• The Plant Pathology Journal
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• v.33 no.2
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• pp.118-124
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• 2017

Bell pepper is an economically important crop worldwide; however, production is restricted by a number of fungal diseases that cause significant yield loss. Chemical control is the most common approach adopted by growers to manage a number of these diseases. Monitoring for the development to resistance to fungicides in pathogenic fungal populations is central to devising integrated pest management strategies. Two fungal species, Fusarium incarnatum-equiseti species complex (FIESC) and Colletotrichum truncatum are important pathogens of bell pepper in Trinidad. This study was carried out to determine the sensitivity of 71 isolates belonging to these two fungal species to fungicides with different modes of action based on in vitro bioassays. There was no significant difference in log effective concentration required to achieve 50% colony growth inhibition ($LogEC_{50}$) values when field location and fungicide were considered for each species separately based on ANOVA analyses. However, the $LogEC_{50}$ value for the Aranguez-Antracol locationfungicide combination was almost twice the value for the Maloney/Macoya-Antracol location-fungicide combination regardless of fungal species. $LogEC_{50}$ values for Benomyl fungicide was also higher for C. truncatum isolates than for FIESC isolates and for any other fungicide. Cropping practices in these locations may explain the fungicide sensitivity data obtained.

• International Journal of Industrial Entomology and Biomaterials
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• v.5 no.1
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• pp.13-22
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• 2002

Stink bug, Canthecona furcellatta (Hemiptera: Pentatomidae), is an important predator of silkworm larvae. Nymphs and adult attack the early stage silkworm larvae and causes about 10-15 per cent loss to silk industry. Synthetic organic pesticides has tremendous impact on minimizing the pest population but repeated and frequent use has created problems of residual toxicity, development of resistance to insecticides, pest resurgence and out break, phyto-toxicity and hazards to non target species and beneficial organism. Silkworms are very sensitive to pesticides; therefore, attempt has made to control the bug population through introduction of its native natural enemies in the silkworm-rearing field. Biological control has tremendous scope in sericulture because it is eco-friendly in nature and non-harmful farmers. Native natural enemies have been screened. Psix striaticeps, Trissolcus spp. and Telenomus spp. have been recorded as the most potential parasitoid against pentatomid bug. Life cycle, sex ratio and other various attributes of the par-asitoids have been recorded. The parasitization potential of the parasitoid is very high and they have the ability to discriminate between parasitized and unpar-asitized host. Mass propopagation technique under laboratory condition has been standaydized.

• The Korean Journal of Mycology
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• v.37 no.2
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• pp.139-143
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• 2009

Several entomopathogenic fungi have been exploited to be developed into biological control agents in insect pest management. The beet armyworm, Spodoptera exigua, is a serious insect pest infesting various crops, but not effectively controlled by commercial chemical pesticides due to its high insecticide resistance. A fungal isolate was isolated from S. exigua larvae collected from cabbage field in Andong, Korea. The fungus could be cultured in potato dextrose agar. Larvae of S. exigua injected with the cultured conidia showed a potent entomopathogenicity. To identify the fungus isolate, its internal transcribed space (ITS) and surrounding partial 18S/28S regions were sequenced. The ITS sequence was highly matched (99%) to that of Nomuraea rileyi. Morphological characters of its hyphae and conidia were well fit to those of known N. rileyi. This study reports the first record of an entomopathogenic fungus, N. rileyi, in Korea.

• Korean Journal of Organic Agriculture
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• v.31 no.4
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• pp.427-439
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• 2023

The silverleaf whitefly, Bemisia tabaci, is a major pest distributing worldwide damaging over 900 host plant species, and is highly resistant to chemical pesti- cides. Due to the high pesticide resistance of whitefly, there is a need for alternatives to chemical control. Entomopathogenic fungi are candidates for biological pesticide that can overcome the resistance problem of chemical pesticide. Therefore, in this study, we tested pathogenicity of the entomopathogenic fungi to select high insec- ticidal activity against whitefly. As a result, IPBL-C (Cordyceps fumosorosea) and IPBL-F (Metarhizium pinghaense) isolates showed high insecticidal activity against whitefly. Additionally, as a result of culturing the selected isolates on spent coffee grounds medium, the conidia of IPBL-F produced on coffee grounds medium showed five times higher heat stability after heat treatment at 45℃ for one hour than conidia produced on PDA medium.

