Bottom-up effects of different host plant resistance cultivars on ber (Ziziphus mauritiana)-fruit fly (Carpomyia vesuviana) interactions

The fruit fly, Carpomyia vesuviana Costa (Tephritidae: Diptera) is an important pest of ber (Ziziphus mauritiana L), leading to significant losses in yield in the hot arid agro-climate of India. Variation in resource input (antixenotics and allelochemicals) to plants trigger bottom-up effects on ber-fruit fly interactions. However, variation in plant extrinsic and intrinsic traits in response to resource availability may modify the bottom-up effects. The objectives of this study were to identify and categorize sources of resistance in ber cultivars to C. vesuviana from the arid region of India. We found that: (i) three cultivars were resistant; 13 cultivars were moderately resistant; 6 cultivars were susceptible and three cultivars were highly susceptible to fruit fly infestation; (ii) the phenol, tannin and flavonoid contents had significant negative correlations with percent fruit infestation. The percent fruit infestation had significant positive correlations with fruit length, pulp: stone ratio and had significant negative correlation with pericarp thickness. Pulp texture and fruit surface were found to be hardy and rough, respectively, in resistant cultivars of ber; and (iii) flavonoid and phenols content explained (89%) of the total variation in fruit fly infestation. Two principal components (PCs) were extracted which explained the cumulative variation of 84.7% in fruit fly infestation. PC1 explained 59.9% of the variation while PC2 explained 24.9% of the variation. Growers can adopt the potential resistant cultivars of ber (Tikadi, Katha and Illaichi cultivars) with minimal financial investment to obtain higher yields. Hence, a benefit of resistance cultivars for yield potential is apparent and resistance cultivars can be used as an important component of sustainable management.