본 연구는 북방농업지대에서 벼 해충의 지역 간 발생상황을 비교하기 위하여 곤충의 발육에 필요한 온도를 이용하여 발생 시기를 추정하는 방법으로 발생세대수나 발생 시기 등을 비교하였다. 벼 해충 6종(벼물바구미, 벼잎벌레, 흰등멸구, 벼멸구, 혹명나방, 멸강나방)에 대해 유효적산 온도를 이용하여 발생 시기를 추정한 결과 월동해충은 지역에 따라 발생 시기에 차이가 있었으며, 동북방향으로 갈수록 발생시기가 늦어져, 북부 고산이나 동해안북부에서는 발생시기가 가장 늦었다. 또한 해충의 발생시기가 6월부터 8월 사이에는 비래해충 1세대 성충 발생시기와 같이 지역 간 발생 시기에 차이가 적어 비슷한 시기에 발생하였으며, 기온이 낮아지는 8월부터 9월에 발생시기가 되면 지역 간 차이가 커서 벼멸구의 2세대 성충이 발생하지 못하거나, 흰등멸구, 혹명나방, 멸강나방 등의 2~3세대 성충의 발생이 안 되는 지역이 많아지고 있음을 알 수 있었다. 이러한 특징으로 보아 북방지역의 동북지역, 동해안북부, 북부내륙, 북부고산지역에서의 벼해충 발생은 적을 것으로 추정되며, 중부산간의 평강, 양덕을 제외한 동해안남부, 수양산 이남, 이북지역은 국내 경기, 강원북부지역과 비슷한 발생을 보일 것으로 추정되었다.

한반도 북방농업지대에서 발생하는 6종 벼 주요해충들의 발생 시기를 곤충 발육모델에 근간하여 추정하였다. 대상 해충들의 발생 시기를 유효적산온도를 이용하여 추정한 결과, 월동 해충들의 발생 시기는 지역 간 차이가 뚜렷하였고, 한반도 북부지역 동북쪽 지역 및 동해안 북부 지역으로 갈수록 발생시기가 늦어졌다. 6-8월 사이 해충 발생 시기는 비래해충 1세대 성충의 발생시기와 같이 지역 간 차이가 적었고, 8-9월에는 지역 간 해충 발생 시기에 있어 차이가 뚜렷한 경향을 보였다. 결과적으로 한반도 북방농업지대에서 동북지역, 동해안북부, 북부내륙, 북부고산 지역에서의 벼 해충 발생은 적을 것으로 보인다. 또한 평강 및 양덕을 제외한 북방지역 동해안남부, 수양산이남·이북지 역은 국내 경기·강원 북부지역에서 발생하는 벼 해충들의 특징과 유사할 것으로 추정된다.

An insect is a ectothermal animal that is vulnerable to the temperature change. As climate change accelerated, the distribution of insects have been rapidly changed. Rice is the most important crop in Korea as it is a staple for Korean people. In the rice paddy, migratory pests from south-east Asia have seriously damaged on the crop. As climate changed, the spatial distribution of pest and their effects on rice paddy may be changed. Therefore, monitoring the pest populations is a basis for establishing further research for pest management strategy against these migratory insect pests. As the first year for this monitoring project, we set 20 rice paddies in Gyeonggi-do and Chungcheongnam-do as continuous monitoring sites for five major migratory pests and summarized the first year’s data. Based on it, we will develop better monitoring plan as well as analysis methods.

Both Nilaparvata lugens Stål and Laodelphax striatellus Fallén has been known as the major rice pests which were irregularly migrated into Korea by wind current from China. We re-arranged and compared the resistance profiles to detect the existence convergent adaptation by using the previously published dataset (N. lugens at 2014, 17:711-716 and L. Striatellus at 2016, 19:247-252 in J. Asia Pac. Entomol., respectively). Both species commonly exhibited the high level of resistance to imidacloprids. Especially, the immigrant populations of L. Striatellus exhibited higher resistance level to indigenous populations, suggesting that they would settle down in Korea with insecticide resistance traits being predisposed. To detect the convergent adaptation to insecticide, pearson correlation analysis were employed by comparing mean dosage of LD50 and resistance ratio to nine insecticides. Strikingly, high and similar dosage responses were observed between the two species with high correlation coefficients of 0.928 (df=7, P <0.001) and 0.950 (df=7, P <0.001), respectively, in the comparison of LD50 vs. resistance ratio. This finding indicates that convergent adaption has occurred in both species through consistent selection by insecticides with similar usage patterns.

