Biochemical properties of digestive carbohydrases and proteases of cereal leaf beetle, Lema melanopa (Coleoptera: Chrysomelidae)

In the recent decade, Lema melanopa L. has become one of the most important pests of wheat fields in Golstan province. Both adults and larvae of this pest feed on the leaves of most cereals and of course wheat and cause severe damage. Due to the lack of information about the physiology of this pest, in the present study, the biochemical properties of alpha amylase, glucosidase, galactosidase and gastrointestinal proteases from adult stage of this pest were investigated. The results showed that the highest level of optimal enzyme activity was observed in the range of 4 to 6 and the optimum temperature of 35 ° C. Electrophoresis showed two isoforms of alpha-amylase in the gut of the insect. The maximum activity of alpha and beta glucosidase enzymes and alpha and beta galactosidase of the gut was obtained in acidity 5 and in the temperature range of 35 to 45°C, respectively. The highest general protease activity was shown among gut proteases at pH 6 and at 45°C. Study Results of the effect of enzymatic inhibitors including EDTA, TLCK, TPCK, PMSF, sodium Iodo Acetate and Iodoacetic acid protease activity showed that cysteine proteinase inhibitors had the greatest inhibitory effect on enzyme activity. Therefore, it can be concluded that this group of proteases is dominant in the gut of cereal leaf beetle. By determining the biochemical properties of important gut enzymes of pest, compounds can be synthesized that are more efficient and reduce the consumption of insecticides and reduce the amount of damage to the environment.