Consequences of global warming on apple orchards in the Mediterranean basin: Challenges of insect pest management

Abstract

Global warming is expected to have diverse effects on fruit orchards. However, predictions suggest that the consequences of extremely high temperatures, rainfall reduction and increased UV radiation will significantly affect those from the Mediterranean basin. Therefore, herbivores feeding upon trees affected by global warming will be directly influenced by the varying geographical distribution and phenology of their populations. Changes in herbivore biology and performance will most likely modify the behaviour and preferences of organisms in the upper levels of the food chain. This review gathers information on the cascade effect of global warming on the different actors in apple fruit trees. It explores the consequences of tree protection and insect pest management in apple orchards of the Mediterranean basin. Scientific evidence suggests that elevated temperatures will generally compromise the performance of the pest’s natural enemies; however, lack of diapause due to warmer winters may benefit certain natural enemies, increasing their presence earlier in the season. On the other hand, using ecological infrastructures will suffer from increased water shortages, and heat and UV radiation will increase the degradation of phytosanitary products, posing significant challenges for pest management. Therefore, predictions of pest development using the variations of climatic factors in mathematical models represent a great tool to prevent outbreaks and improve orchard management. Altogether, global warming is and will be a challenge for apple production in the Mediterranean basin and joint actions of politicians, farmers, and scientists are required to overcome its consequences.