Integrated Pest Management requires consideration of multiple interrelated and interdependent factors that influence pest infestations and population dynamics. Finding the reasons behind damage and the resulting crop loss is a key element to identifying and implementing an effective and sustainable solution with a minimum cost. To this end, DECIPESTS, a DECIsion support system for PEST management in Sugarcane, was developed using Cogui software. As a first step, interactions regarding food webs of different insect communities (Lepidoptera, Coleoptera, Hemiptera, etc.) and the impact of major agricultural practices (insecticides, soil preparation, variety, irrigation, fertilization, etc.) in the agro-system were implemented as causal rules. In the second step, the model was reversed. Based on the expertise gained in IPM and many years of observations of damage in the field, DECIPESTS identifies the potential causes of insect pest infestation. As an example, it is shown how crop stress induced by irrigation mismanagement can increase damage levels by stem borers. Other examples such as over-application of nitrogen can be used with a similar approach. Providing a wider range of information about the agro-system enables identification of the effective cause of pest infestations and proposes a solution to manage them. DECIPESTS is a tool developed to support strategic decisions regarding insect pest management in the sugarcane agrosystem. Addition of knowledge on pathology and disease control is envisaged.