Ohseok Kwon

Biochemical characterization of digestive α-d-glucosidase and β-d-glucosidase from labial glands and midgut of wheat bug Eurygaster maura (Hemiptera: Scutelleridae)

The wheat bug Eurygaster maura (Hemiptera: Scutelleridae) is a potential pest of wheat and barley in Iran and other countries. Two major digestive enzymes of this insect, α‐d‐glucosidase and β‐d‐glucosidase, have been investigated. The midgut has four distinct regions including the first ventriculus (V1), second ventriculus (V2), third ventriculus (V3) and fourth ventriculus (V4). The study showed that the first three regions of the wheat bug midgut were acidic (pH 5.5–6), the fourth region of the midgut and hindgut pH were slightly acidic (pH 6.5–6.9) and the salivary gland (labial gland) pH was determined to be somewhat acidic (pH 5–5.5). Enzyme assay showed that α‐ and β‐glucosidase activity is present in both midgut and salivary glands of adult E. maura. The specific activities of midgut α‐ and β‐glucosidase were 11.2 and 10.8 mU/mg protein, respectively. The specific activities of these enzymes in salivary glands were 3.06 and 2.73 mU/mg protein, respectively. Optimum temperature and pH values for glucosidases were determined to be 30–35°C and 5, respectively. Glucosidases of the midgut were more stable than salivary glucosidases at 35°C. Evaluating enzymatic kinetic parameters showed that glucosidases of the midgut had more affinity as well as more velocity than that of salivary glands.

Fidelity of Hymenoptera and Diptera pollinators in onion (Allium cepa L.) pollination

Onion (Allium cepa L.) is protandrous in nature and requires cross‐pollination to avoid inbreeding. The pollination potential of native bees (Hymenoptera) and true flies (Diptera) was assessed in the perspective of finding the best pollinators for onion cross‐pollination and seed multiplication. The community of pollinators was composed of four bee species and twelve true fly species. Episyrphus balteatus, Eupeodes sp., Musca domestica and Eristalinus aeneus were the most abundant pollinators. The maximum pollinator activity was observed from 12 to 24 days after opening of the flowers. The pollination effectiveness of tested bees (Apis dorsata and Apis florea) was greater than true flies (E. balteatus, Eupeodes sp., M. domestica, E. aeneus and Callihoridae sp.) in terms of Spears values.

Effect of different diets on larval growth of Protaetia brevitarsis seulensis (Kolbe) (Coleoptera: Cetoniidae)

The white‐spotted flower chafer, Protaetia brevitarsis seulensis (Kolbe), is used as an important source of medicinal properties, such as anti‐cancer activity and prevention of liver‐related diseases, in Korea. To use this insect species without endangering wild populations, a mass rearing technique is needed. The present study was carried out to determine whether different diets can affect the larval growth of P. brevitarsis seulensis. Six different diets were investigated in the experiment, and the results showed that 20% rice straw with 80% oakwood sawdust was the best diet for larval growth of this beetle.

Evaluation of nutritional status of an edible grasshopper, Oxya Chinensis Formosana

This study was conducted to examine the nutritional status of the grasshopper (Oxya chinensis formosana, OCF) as human food, exploring it as an alternative edible resource. Analysis of free amino acid shows that there are various essential amino acids in addition to saturated and unsaturated fatty acids in OCF dried powder. Analysis of the mineral contents and vitamins of dried OCF indicates that it is rich in calcium, vitamin B6, and niacin. The heavy metal content of OCF recorded was low, making it safe for human consumption: OCF had plumbum at 0.01–0.03 mg/100 g, cadmium at 0.002–0.005 mg/100 g, arsenic at 0.07–0.17 mg/100 g, and mercury at 0.0003–0.0007 mg/100 g. In conclusion, given its high nutritive quality in terms of proteins and fats, coupled with lower heavy metal content, it would be recommended to use the grasshopper (OCF) as substitute to the traditional sources of protein.

A new record of Tanysphyrus (Tanysphyroides) major Roelofs (Coleoptera: Curculionidae) from Korea

The species Tanysphyrus (Tanysphyroides) major Roelofs is recorded for the first time from Korea. This paper reports the diagnostic characters, and some remarks on its systematics and notes on its biology are also provided.

