• Korean journal of applied entomology
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• v.61 no.1
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• pp.143-154
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• 2022

Plant secondary metabolites play an important role in insect-plant interactions. Herbivorous insects have various strategies to cope with the plant defensive compounds. Polyphagous insects feed on a wide variety of plant species, and their detoxification mechanisms are more complex since they tend to respond to a large array of different plant-derived chemicals. Alternatively, oligophagous insects specialize on only a few related plant species and may be expected to have a more efficient form of adaptation. This adaptation could involve either the production of large quantities of enzymes to detoxify their defensive compounds or the sequestration of the compounds or their metabolites. The oriental tobacco budworm, Helicoverpa assulta, is a specialist herbivore, feeding on a few plants of Solanaceae, such as tobacco and hot pepper. Understanding its host-plant adaptation not provides an important insight on physiology, ecology and evolution of specialist herbivores, but also gives a clue to develop management strategies of the pest species such as H. assulta. This paper briefly reviews the specialist, H. assulta, focusing on its host range, larval associations with the host plants, and detoxification mechanisms to nicotine and capsaicin, two characteristic defensive compounds derived from its two major host plants, tobacco and hot pepper, respectively. It summarizes the relevant research over the last half century and provides a future perspective on this subject.

• Korean journal of applied entomology
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• v.60 no.2
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• pp.167-173
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• 2021

Sweet potato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is an insect pest with sucking mouth part and globally attacks diverse crops and vegetables. Since first reported in 1998, it is now widely spread in many regions in Korea. Due to insecticide resistance, it is necessary for optimal control of the whiteflies to select effective insecticides with precise insecticide resistance monitoring. In this study, B. tabaci individuals were collected from 12 regions in 7 provinces of Korea from June to September in 2020. Using these field populations, insecticide resistance levels were monitored using a residual contact bioassay along with molecular markers. Bioassay results revealed that B. tabaci possessed high levels of resistance to five insecticides exhibiting different modes of action: dinotefuran, spinosad, emamectin benzoate, chlorfenapyr, and bifenthrin. In addition, quantitative sequencing in target sites of organophosphate and pyrethroid insecticides revealed that point mutations reached to saturated or near-saturated levels across the country. This suggests that insecticide resistance management is required for effective control of B. tabaci populations in Korea.

• Korean journal of applied entomology
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• v.61 no.4
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• pp.563-575
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• 2022

Maruca vitrata is one of important pests in leguminous crops, especially red bean. We investigated the effects of temperature on development of each life stage, adult longevity and fecundity of M. vitrata for understanding the biological characteristics of the insect species at eight constant temperatures of 13, 16, 19, 22, 25, 28, 31, and 34℃. Eggs hatched successfully at all temperature subjected and larvae successfully developed to the adult stage from 16℃ to 31℃. The developmental period of egg decreased up to 31℃ and after then increased. The developmental period of larva and pupa, and adult longevity of M. vitrata decreased with increasing temperature. Lower and higher threshold temperature (TL and TH) were calculated by the Lobry-Rosso-Flandrois (LRF) and Sharpe-Schoolfield-Ikemoto (SSI) models. The lower developmental threshold (LDT) and thermal constant (K) from egg hatching to adult emergence of M. vitrata were estimated by linear regression as 12.8℃ and 280.8DD, respectively. TL and TH from egg hatching to adult emergence using SSI model were 14.2℃ and 31.9℃. Thermal windows, i.e., the range in temperature between the minimum and maximum rate of development, of M. vitrata was 17.7℃. In addition, we constructed the oviposition models of adult, using the investigated adult traits including survival, longevity, oviposition period and fecundity. Temperature-dependent development models and adult oviposition models will be helpful to understand the population dynamics of M vitrata and to establish the strategy of integrated pest management in legume crops.

