Conservation strategy for palm groves: Optimal chemical control model for Red Palm Weevil

Abstract

In the Mediterranean area, a major concern is the conservation of palm tree landscapes against the red palm weevil, Rhynchophorus ferrugineus (Olivier, 1790). The methodological approach of conservation ecology, such as multidisciplinary modelling also applies in the management of cultural landscapes concerning ornamental plants like palm trees of the area. In the paper we propose a dynamic model for the control of the red palm weevil, contributing in this way to the sustainability of an existing cultural landscape. The primary data set collected is a sample from the density-time function of a two-cohort pest population. This data set suggests a bimodal analytic description. If, from this data set, we calculate a sample from the accumulated density-time function (the integral of the density-time function), it displays a double sigmoid function (with two inflections). A good candidate for the analytical description of the latter is the sum of two logistic functions. As for the dynamic description of the process, a two-dimensional system of differential equations can be derived, where the solution’s second component provides the analytical description of the original density-time function for the two-cohort population. Since the two cohort waves appear in all three cycle stages, this reasoning applies to the subpopulations of larvae, pupae, and adults. The model fitting is always performed using the SimFit package. Based on these dynamics, an optimal chemical control model is also suggested as a plant conservation tool.