In Korea, six mealybug species have been reported on pears. This study investigated the occurrence of mealybugs in 19 pear orchards from 2013 to 2014. Two species, Crisicoccus matsumotoi (Siraiwa) (Hemiptera: Pseudococcidae) and Pseudococcus comstocki (Kuwana) were mainly found. The dominant species was C. matsumotoi identified on 73% of infested fruit. Toxicities of 14 registered insecticides (7 single formulations and 7 mixed formulations) commonly used to control P. comstocki were evaluated to C. matsumotoi nymphs and adults at the recommended concentration. As a results, all insecticides exhibited strong insecticidal activity with 100% mortality of both nymphs and adults. These results indicate that the 14 insecticides can be used in control for C. matsumotoi in field.

The larvicidal activities and repellency of Magnolia kobus extract against C. pipiens and Ae. albopictus were examined. M. Kobus methanol extraction showed 100% larvicidal activity both two mosquitoes at 500 ppm after treated 24 h. At a concentration of 50 ppm, the hexane fraction showed 100% and 94% mortality against C. pipiens and Ae. albopictus at 24 h, respectively. Purification of the biologically active constituents from the hexane extraction with larvicidal activity was done using silica gel open column chromatography and HPLC. H2 fraction gave >90% mortality to both mosquitoes at 10 ppm after treated 48 h. H21 fraction was determined 100% larvicidal activity to C. pipiens at 10 ppm. However, very low larvicidal activity was obseved to Ae. albopictus. This is considered a synergistic effect between substances. It also appears that there is a susceptibility difference of substance against mosquito species. H21 fraction was analyzed as the lignan, sesamin (C20H18O6) by GC-MS and NMR. Mosquito repellent and olfactory response was using a patch test.

Ionizing irradiation can be used as an alternative to chemical fumigants for disinfestation of cut flowers, agricultural products, seeds, foods, medical products, and spices. In this study, we investigated the effect of electron beam irradiation on reproduction and development in Spodoptera litura. When irradiated to the adults, there was no difference in fecundity. However, egg hatching was considerably decreased. When irradiated to the pupae, fecundity was decreased as dose increased and wing deformity of newly emerged adults was increased as time passed. When irradiated to the larvae, developmental period and pupa deformity was significantly increased. In order to investigate the molecular mechanism of sterility and abnormal development, we performed quantitative real-time PCR and SDS-PAGE.

애멸구(Laodelphax striatellus)는 rice stripe virus (RSV)의 매개충으로 벼에 큰 피해를 주는 해충이다. 본 연구에서는 애멸구의 장·단시형, 암·수, 약·성충에 대한 RSV 보독률과 이병률을 비교하였다. 애멸구의 장·단시형의 RSV 보독률은 각각 60.7%, 63.1%로 크게 차이는 없었다. 암·수에 대한 RSV 보독률은 각각 61.9%, 52.2%로 암컷의 보독률이 더 높았으나 유의성은 없었다. 약·성충의 보독률을 비교한 결과 각각 51.2%, 58.7%로 역시 크게 차이가 나지는 않았다. RSV에 감염된 애멸구에 노출된 건전한 벼의 이병률은 장시형은 53.3%, 단시형은 48.2%를 보였으며, 약·성충의 이병률은 각각 38.2%, 42.6%를 보여 유의성은 없었다. 반면 암컷은 50.5%의 이병률을 보이고 수컷은 22.3%의 이병률을 보여 암컷이 수컷에 비해 22.3% 이병률이 높아 유의성이 있었다. 또한 벼와 애멸구의 RSV 감염여부에 의한 애멸구의 발육기간은 건전한 벼에 RSV 감염 애멸구를 접종 했을 때 가장 긴 것으로 나타났으며, 건전한 벼에 건전한 애멸구를 접종 했을 때 발육기간이 가장 짧은 것으로 나타났다.