• Korean journal of applied entomology
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• v.61 no.4
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• pp.577-590
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• 2022

Ostrinia scapulalis is one of important pests in leguminous crops, especially red bean. In order to understand the biological characteristics of the insect, we investigated the effects of temperature on development of each life stage, adult longevity and fecundity of O. scapulalis at eleven constant temperatures of 7, 10, 13, 16, 19, 22, 25, 28, 31, 34, and 36℃. Eggs and larvae successfully developed next life stage at most temperature subjected except 7, 10 and 13℃. The developmental period of egg, larva and pupa decreased as temperature increased. Lower and higher threshold temperature (TL and TH) were calculated by the Lobry-Rosso-Flandrois (LRF) and Sharpe-Schoolfield-Ikemoto (SSI) models. The lower developmental threshold (LDT) and thermal constant (K) from egg hatching to adult emergence of O. scapulalis were estimated by linear regression as 13.5℃ and 384.5DD, respectively. TL and TH from egg hatching to adult emergence using SSI model were 19.4℃ and 39.8℃. Thermal windows, i.e., the range in temperature between the minimum and maximum rate of development, of O. scapulalis was 20.4℃. Adults produced viable eggs at the temperature range between 16℃ and 34℃, and showed a maximum number, ca. 416 offsprings, at 25℃. Adult models including aging rate, age-specific survival rate, age-specific cumulative oviposition, and temperature-dependent fecundity were constructed, using the temperature-dependent adult traits. Temperature-dependent development models and adult oviposition models will be useful components to understand the population dynamics of O. scapulalis and will be expected using a basic data for establishing the strategy of integrated pest management in leguminous crops.

• Journal of Practical Agriculture & Fisheries Research
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• v.15 no.1
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• pp.183-202
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• 2013

The demand of ginseng which has attracted many people for a long time has expanded further with great spotlight ; but it has caused anxiety of some safety-sensitive customers due to unavoidable pesticides and its weakness for disease and insect pest. On the other hand, sluggish studies on effective doses of ginseng and red ginseng which is produced and processed after hardship have worsened confusion of customers. Against this backdrop, this study is about to find out measures for safe ginseng cultivation and effective dose of white or red ginseng which are safely produced and reaches meaningful conclusions as follows ; As for a study to minimize the use of chemical fertilizers and pesticides or to change them into environmentally-friendly products, ginseng cultivation utilizing Lime Sulfur complex might be an alternative. The effects of Lime Sulfur complex are great on ginseng seeding with under 200 times compound KHCO3 and five-year-old ginseng with over 200 times compound using NaHCO3. When using with green materials like Bordeaux mixture, there would be great potential to realize ginseng without pesticide use.

• Korean journal of applied entomology
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• v.62 no.4
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• pp.333-343
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• 2023

King oyster mushrooms are one of the major fresh agricultural products which their exports are increasing every year in Korea. Lycoriella ingenua, is notorious insect pest in agriculture, especially in mushroom production. Larvae of L. ingenua cause mainly direct crop damage and adults are vectors of several dangerous fungal pathogens. In this study, the effects of electron beam, X-ray, and gamma-ray irradiation on the development and reproduction of L. ingenua were evaluated. In addition, to find the optimal dose to control L. ingenua in a box filled with king oyster mushrooms, an empirical experiment was conducted for each radiation. As a result, the development and reproduction of L. ingenua were inhibited at 50 Gy for all electron beam, X-ray, and gamma-ray irradiation. Additionally, at the top, middle, and bottom of the export box filled with king oyster mushrooms, the development and reproduction of L. ingenua were inhibited by electron beam with 150 Gy, X-ray with 100 Gy, and gamma-ray with 50 Gy. These results can be provided as basic data for establishing an integrated quarantine management system when exporting mushrooms. It will also contribute to the safety of agricultural products and the strengthening of export competitiveness.

• Korean journal of applied entomology
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• v.62 no.4
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• pp.299-305
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• 2023

Bemisia tabaci is one of polyphagous insect pests that transmits Tomato Yellow Leaf Curl Virus (TYLCV) and Cassava Brown Streak Disease (CBSD). Insecticides are primarily applied to control B. tabaci, but it has limits due to the development of resistance. As a result, a fixed precision sampling plan was developed for its integrated pest management (IPM). The tomato plants were divided into top (more than 130cm from the ground), middle (70 cm to 100 cm above the ground), and bottom (50 cm or less above the ground) strata, before visual sampling of the larvae of B. tabaci. The spatial distribution analysis was conducted using Taylor's power law coefficients with pooled data of top, middle, bottom strata. Fixed precision sampling plan and control decision-making were developed with precision levels and action threshold recommended from published scientific papers. To assess the validation of the developed sampling plans, independent data not used in the analysis were evaluated using the Resampling Validation for Sampling Plan (RVSP) program.

