Positioning behaviour in fish shoals: a cost–benefit analysis

Shoal position can have a strong influence on individual fitness. Individuals in front positions of shoals were observed to have higher feeding rates than individuals elsewhere. Manipulation of nutritional state showed that hungry individuals had a stronger preference for front positions and that the duration of food-deprivation was positively correlated with the degree of the position preference. On the other hand, front positions (like other peripheral positions) probably incur costs in terms of increased predation risks. Experiments with Schreckstoff showed that frightened individuals seek the central part of the shoal. This suggests that individuals rotate their shoal positions according to the tradeoff between energy intake and predation risk.     

Raspberry ketone-supplemented diet has no effect on fitness parameters or lure responsiveness in male melon flies,Zeugodacus cucurbitae (Diptera: Tephritidae)

The male annihilation technique (MAT) and sterile insect technique (SIT) are often used to control pestiferous tephritid fruit flies (Diptera: Tephritidae). MAT involves the deployment of traps containing a male attractant and insecticide with the goal of drastically reducing male abundance and ultimately eliminating the entire population. SIT, which involves the mass production, sterilization, and release of the target species, may also be implemented to achieve final extirpation. Generally, simultaneous implementation of MAT and SIT is counterproductive, because the presence of large numbers of male-specific traps in the environment (MAT) would greatly reduce the number of sterile males available for copulating with wild females (SIT). However, studies on the Queensland fruit fly, Bactrocera tryoni (Froggatt), indicate that concurrent use of MAT and SIT may be feasible. Sexually mature males of B. tryoni are attracted to the raspberry ketone and its synthetic analogue cue-lure. Males of B. tryoni fed raspberry-ketone-supplemented diet when newly emerged showed lower attraction to cue-lure baited traps than control males. In addition, newly emerged males provided this diet displayed accelerated sexual maturation, which would allow the early release of sterile males and reduce pre-release holding costs. Here, we examined whether the addition of raspberry ketone to the adult diet of male melon flies, Zeugodacus cucurbitae (Coquillett), produced effects similar to those observed for B. tryoni. Despite using similar methods, no significant effect of raspberry ketone-supplemented diet on time to sexual maturity, survival, mating competitiveness, or attraction to cue-lure baited traps in mass-reared Z. cucurbitae males.     

The electromagnetic basis of social interactions

It has been established that living things are sensitive to extremely low-frequency magnetic fields at vanishingly small intensities, on the order of tens of nT. We hypothesize, as a consequence of this sensitivity, that some fraction of an individual’s central nervous system activity can be magnetically detected by nearby individuals. Even if we restrict the information content of such processes to merely simple magnetic cues that are unconsciously received by individuals undergoing close-knit continuing exposure to these cues, it is likely that they will tend to associate these cues with the transmitting individual, no less than would occur if such signals were visual or auditory. Furthermore, following what happens when one experiences prolonged exposure to visual and like sensory inputs, it can be anticipated that such association occurring magnetically will eventually also enable the receiving individual to bond to the transmitting individual. One can readily extrapolate from single individuals to groups, finding reasonable explanations for group behavior in a number of social situations, including those occurring in families, animal packs, gatherings as found in concerts, movie theaters and sports arenas, riots and selected predatory/prey situations. The argument developed here not only is consistent with the notion of a magnetic sense in humans, but also provides a new approach to electromagnetic hypersensitivity, suggesting that it may simply result from sensory overload.     

Eucalypt leaf decomposition in an intermittent stream in south-eastern Australia

Eucalypt leaf packs were placed at two sites in an intermittent stream during summer to examine the hypothesis that terrestrially-exposed leaf litter accumulates a richer microbial flora than submerged leaves — a phenomenon observed in Canadian temporary vernal pools. This did not occur; during the experiment, microbial biomass (as ATP) rose steadily on submerged leaves but remained low on terrestrially-exposed leaves. Densities of most functional feeding groups on the submerged leaves increased with time. Scrapers appeared to be more important than shredders in eucalypt leaf breakdown at both sites.     

