Relation of allelochemicals and nutritive value of mango cultivars Mangifera indica to infestation with the scale insect Aulacaspis tubercularis (Hemiptera: Diaspididae)

Abstract

The effect of mango (Mangifera indica L.) chemical composition of different cultivars (Keitt, Fagriklan, and Alphonso) on the infestation level with the white mango scale insect Aulacaspis tubercularis (Newstead) (Hemiptera: Diaspididae) was evaluated. The highest seasonal abundance of A. tubercularis was recorded on 1^st May. The number of insects of different instars (Nymph, adult, and gravid) that infested mango leaves were 1200, 748, and 630 individuals/25 leaves for Keitt, Fagriklan, and Alphonso, respectively. Mango cultivars' susceptibility levels could be grouped in the following way: Keitt>Fagriklan>Alphonso. The lowest abundance occurred during mid-January for different cultivars. Analysis of fresh leaf composition on 1^st May revealed that A. tubercularis numbers that infested mango leaves had a strong positive correlation with leaf protein (r= +0.997), Nitrogen (N) (r= +0.994) and Potassium (K) (r= +0.999). On the contrary, it had a high negative correlation with terpenoids (r= -0.949), and a medium negative correlation (r= -0.442) with carbohydrates. Phosphorus (P), allelochemicals such as phenols, and flavonoids showed a weak negative correlation. Variations in chemical content among different mango cultivars were also discussed. It can be concluded that nutritive components and some allelochemicals of mango leaves may play a significant role in the susceptibility of mango leaf cultivars to infestation with the white mango scale insect, A. tubercularis.