Among migratory insect pests, Mythimna seperata and Cnaphalocrocis medinalis are invasive pests introduced into South Korea through westerlies from southern China. M. seperata and C. medinalis are insect pests that use rice as a host. They injure rice leaves and inhibit rice growth. To understand the distribution of M. seperata and C. medinalis, it is important to understand environmental factors such as temperature and humidity of their habitat. This study predicted current and future habitat suitability models for understanding the distribution of M. seperata and C. medinalis. Occurrence data, SSPs (Shared Socio-economic Pathways) scenario, and RCP (Representative Concentration Pathway) were applied to MaxEnt (Maximum Entropy), a machine learning model among SDM (Species Distribution Model). As a result, M. seperata and C. medinalis are aggregated on the west and south coasts where they have a host after migration from China. As a result of MaxEnt analysis, the contribution was high in the order of Land-cover data and DEM (Digital Elevation Model). In bioclimatic variables, BIO_4 (Temperature seasonality) was high in M. seperata and BIO_2 (Mean Diurnal Range) was found in C. medinalis. The habitat suitability model predicted that M. seperata and C. medinalis could inhabit most rice paddies.

Bacillus thuringiensis (Bt) produces a variety of insecticidal crystal proteins and widely used as one of the most successful biological control agents. Recently, studies that introduce cry genes into crops to create pest resistance have made much progress, and the total area of land planted with Bt crops has increased substantially. In this study, pest resistance of 8 transgenic Bt rice events with a synthetic cry1Ac gene linked to rice rbcS-tp sequence were assessed under laboratory conditions. Bioassays were performed against Cnaphalocrocis medinalis, which is a significant pest of rice in Asia. C. medinalis larvae were shown to be susceptible to all eight events, even though there were differences between the causes of death. The results differed between developmental stages of the larvae, despite the fact that all 8 events led to high mortalities. These results may be a significant foundation for the evaluation of improved transgenic Bt rice.

We newly sequenced mitochondrial genomes of Spodoptera litura and Cnaphalocrocis medinalis (Lepidoptera) to obtain further insight into mitochondrial genome evolution and investigated the influence of optimal strategies on phylogenetic reconstruction of Lepidoptera. Estimation of p-distances of each mitochondrial gene for available taxonomic levels has shown the highest value in ND6, whereas the lowest values in COI and COII at the nucleotide level, suggesting different utility of each gene for different hierarchical group when individual genes are utilized for phylogenetic analysis. Phylogenetic analyses mainly yielded the relationships (((((Bombycoidea + Geometroidea) + Noctuoidea) + Pyraloidea) + Papilionoidea) + Tortricoidea), evidencing the polyphyly of Macrolepidoptera. The tests of optimality strategies, such as exclusion of third codon positions, inclusion of rRNA and tRNA genes, data partitioning, RY recoding approach, and recoding nucleotides into amino acids suggested that the majority of the strategies did not substantially alter phylogenetic topologies or nodal supports, except for some familial relationship only in the amino acid dataset.

혹명나방(Cnaphalocrocis medinalis (Guenee))은 인도 서부지역부터, 일본 북부지방까지 분포 가능한 해충으로 우리나라에서는 월동하지 못하고 매년 비래하여 벼에 피해를 주는 해충이다. 혹명나방 개체군 밀도의 효과적인 억제를 위해 적절한 방제시기를 예측하고 방제 수단을 동원하기 위해 발생량 및 발생 최성기를 추정 할 수 있는 수단이 필요하다. 따라서 본 연구는 온도 의존적 수리적 모델과 상용 프로그램을 이용하여 보다 정확한 혹명나방 개체군의 발육 및 밀도 변동을 예측하기 위하여 수행되었다. 예측 모델은 상용프로그램인 DYMEX® (Maywald et. al., 2007)를 이용하여 구축하였으며, 구축된 모델은 Lifecyle 모듈을 포함한 8개의 모듈로 구성하였다. Lifecycle 모듈은 알, 어린유충, 노숙유충, 번데기, 성충의 5개 발육 단계로 구성하였으며, 각 영기의 발육율 계산에 사용된 비선형 모델은 변형된 Sharpe & DeMichele 함수를 사용하였다. 발육완료 함수는 2-parameter weibull 함수를 사용하였으며, 성충 산란모델은 총산란수함수, 사망률함수, 누적산란율 함수로 구성하였다. 성충의 성비는 0.5로 가정하였으며, 구축된 모델은 2005년 국립농업과학원 시험연구사업보고서 (박 등, 2005)에 수록된 자료를 이용하여 평가하였다. 평가 결과 초기밀도를 2005년 8월 4일 성충 46.0마리로 설정 후 프로그램을 구동한 결과 다음세대 성충 밀도 최성기는 9월 14일로 예측되어 육안조사 결과와 일치하였으나 성충 밀도는 1099.1마리로 추정되어 육안으로 조사된 364.9마리보다 약 3배 가까이 많았다. 실제 포장 밀도가 모델에 의해 추정된 밀도보다 크게 낮은 이유 중 하나는 본 모델에서는 실내 실험 결과 발생한 자연 사망률만 반영한데 반해 포장에서는 천적 등 다양한 사망요인이 관여하였던 결과로 추정되었다.

