Influence of climate on desert locust (Schistocerca gregaria Forskål, 1775) plague and migration prediction in tropics

The study aims to assess the suitability and likelihood of the desert locust epidemic occurring in India, motivated by the outbreak of Schistocerca gregaria which originated from the Horn of Africa in 2019–2020 and created an episodic plague in the arid and semi-arid areas of South and Southwest Asia, resulting in hundreds of crores in crop damage after twenty-seven years of absence in India. Utilizing two widely recognized statistical models, Weight-of-Evidence (WoE) and Frequency Ratio (FR), the research evaluated nine critical climatic factors across the western and central parts of India. The Projected Locust Suitability (PLS) was calculated by analyzing the correlation of the considered variables and the occurrence of locust swarms and bands, with the significance of each variable determined using Principal Component Analysis (PCA) and Random Forest (RF) algorithms.

The findings demonstrate that 42.7–52.8% of the studied areas fall under high and very high locust suitability zones, with the Ajmer-Gwalior-Allahabad tract identified as highly prone to future locust occurrences and the Aligarh-Bareilly-Lakhimpur tract as moderately susceptible. The effectiveness of both modeled PLS maps was validated through ROC curve analysis, with AUC results indicating that both the WoE (0.92) and RF (0.90) models performed remarkably well in precisely predicting locust suitability. Furthermore, RF-based IncNodePurity analysis reveals that low to moderate temperatures in the presence of cloud cover significantly impact locust occurrence and migration, with the present findings projected to direct the development of sustainable locust management strategies utilizing proper land use policies in the tropical climate.