Modelling current and future suitable cultivation areas of cashew trees in Benin (West Africa) based on the major parasite and its parasitoid distribution under global climate warming

Abstract

The cashew tree is an essential source of income in West African households, especially in Benin. However, it faces declining productivity due to parasites and climate change. The insect Oecophylla longinoda (Latreille) is commonly used to control the cashew pest Helopeltis schoutedeni Reuter.; however, how climate change affects their distribution and how this can be used to identify suitable cashew cultivation areas remains a challenge. For this purpose, we used machine learning to identify suitable areas for cashew cultivation in Benin, considering occurrence points and environmental factors that limit the distribution of cashew trees, the pest, and the beneficial insect. Globally, models performed well, with mean values of the area under the curve ranging from 0.76 to 0.97 and mean values of the true skill statistics ranging from 0.44 to 0.85. Both precipitation seasonality and isothermality influenced the spatial distribution of cashew trees in Benin; while the mean temperature of the warmest months and annual precipitation determined the distribution of H. schoutedeni. As for O. longinoda, the precipitation of the driest quarter and wind speed determined its distribution. Suitable areas for cashew cultivation in current conditions were mainly concentrated in the agricultural development pole 4 (ATDA 4), encompassing the municipalities of Savalou, Bassila, Bantè, Glazoué, Tchaourou, Ouèssè, Savè, Dassa, and Parakou. These suitable areas are expected to decrease by 15.16–28.47 % by 2070, with a shift towards the south, especially in agricultural development pole 5 (ATDA 5) and 7 (ATDA 7) under ssp245 and ssp585. These findings are relevant for decision-makers in the medium and long-term targeting of suitable cultivation areas of cashew trees in Benin.