelhas e das agregações de argila na corbícula. Eu realizei um experimento de campo para testar a preferência de umidade do substrato. A quantidade de argila transportada aumentou exponencialmente com o tamanho da abelha e o substrato preferido foi o de menor umidade. A quantidade de argila removida e a eficiência de remoção não foram influenciadas pela umidade do substrato. A argila com maior umidade é mais densa, o que sugere que as abelhas gastam mais energia para transportar a mesma quantidade de argila quando ela está mais úmida. Esse pode ser o mecanismo para explicar a preferência de remoção pela argila com menor umidade.Univ Fed Mato Grosso do Sul, Ecol Lab, Programa Posgrad Ecol &Conservacao, BR-79070900 Campo Grande, MS, BrazilUniv Estadual Paulista, Dept Ecol, Programa Posgrad Ecol &Biodiversidade, BR-13506900 Rio Claro, SP, BrazilUniv Estadual Paulista, Dept Ecol, Programa Posgrad Ecol &Biodiversidade, BR-13506900 Rio Claro, SP, Brazi

Larval rearing conditions affect kin-mediated cannibalism in a treehole mosquito

Cannibalistic behavior among Ochlerotatus triseriatus larvae was studied to determine whether cannibals are able to alter their attack behavior based on their relatedness to newly hatched conspecific prey larvae. Fourth instar larvae, reared in one of four different initial densities, were placed with newly emerged first instars and, after 48 h, the number of first instar larvae remaining was recorded. Our data suggest a Type III functional response of non-kin fourth instar larvae to first instar prey density. Several significant effects emerged from our analysis model, namely that the number of first instar prey available, the relationship of the first instar larvae with the cannibals, and the density at which the fourth instar cannibals were reared all affected the number of first instar larvae consumed

To be or not to be … a flower? A test of possible cues influencing hunting site selection in subadult females of the crab spider Epicadus heterogaster

Females of some Thomisidae species are known to use visual and olfactory stimuli to select high quality hunting sites. However, because studies about foraging behavior in this family are concentrated on a few species, the comprehension of the process related to hunting behavior evolution in crab spiders may be biased. In this study we investigated the hunting site selection of a previously unstudied crab spider, Epicadus heterogaster. We performed three experiments to evaluate the hypothesis that subadult females are able to use visual and olfactory stimuli to select hunting sites. In the first experiment, females did not preferentially select flower paper models that matched their body coloration. However, after choosing a model that had the same body color as the spider, they remained on it for longer periods than on models with different colors. In the second experiment, females did not discriminate between flower paper models, natural flower models and crumpled paper models. Females did also not discriminate among different olfactory stimuli in the third experiment. It is possible that subadult females of E. heterogaster need to establish and experience a given hunting site before evaluating its quality. However, it remains to be investigated if they use UV cues to select a foraging area before experiencing it.Univ Estadual Feira de Santana, Dept Ciencias Biol, Feira de Santana, BA, BrazilUniv Estadual Paulista, Dept Zool & Bot, Sao Jose do Rio Preto, SP, BrazilUniv Estadual Paulista, Dept Zool & Bot, Sao Jose do Rio Preto, SP, Brazi

Experimental investigation of the decay from a ship’s propeller

In the present study, an experimental investigation of the decay of the maximum velocity and its turbulent characteristics behind a ship propeller, in “bollard pull” condition (zero speed of advance), is reported. Velocity measurements were performed in laboratory by use of a Laser Doppler Anemometry (LDA) measurement system. Earlier researchers described that the maximum axial velocity is constant at the initial stage of a ship’s propeller jet (Fuehrer and Römisch, 1977; Blaauw and van de Kaa, 1978; Berger et al., 1981; Verhey, 1983) as reported in a pure water jet (Albertson et al., 1950; Lee et al., 2002; Dai, 2005), but a number of researchers disagreed with the constant velocity assumption. The present study found that the maximum axial velocity decays in the zone of flow establishment and the zone of established flow with different rates. The investigation provides an insight into the decays of both the maximum velocity and the maximum turbulent fluctuation in axial, tangential and radial components and the decay of the maximum turbulent kinetic energy. Empirical equations are proposed to allow coastal engineers to estimate the jet characteristics from a ship’s propeller.<br/

Minimal epitope for Mannitou IgM on paucimannose-carrying glycoproteins

Abstract Paucimannosidic glycans are restricted to the core structure [Man1–3GlcNAc2Fuc0–1] of N-glycans and are rarely found in mammalian tissues. Yet, especially [Man2-3GlcNAc2Fuc1] have been found significantly upregulated in tumors, including in colorectal and liver cancer. Mannitou IgM is a murine monoclonal antibody that was previously shown to recognize Man3GlcNAc2 with an almost exclusive selectivity. Here, we have sought the definition of the minimal glycan epitope of Mannitou IgM, initiated by screening on a newly designed paucimannosidic glycan microarray; among the best binders were Man3GlcNAc2 and its α1,6 core-fucosylated variant, Man3GlcNAc2Fuc1. Unexpectedly and in contrast to earlier findings, Man5GlcNAc2-type structures bind equally well and a large tolerance was observed for substitutions on the α1,6 arm. It was confirmed that any substitution on the single α1,3-linked mannose completely abolishes binding. Surface plasmon resonance for kinetic measurements of Mannitou IgM binding, either directly on the glycans or as presented on omega-1 and kappa-5 soluble egg antigens from the helminth parasite Schistosoma mansoni, showed submicromolar affinities. To characterize the epitope in greater and atomic detail, saturation transfer difference nuclear magnetic resonance spectroscopy was performed with the Mannitou antigen-binding fragment. The STD-NMR data demonstrated the strongest interactions with the aliphatic protons H1 and H2 of the α1–3-linked mannose and weaker imprints on its H3, H4 and H5 protons. In conclusion, Mannitou IgM binding requires a nonsubstituted α1,3-linked mannose branch of paucimannose also on proteins, making it a highly specific tool for the distinction of concurrent human tumor-associated carbohydrate antigens.</jats:p