Cellular energy allocation of pistachio green stink bug, Brachynema germari Kol. (Hemiptera.: Pentatomidae) in relation to juvenoid pyriproxyfen

The purpose of this study is to determine the effects of pyriproxyfen (an insect growth regulator compound) on cellular energy allocation of a heterometabolous insect, Brachynema germari Kol. The fifth instar of this insect was treated with 0, 20, 60, 100, 200 and 500 mg l-1 formulation of pyriproxyfen (Admiral 10EC) and the amount of energy available (Ea), energy consumption (Ec) and cellular energy allocation (CEA) were compared. The resulting calculated energy reserves (carbohydrate, glycogen, lipid and protein) showed that total lipid amount varied significantly among doses and between each dose and control. Lipid amounts fell as doses grew to 200 mg l-1 and then increased. A significant difference was observed in total carbohydrate between each dose and control (P < 0.05); however there were no significant differences among doses. The amount of glycogen and total protein and also the amount of energy consumption did not differ significantly from control. Study results showed that pyriproxyfen at low concentrations, raised cellular energy allocation but decreased it at high concentrations.Keywords: Pyriproxyfen, Brachynema germari, cellular energy allocation, lipid, glycogen, proteinAfrican Journal of Biotechnology Vol. 9(35), pp. 5746-5753, 30 August, 201

Biochemical properties of digestive carbohydrases from the sugar beet weevil, Lixus incanescens (Coleoptera: Curculionidae)

The sugar beet weevil, Lixus incanescens B., is one of the most important pests of sugar beet plant in Iran. The petioles and leaves of sugar beet are attacked by larvae and adults of the sugar beet weevil. Chemical application is currently used for controlling the pest. Digestion in the alimentary canal of the sugar beet weevil is facilitated by some carbohydrases. Results of the in vitro studies indicated the presence of alpha-amylase, beta-glucosidase and beta-galactosidase in the digestive tract of the pest. Highest activities of alpha-amylase, beta-glucosidase and beta-galactosidase were at pH 5, pH 5 and pH 4, respectively. No significant alpha-glucosidase and alpha-galactosidase activity was detected in the pest's digestive system. Optimum temperatures for alpha-amylase, beta-glucosidase and beta-galactosidase activity were determined at 45, 50 and 40 oC, respectively. alpha-amylase was more stable under acidic condition (pH 4 to pH 6) than under highly acidic and alkaline condition. Na+ and K+ increased alpha-amylase activity, but sodium dodecyl sulfate significantly decreased amylase activity. Also, the activity of alpha-amylase was inhibited by the other compounds such as MgCl2, CaCl2 and EDTA. Zymogram analysis using native-PAGE revealed one band of alpha-amylase activity in Lixus incanescens. High activity of carbohydrases in the digestive system of adults was determined and further researches are needed to be applied to design new strategies for controlling the sugar beet weevil based on natural carbohydrase inhibitors

Digestive Proteolytic Activity in the Sunn Pest, Eurygaster integriceps

The Sunn pest, Eurygaster integriceps Puton (Heteroptera: Scutelleridae), is one of the most important pests of wheat and causes considerable damage to this valuable crop annually. Digestive proteinase activity of adult insects was investigated using general and specific substrates and inhibitors. Proteolytic activity was low when the common conventional substrates, azoalbumin, azocasein and hemoglobin were used to assay salivary glands and midguts. Using the fluorescent casein substrate (BODIPY FL casein), total proteolytic activity was measured at different pH. Maximum proteolytic activity was detected at pH 7 (100%) and 8(65%) which suggested the presence of serine proteinases in the salivary glands. There was no detectable proteolytic activity in midgut extracts. The inhibitors; PMSF (inhibitor of serine proteinases) and TPCK (a specific chymotrypsin inhibitor) showed greater than 50% inhibitory effect on total proteolytic activity, however, TLCK (specific trypsin inhibitor) and E-64(specific cysteine proteinase inhibitor) did not inhibit total proteolytic activity. Using fluorescent specific substrates for serine and cysteine proteinases (Z-Arg-AMC, Z-Arg-Arg-AMC, Z-Arg-Phe-AMC and Suc-Ala-Ala-Pro-Phe-AMZ) revealed the presence of tryptic and chymotryptic activity in the salivary gland extract. Zymogram analysis under non-reducing SDS-PAGE conditions and using the substrate APNE showed at least 8 tryptic and chymotryptic activity bands in salivary gland extracts. A single high molecular weight band with tryptic activity (165 kDa) was detected using the substrate BApNA in a zymogram analysis uisng native-PAGE. Kinetic studies showed a km value of 0.6 mM for this enzyme against the substrate BApNA .The inhibitor TLCK decreased activity of the trypsin-like enzyme up to 73% and almost completely eliminated the only band related to this proteinase in the zymogram. Soybean Kunitz type trypsin inhibitor showed no effect on proteolytic activity of the trypsin-like serine proteinase. In general, the results revealed the presence of chymotrypsin- and trypsin-like serine proteinases in the salivary gland of E. integriceps, and it seems that the major total proteolytic activity is due to chymotrypsin proteinases

