Impact of Climate Change on Crop Yield due to Pests and Crop Diseases: Future Projections

Abstract

Climate change has a significant impact on agriculture, including decreased crop yields, invasive crops and pests, and shifting agroecosystem boundaries [1]. As the global population continues to grow, there will be an increase in food demand of 70-100% by 2050, putting pressure on agricultural land. Developing nations reliant on agriculture are particularly vulnerable to climate change and food insecurity. Achieving food security, one of the UN SDG is a significant challenge, and addressing factors threatening the sustainability of agricultural production systems is imperative to mitigate the threat posed by global climate change. Insect pests have a significant impact on major staple crops such as wheat, maize, and rice, but are often overlooked when estimating crop losses due to climate change. Elevated temperatures may result in an increase in insect population and metabolic rate, causing more damage to crops [2]. In tropical regions, the rate of insect growth is expected to decrease while increasing in temperate regions, where species that grow during summers will respond more predictably to climate change. As the earth's temperature rises, it is assumed that insect species will migrate to higher latitudes, expanding their niche [2]. Countries closer to the equator, including India, will experience a significant decline in agricultural productivity due to global temperature change, frequent droughts and floods, soil infertility, and increased insect-pest outbreaks. Agricultural productivity plays a dominant role in India's economy, accounting for nearly 28% of the Gross Domestic Product (GDP) and provides a significant source of income for approximately 58% of its population and the country is more vulnerable to the effects of climate change due to its tropical climate and reliance on the monsoon. Yield losses due to pest infestation can be reduced by timely adoption of remedial measures, and this study investigates the relationship between temperature change and precipitation for pest infestation and crop yield estimation in selected areas, focusing on three-time horizons to forecast the number of pest infestations in the future. On the basis of topography and climatic factors study area was classified into coastal and inland districts (Table 1). The selection of these districts was on the basis of occurrence of infestation by identified pest either continuously or consecutively for years. Also, agriculture is a major contributor to the economy in the study area. Rice and maize (major staple crops) were selected for study on the basis of area of cultivation, consumption patterns, economic contribution and pest vulnerability using data obtained from Department of Agriculture and Farmer Welfare, Ministry of Agriculture and Farmer Welfare, and IARI. The country's crop yield loss due to pest infestation was studied, and the major contributors were identified. Pest identification was done using available data from the selected region and subsequently reduction in crop yield has been investigated. It has been observed that reduction in crop yield for rice was 30-70% from stem borer (Scirpophaga incertulas) and for maize was 30-80% from P. sorghi. Accordingly, most prevalent crop pests were identified for maize and rice where average reduction in crop yield was 50% and 55% for rice and maize respectively. A modelling approach has been used to determine the potential impact of climate change on rice and maize, employing knowledge of environmental conditions and predicted number of incidences of pest infestation (range matrix, Table 2 and 3). The meteorological data during the crop season (1971-2019) from selected regions were obtained from Indian Meteorological Department, New Delhi. The data of daily mean temperature and precipitation was used to calculate seasonal average temperature and precipitation. For the given temperature and precipitation, pest infestation was observed in the study locations. Based on observations, a range matrix was created in which temperature and precipitation ranges were predicted to be responsible for pest infestation in the specific crop for a given season. The data on the pest infestation was correlated with the prevailing climatic parameters i.e., (temperature and precipitation) using the range matrix, which was prepared using the data obtained from IMD for crop season, productivity and area wise production. Finally, future projections were done for three scenarios i.e., Near Time Horizon (2010–2039), Mid Time Horizon (2040–2069), and Far Time Horizon (2070-2099). Future projections for incidences of pest infestation for three-time horizons were predicted. Results indicate that there is a decrease in the number of incidences of pest infestation with time and temperature. In India, increase in temperature will affect the lifecycle of the pest and incidences of pest attack may decrease, this was further validated by correlating global temperature change and tolerance of terrestrial insects in a study. It is found that even a small scale rise in temperature in tropics is expected to have most adverse effects on the tropical pest's population as they are extremely sensitive to temperature changes and their present environment is at or close to their optimal temperature [2,3]. Further, prediction results show that the incidences of pest infestation (yellow stem borer) for rice crop were immensely reduced in Alappuzha (coastal district) and Sambalpur (inland district) for mid and far time horizons however, in case of maize, no pest infestation was predicted for Coimbatore district. The maximum production loss per year was reported from YSR (Kadapa) district followed by Thanjavur and East Godavari where the incidence of pest infestation was comparatively high. The findings of this study can be used to forecast the contribution of new pests and other factors in yield loss, and thus will aid the government in adopting management practices well in advance, preventing or minimizing crop loss. The impact of climate change on diseases and pests of tropical crops to quantify the impacts of climate change on regionally important staple food crops. The study emphasizes the need for further research to remove uncertainties in correlating climate change and pest infestation. Farmers rely on pesticides to minimize crop losses, but this adversely affects human health and environmental sustainability which help in achieving the SDG [4,5]. The use of nanomaterials can help in managing insect pests in agriculture and minimizing yield loss, but their ability to increase crops’ stress tolerance and disease resistance needs further investigation. Future studies should focus on environmental fate and transport of these materials for sustainable use. Details of Coastal and Inland districts. The range matrix of pest- Yellow Stem Borer for rice. The range matrix for the pathogen- P. sorghi for maize. Prediction of incidences of pest infestation for Near, Mid and Far time horizons.

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