Abstract
The stem borer Apate terebrans is a pest of tropical regions that considerably limits the production of cashew tree, an important crop for climate change adaptation. This study assessed the effects of cashew tree density on the damage of A. terebrans, for the effective and sustainable management of this insect pest. The density was characterised by the quadrat method in 10 orchards in the localities of Bondoukou and Bouna, in the north-east of Côte d'Ivoire. Based on systematic sampling, monthly counts of A. terebrans infestations were conducted on 1924 cashew trees from July 2018 to June 2020. Temperature and hygrometry were recorded over this period. In Bondoukou, an average density of 515 ± 235.5 cashew trees/ha was recorded, with a coefficient of variation (CV) of 58.64%. This density was significantly higher than that of Bouna (235 ± 39.6 cashew trees/ha), which showed low heterogeneity (CV = 29.44%). Temperature was higher in Bouna than in Bondoukou and vice versa for hygrometry. Linear regression showed a moderate and significant relationship between cashew tree density and damage, mainly in the locality with high spatial heterogeneity (i.e. Bondoukou). Thus, a high density reduces damage. The Morisita and Blackman indices indicated a distribution of damage that tended to be aggregated in Bondoukou and random in Bouna. By establishing the implication of cashew tree density in the control of A. terebrans damage, this work provides perspectives for the landscaping of cashew orchards, with a view to natural control of this pest.