• Korean journal of applied entomology
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• v.2
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• pp.22-26
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• 1963

1) This experiment was planned to determine the biological effectiveness and persistence of malathion residues on the polished rice under the natural storage conditions in Korea from June to September in 1963). 2) Whole kernel rice was treated with malathion as a spray. The test insects(21 days old were exposed) for a period of 8 days at given day intervals, 3) The biological effcetiveness and persistence of malathirm residues on the polished rice was determined as the mortality of the rice weevils, Sithophilus oryzas L. 4) It was observed from Table 1 and Fig. 1 that 100 per cent mortality was resulted in at 3 days from treatment in all dosages used in this experiment. At :1':days after treatment, the dosages of 16ppm and 8ppm gave still 100 per cent mortality, but the dosages of 4 ppm and 2 ppm resulted in $85.8\pm3.70\;and\; 43.3\pm10.77 per cent mortalities, respectively. After 32 days from the treatment,the mortalities in all dosages used did not show any 100 per cent mortality, At. 107 days after treatment, there was no any difference in the mortality of weevils inall dosages used. 5). It was observed from Fig. 1 and Table 2 that the half-life values of malathion residues on the polished rice was 33 days at 2 ppn!, 54 days at 4 ppm, 73 days at 8 ppm, and 93days at 16ppm, respectively. 6). To get a satisfactory control of the rice weevile with the malathion-residues for more than 5 months under the natural storage conditions, it may be necessary to use higher dosages than those used in this experiment.

• Korean journal of applied entomology
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• v.62 no.3
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• pp.139-147
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• 2023

Leaf-spray in vitro bioassays appraise new aphicidal formulations for managing deleterious plant-feeding aphids. The formulation may utilize alternative and integrated strategies. However, leaf spraying even under controlled conditions may affect aphid reproduction and mortality. This study examines leaf spray applications for optimum and reproducible aphicidal results using tobacco leaves overlaid on cotton fabric or water agar surfaces. Infestation of the undersides of tobacco leaves with nymphs of green peach aphids was used in the assays. Spray distance and volume were optimized using water-sensitive paper to ascertain the best surface coverage. Overlays of the leaves on water agar caused less mortality and greater reproduction than the use of cotton fabric. The relative humidity of the insect-rearing chambers changed with the watering regime for the insect - rearing chambers with cotton fabric; 60% relative humidity was optimal. Relative humidity was not affected by the concentration of agar in the water agar chambers. Applications of the chemical aphicidal standard, Sulfoxaflor, under the optimized conditions exhibited similar times for lethality although the rate was faster with leaves on the cotton fabric than on water agar. These studies establish reproducible and sensitive techniques for assessing the lethality and effects on reproduction of potential aphicidal products.

• Korean Journal of Organic Agriculture
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• v.24 no.4
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• pp.821-831
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• 2016

This study was conducted to identify the insecticidal effect of a mixture of sophora extract and Bacillus thuringiensis against Spodoptera exigua on potted chinese cabbage in both laboratory and plastic house condition. In laboratory condition, mortality of larvae by BT ($1{\times}10^5$, $1{\times}10^6$, $1{\times}10^7cfu\;ml^{-1}$) alone was 27.5%, 51.3% and 92.5%, respectively, which was depend upon concentration of BT. Control efficacy of the mixture of BT and sophora extract was 98.8%, 88.8% and 91.3% which was higher than BT treatment only. The mixture of sophora and lower BT concentration was showed more increase of control efficacy. Anti-feedant effect by BT was depend on concentration of BT. At field experiment, the mixture of BT and sophora extract appeared higher mortality (72.2%, 67.8%, 61.1%) than BT treatment only (14.4%, 26.7%, 66.7%) similar with laboratory experiment. The mixture was less affected by environmental condition at field than BT only. Therefore, for effective control of beet armyworm without possibility to develop resistance against BT at farm, treatment of the mixture of sophora extract (0.033%) and BT ($1{\times}10^5cfu\;ml^{-1}$) would be considered more effective than BT treatment only.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.417-421
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• 2014

