• Korean Journal of Environmental Biology
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• v.40 no.2
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• pp.164-171
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• 2022

Frankliniella occidentalis is an invasive pest insect, which affects over 500 different species of host plants and transmits viruses (tomato spotted wilt virus; TSWV). Despite their efficiency in controling insect pests, pesticides are limited by residence, cost and environmental burden. Therefore, a fixed-precision level sampling plan was developed. The sampling method for F. occidentalis adults in pepper greenhouses consists of spatial distribution analysis, sampling stop line, and control decision making. For sampling, the plant was divided into the upper part(180 cm above ground), middle part (120-160 cm above ground), and lower part (70-110 cm above ground). Through ANCOVA, the P values of intercept and slope were estimated to be 0.94 and 0.87, respectively, which meant there were no significant differences between values of all the levels of the pepper plant. In spatial distribution analysis, the coefficients were derived from Taylor's power law (TPL) at pooling data of each level in the plant, based on the 3-flowers sampling unit. F. occidentalis adults showed aggregated distribution in greenhouse peppers. TPL coefficients were used to develop a fixed-precision sampling stop line. For control decision making, the pre-referred action thresholds were set at 3 and 18. With two action thresholds, N_max values were calculated at 97 and 1149, respectively. Using the Resampling Validation for Sampling Program (RVSP) and the results gained from the greenhouses, the simulated validation of our sampling method showed a reasonable level of precision.

• Korean Journal of Environmental Biology
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• v.41 no.3
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• pp.193-203
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• 2023

Ethyl formate (EF) is a naturally occurring insecticidal compound and is used to control pests introduced from abroad, in quarantine, by a fumigation method. In particular, it is mainly used as a substitute for methyl bromide and is less toxic to humans and less harmful to plants. This study aimed to investigate the possible acute toxicity of EF to useful organisms, and how to reduce phytotoxicity in watermelon, zucchini, and oriental melon. After fumigation with EF for 2 h, the LC₅₀ values for earthworms, honey bees, and silkworms were 39.9, 7.09, and 17.9g m^-3, respectively. The degree of susceptibility to EF was in the order of earthworms, silkworms, and honey bees based on the LC₅₀ value, and EF fumigation induced stronger acute toxicity to honey bees. Phytotoxicity was observed in watermelon leaves treated with a concentration of 7.5 g m^-3 EF, and when treated with a concentration of 10.0g m^-3, it was confirmed that the edges of watermelon leaves were charred and seemed to be damaged by acids. Zucchini and melon, and other cucurbits, showed strong damage to the leaves when treated with a concentration of 10 g m^-3, and sodium silicate, at concentrations of 10% and 20%, was used to reduce phytotoxicity. Therefore, acute toxicity towards nontarget organisms and phytotoxicity during the fumigation of EF should be reduced for efficient agricultural pest control.

• Journal of Sericultural and Entomological Science
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• v.18 no.2
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• pp.65-78
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• 1976

The mulberry small weevil, Baris deplanata ROELOFS, has highly infested mulberry trees in Korea. As the damage caused by the mulberry small weevil in mulberry fields has been increased over the country since 1969, the authors has carried out a series of biological and controlling studies on the pest from 1971 to 1972. The results obtained are summarized as follows. 1. The adult weevil is elongate oval in shape with black in color and the probocis is long as usual in curculionidae. The size of adult female is 3.30${\pm}$0.04mm in length, 1.47${\pm}$0.04mm in width, and the length of proboscis is 1.25${\pm}$0.014mm, while adult male is 3.28${\pm}$0.06mm in length, 1.40${\pm}$0.04mm in width, and the length of proboscis is 1.30${\pm}$0.02mm. The antenna is geniculate consisting of 12 segments. The terminal sternite of the abdomen has a pointed tip in male but not in female. 2. The egg is long oval in shape, milky white in color, 0.51${\pm}$0.05mm in length and 0.32${\pm}$0.02mm in width. 3. The mature larva is cylindrical and light yellowow in color except the head of dark brown, and legless, 3.88${\pm}$0.06mm in length, 1.40${\pm}$0.02mm width, each segment bearing many wrinkless and short setae. 4. The pupa is long oval, milky white and exarate, 3.53${\pm}$0.09 in length, 1.40${\pm}$0.03mm in width. 5. Majority of the species has one generation through a year and overwinters as adult in xylem of withered branch and come out again from late April to early May in next year. But some of the female oviposit in the same year and the offsprings overwinter as larva (0.4%) or pupa (0.1%) 6. The eggs are mostly laid under the cork layer of withered branch and the number of eggs deposited by an adult female is 73.44${\pm}$8.74, the average egg-laying period is 33.88${\pm}$6.04 days. The incubation period is 11.69${\pm}$0.39 days, the larval period 45.04${\pm}$1.63 and the pupal period 11.05${\pm}$0.49 days. The period of adult's activity is 46.7${\pm}$5.90 days. 7. The larvae feed on the cambium under the bark and adults feed on the winter bud, the latent bud, the leaf stalk and the base of newly shoot. 8. An active period of adults was observed during the period of 4 months from April to July. However, the peak of adult-density occurred in the early May (in the fields of spring-prunning) and early to middle June(in the fields of summer-prunning). 9. There is a positive correlation between the density of larvae and diameter and length of the branches. 10. The pattern of distributions of the adult of mulberry small weevil is negative binomial distribution. 11. The chalcid fly was disclosed to be a natural enemy which was parasite on the larvae of mulberry small weevil and its parasitic ratio was 11.9%. 12. Phosvel D, Malix D, Salithion EC, DDVP EC, and Phosvel EC were effective for the control of adults and Satchukoto-S EC, and Salithio EC were effective for the control of larvae.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.8 no.1
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• pp.129-177
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• 1970

