최근 기후가 온난화됨에 따라 전북지역에서도 콜라비의 재배면적이 증가하고 있다. 콜라비는 십자화과 식물로 해충의 발생과 피해는 많으나 방제정보가 부족하여 농가에 어려움이 많다. 본시험은 콜라비에 발생하는 담배거세미나방의 경제적 피해허용수준을 설정하여 농가에 방제 기준을 마련하고자 수행하였다. 콜라비를 주간20cm, 조간 30cm로 2014년 5월 8일 정식하고, 가로100cm, 세로 100cm, 높이 100cm의 방충망을 설치한 후 정식 19일 후(5. 27.) 1~2령충 담배거세미나방을 10주당 0, 10, 20, 50, 100마리를 접종하였다. 정식 25일(6.2.), 32일(6.9.), 39일(6.16.), 46일후(6.23.) 자를 이용하여 초장을 조사하였고, 엽수와 피해엽률, 엽당마리를 육안으로 계수하였다. 정식 53일후(6.30) 처리별 뿌리수량을 조사한 결과 담배거세미나방의 접종밀도가 증가할수록 콜라비 뿌리의 수량이 감소하였다. 뿌리수량 감소율에 따른 회귀식을 산출한 결과 y=0.2113x+2.5325이었다. 이를 근거로 5%의 경제적 피해수준은 10주당 11.7마리가 산출되었고, 여기에 20%의 경제적 피해허용수준을 적용한 결과 9.3마리였다. 따라서 농가에서 콜라비 재배시 10주당 9.3마리, 주당 0.9마리의 담배거세미나방 유충이 발생할 경우 방제를 하는 것이 좋을 것으로 생각되었다.

시설 배추 벼룩잎벌레의 발생밀도와 피해량을 상호 분석하고 요방제 수준 설정을 통해 신속하고 합리적인 방제체계를 확립하고자 본 시험을 수행하였다. 시설 봄배추 생육초기 벼룩잎벌레 성충 접종밀도(X)와 수량감소율(Y) 관계는 Y = 1.3475X + 2.135, R2 = 0.8699이었다. 시설봄배추 생육중기 벼룩잎벌레 성충 접종밀도(X)와 수량감소율(Y) 관계는 Y = 0.703X - 1.78, R2 = 0.966이었다. 이와 같은 결과를 토대로 시설배추 봄 재배시 접종한 성충밀도와 배추 피해지수간의 상관성을 바탕으로, 수량 감소율(gain threshold, 수익역치) 5%로 전제한 벼룩잎벌레 요방제 밀도는 배추 생육초기 발생시 10주당 2.1 마리, 생육중기 발생시 10주당 9.6마리로 분석되었다.

 ,  , This study was conducted to develop economic injury level (EIL) of onion thrips, Thrips tabaci, on welsh onion (Allium fistulosum L. var) in the early transplanting stage. The changes of welsh onion biomass, yield loss, and T. tabaci density were investigated according to the inoculation periods of T. tabaci. In the early transplanting stage of welsh onion, the yield loss (%) increased with increasing inoculation periods: 17.0, 53.3, 38.4, and 80.8% yield loss in 5, 10, 15, and 20 d inoculation periods, respectively. The relationship between Cumulative Insect Days (CID) of T. tabaci and yield loss (%) of welsh onion was well described by a nonlinear logistic equation. Using the estimated equation, EIL of T. tabaci on welsh onion was estimated to 30 CID per plant based on the yield loss 12% (an empirical gain threshold 5% + marketable rate 93% of welsh onion). ET was calculated to 24 CID, which corresponds to 80% of EIL. Until a more defined EIL-model is developed, the present results should be useful for T. tabaci management in early growth stage of welsh onion. The effect of T. tabaci attack on the yield of welsh onion in late growing season (120 days after transplanting) was also examined. The yield of welsh onion increased at a low population density of T. tabaci and decreased at higher densities, showing a typical over-compensatory response.