The beet armyworm, Spodoptera exigua is pest which is difficult to control. For eco-friendly beet armyworm managements, we isolated entomopathogenic fungi from soil samples by insect-bait method using Tenebrio molitor and conducted bioassay to larvae of beet armyworm. The result of bioassay, a selected strain Metarhizium anisopliae FT83 caused 100% mortality against first ~ third instar larva of S. exigua at $1{\times}10^8conidia/ml$ and medial lethal time ($LT_{50}$) were 0.5 days, 2.6 days and 2.5 days respectively. Mortality against fourth and fifth larvae were $83.3{\pm}6.2%$ and $86.0{\pm}5.7%$ and medial lethal time ($LT_{50}$) were 4.2 days and 3.6 days respectively. Mortality against pupae and eggs of S. exigua were 100%. M. anisopliae FT83 showed high virulence at all developmental stages of S. exigua.

• Korean journal of applied entomology
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• v.62 no.1
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• pp.43-48
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• 2023

The efficacy of spinetoram sprayed from an unmanned helicopter to control two insect vectors of pine wood nematodes, Monochamus alternatus and M. saltuarius was assessed. By using a ULV (Ultra Low Volume) sprayer, the mortality rates of phenthoate, bifenthrin, etofenprox, and diflubenzuron, which are registered for use against coleopteran insects, indoxacarb and spinetoram, which are registered for use against lepidopteran insects, were evaluated for efficacy as aerial spraying agents. The ULV test, using 33- and 55-fold dilutions of phenthoate, bifenthrin, indoxacarb, and spinetoram demonstrated a 100% insect mortality rate upon contact and feeding mortality on the third day after treatment, while etofenprox and diflubenzuron exhibited a slightly lower mortality rate than the remaining compounds. Consequently, spinetoram was selected as a candidate pesticide for aerial spraying and its efficacy to control the insect vectors was assessed. The x 33 dilution of spinetoram resulted in a 98.6-100% control efficacy against two insect vectors. However, risk assessment for bees following aerial spraying will be necessary before applying the pesticide to control insect vectors.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.5
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• pp.659-666
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• 2010

Lysobacter antibioticus HS124 was isolated from rhizosphere soil in previous experiments, which produced lytic enzymes such as chitinase, gelatinase, lipase and protease. In addition, HS124 released an antibiotic compound, 4-hydroxyphenylacetic acid (4-HPAA). When larvae of P. xylostella was treated with HS124 culture broth, its body was destroyed, and degraded with the increase of incubation time, yielding glycine which was detected from HS124 culture broth. When 4-HPAA produced from HS124 was sprayed, larvae mortality increased with increasing concentration of 4-HPAA. When HS124 culture supplemented with Tween 80 was sprayed, its insecticidal activity against larvae was approximately 1.4 times higher compared to the culture without Tween 80. Insecticide (IS), HS124 culture broth (HS124), Magic-pi (MP) and HS124 culture broth+Magic-pi (HS124+MP) were each treated against larvae of P. xylostella to investigate their insecticidal effect where sterile diluted water (SDW) was used as a control. The highest mortality of larvae was found in HS124+MP, followed by IS, MP, HS124 and SDW respectively. Mortality of larvae in HS124 was 31% higher than that in SDW, but 41% lower than that in HS124+MP, meaning that both enzymes and antibiotics produced from HS124 may synergistically act as active agents with plant extract containing neem oil and turmeric in HS124+MP treatment. These results suggested that L. antibioticus HS124 together with plant extract can be one of candidates for biocontrol agents against Plutella xylostella.