Comparison of glutathione S-transferase and general esterase in two bugs, Eurygaster integriceps Puton (Heteroptera: Scutelleridae) and Brachynema germari Kolenati (Heteroptera: Pentatomidae)

Glutathione S‐transferases (GSTs) and general esterases play important roles in the detoxification of many substances including allelochemicals from plants and chemical pesticides. In this study, to determine the feeding status and effects of agronomical practices on GST and general esterase, two bug species, Eurygaster integriceps and Brachynema germari, were selected with differences in these cases. GST and general esterase responses varied when switching from 1‐chloro‐2,4‐dinitrobenzene (CDNB) and α‐naphtyl to 1,2‐dichloro‐4‐nitro‐benzene (DCNB) and β‐naphtyl in E. integriceps and B. germari, respectively. The activities of GST and esterase by using CDNB and α‐naphtyl were higher than that of DCNB and β‐naphtyl for both insects. It was shown that the optimal pH for GST and general esterase activity varied between pH 5.5 and 6. While the Michaelis constant (Km) value related to E. integriceps toward CDNB and α‐naphtyl was lower than Km for B. germari, Km values calculated for E. integriceps toward DCNB and β‐naphtyl corresponding to those related to A. hejeri were similar to CDNB and α‐naphtyl values. The maximal reaction velocity (Vmax) values related to E. integriceps for both substrates (CDNB and α‐naphtyl) were always higher than those from B. germari and showed significant differences. At the basement of the native‐PAGE electrophoresis, five bands were observed in for GST and three were visualized for B. germari, with a large, darker band for E. integriceps in the case of esterases. Studies on the detoxification enzymes of herbivores should be undertaken to determine accurately the effect of the host plants on the organisms eating them, particularly in terms of biochemical and ecological advantages.

Effects of added nitrogen on leaf nitrogen concentration and population dynamics of insects associated with Rumex obtusifolius L.

A series of experiments was designed to study the effects of changes in leaf nitrogen (N) concentration on population dynamics of a range of insects associated with Rumex obtusifolius. During the study period, the N concentration in leaves fluctuated between 2 and 6% dry weight. The insects at both study sites showed a pattern of shift in time for peak population density (time‐shift). This suggests that the insect community dynamics might be closely related to the allocation and distribution of resources by the host‐plant. The elevated N concentration in the host‐plant did not change the temporal order of the peak population densities of the insects, although it may determine the time for the optimal exploitation of resources by each insect species.

Effects of fermented aloe vera mixed diet on larval growth of Protaetia brevitarsis seulensis (Kolbe) (coleopteran:Cetoniidae) and protective effects of its extract against CCl4‐induced hepatotoxicity in Sprague–Dawley rats

The present study was conducted to evaluate the efficacy of fermented aloe vera mixed diet on larval growth of Protaetia brevitarsis seulensis (Kolbe) (coleopteran: Cetoniidae) and protective effects of extract of larvae of P. brevitarsis seulensis fed fermented aloe vera mixed diet against Carbon tetrachloride (CCl4)‐induced hepatotoxicity in Sprague–Dawley rats. To determine whether different diets can affect the larval growth of P. brevitarsis seulensis, six different diets were investigated in the experiment, and the results exhibited that 15% fermented aloe vera with 85% fermented oakwood sawdust was the best diet for larval growth of this insect, followed by 9% fermented aloe vera with 91% fermented oakwood sawdust. Adult male Sprague–Dawley rats (n= 30) were separated into five groups of six each, as follows: control group; CCl4 group; CCl4 plus larval extract group (without fermented aloe vera); CCl4 plus 9% and 15% larval extract groups (with fermented aloe vera). All extract groups were fed with 30 mg/kg extracts of fermented oakwood sawdust only and fermented oakwood sawdust plus 9% and 15% fermented aloe vera, respectively, once every consecutive day, with administration of CCl4 (1.5 mL/kg, 20% CCl4 in olive oil) twice a week for 3 weeks. Administration of CCl4 increased the serum alanine aminotransferase, aspartate aminotranseferase and thiobarbituric acid reactive substance levels in rats and reduced levels of glutathione in the liver. Treatment with extract of larval‐fed fermented aloe vera mixed diet significantly alleviated these changes to nearly normal levels. The histopathological changes induced by CCl4 were also significantly attenuated by extract of larval‐fed fermented aloe vera mixed diet treatment. The results suggest that the beneficial effect of fermented aloe vera mixed diet on larval growth may be to stimulate the larval life cycle, and 15% larval‐fed fermented aloe vera mixed diet exhibits potent hepatoprotective effects on CCl4‐induced liver injury in rats, likely due to increased glutathione contents and the inhibition of lipid peroxidation.

Immature stages of Tanysphyrus (Tanysphyroides) major Roelofs (Coleoptera: Curculionidae: Erirhininae) from Korea

Detailed morphological descriptions and illustrations of immature stages of Tanysphyrus (Tanysphyroides) major Roelofs are presented for the first time in Korea.

General biology of Ostrinia palustralis memnialis (Walker), a potential biological control agent of Rumex spp. in Korea

Ostrinia palustralis memnialis is an oligophagous insect that feeds on the species of the genus Rumex. Continuous rearing of O. palustralis memnialis was carried out from 2004 to 2005, and its general biology was studied. The preliminary host specificity test showed a promising result for O. palustralis memnialis as a potential biological control agent for Rumex spp.