Impacts of climate change IPPC report (2007) predicts that by the end of 21 st century there will be an expected climate change. Evidences include increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level, and that most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in greenhouse gas conditions. Other global manifestations of climate change are the natural hazards that are becoming more frequent and more intense such as more floods, more droughts, more intense storms, typhoons and more heatwaves. Since the 1970’s, more intense and longer drought have been observed over wider areas, particularly in the tropics. Frequency of heavy rains has also increased over most land areas. In the Philippines, analysis of the observed climatic data showed that there has been an increased in annual mean temperature by 0.57 o C. In terms of maximum and minimum temperatures, the increases have been 0.35 and 0.94 o C. Results of analysis of trends of tropical cyclone occurrence showed that an average of 20 tropical cyclones per year, that there still no indication of increase in the frequency, but with slight increase in the number of tropical cyclones with maximum sustained winds of greater than 150kph. The analysis of trends of extreme daily temperatures and extreme daily rainfall indicate significant increase in number of hot days but decrease of cool nights, and those of rainfall (extreme rainfall intensity and frequency) are not clear, both in magnitude and direction. The findingson the analysis of future climates showed that all areas of the Philippines will get warmer especially in the summer months. Annual mean temperatures (average of maximum and minimum temperatures) in all areas in the country are expected to rise by 0.9 o C in 2020 by 1.8 to 2.2 o C in 2050. In terms of seasonal rainfall change, generally, there is a substantial spatial difference in the projected changes in rainfall in 2020 and 2050 in most parts of the Philippines, with reduction in rainfall in most provinces during the summer season making the usually dry season drier. During the southwest monsoon season, larger increases in rainfall is expected in provinces in Luzon (0.9% to 63%) and Visayas (2% to 22%) but generally decreasing trends in most of the provinces in Mindanao in 2050. However, projections for extreme events in 2020 and 2050 showed that hot temperatures (indicated by the number of days with maximum temperature exceeding 35 o C) will continue to become more frequent, number of dry days will increase in all parts of the country and heavy daily rainfall events will also continue to increase in number in Luzon and Visayas. Climate change effects on rice Increase in temperature may lead to yield reduction as caused by heat stress, decreased sink formation, shortened growing period, and increase maintenance respiration. Given the 10% yield reduction for every 1 o C increase in temperature, an estimated 1.5 M M/t of rice harvest will be lost. Since the Philippines is considered to be vulnerable to extreme meteorological events like typhoons, floods and droughts, it was estimated that approximately 84% of the about 2.32 M hectares of rice land will be affected by climate change. Climate change effect on insect pests and natural enemies Temperature is very important factor influencing insect behavior, distribution, development, survival and reproduction (Bale et. al., 2002). In Japan, it has been estimated that with a 2 o C temperature increase insects might experience one to five additional life cycles per season (Yamamura and Kiritani 1998). Moreover, climate change may affect the population dynamics of arthropods that will lead to change in the species composition of ecosystem, pests’ migration and change in the geographic distribution of pests. Naturally occurring biological control is expected to become a more important control tactic in the future although, warming might also have a negative effect on some natural enemies such as hymenopterans and small predators. Furthermore, there are attempts to correlate relative humidity with insect development and survival. A study showed that the population of Nilaparvata lugens reached high levels when plants of the Peta variety were transplanted close together, probably because of the high relative humidity created in the insect’s habitat (IRRI, 1973). A more detailed study was conducted in the IRRI phytotron and results showed that that N. lugens had high survival in 50-60% relative humidity as compared to 80% relative humidity (IRRI, 1976). Work in the Philippines showed that more insect pests were observed in wet season as compared to dry season (Calora and Ferino, 1968; Hsieh, 1972; Ferino, 1968; Alam, 1971). Hence, if there will be more frequent and severe climate extremes like more rainfall and flooding, some pests may become more serious. On the other hand, a long drought followed by rainfall may cause outbreak of locust, armyworms, and leaffolders. Adaptation to adverse impacts of climate change In the Philippines, rice varieties for adverse environments are available such as submergence and drought-tolerant varieties. The use of aerobic rice production system maybe useful in the future especially if there will be limited water supply since in this technology, the water use is only half of that of lowland rice systems. In rice insect pest management, understanding the impact of climate change to rice plant, insects pests and their natural enemies is very important in preparing for and adapting management strategies against pests that may become established due to changes in the environment. It is also necessary to assess pest problems in vulnerable areas affected by climate change. The applications of agro-meteorological information using modern information communication tools may provide timely provision of weather and climate information for farmers use.