• Korean journal of applied entomology
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• v.42 no.2
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• pp.153-157
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• 2003

This experiment was conducted to investigate control effect of Spodoptera litura using nucleopolyhedrovirus in chrysanthemum seedlings of open field and plastic house. Values of LT$_{50}$ of treatment 1.0$\times$10$^{6.8}$ PIBs/ml were 6.2-5.1 days in open field and 6.9-5.4 days in plastic house. Values of LT$_{50}$ and LT$_{95}$ were shorter in open field than in plastic house. Cumulative mortality was 100% in 1.0$\times$10$^{7.8}$ PIBs/ml and also higher in open field than in plastic house. In chrysanthemum field, organic synthetic insecticide (endosulfan EC) killed S. litura larvae in 2 days after application. Motality of S. litura larva inoculated with S. litura nucleopolyhedrovirus (SINPV) 1.0$\times$10$^{6.8}$ PIBs/ml was found out from 4 days after application and maintained during 14 days. Protection values of with SINPV 1.0$\times$10$^{8}$ PIBs/ml after 16 days were 94.0% and 89.4% in open field and plastic house, respectively, and those of endosulfan 350 ppm were 91.4% and 88.6%, respectively.

• The Korean Journal of Pesticide Science
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• v.3 no.1
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• pp.84-89
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• 1999

This experiment was conducted to select the selective aphicides to Myzus persicae adults and its predator, Harmonia axyridis adults. The effects of the selective aphicides on the longevity, fecundity and hatchability of predaror were examined. All experiments were tested at the recommended concentration of those aphicides. Mortalities of adult H. axyridis to pirimicarb (162.5 ppm), fenvalerate (50 ppm) and endosulfan (577.5ppm) were shown 0, 20 and 22.5%, respectively. Endosulfan and fenvalerate showed the mortality above 48% to eggs and larvae H. axyridis, but pirimicarb was not toxic to those stages. Pirimicarb did not affect to the longevity, fecundity and hatchability of H. axyridis, but endosulfan and fenvalerate severely affected to the predators. From these results, pirimicarb can be used in biological controls for M. persicae.

• Korean journal of applied entomology
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• v.48 no.1
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• pp.53-57
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• 2009

Biological Characteristics of Lycorma delicatula and insecticidal activity of some insecticides against nymphs of L. delicatula was investigated. Nymph of L. delicatula had 4 instars, and color of body was black. There were white spots on the body of 1st-3rd nymph. Upper body became red at 4th nymph. Adult forewings were brownish, and had black spots. Color of hind wing were red. The egg mass was covered with a yellowish brown secretion. The adult of L. delicatula emerged once a year. Among test insecticides, deltamethrin 1% EC and fenitrothion 50% EC showed very quick and strong insecticidal activity against the 2nd-3rd nymphs of L. delicatula. Imidacloprid 4% SL and clothianidin 8% SC showed 100% insecticidal activity at 24h after treatment. Thiacoprid 10% SC revealed the weakest insecticidal activity among the insecticides tested.

• Korean Journal of Organic Agriculture
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• v.18 no.4
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• pp.573-586
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• 2010

This study was carried out to evaluate characteristics of Chrysanthemum sp. and to bioassay Tetranychus urticae, Nilaparvata lugens, and Aphis gossypii by different extracts part and method. Flower type of Chrysanthemum sp. line was anemone except 0706 line which was pompon. The flowering date was from April to June but 0721 line kept up November. They could overwinter except 0706 line. The Ethanol extracts of 0718 line of flower was high mortality as 63.8% on Tetranychus urticae. Ethanol mixed emulsifier extracts were the highest mortality as 69.4% at 5 days after. Mortality in water extract was lower than in ethanol and ethanol mixed emulsifier extracts. Ethanol mixed emulsifier extracts were higher mortality as 69.4% at 5 days after in 0718 line on Nilaparvata lugens. Mortality in water extract was lower than in ethanol and ethanol mixed emulsifier extracts. On Aphis gossypii, Chrysanthemum flower extracts could decrease the density of aphids in early days but the density of that was increase as time goes by because aphids produce offspring.