Economic injury levels (EILs) and economic control threshold (ET) were estimated for the Tea red spider mite, Tetranychus kanzawai Kishida(Acari, Tetranychidae) in Rubus coreanus Miquel. T. kanzawai density increased until the early-July and thereafter decreased in all plots except the non-innoculation plot where initial density of the mite were different each 0，5, 10, 20 and 40 adults per plant branch on May 7 in 2008. And the occurrence of the densities were increased higher innoculated density than different innoculation density. The yield was decreased with increasing initial mite density and thereby the rates of yield loss was increased with increasing initial mite density. And T. kanzawai occurrence density, yields and the rates of yield loss, where initial density of the mite were different each 0,2, 5, 10 and 20 adults per plant branch on May 8 in 2009 were similar tendency to 2008 year results. The relationship between initial T. kanzawai densities and the yield losses was well described by a linear regression, Y = 0.6545X + 3.0425 (R<SUP>2</SUP> = 0.93) in 2008, Y = 0.9031X + 2.0899(R<SUP>2</SUP> = 0.96) in 2009. Based on the relationship, the number of adults per plant branch(EILs) which can cause 5% loss of yield was estimated to be approximately 3.0 in 2008 and 3.2 in 2009. And the ET was estimated to be approximately 2.4 in 2008 and 2.6 in 2009. The relationship between initial T. kanzawai densities and occurrence density of mid-May considering the best spray timing against T. kanzawai was well described by a linear regression, Y = 0.471X + 2.495(R<SUP>2</SUP> = 0.95) in 2008, Y = 0.9938X + 3.1858(R<SUP>2</SUP> 二 0.96) in 2009. Based on the relationship, the number of adults per Ieaf(ET) in mid-May which can cause 5% loss of yield was estimated to be approximately 3.6 in 2008 and 5.8 in 2009.

국화에서는 파밤나방은 7~10월에 주로 발생하여 잎과 줄기, 꽃잎에 피해를 주는 해충이다. 시설에서 재배되는 국화에 대하여 파밤나방에 대한 경제적피해수준 및 요방제 수준을 추정하였다. 파밤나방의 접종시기와 접종량에 따른 수량과 관계를 조사하였다. 국화 백선을 정식후 14일과 정식후 83일(꽃눈형성기)에 파밤나방을 100주와 20주에 각각 0, 5, 10, 20, 40마리를 접종하였다. 100주에서 20마리 접종 과 40마리 접종에서 9월13일 피해엽율은 각각 58.3%, 57.6%를 나타내었다. 파밤 나방 무방제구에 대한 수량은 47,142.9본/10a이었으며 수량감소율은 72.5%로 12964.2본/10a 였다. 꽃눈형성기에 국화 파밤나방의 유충밀도와 수량감소율과의 상관관계식은 Y = 18.5X-13.5 (R2=0.9661)의 회귀식을 얻을 수 있었고 파밤나방 접종밀도에 따른 피해엽율과 수량감소율의 관계는 정의 상관관계가 있는 것으로 나타났다. 경제적허용수준은 20주당 유충 1마리이며 방제가 필요한 수준은 20주 당 유충 0.8마리였다.

This study was conducted to develop economic injury level (EIL) and economic threshold (ET) of Cabbage armyworm, Mamestra brassicae L. on cabbage (Brassica oleracea L. var). The changes of cabbage biomass and M. brassicae density were investigated after introduction of larval M. brassicae (2nd instar) at different densities: 0, 1, 2, 4, 8, and 16 larvae per plant at 40 d after planting for an open field experiment, and 0, 2, 5, 8 and 12 larvae per plant at 25 d after planting for a glass house experiment. In the field experiment, the yield loss of cabbage was not significantly different among treated-plots at 30 d after the larval introduction, showing an over-compensatory response of cabbage plants to M. brassicae attack. In the glasshouse experiment, however, the biomass of cabbage at 15 d after the larval introduction significantly decreased with increasing the initial introduced number of M. brassicae, resulting in 38.3, 36.7, 21.7, 23.3 and 16.7g in above treated-plots, respectively. The relationship between cumulative insect days (CID) and yield loss (%) of cabbage was well described by a nonlinear logistic equation. Using the estimated equation, EIL of M. brassicae on cabbage was estimated at 44 CID per plant based on the yield loss 14%, which take into account of an empirical gain threshold 5% and marketable rate 91% of cabbage. Also, ET was calculated at 80% of the EIL: 35 CID per plant. Until a more elaborate EIL-model is developed, the present result may be useful for M. brassicae management at early growth stage of cabbage.

양배추 유묘에서 도둑나방(Mamestra brassicae L.) 유충의 경제적 피해허용 수준과 요방제 수준을 설정하기 위하여 도둑나방 유충 접종 밀도에 따른 양 배추의 생육, 피해 및 수량을 조사하였다. 정식 25일 양배추 유묘에 주당 0, 2, 5, 8, 12마리의 도둑나방 2령 유충들을 접종한 결과 15일 후 양배추의 평균 생체중은 무처리에서 38.3g, 2마리 접종구에서 36.7g, 5마리 접종구에서 21.7g, 8마리 접종구에서 23.3g, 12마리 접종구에서 16.7g,으로 도둑나방 유충의 접종 수가 증가할수록 양배추의 생체중은 유의하게 줄어들었다. 도둑나방 유충 발 생과 수량손실과의 관계를 구명하기 위하여 누적발생일수(cumulative insect days)와 양배추 유묘의 손실률(%)과의 관계를 회귀분석한 결과 비선형식인 logistic 모형에 잘 적용되었다. 이 식으로부터 수익한계인(gain threshold) 5%와 양배추 상품화율(91%)을 감안한 수량 감소율 14%에서 도둑나방 2령 유충 경 제적피해수준을 추정한 결과 CID 값으로 44가 되었다. 또한 요방제 밀도는 경제적 피해수준의 80%가 되는 35 CID로 추정되었다. 본 결과는 양배추 유묘 시기 도둑나방 유충관리에 활용될 수 있을 것으로 판단된다.

