Distributed Delay Models and ROOT: building a software to simulate pest insects' life cycle using the daily temperature

Abstract

ROOT is a software package developed from a CERN project, started in 1994 by René Brun for statistical analysis in high-energy physics. Nevertheless, its potentialities can be used also in the field of plant protection against pest insects. Since long time, indeed, there is a large use of the Distributed-Delay Model (Manetsch, 1976), but to date there is no specific software capable of carrying out all the operations necessary for researchers. During a simulation process, we can individuate two main phases: at the beginning, there is a “laboratory phase” in which entomologists have to estimate a series of specie’s parameters thru constant-temperature farms in climatic cells, and then a simulation can be done, with validations using field data. Once completed this work, distributed delay model equations can help farmers to forecast the peaks of pest insects, helping them to individuate the best period for treatments. The ROOT’s main feature, is the use of C++ language, and to have not only a graphical interface, but also specific packages for statistical analysis, fitting and minimization of functions, multivariate analysis of data, and other tools which allow solutions for mathematical problems. The aim of this work is to build, through the ROOT’s libraries, a series of macros that consent to do non-linear fits with functions like Erlang PDF, linear-rate, Logan, Briére, Sharpe and De Michele, giving, first, support to the parameters-estimate step in laboratory sessions, and then, to solve numerically the Distributed-Delay Model equations. The results will be given both in graphical and numerical way. Concerning the validation in open field, has been developed another macro which puts in relation the simulations results, with field data, and choose the nearest to reality. Every macro has been developed individually, and can be used independently from the others, even if they are linked by the logical thread of the actions in estimation process. This helped us to check the software operation and is helpful for users that can call only the specific part that they need. Furthermore, for completion, all these tools are contained in a main (now at version 1.0) managed from command line, and with the selection possibility.