The two major factors that are responsible for low yields are weather (floods, drought and typhoon) and pest epidemics. The tropical rice field of the Philippines is exposed to several organisms that are injurious to the rice plant. About 20 species of insects are considered important pests in the Philippines and at times contribute to low rice yield. These insect pests are divided into stem borers, sap feeders, defoliators, grain feeders and root feeders. Stem borers are chronic insect pests and always found in the field although outbreak proportions are seldom. There is no commercial variety released in the Philippines that is resistant to rice stem borer. The sap feeders are composed of several species of planthoppers, leafhoppers and a pentatomid bug. Most of the planthoppers and leafhoppers are vector of important diseases of rice like tungro, ragged stunt and grassy stunt. The grain feeders are composed of several species of Leptocorisa. A Lygaeid bug was recently reported as a new pest of rice grain in the field. The most common defoliators are leaffolders, whorl maggot and rice caseworm. Root feeders are seldom a problem in irrigated lowland rice in the Philippines. Management of rice insect pests is normally through integration of the different management strategies. These strategies include host plant resistance, biological control, cultural control and the use of insecticides as a last resort. Since a tropical rice ecosystem like the Philippine rice field is rich in communities of beneficial organisms, conservation of these naturally occurring biological control agents like predators and parasitoids is our primary control tactics against insect pests of rice. Maximizing the use of these beneficial organisms is a very important principle in Integrated Pest Management (IPM) of rice insect pests.

This research is aiming to develop generic attractants for lepidopteran pests that can be used as a control tool for environmentally friendly management against the lepidopteran pests in orchards. During the first year of this research we carried out various trapping experiments in apple orchards in Korea. Field trapping experiments were carried out at two apple orchards in UaiSung-Gun, GyungBuk Province during May – September 2010, using different rice wines and fruit-based fermenting baits. Overall, when six major moth pest species(Grapholita molesta, Carposina sasakii, Adoxophyes orana, Choristoneura longicellana, Archippus breviplicanus, Phyllonorycter ringoniella) in apple orchards were counted, 445 moths were captured in raw material-baited traps and 1,566 moths in sex pheromone-baited traps. There were no clear differences in the attractiveness to the moths between different kinds of rice wines and fruit baits when the attractiveness of fifteen different rice wines and seven fermenting fruit baits were compared in the apple orchards. One rice wine (‘Chung-ju’ rice wine) and fermenting pineapple showed somewhat higher attractiveness to G. molesta than other raw baits, which will be re-examined in 2011 – 2012 periods.

