Post Infectional Biochemical Changes Induced by Mealybug Paracoccus marginatus (Hemiptera: Pseudococcidae) in Leaves of Superior Seedless Grapes

Mealybug (Paracoccus marginatus) belonging to the family Pseudococcideae, is a devastating pest of grapevine in different parts of the world including India. Due to its piercing sucking type feeding behaviour, it injures the vines mechanically and induces several physiological & biochemical alterations in the host. To evaluate reaction of Superior Seedless to this pathogen, this study was undertaken at Punjab Agricultural University, Ludhiana (Punjab) in 2017. The post infectional alterations were compared in healthy and mealybug infested leaves of grapevines under natural conditions in order to decipher the defense response of the plant. A substantial decrease of 3.38, 3.37, 3.36, 36.84, 10.34, 21.23 and 48.02 percent was recorded in chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, total soluble sugars, total soluble proteins and free amino acid content respectively in mealybug infested leaves compared to healthy ones, while total phenols, ortho-dihydroxy phenols, flavonoids, peroxidase and polyphenol oxidase activity increased by 31.84, 24.20, 21.60, 17.79 and 10.16 per cent, respectively. Hence, mealybug infestation led to sequence of physiological and biochemical alterations in the host plant.