Foraging Behavior of Tetramorium Caespitum in an Urban Environment: the Effect of Food Quality on Foraging

Animals\u27 foraging strategies are directly related to their fitness. Proposed models of optimal foraging assume that animals strategize in terms of maximizing benefits over the cost of acquiring resources. Ants are social insects that are comparable in biomass to humans inhabiting the plant. As such, it is crucial to understand the foraging strategies of such an influential member of the ecosystem. With the ever-increasing rate of urbanization and human encroachment, it is even more important to consider the foraging patterns of species inhabiting urban areas. In this study we investigate optimal foraging strategies in the pavement ant, Tetramorium caespitum. Specifically, our study examined if pavement ant colonies would alter their foraging behavior so as to maximize benefits and minimize costs. To do this, we exposed the ants to food of two varying nutritional qualities to test how they allocated foragers across these two resources.Food quantity, distance to the food source and terrain were the same in both types of resources. Across a two day period, we saw that T. caespitum colonies increased ant recruitment when food quality increased and decreased ant recruitment when food quality decreased. Our control treatments where food quality did not change also did not see a change in ant recruitment. This study shows that species that live in urban areas, such as T. caespitum, can adapt to forage optimally. Studies like this can be used to make predictions about survival of species that are newly associated with urban environments

New evolutionary frontiers from unusual virus genomes

The sequences of two giant viral genomes, Mimivirus and a polydnavirus, have recently been published. Mimivirus has the largest known viral genome and encodes an unprecedented number of proteins, whereas the polydnavirus genome has an extremely low coding density and does not encode DNA-replication proteins. These and other unusual features challenge the way we view the evolution and definition of viruses

Etudes phytochimique et pharmacologique de Bridelia ferruginea benth (euphorbiaceae) sur la motricite du Taenia coli de cobaye

L’étude phytochimique des extraits de Bridelia ferruginea a montré que cette plante contient des quinones, des tanins catéchiques et galliques, des alcaloïdes, des stérols, des polyterpènes, des polyphénols, des composés réducteurs, des flavonoïdes et des saponosides. L’extrait aqueux de Bridelia ferruginea provoque entre 10-5mg/mL et 10-1mg/mL une augmentation des contractions rythmiques de muscle lisse Taenia coli de cobaye. Ces effets inotropes positifs antagonisés par l’Atropine (10-6mg/mL) sont totalement abolis en milieu pauvre (0Ca2+) et dépourvus de calcium (0Ca2++ EDTA 10-5M).Ces résultats suggèrent la présence de substances cholinomimétiques dans l’extrait brut. Ces substances favoriseraient l’entrée de calcium dans la cellule musculaire lisse par stimulation des récepteurs muscariniques. Ces substances cholinomimétiques justifieraient l’usage traditionnel de cette plante comme laxatif ou purgatif.Mots-clés : Bridelia ferruginea, Taenia coli, récepteur muscarinique.

The use of light to enhance weaver ant Oecophylla longinoda Latreille (Hymenoptera: Formicidae) queen catches

Production of live weaver ant (Oecophylla longinoda and O. smaragdina) colonies is being developed as the ants provide several ecosystem services in agriculture and as they are used in education and research laboratories. Founding queens needed for colony production can be caught in artificial nests made of live leaves that are curled on trees. In this study we investigated if the catch rate of O. longinoda queens in artificial nests could be improved by attracting queens to trees with a light source (electric torches). We compared catch rates of 50 artificial nests on each of eight citrus trees, four of them with light and four without light. During two mating seasons covering 9 mating flights we caught a total of 178 queens. However, 3.8 times more queens were caught in the trees with light compared to trees without light. We conclude that queen catches can be highly improved by combining artificial nests with an attracting light source

Sensitivity of asymmetric rate-dependent critical systems to initial conditions: Insights into cellular decision making

The work reported here aims to address the effects of time-dependent parameters and stochasticity on decision making in biological systems. We achieve this by extending previous studies that resorted to simple bifurcation normal forms, although in the present case we focus primarily on the issue of the system's sensitivity to initial conditions in the presence of two different noise distributions, Gaussian and Lévy. In addition, we also assess the impact of two-way sweeping at different rates through the critical region of a canonical Pitchfork bifurcation with a constant external asymmetry. The parallel with decision making in biocircuits is performed on this simple system since it is equivalent in its available states and dynamics to more complex genetic circuits published previously. Overall we verify that rate-dependent effects, previously reported as being important features of bifurcating systems, are specific to particular initial conditions. Processing of each starting state, which for the normal form underlying this study is akin to a classification task, is affected by the balance between sweeping speed through critical regions and the type of fluctuations added. For the heavy-tailed noise, two-way dynamic bifurcations are more efficient in processing the external signals, here understood to be jointly represented by the critical parameter profile and the external asymmetry amplitude, when compared to the system relying on escape dynamics. This is particular to the case when the system starts at an attractor not favored by the asymmetry and, in conjunction, when the sweeping amplitude is large

Normative EMG activation patterns of school-age children during gait

Gait analysis is widely used in clinics to study walking abnormalities for surgery planning, definition of rehabilitation protocols, and objective evaluation of clinical outcomes. Surface electromyography allows the study of muscle activity non-invasively and the evaluation of the timing of muscle activation during movement. The aim of this study was to present a normative dataset of muscle activation patterns obtained from a large number of strides in a population of 100 healthy children aged 6-11 years. The activity of Tibialis Anterior, Lateral head of Gastrocnemius, Vastus Medialis, Rectus Femoris and Lateral Hamstrings on both lower limbs was analyzed during a 2.5-min walk at free speed. More than 120 consecutive strides were analyzed for each child, resulting in approximately 28,000 strides. Onset and offset instants were reported for each observed muscle. The analysis of a high number of strides for each participant allowed us to obtain the most recurrent patterns of activation during gait, demonstrating that a subject uses a specific muscle with different activation modalities even in the same walk. The knowledge of the various activation patterns and of their statistics will be of help in clinical gait analysis and will serve as reference in the design of future gait studie

An Annotated Bibliography Of Chickpea Diseases 1915-1976

The purpose of this bibliography, on which work began in 1975, is to provide a working file of the literature concerned wi th chickpea (Cicer arietinum L.) diseases that wi l l assist in the identification of fungal and bacterial microorganisms associated wi th chickpea seeds. Chickpea is one of the more important pulse crops of the Eastern Hemisphere, where it has been cultivated for centuries. The primary function of this bibliography is to make the chickpea disease literature available to agricultural workers throughout the wor ld, especially in countries where such reference material is difficult to obtain