Many forest pests present a problem during wood quarantine. The effectiveness of phosphine (PH3), which is an altered form of MB, was examined in Monochamus saltuaris and M. alternatus. After 24 h, the larvae and the adults of both insects were susceptible to PH3 at 3 mg/L at 20°C. However, the larvae of both pests were rather than dead, seem to have been quiescent condition. PH3 showed increasing insecticidal activity in a time-dependent manner in the larva stage of both pests. We investigated the fumigants at all stages of M. saltuaris and M. alternatus, as well as the synergistic effects of PH3 in controlled atmospheres of 50% and 80% oxygen. The atmospheric oxidation of PH3 fumigation slightly increased the toxicity of the fumigant to larva stages in 125 L container at 4 mg/L. These results indicate that highly concentrated atmospheric oxidation of PH3 could be useful as a fumigant agent against M. saltuaris and M. alternatus.

The repellent activities of 33 plant extracts against Aedes albopictus were examined using a patch test for adult. The six plant extracts (Magnolia denudate, Dryopteris crassirhizoma, Cnidium officinale, Lindera obtusiloba, Magnolia kobus, and Houttuynia cordata) showed over 70% repellency activities to Ae. albopictus. The insecticidal activity of Curcuma longa against Ae. albopictus was also determined. C. longa hexane extraction showed 100% larvicidal activity at 1,000 ppm after treated 24 h. Purification of the biologically active constituents from the hexane extraction with larvicidal activity was done using silica gel column chromatography. H1 fraction gave 100% mortality to Ae. albopictus at 100 ppm. H12 fraction was determined 87.8% larvicidal activity to Ae. albopictus at 50 ppm. Active constituent was analysed as the sesquiterpene, ar-turmerone (C15H20O) by GC and GC-MS. C. longa extract gave highly protection against mosquito bites. The hexane extraction showed complete protection at 10 mg over 6 h. In this study, the sesquiterpene from C. longa induced a protection time, repellency, landing time, and biting time against Ae. albopictus. These results suggest that the some plant extracts and C. longa have the potential to be used an eco-friendly materials for the control of mosquitoes.

The melon and cotton aphid Aphis gossypii Glover (Hemiptera; Aphididae) is one of the most serious pests worldwide. We surveyed insecticide susceptibility in A. gossypii field populations to 12 insecticides to examine resistance ratios. The levels of insecticide resistance were extremely high, especially to neonicotinoids. One point mutation was found in the beta1 subunit loop D region of the nicotinic acetylcholine receptor (nAChR) of the imidacloprid-resistant strain. Feeding behavior analysis using an electrical penetration graph showed that sublethal doses of imidacloprid had significant effects on the duration of phloem ingestion. In addition, higher doses of imidacloprid induced contact toxicity rather than inhibition of feeding behavior. Temperature and insecticide are two important factors that affect survival, reproduction and other physiological processes of insects. To determine interactions of temperature and insecticide treatment on susceptible and imidacloprid-resistant strains of A. gossypii, adults were exposed to three temperatures (17, 22, and 28℃) or combinations of three temperatures and imidacloprid (LC20), and the expression of several genes (heat shock protein 70, cuticle protein, cytochrome P450, and elongation factor) were analyzed. Additionally, the effect of electron beam irradiation on development, reproduction, and several gene expression of imidacloprid-resistant and -susceptible A. gossypii were compared.

4종 해충(복숭아혹진딧물, 점박이응애, 아메리카잎굴파리, 대만총채벌레)에 이온화에너지인 전자빔과 X-ray를 각각 조사하여 이들 해충 의 발육과 생식에 미치는 영향을 비교하여 억제선량을 결정하였다. 복숭아혹진딧물 약충에 전자빔과 X-ray 조사 시, 전자빔의 경우에는 100 Gy, X-ray의 경우에는 30 Gy에서 우화성충의 산자가 완전히 억제되었다. 복숭아혹진딧물 성충의 경우 200 Gy (전자빔)와 50 Gy (X-ray)에서 각각 F1 세대 약충의 우화가 억제되었다. 그러나 이들 두 이온화에너지 모두 성충수명에는 영향을 주지 않았다. 점박이응애의 알에서는 전자빔 150 Gy와 X-ray 50 Gy 선량에서 알의 부화가 완전히 억제되었다. 아메리카잎굴파리 번데기에서는 X-ray 조사선량이 증가할수록 우화율이 감소하 였다. 대만총채벌레 성충에 조사 시 전자빔의 250 Gy와 X-ray의 200 Gy 선량에서 F1 세대 알의 부화가 완전히 억제되었다.

