Climate Change and Insect Pests: Economic Damages and Adaptive Strategies in Mediterranean Olive Groves

Introduction

The olive (Olea europaea L.) tree is the most emblematic tree of the Mediterranean region with considerable economic, social, and ecological importance. The use of olive trees as a source of food, wood, and cattle feed explains the spread of olive groves alongside the development of human civilization (Rapoport et al., 2016). Nowadays, the olive is one of the most cultivated trees in the world and is found on all five continents for cultural (traditions, landscapes), economic (oil and olives), and ecological (landscape) reasons. In recent decades, the olive growing areas have expanded and the global production of olive oil has increased, though the effect of biennial or alternate production (high/low yield years) is still noticeable. Approximately 11.2 million ha are devoted to olive cultivation worldwide in 2019, and the Mediterranean basin accounts for more than 95% of this area, mainly in Spain (23%), Tunisia (19%), Italy (10%), Morocco (10%), Greece (8%) and Turkey (8%) (FAOSTAT, 2019) (Table 1). World olive oil production in 2019 is estimated at 3.1 million tons, and the main producing countries are Spain (36%), Italy (11%), Greece (9%), Tunisia (8%), Morocco (7%), and Turkey (7%) (FAOSTAT, 2019) (Table 1). The use of fast-growing, high-yielding varieties planted at higher densities, innovative orchard management practices such as pruning, tillage, and plant protection, as well as drip irrigation that allows for the application of fertilizer, are factors that have contributed to this significant increase in oil production. However, olive growers are now facing new difficulties and challenges, climate change being one of the most important. Indeed, global warming is predicted to result in increased temperatures, altered rainfall patterns, and other derived factors that may have unknown effects on the distribution, abundance, and impact of species in natural and agricultural systems (Gutierrez, et al., 2010). Such climatic variations have significant effects on insect pest populations and their dynamics (Woiwod, 1997). In fact, pest development is strongly influenced by environmental factors, including humidity and temperature. Therefore, climate change may affect the distribution and life cycle of pest species, their migratory behavior, and their interaction with natural enemies, and could result in an increase in their growth rate and the number of generations. Hence, a changed pattern in climatic factors has the potential to drastically affect the pest situation in olive groves and eventually lead to yield losses. More than 255 species make up the group of organisms that could be harmful to O. europaea, including insect pests, mites, nematodes, and phytopathogenic agents (Montiel-Bueno and Jones, 2002). According to estimates, annual losses due to insect pests account for approximately 15% of total production in the Mediterranean Basin (Haniotakis, 2005). In this region of the world qualified as a “hotspot” of global changes (Giorgi, 2006), these pests could be affected by climate change with direct impacts on their biology and indirect impacts related to their environment, host plants, and natural enemies. This situation will create new challenges for olive growers who will have to protect their production and maximize their profit while adopting economically viable solutions and environmentally friendly strategies in the framework of sustainable agriculture. This chapter provides an overview of the impacts of climate change on olive insect pests and strategies to mitigate their damage in olive groves.