CARBOHYDRASES IN THE DIGESTIVE SYSTEM OF THE SPINED SOLDIER BUG, Podisus maculiventris (SAY) (HEMIPTERA: PENTATOMIDAE)

Abstract

The spined soldier bug, Podisus maculiventris, is a generalist predator of insects and has been used in biological control. However, information on the digestion of food in this insect is lacking. Therefore, we have studied the digestive system in P. maculiventris, and further characterized carbohydrases in the digestive tract. The midgut of all developmental stages was composed of anterior, median, and posterior regions. The volumes of the anterior midgut decreased and the median midgut increased in older instars and adults, suggesting a more important role of the median midgut in food digestion. However, carbohydrase activities were predominant in the anterior midgut. In comparing the specific activity of carbohydrases, α-amylase activity was more in the salivary glands (with two distinct activity bands in zymograms), and glucosidase and galactosidase activities were more in the midgut. Salivary α-amylases were detected in the prey hemolymph, demonstrating the role of these enzymes in extra-oral digestion. However, the catalytic efficiency of midgut α-amylase activity was approximately twofold more than that of the salivary gland enzymes, and was more efficient in digesting soluble starch than glycogen. Midgut α-amylases were developmentally regulated, as one isoform was found in first instar compared to three isoforms in fifth instar nymphs. Starvation significantly affected carbohydrase activities in the midgut, and acarbose inhibited α-amylases from both the salivary glands and midgut in vitro and in vivo. The structural diversity and developmental regulation of carbohydrases in the digestive system of P. maculiventris demonstrate the importance of these enzymes in extra-oral and intra-tract digestion, and may explain the capability of the hemipteran to utilize diverse food sources.

Impact of carbohydrase inhibition on Habrobracon hebetor in a tritrophic diet‐host‐parasitoid system

“…() investigated the inhibitory potential of acarbose on some bruchid beetles and several species of parasitic wasps, and found a greater ability of acarbose to inhibit α‐amylase activity compared to α‐amylase inhibitor taken from wheat. High sensitivity of amylase from the bruchid Zabrotes subfasciatus (Boheman) (Grossi de Sa et al., ), the bug Podisus maculiventris (Say) (Ghamari et al., ), and the weevil Sitophilus zeamais Motschulsky (Lopes et al., ) to the inhibitor has been also reported. In our previous study we found high inhibitory potential of acarbose on α‐amylase activity, as well as effects of acarbose on weight, size, and physiological and biological parameters of P. interpunctella (Masoumzadeh et al., ).…”

“…Impacts of pH were determined according to Ghamari et al. () with slight modifications. The effect of pH was determined with a universal buffer (40 mM citrate‐phosphate‐borate, pH 3‐8).…”

“…The reaction mixture was heated in boiling water for 10 min, and the absorbance was measured at k = 540 nm. Impacts of pH were determined according to Ghamari et al (2014) with slight modifications. The effect of pH was determined with a universal buffer (40 mM citrate-phosphate-borate, pH 3-8).…”

“…Enzyme inhibitors such as α‐amylase inhibitors are appropriate candidates for protection of plants and their products against damage by herbivorous and granivorous insects (Gatehouse, ). The non‐proteinaceous α‐amylase inhibitor acarbose is known for its inhibitory effect on the carbohydrases of herbivorous and carnivorous insects (Hubert et al., ; Kaufnerová et al., ; Ghamari et al., ; Masoumzadeh et al., ). Acarbose is an anti‐diabetic drug that is obtained from fermentation processes of the microorganism Actinoplanes utahensis Couch (Wang et al., ).…”

Digestive Hydrolases of Wheat Bugs: Properties, Significance and Possible Ways to Limit Their Activity

“…растительноядных насекомых, α-амилазы входят в число наиболее важных пищеварительных гидролаз (Da Lage, 2018). У насекомых, включая клопов, как и у других животных, геном, как правило, содержит несколько вариантов генов α-амилаз, что предположительно расширяет возможности утилизации разных форм крахмала в различных условиях (Da Lage et al, 2002;Da Lage, 2018;Ghamari et al, 2014). В целом, α-амилазы насекомых по структуре близки α-амилазам других животных и объединены в подсемейство гликозилгидролаз GH13_15 совместно с аналогичными ферментами других беспозвоночных (Stam et al, 2006).…”