For the purpose of establishing the systematized technical scheme of the cooperative rice cultivation which has most significant impact to improve rice productivity and the farm management, the author have studied the cultivation practices, and the variation of rice growth and yield between the cooperative rice cultivation and the individual rice cultivation at random selected 18 paddy fields. The author also have investigated through comparative method on the cultivation practices, management, organization and operation scheme of the two different rice cultivation methods at 460 paddy fields. The economic feasibility has been ana lysed and added in this report. The results obtained from this study are summarized as follows; 1. In the nursery, the average amount of fertilizer application, especially, phosphate and potassium, and the frequency of chemicals spray for the disease, insect and pest control at the cooperative rice cultivation are significantly higher than those of the individual rice cultivation. 2. The cultivation techniques of the cooperative rice farming after the transplanting can be characterized by a) the earlier transplanting of rice, b) the denser hills per unit area and the lesser number of seedlings per hill, c) the application of larger quantities of fertilizer including nitrogen, phosphate and potassium, d) more divided application of fertilizers, split doses of the nitrogen and potassium, e) the increased frequencies of the chemicals spray for the prevention of disease, insect and pest damages. 3. The rate of lodging in the cooperative rice cultivation was slightly higher than that of the individual rice cultivation, however, the losses of rice yield owing to the occurrence of rice stem borer and grass leaf roller in the cooperative rice cultivation were lower than that of the individual rice cultivation. 4. The culm length, panicle length, straw weight and grain-straw ratio are respectively higher at the cooperative rice cultivation, moreover, the higher variation of the above factors due to different localities of the paddy fields found at the individual rice cultivation. 5. The number of panicles, number of flowers per panicle and the weight of 1, 000 grains, those contributing components to the rice yield were significantly greater in the cooperative rice cultivation, however, not clear difference in the maturing rate was observed. The variation coefficient of the yield component in the cooperative cultivation showed lower than that or the individual rice cultivation. 6. The average yield of brown rice per 10 are in the cooperative rice cultivation obtained 459.0 kilograms while that of the individual rice cultivation brought 374.8 kilograms. The yield of brown rice in the cooperative rice cultivation increased 84.2 kilogram per 10 are over the individual rice cultivation. With lower variation coefficient of the brown rice yield in the cooperative rice cultivation, it can be said that uniformed higher yield could be obtained through the cooperative rice cultivation. 7. Highly significant positive correlations shown between the seeding date and the number of flowers per panicle, the chemical spray and the number of flowers per panicle, the transplanting date and the number of flowers per panicle, phosphate application and yield, potassium application and maturing rate, the split application of fertilizers and yield. Whilst the significant negative correlation was shown between the transplanting date and the maturing rate 8. The results of investigation from 480 paddy fields obtained through comparative method on the following items are identical in general with those obtained at 18 paddy fields: Application of fertilizers, chemical spray for the control of disease, insects and pests both in the nursery and the paddy field, transplanting date, transplanting density, split application of fertilizers and yield n the paddy fields. a) The number of rice varieties used in the cooperative rice cultivation were 13 varieties while the individual rice cultivation used 47 varieties. b) The cooperative rice cultivation has more successfully adopted improved cultivation techniques such as the practice of seed disinfection, adoption of recommended seeding amount, fall ploughing, application of red soil, introduction of power tillers, the rectangular-type transplanting, midsummer drainage and the periodical irrigation. 9. The following results were also obtained from the same investigation and they are: a) In the cooperative rice cultivation, the greater part of the important practices have been carried out through cooperative operation including seed disinfection, ploughing, application of red soil and compost, the control of disease, insects and pests, harvest, threshing and transportation of the products. b) The labor input to the nursery bed and water control in the cooperative rice cultivation was less than that of the individual rice cultivation while the higher rate of labor input was resulted in the red soil and compost application. 10. From the investigation on the organization and operation scheme of the cooperative rice cultivation, the following results were obtained: a) The size of cooperative rice cultivation farm was varied from. 3 ha to 7 ha and 5 ha farm. occupied 55.9 percent of the total farms. And a single cooperative farm was consisted of 10 to 20 plots of paddies. b) The educational back ground of the staff members involved in the cooperative rice cultivation was superior than that of the individual rice cultivation. c) All of the farmers who participated to the questionaires have responded that the cooperative rice cultivation could promise the increased rice yield mainly through the introduction of the improved method of fertilizer application and the effective control of diseases, insects and pests damages. And the majority of farmers were also in the opinion that preparation of the materials and labor input can be timely carried out and the labor requirement for the rice cultivation possibly be saved through the cooperative rice cultivation. d) The farmers who have expressed their wishes to continue and to make further development of the cooperative rice cultivation was 74.5 percent of total farmers participated to the questionaires. 11. From the analysis of economical feasibility on the two different methods of cultivation, the following results were obtained: a) The value of operation cost for the compost, chemical fertilizers, agricultural chemicals and labor input in the cooperative rice cultivation was respectively higher by 335 won, 199 won, 288 won and 303 won over the individual rice cultivation. However, the other production costs showed no distinct differences between the two cultivation methods. b) Although the total value of expenses for the fertilizers, agricultural chemicals, labor input and etc. in the cooperative rice cultivation were approximately doubled to the amount of the individual rice cultivation, the net income, substracted operation costs from the gross income, was obtained 24, 302 won in the cooperative rice cultivation and 20, 168 won was obtained from the individual rice cultivation. Thereby, it can be said that net income from the cooperative rice cultivation increased 4, 134 won over the individual rice cultivation. It was revealed in this study that the cooperative rice cultivation has not only contributed to increment of the farm income through higher yield but also showed as an effective means to introduce highly improved cultivation techniques to the farmers. It may also be concluded, therefore, the cooperative rice cultivation shall continuously renovate the rice production process of the farmers.