Economic injury level and control thresholds for the management of beet army worm, Spodoptera exigua (Lepidoptera: Noctuidae) were evaluated on chinese cabbage of two different planting time. Two inoculation times were tested for each planting and the number of inoculated larva was 10, 20, 40, 80, respectively. Damages of leaves by first inoculation were 63.2% after eight days planting on 80 larva inoculation plot. By the second inoculation, those were below 50% after 20 days planting on the end of September. The linear relationships between population density and yield reduction were as following, Y = -10.62x + 867.9 (R² = 0.643) for 5 days and Y=-6.432x + 1074 (R² = 0.720) for 20 days. Based on these results the economic injury level was 5.4 larva for five days and 9.0 larva for 20 days per 20 chinese cabbage. The control thresholds calculated by 80% level of economic injury level were 4.3 and 7.2 larva, respectively.

This study was conducted to estimate the economic injury level (EIL) and economic threshold (ET) of the green peach aphid, Myzus persicae, on Chinese cabbage (Brassica campestris var). The changes of biomass of Chinese cabbage and M. persicae density were investigated after introduction of M. persicae at different density (0, 2, 5, 10, 15, and 20 per plant, inoculated at 10d after planting). The densities of M. persicae largely increased from the above initial densities to 0, 92.3, 177.4, 406.9, 440.4, and 471.3 aphids per plant at 18d after the initial inoculation, respectively. The biomass of Chinese cabbage significantly decreased with increasing the initial inoculated density of M. persicae: 602.0, 264.2, 262.0, 109.3, 151.0, and 67.3 g in above plots with different initial densities, respectively. The relationship between cumulative aphid days (CAD) and yield loss (%) of Chinese cabbage was well described by a nonlinear logistic equation. Using the estimated equation, EIL of M. persicae on Chinese cabbage was estimated 25 CAD per plant based on the yield loss 13%, which take into account of an empirical gain threshold 5% and marketable rate 92% of spring Chinese cabbage. Also, ET was calculated at 80% of EIL: 20 aphids per plant. Until a more elaborate EIL-model is developed, the present result may be useful for M. persicae management at early growth stage of Chinese cabbage.

Economic injury levels (EILs) and economic threshold (ET) were estimated for the two spider mite, Tetranychus urticae Koch (Acari, Tetranychidae) on greenhouse eggplants. T. urticae density increased until the mid-July and thereafter decreased in all plots where initial density of the mite were different each 0, 2, 5, 10 and 20 adults per plant was innoculated on June 7. Growth variables of were not different among experimental plots but fruit weights were lower in plots with higher initial mite density than in plots with lower initial mite density. Total number of fruits and the number of marketable fruits decreased in plots with higher initial mite density. The rates of yield loss increased with increasing initial mite density, resulting in 0, 3.9, 11.3, 14.5, 22.8% reduction in each of the above plots, respectively. The relationship between initial T. urticae densities and yield losses was well described by a linear regression, Y = 1.085X + 2.474, R² = 0.9659. Based on the relationship, the number of adults per plant which can cause 5% loss of yield was estimated to be approximately 1.8.

Pyrausta panopealis is the major pest in green perilla. The larva weaves a web on the shoot of green perilla and damages. In case of extreme, The larva cuts the main branch of green perilla and the leaf of green perilla isn’t harvested anymore. A field study was conducted to estimate economic injury levels (EILs) and control thresholds (CTs) for P. panopealis injuring green perilla in green-houses. Different densities of P. panopealis ranged from 1 to 20 crops (2 units per crop) per 100 crops on 13. June, early inoculation. The number of injured leaf and the rate of injured crop were increased by 23. June, on the other hand were decreased after that day. Also, the amount of yield sow the same result above. The economic loss time calculated by the ratio of cost managing this moth to market price (C/V) (C: cost managing a moth, V: Market price) was 4.0%. The economic injury level was 5.1 larval per 100 crops. The control thresholds calculated by 80% level of economic injury level was 4.1 larval per 100 crops.