The insecticidal activities of materialsderived from Dryopteris crassirhizoma Nakai against third instar larvae of three species mosquitoes (Culex pipiens, Aedes albopictus and Anopheles sinnensis) were evaluated using a direct contact mortality bioassay. The methanol extracts of D. crassirhizoma showed 100%, 87.8% and 100% larvicidal activity at 1,000 ppm against Cx. pipiens, Ae. albopictus and An. sinensis, respectively. Hexane fraction showed 100% larvicidal activity three species mosquitoes at 500 ppm after 24 hrs. Purification of the biologically active constituents from the hexane extraction with larvicidal activity was done using silica gel column chromatography. H1 and H3 fractions gave 100% mortality to Cx. pipiens, Ae. albopictus and An. sinensis at 100 ppm. H1 fraction separated with methanol to give a H111 through centrifugation. Fraction of the biologically active constituents from the H3 fraction with larvicidal activity was done using methanol. H31 fraction was determined 100% mortality to Cx. Pipiens, Ae. albopictus and An. sinensis at 50 ppm, respectively. Two fractions were analyzed C14H22O (H111, MW206.0) and C11H14O4 (H31, MW210.08) by GC and GC-MS. D. crassirhizoma derived compounds described herein could be useful for managing filed populations as larvicide of Cx. pipiens, Ae. albopictus and An. sinensis.

This study compared the development, reproduction, and DNA damage in insecticide (acequinocyl, bifenazate, and etoxazole)-resistant (AR, BR, and ER) and -susceptible (S) strains of Tetranychus urticae by electron beam irradiation. When eggs were irradiated with 150 Gy, the egg hatching was completely inhibited in all strains. When nymphs were irradiated, their emergence rate was decreased with increasing doses of electron beam irradiation. When adults were irradiated, the longevity and the number of eggs was not affected at all target dose in all strains. However, hatchability of F1 generation was perfectly inhibited at 400 Gy in all strains. The DNA damage caused by electron beam irradiation was evaluated by an alkaline comet assay. These results suggest that electron beam irradiation induced abnormal development and reproduction in S, AR, BR, and ER strains of T. urticae.

The two spotted mite, Tetranychus urticae Koch, is a global pest, and has developed severe resistance to several types of acaricides. Acequinocyl-resistant strain and bifenazate-resistant strain of T. urticae showed higher relative activity level of glutathion-S-transferases (GSTs) than susceptible strain. Studies of resistance in T. urticae have focused on classical detoxifying enzyme system, such as GSTs. We examined the expression of six GSTs genes in T. urticae belong to five different cytosolic classes, including two in delta, one in omega, one in mu, one in zeta, and one mitochondrial GSTs class, kappa. RT-qPCR results showed that, among these six GSTs genes, the relative expression level of delta 1 was significantly higher in bifenazate-resistant strain than in other strains (susceptible, abamectin, acequinocyl, etoxazole and pyridaben strain). Expression level of the delta 2 was also higher in acequinocyl-resistant strain than in other strains. The elevated GSTs gene transcripts following exposure to acequinocyl, bifenazate might be one of the mechanisms involved in detoxification of these acaricide. These results may be caused by different mechanisms in the resistance development of T. urticae to these two different types of acaricides.

The larvicidal and repellent activities of 33 plant extracts against two mosquitoes as Culex pipiens and Aedes albopictus were examined using direct contact application for larva and a patch test for adult. Chrysanthemum zawadskii var. alpinum, Cnidium officinale, Ginkgo biloba, Magnolia kobus, and Magnolia denudate at 1,000 ppm caused 100% mortality to Cx. pipiens larva within 24 hr. Ailanthus altissima, Dryopteris crassirhizoma, Houttuynia cordata, Mentha arvensis, Phyllostachys nigra, and Parthenocissus tricuspidata showed over 90% mortality to Cx. pipiens. C. zawadskii var. alpinum, C. officinale, G. biloba, M. kobus, M. denudate, and P. nigra gave 100% mortality at 1,000 ppm to Ae. albopictus. Acorus gramineus, Campanula takesimana, and D. crassirhizoma, showed 97.8%, 94.5%, and 94.4% mortality to Ae. albopictus at 24 hr, respectively. Five plant extracts (C. zawadskii var. alpinum, C. officinale, G. biloba, M. kobus, and M. denudate) showed 100% mortality both Cx. pipiens and Ae. albopictus. However, A. altissima gave 90% larvicidal activity to Cx. pipiens, whereas 7.8% mortality to Ae. albopictus. Several plant extracts which have highly larvicidal activities, were determined repellency against two mosquitoes species.

