Digestive Amylase and Glucosidases in the Larval Stage  of Elm Leaf  Beetle, Xanthogaleruca Luteola  (Col.: Chrysomelidae)

Vatan Parast, Mohammad; Hosseini Naveh, Vahid; Sajadian, Minoo

doi:10.22059/ijpps.2013.30249

Digestive Amylase and Glucosidases in the Larval Stage of Elm Leaf Beetle, Xanthogaleruca Luteola (Col.: Chrysomelidae)

Authors

mohammad vatan parast

vahid hosseini naveh

minoo sajadian

10.22059/ijpps.2013.30249

Abstract

Elm leaf beetle, Xanthogaleruca luteola, is a serious pest (particularly at its larval stage) of elm trees in many areas. The existence of three important enzyms namely: ?-amylase, ?- glucosidase and ?-glucosidase in the midgut of the insect at its larval stage was investigated. Optimum activity for ?-, ?-glucosidase and ?-amylase was recorded at pHs 5.0, 6.0 and 6.0 against p-nitrophenyl-?-D-glucopyranoside, p-nitrophenyl-?-D-glucopyranoside and starch respectively. ? and ?-glucosidase exhibited more stability at pHs 4.0-6.0 than at either highly acidic or and alkaline pHs. These enzymes were respectively more stable at pH 5.0 and 6.0 with increased incubation time. ? -amylase was stable at pHs 4.0-8.0. ? and ?-glucosidase and also ?-amylase, when incubated at different temperatures were found to be maximally active at 45, 60 and 40°C, respectively. Alpha- glucosidase activity significantly decreased in the presence of Ca2+ and Mg2+. On the contrary, the ions K+ and Na+ did not significantly affect the enzyme’s activity. The ions K+, Mg2+ and Na+ did not significantly affect the enzyme activity. Zymogram analysis revealed the presence of one band each of amylase, ?- and ?-glucosidase activity in the insect’s larval midgut extract.

Keywords

Carbohydrase

Digestive

Xanthogaleruca luteola