Time filter

Source Type

Rosa G.S.,Sao Paulo State University | Costa M.I.S.,Laboratory Nacional Of Computacao Cientifica | Corrente J.E.,Sao Paulo State University | Silveira L.V.A.,Sao Paulo State University | Godoy W.A.C.,University of Sao Paulo
Neotropical Entomology | Year: 2011

In this study we investigated the population dynamics of Chrysomya albiceps (Wiedemann) with laboratory experiments, employing survival analysis and stage structure mathematical models, emphasizing survival among life stages. The study also assessed the theoretical influence of density dependence and cannibalism during immature stages, on the population dynamics of the species. The survival curves were similar, indicating that populations of C. albiceps exhibit the same pattern of survival among life stages. A strong nonlinear trend was observed, suggesting density dependence, acting during the first life stages of C. albiceps. The time-series simulations produced chaotic oscillations for all life stages, and the cannibalism did not produce qualitative changes in the dynamic behavior. The bifurcation analysis shows that for low values for survival, the population reaches a stable equilibrium, but the cannibalism results in chaotic oscillations practically over all the parametric space. The implications of the patterns of dynamic behavior observed are discussed. © 2011 Sociedade Entomológica do Brasil.

Meza M.E.M.,Federal University of ABC | Costa M.I.D.S.,Laboratory Nacional Of Computacao Cientifica
Mathematical Biosciences | Year: 2011

Continuous time models of single exploited populations usually generate outcomes expressing a dependence of yield and economic items on harvest intensity. In this work it is shown that a known threshold policy is able to generate yield and related economic items that do not depend on harvest intensity, but rather on the values of the population threshold itself and the species intrinsic parameters. It is argued that since this result can be carried over to other models of single species dynamics, it may have significant implications in the management and conservation of exploited populations. © 2011 Elsevier Inc.

Serra H.,Federal University of Grande Dourados | Costa M.,Laboratory Nacional Of Computacao Cientifica | Godoy W.,University of Sao Paulo
Neotropical Entomology | Year: 2011

We combined two models to investigate the theoretical dynamics of five exotic and native blowfly species in response to the Allee effect by using demographic parameters estimated from experimental populations. Most of the results suggest stabilization of dynamic behavior in response to the Allee effect. However, the results depended on the magnitude of the demographic parameters of each species, and also indicated chaotic fluctuations and limit cycles. The results are discussed in the context of larval aggregation, an important biological process for blowflies, which naturally incorporates the Allee effect. © 2011 Sociedade Entomológica do Brasil.

Costa M.I.S.,Laboratory Nacional Of Computacao Cientifica | Faria L.B.,Federal University of Lavras
Neotropical Entomology | Year: 2010

An Integrated Pest Management is formulated as a threshold policy. It is shown that when this strategy is applied to a food web consisting of generalist, specialist predators and endemic and pest prey, the dynamics can be stable and useful from the pest control point of view, despite the dynamical complexities inherent to the application of biocontrol only. In addition, pesticide toxicity depends rather on the species intrinsic parameters than on the chemical agent concentration.

Lemonge A.C.C.,Federal University of Juiz de fora | Barbosa H.J.C.,Laboratory Nacional Of Computacao Cientifica | Bernardino H.S.,Laboratory Nacional Of Computacao Cientifica
2012 IEEE Congress on Evolutionary Computation, CEC 2012 | Year: 2012

Real world engineering optimization problems are often subject to constraints which are complex implicit functions of the design variables. Frequently, such constrained problems are replaced by unconstrained ones by means of penalty functions. A family of adaptive penalty schemes for steady-state genetic algorithms is proposed here. For each constraint, a penalty parameter is adaptively computed along the run according to information extracted from the current population, such as the existence of feasible individuals and the level of violation of each constraint. The performance of each variant in the family is examined using test problems from the evolutionary computation as well as mechanical and structural optimization literature. © 2012 IEEE.

Discover hidden collaborations