The insecticidal effect for several commercially available environment friendly agricultural materials (EFAMs) is investigated to Cnaphalocrocis medinalis, Narana aenescens, Pseudaletia unipuncta and Parnara guttata on rice. In the insecticidal effects for 2-3rd instar larvae of lepidopteran after treatment with 19 EFAMs, more than 95% of mortality rate showed 5 EFAMs in C. medinalis, 12 EFAMs in N. aenescens, 9 EFAMs in P. unipuncta, and 14 EFAMs in P. guttata, respectively. Among 4 EFAMs selected for C. medinalis in indoor, more than 70% in control effect is seen EFAM-B(85.2%), EFAM-I(79.1%) and EFAM-M (78.3%), respectively, in rice field. The insecticidal effect for EFAMs is investigated to Nilaparvata lugens, Laodelphax striatellus and Nephotettix cincticeps on rice. In the insecticidal effects for 2-3rd nymph and adult after treatment with 19 EFAMs, more than 95% of mortality rate showed 5 EFAMs in N. lugens adult, 7 EFAMs in N. lugens nymph, 6 EFAMs in L. striatellus, and 5 EFAMs in N. cincticeps, respectively. Insecticidal effect for N. lugens was sustained until 10 day in rice treated with 7 EFAMs selected in indoor. Among them, EFAM-L, EFAM-P and EFAM-R was sustained in low density until 27 day. But EFAM-D, EFAM-L, EFAM-N and EFAM-S showed high density until 27 day and additional control was needed.

Two complete mitochondrial genomes of the tobacco cutworm, Spodoptera litura (Lepidoptera: Noctuoidea) and the rice leaf roller, Cnaphalocrocis medinalis (Lepidoptera: Pyralidae), were sequenced. Each 15,388 bp and 15,368 bp-long genome contained both the lepidopteran specific gene arrangement that differ from the most common arrangement of insects by the movement of tRNAMet to a position 5’-upstream of tRNAIle. Neither of the species have typical COI start codon. Instead, the CGA (arginine) sequence that is commonly present in other lepidopterans was also found both in S. litura and C. medinalis. The evolutionary rates among 13 protein-coding genes (PCGs) in Lepidoptera showed ATP8 the highest, whereas COI the lowest. The high A+T-content, which is characteristic of mitochondrial genome was well reflected in the two lepidopteran mitochondrial genomes: higher frequency of A/T-rich codons, severe A/T bias in 3rd codon position, and extremely high A/T content in the A+T-rich region. Because insect mitochondrial genomes harbor biased nucleotide and resultantly biased amino acid sequences, phylogenetic inference is often misled by them. Although each recoded and unrecoded datasets for nucleotide sequences and amino acid sequences of PCGs provided overall identical topology, regardless of recoded scheme, each nucleotide and amino acid dataset provided difference in the status of Macrolepidoptera, providing a monophyletic group by amino acid dataset, whereas non-monophyletic group by nucleotide dataset.

