In Mediterranean agriculture, pests, diseases and weeds constitute some of the main limiting factors, owing to the direct and indirect damages that they cause in crops, with the result that control measures are needed to palliate their effects.These control measures are currently framed within what is known as Integrated Control, harmonising chemical, biological, physical, cultural and other methods of control.

Nowadays, the rational use of pesticides (insecticides, acaricides, fungicides, herbicides) is the most commonly used control tool.In this context, the development of resistance to pesticides by pests, diseases and weeds is one of the main technical problems in phytosanitary control.The appearance of resistance phenomena may lead to the lack of efficacy of some products, while in many cases no other control alternatives are available.This phenomenon comes about due to an abusive use or improper use of products (inadequate doses, repetition of treatments with the same product, too frequent applications, etc.).Nevertheless, it is an avoidable and reversible phenomenon if suitably

handled.In order to maintain the efficacy of products, it is necessary to devise strategies for handling the resistance which will contribute to optimising pesticide applications (in products, dosage and number), obtaining an acceptable control.All of this, with the aim of achieving a sustainable agriculture, producing safe and healthy food.

To this end, it is necessary to know what resistance is, what the present situation is, why it has developed, which mechanisms are involved, and what the most suitable anti-resistance strategies are.The aim of this Symposium is to attempt to respond to these questions, with a view to setting out the bases for an appropriate response to resistance in Mediterranean crops.

Pablo Bielza Lino
Department of Vegetal Production
Higher Technical College of Agricultural Engineering
Polytechnic University of Cartagena