digestive amylase and glucosidases in the larval stage of elm leaf beetle, xanthogaleruca luteola (col.: chrysomelidae)

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.