• Korean Journal of Organic Agriculture
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• v.10 no.3
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• pp.67-77
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• 2002

This study was conducted to investigate an effects on ago-chemical alternative materials such as the wood vinegar, a lactic acid bacteria serum, the fermented plant juice, the brown rice vinegar and a Chitosan used for amount and qualities of fruits and to examine the pest protection efficiency for their uses in the apple and pear orchard farms. An apple yields in the orchard cultivated with using the ago-chemical alternative materials without appling the fertilizer and pesticides were decreased at 56% relative to the conventional farming practice method. Also, it was indicated that there was difficult to produce the fruits with marketability because the small sizes of fruits were produced. For the quality of fruits, the brix of apple produced in the orchard cultivated with using the ago-chemical alternative materials was similar, but Vitamin C content was greater than that of the conventional farming practice method. As a results of treating with the wood vinegar, a lactic acid bacteria serum, the fermented plant juice, the brown rice vinegar and a Chitosan instead of applying pesticides, the fruit disease in the Chitosan treatment was a little decreased, but was great occurred in the other treatments compared with the conventional farming practice mehod. However, it observed that brix and Vitamin C content of apple produced in the Chitosan, brown rice vinegar, fermented plan juice and fish amino acid treatments and in the Chitosan, brown rice vinegar, charcoal power and peat moss treatments were greater than those of the conventional farming practice method, respectively. Over all, it considered that there was very difficult to manage the orchard depended on the ago-chemical alternative materials without appling the chemical fertilizer and pesticides in the apple orchard, but it might be proper to use the ago-chemical alternative materials as an auxiliary means to decrease the appling amount of chemical fertilizer and pesticides. Furthermore, the general effects on the ago-chemical alternative materials to the perennial fruits should be investigated with considering the changes of soil fertility, soil microbial status and natural enemy creatures after treating them for a long time.