• Journal of Crop Science and Biotechnology
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• v.11 no.4
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• pp.243-248
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• 2008

The bean bug Riptortus clavatus Thunberg (Heteroptera: Alydidae) is an important pest, causing serious yield loss in soybean. But the information on mechanism of resistance to R. clavatus is limited. The objective of this study was to identify QTLs for R. clavatus resistance using simple sequence repeat (SSR) markers in a soybean population of recombinant inbred lines (RILs) developed from the cross PI 171451 ${\times}$ Hwaeomputkong. A genetic map from this population was constructed with a total of 136 SSR markers covering 1073.9 cM on 20 linkage groups (LGs). With 126 $F_5$ RILs, two independent QTLs for resistance to R. clavatus were mapped on LGs B1 and C2. The amount of phenotypic variation explained by these QTLs ranged from 12 to 16%. PI 171451 showed an escape response to R. clavatus. Under feeding conditions, 14.4% of RILs showed greater resistance to R. clavatus than the resistant parent. The resistance to R. clavatus in soybean from PI 171451 was incomplete and quantitatively inherited and the QTLs for resistance to R. clavatus detected in the RIL population were not significantly affected by epistatic interactions.

• Molecular & Cellular Toxicology
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• v.3 no.1
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• pp.11-18
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• 2007

Mechanisms of insecticide resistance found in insects may include three general categories. Modified behavioral mechanisms can let the insects avoid the exposure to toxic compounds. The second category is physiological mechanisms such as altered penetration, rapid excretion, lower rate transportation, or increased storage of insecticides by insects. The third category relies on biochemical mechanisms including the insensitivity of target sites to insecticides and enhanced detoxification rate by several detoxifying mechanisms. Insecticides metabolism usually results in the formation of more water-soluble and therefore more readily eliminated, and generally less toxic products to the host insects rather than the parent compounds. The representative detoxifying enzymes are general esterases and monooxygenases that catalyze the toxic compounds to be more water-soluble forms and then secondary metabolism is followed by conjugation reactions including those catalyzed by glutathione S-transferases (GSTs). However, a change in the resistant species is not easily determined and the levels of mRNAs do not necessarily predict the levels of the corresponding proteins in a cell. As genomics understands the expression of most of the genes in an organism after being stressed by toxic compounds, proteomics can determine the global protein changes in a cell. In this present review, it is suggested that the environmental proteomic application may be a good approach to understand the biochemical mechanisms of insecticide resistance in insects and to predict metabolomic changes leading to physiological changes of the resistant species.

• Journal of Applied Biological Chemistry
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• v.43 no.4
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• pp.185-191
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• 2000

Pest insect control is dependent on about 200 insecticides that work by relatively few mechanisms. The targets they disrupt are mostly involved in the nervous system, respiratory chain, growth and development, or the gut. The major nerve targets are: acetylcholinesterase for the organophosphates and methylcarbamates; the nicotinic acetylcholine receptor for the neonicotinoids; the $\gamma$-aminobutyric acid receptor for several chlorinated hydrocarbons and fipronil; the voltage-gated sodium channel for DDT and pyrethroids. Selection of resistant strains often confers cross-resistance to some or all other insecticides working at the same site. The toxicological properties of different compounds acting on the same target are increasingly considered together, summating the risk even though the compounds are of quite diverse chemical types. Continuing attention is also being given to secondary targets not involved in the primary mechanism of toxicity but instead in side effects that must be considered in the overall safety evaluation. Research on insecticide targets is important in learning to keep up with resistance and changing concepts and policies on safety. These relationships are illustrated by recent studies in the Environmental Chemistry and Toxicology Laboratory of the University of California at Berkeley.

• The Korean Journal of Pesticide Science
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• v.7 no.4
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• pp.296-301
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• 2003

This study was conducted to select low toxic insecticides against natural enemies, and to evaluate resistance stability and cross-resistance to resistance strain for the fulfillment of integrated pest management development. Toxicity of imidacloprid and spinosad to Amblyseius cucumeris was relatively low regardless of the adopting test methods. In addition, those to the Amblyseius fallacis was also low by slide dipping method. The slide dipping method was useful to eliminate repellency effect by mites to the tested insecticides. Mortality of A. fallacis to deltamethrin recorded in 1994 and 1999 was 21.6% and 7.4%, respectively. Meanwhile, the permethrin-resistanct strain of A. fallacis was maintained its resistance to deltamethrin. However, the cross-resistance to the newly introduced insecticides namely imidacloprid, fipronil, chlorfenapyr, abamectin, and spinosad. was relatively low.