The insecticidal activities of materials derived from the rhizomes of turmeric, Curcuma longa L., against third instar larva of Culex pipiens and Aedes albopictus were evaluated using a direct contact mortality bioassay. Curcuma longa L. hexane extraction showed 100% larvicidal activity both two mosquitoes species at 1,000 ppm after treated 24 h. Purification of the biologically active constituents from the hexane extraction with larvicidal activity was done using silica gel column chromatography. H1 fraction gave 100% mortality to C. pipiens and A. albopictus at 100 ppm. H12 fraction was determined 100% and 87.8% larvicidal activity to C. pipiens and A. albopictus at 50 ppm, respectively. H12 fraction was analyzed as the sesquiterpene, ar-turmerone (C15H20O) and turmerone(C15H22O) by GC and GC-MS.

The detoxification enzymes activities were investigated to Tetranychus urticae Koch using five acaricide-resistant strains. Activities of detoxification enzymes which are glutathione S-transferase (GST), general esterases (α-naphthyl acetate and β-naphthyl acetate), and cytochrome C oxidase were determined to each resistant strain mite. Acequinocyl-resistant strain and bifenazate-resistant strain of T. urticae were showed 2.1 folds and 1.6 folds higher relative activity (RA) level of GST than susceptible strain. Other three resistant strain mites were not significant different to susceptible strain mite. General esterases and cytochrome C oxidase were not significant to all the strain of T. urticae. Acaricidal activities of acequinocylresistant strain and bifenazate-resistant strain of T. urticae showed cross-resistant both acequinocyl and bifenazate. However, other strain mites were showed susceptible acaricidal activities to two acaricides. In this result suggests that resistance of two acaricides (acequinocyl and bifenazate) might be influenced by glutathione S-tansferase activity.

The fumigant activity of phosphine (PH3) and ethyl formate (EF) was determined to all stage of Phthorimaea operculella (Zeller) under high oxygen concentration (50% and 80%). Oxygenated PH3 and EF were tested at two different temperatures (20°C and 4°C) during 7 days. Two oxygenated fumigants were treated with LC10, 30 and 50 values of single fumigant against each stage of P. operculella. At 10% inhibition of hatchability concentration value, inhibition of hatchability of P. operculella eggs was shown 20.3% and 9.2% with 50% and 80% oxygenated PH3 at 20°C at 1 day after treatment, respectively. The fumigant activity of oxygenated PH3 was increased at all stage of P. operculella except eggs both 20°C and 4°C. However, oxygenated EF was determined low fumigant efficacy to hatchability of eggs and emergence rate of pupae. The insecticidal activities of P. operculella larvae and adults were slightly increased mortality rather than single EF. In this result suggests that oxygenated phosphine is effective method for managing P. operculella. But, oxygenated EF is not effective.

In this study, we investigated the effects of X-ray irradiation to control six important insect pests of floriculture crops: Liriomyza trifolii, Spodoptera litura, Myzus persicae, Tetranychus urticae, Bemisia tabaci, and Frankliniella intonsa. We irradiated on six insect pests that were placed in different positions (top, middle, and bottom) of export flower boxes after filling the boxes with roses and chrysanthemums, respectively. When irradiated with X-ray of 150 Gy, the eggs of T. urticae, B. tabaci, F. intonsa, L. trifolii, and S. litura were prevented from hatching at every position in the boxes. The pupation and emergence of L. trifolii larvae and S. litura larvae and B. tabaci nymphs and F. intonsa nymphs were inhibited at every position in the boxes. However, the emergence of T. urticae and M. persicae nymphs was not inhibited, even at the top position in the boxes. When pupae were irradiated, the emergence of L. trifolii was inhibited at every position in the boxes, while S. litura was not inhibited completely, even at the top position in the boxes. When adult T. urticae, S. litura, and L. trifolii were irradiated, the hatching rate of the F1 generation was not completely inhibited at every position. The insect pests that were not inhibited completely at the dose of 150 Gy showed much higher inhibitory effects at the dose of 250 Gy. Therefore, the dose of X-ray irradiation required to inhibit may vary according to the types of flowers and insect pests and according to their positions within the boxes.

