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Mealey bug (Maconellicoccus hirsutus) is a serious pest of Terminalia arjuna which is the primary food for Tropical tasar silkworm Anthereae Mylitta Drury. It attacks the leaves of the host plant causing considerable damage which alters the leaf quality. An attempt was made to know the changes in the Biochemical components (Total soluble proteins, free amino acids, total reducing sugars, total soluble sugars),secondary metabolites(Starch, Phenols, Phytic acid, Acid detergent fibre) and photosynthetic pigments (total chlorophyll,chlorophyll– a,chlorophyll – b and carotenoids) in Terminalia leaves under infestation by Mealey bug. The results revealed that total soluble proteins and total soluble sugars increased by 17.8% and 31.28% while free amino acids and total reducing sugars were decreased by 38% and 64.97%.Total chlorophyll, chlorophyll– a, and chlorophyll– b were reduced significantly as 45.38,45.95 and 41.94% respectively. The results also show a drastic reduction (44.9%) in the carotenoid content. The experimental results on quantitative estimation of secondary metabolites in mealey bug infestation showed significant increase (45.95%) in ADF and starch(59.5%) whereas phytic acid and phenols were reduced by 18.53 and 46.5% respectively.
Biochemical components, secondary metabolites, photosynthetic pigments, Mealy bug, Terminalia arjuna
Terminalia arjuna is the primary host plant of the Tropical Tasar silkworm Anthereae mylitta drury in commercial sericulture. Silkworms feed on leaves during their entire larval period and utilize the leaf metabolites for the biosynthesis of silk. It is therefore clear that host plant plays a dominant role in cocoon production as a source of nutrition to the silkworms. However, foliage is prone to depredation by disease causing organism such as pathogens and pests. Among the several pests known to attack Tasar plants Mealy bug (Maconellicoccus hirsutus) has attained a serious status. It has long been recognized that levels of proteins and carbohydrates in plants have significantly influenced by infection and metabolism alters accordingly by the rate of infection . Increase in protein concenteration was noted in the various tissues infected with root knot nematodes .An elevated protein levels was also observed in giant cells of okra infected with M.incognita acrita . A significant increase in the total sugars and decrease in total reducing sugars of M5 mulberry leaves due to leaf roller infestation and mealy bug infection in hibiscus had been reported [4,5]. Decrease in the secondary metabolites like phenols and phytic acid and increase in starch and ADF (acid detergent fibre) has reported [6, 7] observed a combined loss of total chlorophyll and carotenoids in the thrips – infested mulberry leaves. So the present experiment has taken up to identify the levels of primary, secondary metabolites and photosynthetic pigments in mealybug infected Terminalia arjuna a primary host plant of Tasar silk worm Anthereae mylitta drury.
Thus in conclusion, mealey bug infection in Terminalia arjuna decreased significantly the components like aminoacids, total reducing sugars, phenols, phyticacid, total chlorophyll-a, chlorophyll-b and carotenoids whereas total soluble proteins, total soluble sugars, starch and ADF (acid detergent fibre) were increased profoundly.
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