**11. Climate change and its effects on plant pests and diseases**

The importance of climate in the growth and development of plant diseases has been known for more than 2000 years. The ancient Greeks (286–370 BC) determined that cereals cultivated in the Highlands had less disease compared to cereals cultivated in low-lying areas [62]. Understanding the history of pests may shed light on possible future trends and strengthen the evidence base of national and international policies on plant conservation. Today, it is widely believed that increased international trade and travel will accelerate the pace of pest arrivals, which is caused by adverse globalization outcomes [63]. There is also the view that climate change may accelerate the establishment of new pests [63].

Increasing CO2 levels associated with climate change may affect plant distribution, abundance, and yield, pests, and pathogens [64]. Research by Anderson et al. [63] on the origin of new plant, outbreaks showed that 56% of diseases were caused by new pathogens.

Lucke et al. [65] investigated pathogens in four major food crops of wheat, rice, soybeans, and potatoes. The limited data show that depending on the interaction between host and pathogen, the effect will be positive, negative, or neutral. Plant pathogens will have different responses to climate change while the life cycle of some pathogens is limited by rising temperatures, e.g., *Puccinia striiformis* f. sp. Tritici. In addition, other climatic factors such as increased CO2 may provide more favorable conditions for pathogens such as *Fusarium pseudograminearum*.

Major factors of climate change that are likely to affect the severity and spread of plant diseases are increased CO2 content, heavy and unseasonal rainfall, increased humidity, drought, hurricanes, and warmer winters [65, 66].

The reaction of diseases and pests to climate change can be directly and indirectly. The indirect reaction includes changes in crop type, crop soils, agricultural operations as well as changes in plant and animal natural habitats that occur after climate change. Thus, there will be changes in the resources needed for pathogens and pests. There are plenty of articles and writings on the interaction between pests, diseases, weeds, and climate change, but many of them are still disputed. Changes during the growing period have unfortunately affected the biological territory and life cycle of living organisms. Increasing the length of the growing season has caused changes in the pattern of bird migration, increased infection induced by insects, and changed the habitat of living organisms. The longer the growing season, the more insects such as locusts will be able to complete their reproductive cycle several times during spring, summer, and autumn. Higher winter temperatures may allow larvae to survive the whole winter in areas where the cold threatened them with death, therefore, this will lead to more infections in the next season [6].

Disproportionate warming of high latitudes and elevated areas in winter and at night can affect plant growth and development can change the geographical distribution pattern of production activities and will change the ecological balance between crops and pests. It is possible that, even without climate change, pest management will face major challenges over the coming decades [5].

Insects react to high temperatures by increasing the rate of growth and development and shortening the time between generations (very high temperatures reduce the lifespan of the insect). Warmer winters reduce insect mortality; consequently,

the insect population will increase in the coming seasons. Warmer temperatures occur earlier in spring and cause the pest population to expand during sensitive stages of plant growth and development. Warmer winter temperatures will affect pests that cannot currently spend winter (do overwintering) in high latitudes, but these insects will spend winter in lower latitudes areas; then, migrate to agricultural fields in spring and summer [67].

As higher temperatures lead to longer growing seasons in temperate regions, this will provide an opportunity to increase insect damage. Prolonging the growing season will allow pest insects to create an extra generation and subsequently increase the pest population [67].

As temperatures rise, there will be a shift in the agroclimatic regions towards the pole, whereby many pathogens will spread into new geographic regions, where they will encounter potential new hosts [68].

Climate change can have various effects on natural enemies of pest species. Today, the effects of climate change on different aspects of pests and diseases activity on the plant growth process has been considered by researchers globally. Vector and pathogenic response to climate change, pathogen-host interaction response to climate change, the impact of climate change on host resistance, climate change and disease management, climate change effects on natural enemies agricultural pests, the distribution of plants, hosts and natural enemies, and the coincidence of enemyhosts are among the topics that have attracted the attention of researchers [69].