• The Korean Journal of Pesticide Science
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• v.17 no.4
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• pp.264-270
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• 2013

Imidacloprid is a systemic insecticide which act as an insect neurotoxin. It used for control of pest such as aphids and other sucking insects in fruits and vegetables. Systemic pesticides move inside a crop following absorption by the plant, and these were converted into a variety of metabolites. Sometimes these metabolites make a problem about safety of agricultural products. So a simultaneous determination method of pesticide and its metabolites is needed, to monitor their presence in agricultural product and study on the fate of pesticide in a plant. This study's aim is to investigate simultaneous analysis method of imidacloprid and its metabolites, imidacloprid guanidine, imidacloprid olefin, imidacloprid urea, and 6-chloronicotinic acid in red pepper using QuEChERS method and LC-MS/MS systems. QuEChERS method was modifed beacuase $MgSO_4$ salts decreased the recoveries of 6-chloronicotinic acid in extraction procedure. Imidacloprid and its metabolites were extracted by acetonitrile with 1% glacial acetic acid and the extracts were purified through QuEChERS with primary secondary amine (PSA) and $C_{18}$ and analyzed with LC-MS/MS in ESI positive mode. Standard calibration curves were made by matrix matched standards and their correlation coefficients were higher than 0.999. Recovery studies were carried out on spiked pepper blank sample at four concentration levels (0.01, 0.04 and 0.1, 0.4 mg/kg). The average recoveries of imidacloprid and its metabolites were in the range of 70~120% with < 20% RSD. This result indicated that the method using QuEChERS and LC-MS/MS was suitable for the simultaneous determination of imidacloprid and its metabolites in red pepper.

• Korean journal of applied entomology
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• v.54 no.2
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• pp.91-97
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• 2015

The sweetpotato whitefly, Bemisia tabaci, is the major insect pest that transmitted over 100 plant viruses including tomato yellow leaf curl virus (TYLCV) of tomato plant as virus vector in the world. In this study, cDNA library of whitefly was constructed using Gateway system for selecting target gene in order to control of B. tabaci using virus-induced gene silencing (VIGS) vector with RNAi. First of all, when using oligo d(T) rimer, the calculated titer of cDNA library was confirmed with $1.4{\times}10^4$ clones and average insert sizes was confirmed with 1 kb. However, insert size was very big for construction of cDNA. Otherwise, when using attB-N25 random primer and sonication for 6 sec, the calculated titer of cDNA library was confirmed with $1.04{\times}10^5$ clones. But mostly insert band wasn't identified on the electrophoresis, because it seemed that insert size is too small (${\leq}100bp$), also the size of identified insert was somewhat big. Finally, when using oligo d(T) primer and sonication for 1 sec, cDNA insert of whitefly was appropriated for VIGS with 300-600 bp. However, cDNA sequence included a poly A and titer was very low to $5.2{\times}10^2$ clones. It was supposed that heat shock transformation was used instead of electro-transformation. It is considered that when constructing cDNA library for using VIGS vector, (1) random primer should be used for First strand cDNA synthesis in order to remove poly A and (2) sonication for 1 sec should be performed in order to get appropriated insert size and (3) electro-transformation should be performed in order to improve transformation efficiency.

• Korean journal of applied entomology
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• v.49 no.3
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• pp.205-210
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• 2010