This paper presents the occurrence and damage characteristics of the rice leaf-folder populations in the paddy fields of Dangsu-dong, Suwon from 2004 to 2007, and also reports the insecticide response of rice leaf-folder populations, which were collected from 2005 to 2006 in Korea and Vietnam. Laboratory measurements of the head capsule width and body length data enabled the identification of the rice leaf-folder larva stages collected in the field. The rice leaf-folder population in Suwon from 2004 to 2007 has a clear pattern consisting of two different group: the low and high density years. During the low density years (2004 and 2006), only one adult peak was noted in late August, with the damaged-hill percent less than 10% in late July, and the damaged-leaf percent around 2% in September. In contrast, during the high density years (2005 and 2007), two adult peaks were noted in early August and mid-September, with the damaged-hill percent was around 30% in late July, and the damaged-leaf percent 15 to 30% in September, which was beyond the economic injury level of rice leaf-folder. High correlations existed between the occurrence of rice leaf-folder in late July and early August and damages to rice during September. Based on these results, we suggest that the information on the rice leaf-folder population monitored by the adult density or damaged-hill percent in late July and early August would be very useful for predicting the damages later in the season for aiding in decision-making for timely control. In addition, the regional populations of rice leaf-folder showed the similar responses to the insecticides tested: high susceptibility to IGRs (tebufenozide and methoxyfenozide) and organophosphates (chlorpyrifos-methyl, pyridaphenthion), but relatively low to cartap.

This study was conducted to evaluate the attractiveness of the sex pheromone trap of Cnaphalocrocis medinalis Guenée as a forecasting tool from 2006 to 2008 in Suwon, Gyeong-gi province and Seosan, Chung-nam province, Korea. The sex pheromone lure was composed of Z11-18:Ald (55㎍): Z13-18:Ald (500㎍): Z11-18:OH (120㎍): Z13-18:OH (180㎍): Z13-18:Ac (55㎍) per a rubber septum, which set in a cylindrical cone trap. The trap catches of male moths was counted on a weekly basis and the lures were renewed every two weeks. The flight activity of C. medinalis moths monitored by the sex pheromone trap revealed two distinct peaks a year in both experimental areas from 2006 to 2008. Degree-days accumulation was calculated using lower developmental threshold (13.3℃) and degree-days (386.4DD) since adults had been first recorded. Estimated adult peak of the first generation was almost coincident with that observed by sex pheromone trap except in Suwon in 2008.

This study was carried out to investigate the effect of each single component of the synthetic sex pheromone in the rice green caterpillar, Naranga aenescens and rice leaf roller, Cnaphalocrocis medinalis. Trap catches with each single component or binary mixtures of the sex pheromone in N. aenescens were significantly lower than that with an optimum mixture (2: 1: 4) of Z9-14:Ac, Z9-16:Ac and Z11-16:Ac. But only few number of C. medinalis male was caught in trap baited with each component of the sex pheromone excepting Z13-18:Ald. In an optimum composition of the sex pheromone in C. medinalis, trap catches baited with an 11: 100: 11 mixture of Z11-18:Ald, Z13-18:Ald, and Z13-18:Ac without two alcohol components (Z11-18:OH and Z13-18:OH) was higher than that baited with an optimum mixture of Z11-18:Ald, Z13-18:Ald, Z11-18:OH, Z13-18:OH, and Z13-18:Ac. The efficacy of the sex pheromone lure of N. aenescens kept over 4 weeks. The occurrence of N. aenescens caught in trap baited with sex pheromone gave three peaks and C. medinalis showed two distinct peaks throughout the flight season. Therefore, it can be expected that pheromone-baited trap provides a simple tool for monitoring N. aenescens and C. medinalis in Korea.

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.

This paper reports a simple rearing system for Cnaphalocrocis medinalis based on com seedlings diet. C. medinalis population under this system has been maintained by four stages (egg, young larva-1st to 3rd instar, old larva-4th to prepupa, and adult) at 25±2℃, 40±10% RH, and 16L:8D photoperiod in a laboratory. We have elaborated a new egg collection method using a polystyrene container (top Ø11.3 × bottom Ø9 × H8㎝) which has made a great contribution in easy collection of eggs and storage of them for long period. Under this system, pupation and adult emergence rate and pupal weight of C. medinalis population were close to the other reports by corn seedling diet and superior to those by artificial diets. Therefore this rearing system would be useful in obtaining C. medinalsis population suitable to each specific needs.