Physico-biochemical characteristics of two cashew accessions: susceptibility to the wood borer, <i>Apate terebrans</i> (Coleoptera: Bostrichidae), a major insect pest of this crop in West Africa

Abstract Apate terebrans (Pallas, 1772) is a wood borer that considerably limits the productivity of cashew trees ( Anacardium occidentale Linnaeus, 1753) in West Africa, particularly in Côte d’Ivoire. Systemic chemical control is the main method of controlling this pest. This study aimed to identifying if a cashew accession is less susceptible to A. terebrans . Specifically, infestation rates, agro-morphological and biochemical characteristics of the two most grown cashew accessions, including ‘yellow apple (YA)’ and ‘red apple (RA)’ were assessed under natural conditions. Apate terebrans infestations were assessed monthly on 1924 cashew plants during two production seasons (i.e. 24 months of sampling) in the north-east of Côte d'Ivoire. Agro-morphological characterization of the fruit and analyses of primary compounds and secondary metabolites of cashew bark were carried out. The occurrence of the YA accession in the study sites (54–57%) was significantly higher than RA accession (43–46%) ( P &lt; 0.001). The mean cashew nut weight of accession YA (6.62 ± 1.23 g) was significantly higher than that of accession RA (6.11 ± 1.49 g) ( P &lt; 0.001). However, the average infestation rate of accession RA (4.18%) was significantly lower than that of accession YA (6.58%) ( P = 0.02). Accession RA was lower in primary compounds, but its content of secondary metabolites, polyphenols, flavonoids and tannins was significantly higher than YA accession ( P &lt; 0.01). By highlighting the variability in physico-biochemical characteristics and susceptibility to A. terebrans of RA and YA cashew accessions, this study provides avenues for future varietal selection with a view to sustainably improving cashew tree productivity. Significance of the study What is already known on this subject? In West Africa, Apate terebrans considerably affects the productivity of cashew trees, which are a crop of socio-economic interest. Several cashew accessions coexist in the orchards, but little is known about their physical and biochemical characteristics and their susceptibility to insect pests. What are the new findings? The two cashew accessions studied, the ‘yellow apple’ and the ‘red apple’, showed significant differences in their physical and biochemical characteristics and in their susceptibility to A. terebrans . The fruits of the ‘yellow apple (YA)’ accession were the largest, with a higher weight. This accession was the most abundant in the orchards. However, the ‘YA’ accession was the least attacked by A. terebrans . These levels of primary compounds (nutrients for the pest) and secondary metabolites (toxins against the pest) were lower and higher, respectively. What are the expected impacts on horticulture? This knowledge will help inform decision-making for developing improved pest-resistant cashew varieties, with the aim of improving cashew tree productivity.