The bean bug, Riptortus pedestris (=clavatus) Fabricius (Hemiptera: Alydidae) is a serious pest of soybean in many countries. It enters a reproductive diapause in the winter by short day length (<13.5 h.) in Korea and Japan. The combined effects of temperatures ($25^{\circ}C$ and $8^{\circ}C$) and day lengths (10L:14D and 14L:10D) upon the termination of the male's diapause were studied. The combinations are (1) HTLD = $25^{\circ}C$, 14L:10D treatment for 1, 2, 3 weeks and 30 days; (2) HTSD = $25^{\circ}C$, 10L:14D treatment for 1, 2, and 3 weeks; (3) LTLD$\rightarrow$HTLD = $8^{\circ}C$, 14L:10D treatment for 1, 2, and 3 weeks followed by HTLD treatment; (4) LTSD$\rightarrow$HTLD = $8^{\circ}C$, 10L:14D treatment for 1, 2, and 3 weeks followed by HTLD. The amount of aggregation pheromone components secreted was adopted as the criteria for diapause termination in males. Males did not secrete aggregation pheromone under HTSD conditions. However, the males treated with HTLD for more than 21 days secreted significantly higher amounts of aggregation components, (E)-2-hexenyl (Z)-3-hexenoate and (E)-2-hexenyl (E)-2-hexenoate, compared to the control or HTSD treatments. The three components of the aggregation pheromone were secreted by the 14%, 29%, and 100% males treated with HTLD for 7 days, respectively. However more than 83% of the HTLD-treated males secreted all three components by the $30^{th}$ day under the treatment. In comparison, the pheromone amounts secreted by the males treated with LTLD$\rightarrow$HTLD or LTSD$\rightarrow$HTLD were equal or less than those secreted by males with continuous HTLD treatment.

• Korean journal of applied entomology
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• v.57 no.2
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• pp.57-64
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• 2018

The fungus gnat, Bradysia difformis, has been recognized as an important pest of greenhouse crops. There is a need for research on the control of the fungus gnat. However, it is difficult to obtain many generations of the fungus gnat for several kinds of research. Indoor propagation is a very useful method for obtaining enough individuals in cases where the need is for larvae in soil. This study was conducted to determine the optimum growing media and temperature conditions for rearing the fungus gnat in the laboratory. Under experimental temperature conditions, hatching, pupation, and eclosion rates were the highest at $20^{\circ}C$. The developmental period of the fungus gnat was shortened with higher temperatures. The greatest number of eggs was an average of 144 at $20^{\circ}C$. Using different types of larvae growth media, the highest hatching rates were 84.7 and 84.4% in water agar and potato disks, respectively. The larval period was the shortest, at 14.7 days, when grown on potato disks. The highest pupation and eclosion rates were 85.2 and 82.6% on potato disks, respectively. The highest number of eggs was an average of 125.6 on potato disks. Regarding the effects of different growth media on the eclosion rate of B. difformis, the highest eclosion rate was 88.4% on the soil mix, and was 50% on oatmeal, 25% on shredded potato. The results of four different inoculation levels of larvae on eclosion rate of B. difformis showed that the highest eclosion rate was 84.7% for 1,000 larvae. The eclosion rate was shortened with a higher number of larvae inoculated/cage. In the growth medium used, 3,000 eggs were better for the initial level of inoculation, showing a relatively high emergence rate and short developmental period. Mass rearing procedures were explained in detail.

• Korean journal of applied entomology
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• v.49 no.2
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• pp.115-121
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• 2010

The bean bug, Riptortus clavatus Thunberg (Hemiptera: Alydidae), is a pest of soybeans and tree fruits. It enters reproductive diapause during winter. We studied the effect of different combinations of temperature, day length, and treatment period on the termination of diapause in R. clavatus using adult females collected in October and November 2006. Ovarian development was used to determine diapause termination. The treatments were: (1) HTLD; $25^{\circ}C$, 14L:10D treatment for 1, 2, 3 weeks and 30 days, (2) HTSD; $25^{\circ}C$, 10L:14D treatment for 1, 2, and 3 weeks, (3) LTLD; $8^{\circ}C$, 14L:10D treatment for 1, 2, and 3 weeks followed by HTLD for 3 weeks, and (4) LTSD; $8^{\circ}C$, 10L:14D treatment for 1, 2, and 3 weeks followed by HTLD for 3 weeks. The HTSD treatments did not affect ovarian development, and resulted in no significant difference in the number of mature eggs in ovaries or the percentage of diapause-terminated females compared to the control females before treatment. The percentage of females that terminated diapause was significantly higher in the HTLD treatment than in the HTSD treatment. The HTLD treatment for more than 14 days increased the percentage of diapause-terminated females, accelerated the development of the ovaries, and increased the number of mature eggs in ovaries. Compared with the HTLD or HTSD treatments, the LTLD or LTSD treatments followed by the HTLD treatment accelerated ovarian development and increased the number of ovipositing females. The pre-LTSD treatment for 1 week was enough to increase the number of eggs oviposited.