• Korean journal of applied entomology
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• v.63 no.1
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• pp.33-42
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• 2024

The green peach aphid, Myzus persicae is a representative agricultural insect pest that is polyphagous and causes serious damage to tobacco, potatoes, peppers, cabbage, and peaches. In this study, we analyzed the level of development of insecticide resistance to λ-cyhalothrin, imidacloprid, and flupyradifurone and the point mutations (R81T, L1014F, M918L) in 12 field populations of M. persicae. In addition, the expression level of CYP6CY3, a cytochrome P450 gene, was analyzed through qRT-PCR. As a result, λ-cyhalothrin showed high resistance ratio (RR) of > 200 in all 12 populations. Imidacloprid and flupyradifurone showed high RR of >200 in YS, UR, HY, and WJ populations. The R81T was detected in approximately 50%, L1014F in approximately 33.3%, and M918L in 100% of the 12 populations. Additionally, the expression level of subunit CYP6CY3 was highest in imidacloprid-resistant population (YS). These results suggest that M918L point mutation can be used as λ-cyhalothrin-resistance molecular diagnostic and R81T point mutation and the high expression of CYP6CY3 can be used as imidacloprid-resistance molecular diagnostic markers.

• Korean Journal of Environmental Biology
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• v.41 no.4
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• pp.627-636
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• 2023

Bemisia tabaci Gennadius, one of the most invasive insect pests, has spread quickly nationwide since it was introduced to South Korea in 2008. The use of insecticides is the main management strategy for this pest, but the control efficiency has been decreased due to insecticide resistance. We collected 12 local B. tabaci populations to investigate the regional differences in efficiency and observed the mortality from 14 commercial insecticides applied at recommended concentrations (RC) and dilutions (0.1 RC and 0.01 RC) using the leaf dipping bioassay. Except for etofenprox (46-64%), thiamethoxam (37-60%), pyriproxyfen (21-61%), and pyridaben (61-65%), the other insecticides showed excellent insecticidal efficacy of 70% to 100% at their RC. In particular, flupyradifurone, emamectin benzoate, and cyantraniliprole showed high insecticidal efficacy of over 90% in all of the tested populations. Some insecticides that rapidly decreased in activity (less than 30%) at diluted concentrations or showed high resistance levels in nearby regions were classified for cautious use due to the possibility or potential to develop resistance. The results provide selected insecticides for B. tabaci control by region and could contribute to reducing insecticide abuse and increasing insecticidal efficiency in farming fields.

• Korean journal of applied entomology
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• v.47 no.2
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• pp.155-162
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• 2008

The Welsh onion beet armyworm, Spodoptera exigua (Hubner), has attacked Welsh onion and is now the most important pest of Welsh onion in southwestern Korea. The beet armyworm has a wide host range, occurring as a serious pest of vegetable and fields. The relatively high abundance of beet armyworm has stimulated frequent application of insecticides to foliage. Insecticide resistance is a major problem in management of this insect. Accordingly, pesticide application for the control of beet armyworm was tried in both the open field and in laboratory, using 4 synthetic compounds such as metaflumizone and chlorfenapyr, indoxacarb, flufenoxuron, emamectin benzoate. In the laboratory, each developmental stages from eggs, larva to pupa was tested against 4 insecticides. Against the eggs of welsh onion beet armyworm, there was no significantly different with each other. These tested chemicals no killing effect to eggs. However, the population of 1st larva hatched from eggs were reduced because they eaten the egg shell with residual insecticides. The tested insecticides were taken very high mortalities to 1st to 3rd larva of Welsh onion beet armyworm. Otherwise, there were decreased the death rate from 4th to 6th larva. On the other hand, their value of control effects were relatively good against Welsh onion beet armyworms in the field between 87.2 and 90.5% on 10 days after insecticide application.