Genetic diversity of six isolated populations of the leopard moth, Zeuzera pyrina (Lep: Zeuzeridae)

The leopard moth, Zeuzera pyrina (Lep: Zeuzeridae), is an important pest of a wide range of trees and shrubs including walnut and apple across the world. The natural populations of the leopard moth in different geographical areas of Iran show significant differences in some of their biological characteristics such as time of emergence, generation time and host specificity. So, we hypothesized that these populations may represent different subspecies that move toward a speciation event in their evolutionary route. In this study, we evaluated the genetic diversity of six different geographically isolated populations of the leopard moth using the sequence alignment of cytochrome oxidase c subunit one (COI). A fragment of 642 base pairs was amplified in all six populations and the phylogenetic tree was created based on sequenced fragments. Our results revealed significant differences in the nucleotide sequence of COI gene in these populations. Differences in climatic conditions of these regions seem to be the most powerful force driving this diversity among the studied populations

Effect of proline as a nutrient on hypopharyngeal glands during development of Apis mellifera (Hymenoptera: Apidae)

Proline is known to be an energy source for protein synthesis and appears to have a major role in insect flying metabolism. Insects can detect proline in their food and use it as an energy substrate to start flight and other high energy consuming activities. Honey bee has a feeding preference for nectars with higher concentrations of this amino acid. In this research we present evidence that L-proline can be utilized as a phagostimulant for the honeybee worker (Apis mellifera). We reported the L-proline increase hypopharyngeal glands acini diameter and syrup consumption at the experimental cage. Honeybee workers fed on 1000 ppm treatment prolin consumed 773.9±31.8 ul/bee after 18-days. It is obvious that the honeybee workers consumed 1000 ppm the more than other treatment. The feeding decreased when concentration of L-proline increased to 10000 ppm. The hypopharyngeal glands development increased gradually from honeybee workers emergence and started to decrease after 9 days old. The maximum acini diameter (0.1439±0.001 mm) was recorded in the 9th day when newly emerged bees were fed on 1000 ppm proline syrup

Enzymatic activity of α-amylase in alimentary tract Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae): Characterization and Compartmentalization

The Egyptian cotton leafworm, Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) damages a wide variety of crops in Middle East. Their hosts include cotton, alfalfa, eggplant, tomato, lettuce, bean and some ornamental crops. The intensive use of broad-spectrum insecticides against S. littoralis has led to the development of resistance to many registered pesticides use for its control. The purpose of the present study is biochemical characterization of digestive enzymes of this pest to gain a better understanding of the digestive physiology. The physiology and biochemistry of the insect digestive enzyme had an important role in the study of novel insecticidal strategies. The Egyptian cotton leafworm alimentary canal consists of a short foregut, a long midgut and a short hindgut. Application of pH indicators showed that alimentary canal was alkaline. Our results showed that activities of gut α-amylase were different in three parts of the insect gut. Also shown the greatest activity of α-amylase observed in the midgut followed by hindgut and foregut, respectively. However, there were not significant differences in activity of the enzyme in the midgut and hindgut. The optimal pH α-amylase in foregut, midgut and hindgut were 10.0. Zymogram analysis of different part of gut showed four bands in midgut, hind gut and two bands in foregut. Therefore, in midgut of S. littoralis, four isoenzymes were present. These results explain why more amylase activity was seen in these regions in the spectrophotometric assay

Some Brain Peptides Regulating the Secretion of Digestive Enzymes in the Indian Meal Moth, Plodia Interpunctella (Lepidoptera: Pyralidae)

The Indian meal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) is a destructive polyphagous pest of many stored products. To interfere with the physiological processes, especially digestion, of the larval pest, more information on the regulatory mechanisms is needed. The brain extract from 1-day-old last instar larvae of P. interpunctella was examined. In the bioassays, the midguts were treated with the brain extract, and the carbohydrase and protease activities were measured. The brain extract showed increasing dose-dependent effects on α-amylase, α-glucosidase, β-glucosidase, α-galactosidase, β-galactosidase, and trypsin secretion in the larval midgut. The extract was further characterised and partially purified using high performance liquid chromatography (HPLC). Several peptides were determined in the brain extract regulating hydrolase activities in the larval midgut of the pest

Some Brain Peptides Regulating the Secretion of Digestive Enzymes in the Indian Meal Moth, Plodia Interpunctella (Lepidoptera: Pyralidae)

The Indian meal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) is a destructive polyphagous pest of many stored products. To interfere with the physiological processes, especially digestion, of the larval pest, more information on the regulatory mechanisms is needed. The brain extract from 1-day-old last instar larvae of P. interpunctella was examined. In the bioassays, the midguts were treated with the brain extract, and the carbohydrase and protease activities were measured. The brain extract showed increasing dose-dependent effects on α-amylase, α-glucosidase, β-glucosidase, α-galactosidase, β-galactosidase, and trypsin secretion in the larval midgut. The extract was further characterised and partially purified using high performance liquid chromatography (HPLC). Several peptides were determined in the brain extract regulating hydrolase activities in the larval midgut of the pest