Biological control of rice insect pest is an important component of an IPM program. There are many species of natural enemies which contribute to the suppression of rice pest populations below economic injury levels. In order to use biological control more efficiently, it is a need to identify beneficial species and determine their roles in possible regulation of insect pests. There is a rich complex of biological control agents in rice and bund. This research was carried out to investigate the population density of insect pests and natural enemies in the rice field and bund. A total of 7 pest species and 15 natural enemy species were collected in the rice field. 10 pest species and 20 natural enemy species were collected in the bund, also. Changes in population density of insect pests and its prey were investigated in the rice field and bund. Population densities of insect pests were low at any time during the rice growth period in the field. This could be the high density of natural enemies. Bunds served as refuge for natural enemies when rice maturity. There are rich complex of biological control agents in rice field and bund. So, when we practice integrated pest management(IPM) of rice insect pests, we should use various natural enemies.

For biological control of larva of Cnaphalocrocis medinalis and Naranga aenescens do considerable damage to crops by folding and scraping the leaf tissue of rice, a large number of Bacillus thuringiensis isolates have been obtained from soil samples in Korea and the pesticidal activity was assayed against two insect pest species described above. Among 53 Bt isolates tested in bioassay, 18 and 13 isolates showed over 90% mortality against C. medinalis and N. aenescens, respectively. Some isolates (11 isolates including CAB141) presented dual activity against C. medinalis and N. aenescens. These isolates showed over 96% control effect in pest control in laboratory against larvae of C. medinalis. Also, it was investigated that pupation, pupal length, and adult emergence of larvae exposed to Bt suspension decreased. Especially, the pupal length of C. medinalis after being fed corn seedling leaves treated Bt suspension for 10 days, were much smaller than that of control.

우리나라 남부지방에서 벼 기계이앙 및 직파재배에 따른 수도 주요해충의 발생피해를 조사한 결과, 끝동매미충, 혹명나방은 기계이앙답에서 다소 많은 발생을 보였으나 벼멸구, 애멸구는 직파재배답에서 더 많은 밸생을 보였다. 그리고 이화명나방, 흰등멸구, 벼줄기굴파리는 그 차이를 인정하기 어려웠다. 조사 해충 모두 기계이앙이나 직파재배보다는 재배시기가 발생 피해에 더 큰 영향을 주었다. 벼멸구, 흰등멸구, 애멸구, 끝동매미충은 재배시기가 늦을수록 발생량이 많았으나, 이화명나방과 혹명나방은 그 시기가 빠를수록 발생피해가 컸다.

우리나라 남부지방에서 벼 이앙시기 및 시비수준과 주용해충 발생치해와의 관계를 조사한 결과, 조사해충은 모두 시비수준보다 이앙시기가 발생 피해에 더 큰 영향을 주었다. 특히 벼멸구 흰등멸구, 애멸구, 끝동매미충, 벼물기굴파리는 이앙시기가 늦을수록 발생량이 많았으나, 이화명나방, 혹명나방은 이앙시기가빠를수록 발생량도 많았고, 피해도 컸다. 그리고 끝동매미충과 이화명나방을 제외한 해충들은 이앙시기가 늦으면서 질소질비료가 많으며 발생량이 증가하는 경향이었다.

우리나라의 본농초기 해충군과 비래성 멸구류를 통합관리할 수 있는 살충제의 체계적 처리법을 확립하기 위하여 이앙직접 carbofuran 토양혼화처리후에 벼멸구 비래시기와 buprofezin 처리시기 및 처리약량을 달리하였을때의 벼멸구 밀도 억제효과를 조사하였다. 이앙직전 carbofuran (3G) 토양혼화처리의 효과로부터 벗어난 7월중 비래 벼멸구에 대한 buprofezin (25% WP)의 적정처리시기는 7월말~8월초이었다. 이때 buprofezin 의처리약량은 관행처리량보다 훨씬 낮은 수준인 7.0 g a.i./10a으로도 벼멸구의 증식밀도를 효과적으로억제할 수 있었다. 이와 같은 carbofuran 토양혼화처리와 buprofezin 처리는 흰등멸구에 대해서도 탁월한 방제효과를 나타내었으며 멸구류를 천적인 거미밀도에 대해서는 영향을 미치지않았다. 따라서 우리나라의 수도해충 발생특성을 고려할 때 carbofuran 과 buprofezin을 이용한 살충제 체계적 처리 즉, 이앙직전 carbofuran 토양혼화처리후 7월말-8월초 bupro-fezin처리는 본 논초기 발생해충들 및 비래성 멸구류를 효과적으로 방제할 수 있는 방제체계로 생각된다.