Three insect pest, Myzus persicae, Tetranychus urticae, and Liriomyza trifolii were irradiated with electron beam (50-250 Gy) or X-ray (10-150 Gy). Longevity, egg hatching, emergence and fecundity of the test insects were measured. When irradiated to the M. persicae, emergence of nymphs did not show any differences, but fecundity was inhibited at 100 Gy (electron beam) or 30 Gy (X-ray). When irradiated to the T. urticae, egg hatching was completely inhibited at 150 Gy (electron beam) or 50 Gy (X-ray) and egg hatching of F1 generation was decreased at 150 Gy of electron beam or 50 Gy of X-ray. When irradiated to the L. trifolii, egg hatching was completely inhibited at 30 Gy of X-ray, however, electron beam irradiation was not inhibited even at 200 Gy. Egg hatching from irradiated adults was completely inhibited at 150 Gy of electron beam and X-ray. These results indicate that electron beam and X-ray irradiation induced abnormal development and reproduction, however, the dose of irradiation required to inhibit may vary according to the types of insect pests.

The effects of X-ray irradiation on development and reproduction of Spodoptera litura were examined. Eggs, larvae, pupae, and adults were irradiated at target doses of 10 - 250 Gy. When eggs were irradiated with 30 Gy, egg hatching was completely inhibited. When irradiated to the larvae, pupation was inhibited at 100 Gy and larval period was delayed. When irradiated to the pupae, emergence was inhibited at over 100 Gy. When irradiated to the adults, longevity and fecundity did not show any differences. However, egg hatching was significantly decreased at 70 Gy and above. Also, X-ray irradiation was not induced the rapid death of S. litura. Reciprocal crosses between irradiated and unirradiated moths demonstrated that males were more radiotolerant than females. The levels of DNA damage in S. litura adults were evaluated using the alkaline comet assay. Our results indicate that X-ray irradiation increased levels of DNA damage. The recovery of DNA damage in S. litura adults increased as time passed. But DNA damage hasn't recovered fully. These results indicate that X-ray irradiation induced abnormal development and reproduction by DNA damage in S. litura.

The effect of electron beam irradiation on development and reproduction of susceptible strain (S) and imidacloprid-resistance strain (IMI-R) of Aphis gossypii were compared. Nymphs and adults of S and IMI-R strain were irradiated at target doses of 50, 100, 150, and 200 Gy. When nymphs were irradiated, emergence rate was not affected at all target dose, but number of F1 nymphs was perfectly inhibited at 150 Gy in both strains when irradiated to the adults, longevity slightly decrease at 150 Gy and above. Fecundity was strongly decreased at 100 Gy, but was not completely inhibited even at 200 Gy. Emergence rate of F1 nymph was decreased at 100 Gy and completely inhibited at 200 Gy. However, there was no significant differences on development and reproduction of S and IMI-R strain. We also conducted the comet assay immediately after irradiation and over the following 7 day periods. In addition, we performed quantitative real-time PCR on several genes.

The melon and cotton aphid Aphis gossypii Glover (Hemiptera; Aphididae) is one of the most serious pests worldwide. We surveyed insecticide susceptibility in A. gossypii field populations to 12 insecticides (6 neonicotinoids, 3 pyrethroids and 3 others) to examine resistance ratios. The levels of insecticide resistance were extremely high, especially to neonicotinoids, such as acetamiprid, clothianidin, thiacloprid and imidacloprid. To identify the neonicotinoid resistance mechanisms, we used an imidacloprid-resistant (IMI-R) strain as a model strain. IMI-R showed an extremely high resistance ratio and also cross-resistance to all the test neonicotinoids. However, there was little or no cross-resistance to the other insecticides, including sulfoxaflor. Synergist tests and enzyme activity assays suggested the absence of resistance mechanisms based on enhanced detoxification enzymes, such as cytochrome P450, esterase and glutathione S-transferase. One point mutation was found in the beta1 subunit loop D region of the nicotinic acetylcholine receptor (nAChR) of the IMI-R strain. This R81T point mutation was also found in field populations collected from 5 regions. Therefore, the R81T point mutation was identified as an important mechanism of imidacloprid resistance in A. gossypii.