Modeling warfare in social animals: a "chemical" approach

`Friend or foe' and decision making initiative in complex conflict environments

We present a novel mathematical model of two adversarial forces in the vicinity of a non-combatant population in order to explore the impact of each force pursuing specific decision-making strategies. Each force has the opportunity to draw support by enabling the decision-making initiative of the population, in tension with maintaining tactical and organisational effectiveness over their adversary. Each dynamic model component of force, population and decision-making, is defined by the archetypal Lanchester, Lotka-Volterra and Kuramoto-Sakaguchi models, with feedback between each component adding heterogeneity. Developing a scheme where cultural factors determine decision-making strategies for each force, this work highlights the parametric and topological factors that influence favourable results in a non-linear system where physical outcomes are highly dependent on the non-physical and cognitive nature of each force's intended strategy.

Sub-lethal doses of imidacloprid alter food selection in the invasive garden ant Lasius neglectus

Despite several restrictions to their use, neonicotinoid insecticides are still widely employed worldwide. Residual sub-lethal amounts of these chemicals can have detrimental effects on the behavior of non-target insects. Toxic effects on economically important species such as bees have been widely documented, but less is known about their toxic action on other social insects, such as ants. In this study, we assessed the effect of different sub-lethal doses of the neonicotinoid imidacloprid on the ability of colonies of the invasive ant Lasius neglectus to select the most profitable resource. We used Y-shaped mazes having an imidacloprid-polluted or an unpolluted sucrose solution on the two branches. Two sucrose (0.1 M, 0.5 M) and two imidacloprid (1 μg/ml, 10 μg/ml) concentrations were used. In parallel, we evaluated the marking activity of foragers who fed on the same solutions. We found that the 0.1 M sugar solution polluted with 1 μg/ml imidacloprid was significantly more frequently selected in binary choices experiments than the unpolluted resource. Moreover, the ingestion of the same combination of sugar and imidacloprid significantly increased the marking rate of foragers. The higher concentration of the pollutant had lower effects, probably because of the hormesis phenomenon. Results suggest that the lower sub-lethal dose of imidacloprid can lead ants to select again the polluted resource. This "active" selection of the pollutant may magnify the negative effects on the colonies. Due to their ecological role, any impairment of ant survival or behavior may have detrimental cascade effects on the whole ecosystem.

Analysis, Simulation and Optimization of the Milking Process in a Cowshed for the Production of Parmigiano Reggiano

The aim of this study is to optimize the milking process of a cowshed, located near Parma (Italy), which provides milk to some dairy companies, for the production of Parmigiano Reggiano cheese. The ultimate goal of the analysis is to reduce the time required for milking operations, thus optimizing the whole management of the farm processes. A discrete-event simulation model is designed under Simul8™ to reproduce the main processes of the cowshed and the movements of the animals inside the cowshed, before and after milking. The model exploits real data collected from the direct observation of the farm and is validated by comparing the results provided with the real performance of the milking activities. Then, it is used to test two new configurations of the cowshed layout and to assess their performance, in terms of the total time required for milking. Interesting savings in the total milking time are found.