비 이앙직전 carbofuran 토양혼화처리의 본논초기 발생해충 방제효과 및 비래성 해충인 벼멸구에 대한 약효지속효과를 조사하여 다음과 같은 결과를 얻었다. 포장에서 5월 하순 이앙직전 carbofuran 토양혼화처리는 6월 중순 carfuran 수면시용처리나 diazinon (3G) +BPMC (50% EC) 2회처리보다 본논초기 발생해충인 애멸구, 끝동매미충, 이화명나방 1화기에 대한 방제효과가 우수하였다. 폿트에서 carfuran 토양혼화처리의 벼멸구 암컷성충에 대한 직접살충효과는 약처리 1개월후에 50%정도로 떨어졌으나 그의 차세대에 대한 밀도억제효과는 약처리 37일후까지 90%이상, 46일후에도 70%정도를 유지하였다. 따라서 이상의 결과로부터 이앙직전 carfuran 토양혼화처리는 본논초기 발생해충 전반에 대한 효과적인 방제수단이 될 수 있으며 6월중 비래하는 벼멸구에 대해서 90%이상 그리고 7월 초순에 비래하는 벼멸구에 대해서도 어느정도의 밀도 억제효과를 발휘할 수 있을 것으로 생각된다.

In reality, it is a green revolution of the entire agricultural matrix in Korea that integrated pest control plays an important role in the possible breakthrough in rice self-sufficiency. In paddy agroecosystem as man-modified environment, rice is newly established every year by transplantation under diverse water regimes which affect a microclimate. Standing water benefits rice by regulating the microclimate, but it favors the multiplication of certain pets through the amelioration of the microclimate. Further, the introduction of high yielding varieties with the changing of cultural practices results in changing occurrence pattern of certain pests. In general, japonica type varieties lack genes resistant to most of the important pests and insect-borne virus diseases, whereas indica type possesses more genes conferring varietal resistance. Thus, this differences among indica type, form the background of different approaches to pest management. The changes in rice cultivation such as double cropping, growing high-yielding varieties requiring heavy fertilization, earlier transplanting, intensvie-spacing transplanting, and intensive pesticide use as a consequence of the adoption of improves rice production technology, have intensified the pest problems rather than reduced them. The cultivation of resistant varieties are highly effective to the pest, their long term stability is threathened because of the development of new biotypes which can detroy these varieties. So far, three biotypes of N. lugens are reported in Korea. Since each resistant variety is expected to maintain several years the sequential release of another new variety with a different gene at intervals is practised as a gene rotation program. Another approach, breeding multilines that have more than two genes for resistance in a variety are successfully demonstrated. The average annual rice losses during the last 15 years of 1977-’91 are 9.3% due to insect pests without chemical control undertaken, wehreas there is a average 2.4% despite farmers’insecticide application at the same period. In other words, the average annual losses are prvented by 6.9% when chemical control is properly employed. However, the continuous use of a same group of insecticides is followed by the development of pest resistance. Resistant development of C. suppressalis, L. striatellus and N. cincticeps is observed to organophosphorous insecticides by the mid-1960s, and to carbamates by the early 1970s in various parts of the country. Thus, it is apparent that a scheduled chemical control for rice production systems becomes uneconomical and that a reduction in energy input without impairing the rice yield, is necessarily improved through the implementation of integrated pest management systems. Nationwide pest forecasting system conducted by the government organization is a unique network of investigation for purpose of making pest control timely in terms of economic thresholds. A wise plant protection is expected to establish pest management systems in appropriate integration of resistant varieties, biological agents, cultural practices and other measures in harmony with minimizing use of chemical applications as a last weapon relying on economic thresholds.