Economic injury levels and economic thresholds were estimated for the american serpentine leafminer (Liriomyza trifolii) on greenhouse eggplant. Liriomyza trifolii density was increased until the late June and decreased after the July in innoculation on may 17. Growth of an aerial plants and fruits were not different in treatment respectively. But total number of fruits and yields were decreased on higher inoculation density. Whereas the rate of yield loss was increased. The rates of damaged leaf by L. trifolii were increased on higher inoculation density and the peak was 65%. The number of commodity fruits and the rates of commodity fruit were become lower than non-treatment (72.2%). The rates of damaged leaf area were 5.3, 11.7, 19.7, 25.7% on inoculation densities and the rates of yield loss were 0.6, 4.8, 9.8, 14.7%, respectively. There existed close correlation between rate of yield loss and inoculation density (Y = 0.76779X + 0.298354, R² = 0.9599). Considerated of the results, the economic injury levels of L. trifolii on eggplant greenhouse was 6.1 adults per 4 plant and the economic thresholds was 4.9 adults per 4 plant

The damage aspects of soybean by common cutworm, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) at different larval density and different growth stage of soybean were studied in soybean field. The percent yield reduction(Y) of soybean infested by different densities of S. litura (X, no. of larvae/plant) under outdoor conditions for a three week period were estimated by the following equations: (1) Y = 1.655X - 6.025 (R² = 0.952) for the R1 (flowering stage), (2) Y = 0.725X - 0.475 (R² = 0.986) for the R3 (beginning pod stage), and (3) Y=0.635X - 1.325 (R² = 0.986) for the R5 (beginning seed stage). Based on the relationships between the densities of S. litura larvae and the yield index of soybean, the number of larvae (2nd-3rd instar) which caused 5% loss of yield (Tolerable injury level) was estimated to as approximately 6.7 for the R1, 7.5 for the R3, and 10.0 per plant for the R5, respectively. Average soybean leaf areas consumed by 1st, 2nd, 3rd, 4th, 5th and 6th larvae of Spodoptera litura during 24 hr at 28℃ was 0.3, 0.7, 2.6, 4.0, 20.1, and 55.8 ㎠, respectively.

This study was carried out to determine the economic injury level of the rice leaffolder, Cnaphalocrocis medinalis G.. The damage aspects of rice plant (at tilling stage) by leaf folders at different larval density per plant were studied in pot experiment (24 ㎝ in diameter, 18 ㎝ in height). One leaf folder consumed 6-7 leaves during larval stage. The damage by leaf folders was simulated by cutting off 0, 10, 30, 50, 70, and 90% of leaves before and after heading stage July 15th (at panicle initiation stage) and August 15th (at milk stage), respectively. When leaves were cut before the heading of rice, the linear relationships between the leaf cutting rate (X) and each factors of yield (Y) were as following, for grain maturity it was Y = -9.379X + 83.630 (R² = 0.493), Y = 0.139X + 0.490 (R² = 0.925) for yield, and Y = -4.880X + 81.116 (R² = 0.665) for head rice. When leaves were cut after the beading of rice, it was Y = -23.014X + 83.589 (R² = 0.915) for grain maturity, Y = 0.141X + 3.466 (R² = 0.842) for yield, and Y = -13.795X + 81.964 (R² = 0.898) for head rice. We found that when leaf cutting after the heading stage caused more damage than before the heading in terms of yield and yield components. Based on theses results the economic threshold level was estimated to be 30% and 7% leaf loss before and after heading stage.

According to the preceding survey on insect pests of the green perilla, Perilla frutescens var. japonica HARA, The major pests were Aphis egomae Shinji, Pyrausta panopealis (Walker), Tetranychus urticae Koch, Polyphagotarsonemus latus Banks, Tetranychus kanzawai Kishida at Guemsan, Chungnam, 2004. Aphis egomae causes nearly 100% injury of the green perilla in uncontrolled green houses. A field study was conducted to estimate economic injury levels (ElLs) and control thresholds (CTs) for A. egomae injuring green perilla in green houses. Different densities of A. egomae ranged from 1 to 80 aphids per 100 plants in early inoculation. The mean injurying rate of plant was 2.4% to 40.5% at the end of June at differently inoculated levels. The economic loss time calculated by the ratio of cost managing aphid to market price (C/V) (C: cost managing aphid, V: Market price) in early season (from May to 13. June) was 5.8% and in peak season (from 13. June to 30. June) was 9.3%. Economic injury level in early and peak season was 5.3 aphids per plant and economic injury levels in peak season were 0.6 aphids per plant and 7.6% injured rate of plant. The control thresholds calculated by 80% level of economic injury level in peak season were 0.5aphids per plant and 6.1% injury rate of plant, respectively.