Habitat Suitability Modelling of Desert Locust Breeding Locations in East Africa.

Abstract:

The desert locust Schistocerca gregaria, is one of the short-horned grasshoppers’ species that can migrate great distances during its gregarious phase in search of vegetation. The horn of Africa has recently experienced an unprecedented invasion of huge swarms of desert locusts that has never been witnessed in past 70 years. In the present study, we accessed a historical desert locust hoppers and bands occurrence dataset that had been consistently collected by the Food and Agriculture organization (FAO) of the United Nations for the last 30 years in three countries viz., Morocco, Mauritania, and Saudi Arabia. Then we applied an ecological niche machine-learning modelling algorithm (i.e. MaxEnt) to predict the suitable areas for oviposition and breeding of desert locusts in Kenya, Uganda, South Sudan, and Sudan. Our model utilized key climatic (temperature and rainfall) and edaphic (sand and moisture contents) variables that have been reported to influence the breeding of locusts as predictor features. The performance of the models was validated using the area under the curve (AUC) of the receiver operating characteristic curve (ROC) with 30% independent test data out of 5406 historical records that were accessed. Descriptive statistics were also generated from the model outputs to identify the projected models that better captured the desert locust occurrence records in the country of projection. In addition, we performed a comparative analysis of the projected desert locust breeding suitability using geo-referenced desert locust observations surveys in Kenya and Sudan. The variability in the on-set of vegetation, which is a proxy for suitable desert locust breeding locations was also assessed in the test countries using a 10-day greenness index dataset. The results showed high models’ performance for predicting desert locust breeding locations, with AUC ranging between 0.8 and 0.9. The study reveals that vast areas of Kenya, Sudan, north eastern regions of Uganda, and south eastern and northern regions of South Sudan have the conductive environmental conditions to support the oviposition and breeding of desert locusts. Our study provides information for preparedness and prioritization of ground surveillance on desert locust breeding and deployment of best-bet solutions for effective management of the pest.