• Korean journal of applied entomology
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• v.61 no.1
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• pp.197-210
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• 2022

Entomopathogenic fungi can be used to control a variety of sucking and chewing insects, with little effect on beneficial insects and natural enemies. Approximately 170 entomopathogenic fungal insecticides have been registered and used worldwide, with the recent focus being on the mode of action and mechanism of insect-fungal interactions. During the initial period of research and development, the industrialization of entomopathogenic fungi focused on the selection of strains with high virulence. However, improvement in productivity, including securing resistance to environmental stressors, is a major issue that needs to be solved. Although conidia are the primary application propagules, efforts are being made to overcome the limitations of blastospores to improve the economic feasibility of the production procedure. Fungal transformation is also being conducted to enhance insecticidal activity, and molecular biology is being used to investigate functions of various genes. In the fungi-based pest management market, global companies are setting up cooperative platforms with specialized biological companies in the form of M&As or partnerships with the aim of implementing a tank-mix strategy by combining chemical pesticides and entomopathogenic fungi. In this regard, understanding insect ecology in the field helps in providing more effective fungal applications in pest management, which can be used complementary to chemicals. In the future, when fungal applications are combined with digital farming technology, above-ground applications to control leaf-dwelling pests will be more effective. Therefore, for practical industrialization, it is necessary to secure clear research data on intellectual property rights.

• Applied Biological Chemistry
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• v.48 no.1
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• pp.1-15
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• 2005

Pathogens, insects and weeds have significantly reduced agricultural productivity. Thus, to increase the productivity, synthetic agricultural chemicals have been overused. However, these synthetic compounds that are different from natural products cannot be broken down easily in natural systems, causing the destruction of soil quality and agricultural environments and the gradually difficulty in continuous agriculture. Now agriculture is faced with the various problems of minimizing the damage in agricultural environments, securing the safety of human health, while simultaneously increasing agricultural productivity. Meanwhile, plants produce secondary metabolites to protect themselves from external invaders and to secure their region for survival. Plants infected with pathogens produce antibiotics phytoalexin; monocotyledonous plants produce flavonoids and diterpenoids phytoalexins, and dicotylodoneous plant, despite of infected pathogens, produce family-specific phytoalexin such as flavonoids in Leguminosae, indole derivatives in Cruciferae, sesquitepenoids in Solanaceae, coumarins in Umbelliferae, making the plant resistant to specific pathogen. Growth inhibitor or antifeedant substances to insects are terpenoids pyrethrin, azadirachtin, limonin, cedrelanoid, toosendanin and fraxinellone/dictamnine, and terpenoid-alkaloid mixed compounds sesquiterpene pyridine and norditerpenoids, and azepine-, amide-, loline-, stemofoline-, pyrrolizidine-alkaloids and so on. Also plants produces the substances to inhibit other plant growths to secure the regions for plant itself, which is including terpenoids essential oil and sesquiterpene lactone, and additionally, benzoxazinoids, glucosinolate, quassinoid, cyanogenic glycoside, saponin, sorgolennone, juglone and lots of other different of secondary metabolites. Hence, phytoalexin, an antibiotic compound produced by plants infected with pathogens, can be employed for pathogen control. Terpenoids and alkaloids inhibiting insect growth can be utilized for insect control. Allelochemicals, a compound released from a certain plant to hinder the growth of other plants for their survival, can be also used directly as a herbicides for weed control as well. Therefore, the use of the natural secondary metabolites for pest control might be one of the alternatives for environmentally friendly agriculture. However, the natural substances are destroyed easily causing low the pest-control efficacy, and also there is the limitation to producing the substances using plant cell. In the future, effects should be made to try to find the secondary metabolites with good pest-control effect and no harmful to human health. Also the biosynthetic pathways of secondary metabolites have to be elucidated continuously, and the metabolic engineering should be applied to improve transgenics having the resistance to specific pest.