A historical review of research on the weaver ant Oecophylla in biological control

1 Although the weaver ant Oecophylla is the first written record of biological control, dating from 304 ad , there have been fewer than 70 scientific publications on this predator as a biological control agent in Asia, from the early 1970s onwards, and fewer than 25 in Africa. 2 Apart from crop‐specific ecological and perceptual factors, a historical review shows that political and market forces have also determined the extent to which Oecophylla was incorporated into research and development programmes. 3 In Africa, research on weaver ants in biological control concentrated on export crops, such as coconut and cocoa, whereas, in Asia and Australia, research focused on fruit and nut crops, primarily destined for domestic markets. 4 Increased evidence of pesticide inefficiency under tropical smallholder conditions, changing paradigm shifts in participatory research and a growing scientific interest in local knowledge in the early 1990s opened up new avenues for research on conservation biological control. 5 Lobbying and advocacy have been needed to ensure that Oecophylla was recognized as an effective biological control agent. 6 With an increased market demand for organic produce, holistic approaches such as conservation biological control, particularly the use of Oecophylla, are increasing in importance. 7 Multi‐stakeholder strategies for collaborative learning are proposed for a better control of major fruit, nut and timber tree pests in Africa, Asia and Australia.     

VS-oscilloscope: A new tool to parameterize tree radial growth based on climate conditions

It is generally assumed in dendroecological studies that annual tree-ring growth is adequately determined by a linear function of local or regional precipitation and temperature with a set of coefficients that are temporally invariant. However, various researchers have maintained that tree-ring records are the result of multivariate, often nonlinear biological and physical processes. To describe critical processes linking climate variables with tree-ring formation, the process-based tree-ring Vaganov–Shashkin model (VS-model) was successfully used. However, the VS-model is a complex tool requiring a considerable number of model parameters that should be re-estimated for each forest stand. Here we present a new visual approach of process-based tree-ring model parameterization (the so-called VS-oscilloscope) which allows the simulation of tree-ring growth and can be easily used by researchers and students. The VS-oscilloscope was tested on tree-ring data for two species (Larix gmeliniiand Picea obovata) growing in the permafrost zone of Central Siberia. The parameterization of the VS-model provided highly significant positive correlations (p < 0.0001) between simulated growth curves and original tree-ring chronologies for the period 1950–2009. The model outputs have shown differences in seasonal tree-ring growth between species that were well supported by the field observations. To better understand seasonal tree-ring growth and to verify the VS-model findings, a multi-year natural field study is needed, including seasonal observation of the thermo-hydrological regime of the soil, duration and rate of tracheid development, as well as measurements of their anatomical features.     

Fish predation on epiphytic microcrustacea in Tivoli South Bay,a Hudson River tidal freshwater wetland

The littoral microcrustacean fauna of Tivoli South Bay was studied from July to September, 1989. The effects of fish predation on microcrustacean densities were tested in a short-term predator exclusion experiment. Fish were excluded from water chestnut (Trapa natans) plots in four screened exclosures. An equal number of open cages allowed foraging. Fish predation did not have a significant effect on densities of ostracods or other microcrustaceans. Ostracod densities increased in cages throughout the experimental period, whereas cladoceran and copepod densities decreased in both treatments. Gut contents analysis of banded killifish (Fundulus diaphanus) revealed that ostracods and other microcrustaceans were commonly ingested by larval, juvenile, and adult killifish utilizing T. natans as habitat. These results suggest that ostracods and other microcrustacean epifauna associated with T. natans may represent an important trophic link in the tidal freshwater wetlands of the Hudson River Estuary. Deceased     

A novel galactosyl-binding lectin from the plasma of the blood clam,Anadara granosa (L) and a study of its combining site

Control Analysis has been carried out in the first steps of a rat liver glycolytic system. Attention has been focused on the effect of several glucose concentrations on the control, particularly regarding the role of glucokinase. From kinetic studies of the whole metabolic system we have obtained information on the flux variation under different glucose concentrations. This information together with the kinetics of glucokinase has allowed us to calculate Flux Control and Elasticity Coefficients for glucokinase and the Response Coefficient of the system with respect to glucose. The changes in of the value of Flux Control Coefficients demonstrates that in conditions of low glucose concentration, glucokinase is the main enzyme in controlling the flux through the pathway, but at high glucose concentration the control moves to phosphofructokinase. Next, we have compared our results with those obtained with the shortening and titration method, previously described (Torres, N.V., Mateo, F., Mélendez-Hevia, E. and Kacser, H., (1986) Biochem. J. 234, 169–174; Torres, N.V. and Meléndez-Hevia, E. 1991. Molec. Cell. Biochem. 101, 1–10). Furthermore, from knowledge of the enzyme kinetics of the system we have been able to build a model of the pathway that allows us computer similation of its behavior and calculation of the Flux Control Coefficient profile at different glucose concentrations. By the three methods the results correlate, supporting the use of the pathway substrate as external modulator of the metabolic system as a tool for practical application of Control Analysis.