The alfalfa weevil is a destructive invasive pest of Chinese milk vetch, a main source of honey products. Because apiarists and farmers disfavor the use of insecticides, a specialist larval parasitoid wasp, Bathyplectes anurus, was introduced for biological control of the weevil. Although the introduced parasitoid initially had showed very low percentages of parasitism in early 1990’s, it gradually increased its parasitism and hence effectiveness of control. Finally, the parasitoid successfully suppresses the alfalfa weevil in 2000’s. Although this is a good example of successful biological control, one major question remains unanswered: why does the parasitoid expand and increase so slowly? Field and laboratory experiments show: (1) the parasitoid prefers alfalfa weevils on common vetch rather than those on Chinese milk vetch; (2) Chinese milk vetch fields (= rice paddies) are not the source of parasitoids, but weedy areas with common vetch plants around rice paddies are the main habitat of the parasitoid where it can successfully overwinter; (3) hunger level of adult parasitoids searching in Chinese milk vetch fields is much higher than that in common vetch fields; (4) common vetch plants have extra-floral nectary glands which are found to be a main sugar source for the introduced parasitoid; and the effectiveness of the parasitoid is rather low in areas where common vetch is rather rare. These results strongly indicate that the conservation of parasitoid habitats, in this case, weedy areas with common vetch, is a key factor affecting the success of biological control with B. anurus parasitoids. Thus, great care should be taken whether we can make the agro-environment suitable for natural enemies.

옥수수 포장에서 발생하는 Trichogramma속 조명나방 알기생벌의 종 분포를 조사하기 위해 채집된 알기생벌로부터 핵내 ITS2 DNA 전체 염기서열 정보를 해독하였다. 그리고 종 구별을 위한 참고정보로 NCBI GenBank에 등록된 Trichogramma속 60종의 ITS2 전체 염기서열을 확보하여 비교하였다. 국내 채집 알기생벌은 ITS2 DNA 길이와 3′ 말단 염기서열 패턴에 따라 3개 그룹(K-1, -2, -3)으로 구분되었다. 국내 채집 그룹 내 염기서열 차이 추정값(Evolutionary distance, d)은 0.005 이하로 그룹 간 비교 시 d 값(≥0.080)보다 낮았다. 그룹 및 GenBank 등록 종 간 비교 시 K-1은 T. ostriniae, K-2는 T. dendrolimi, K-3은 T. confusum과 d 값이 각각 0.016, 0.001, 0.002로 가장 작았다. 추론된 분자계통수에서 K-1은T. ostriniae, K-2는 T. dendrolimi와 각각 분지되었으나 K-3는 T. confusum, T. chilonis, T. bilingensis와 함께 분지되었다. NCBI BLAST 결과에서도 K-1은 T. ostriniae와 K-2는 T. dendrolimi와 99% identity를 보였다. 그러나 K-3의 홍천 채집 기생벌들은 T. confusum, T. chilonis와 99-100% identity를 보였지만, 고창 채집 기생벌은 T. bilingensis, T. confusum, T. chilonis와 98% identity를 보였다. 이상의 분석 결과 본 연구에서 채집된 알기생벌 K-1과 K-2는 각각 T. ostriniae와 T. dendrolimi, 단일한 종으로 추정되었으나 K-3는 ITS2 정보만으로 종을 추정하기 어려웠다.

Riptortus pedestris (Hemiptera: Alydidae) is known to occur in barley field during spring. But, it is unlikely that R. pedestris can find host resource to reproduce in the spring season. To test this hypothesis, we assessed the reproduction of R. pedestris population collected from field from March to September. Riptortus pedestris were collected at intervals of three days from 15th of each month. Females of R. pedestris collected from trap were provided with just water in a breeding dish, and eggs laid were collected daily. Quality of R. pedestris eggs at each month was also evaluated by providing them as host resource to two egg parasitoids. The collected eggs were divided into three groups and tested for hatchability and parasitism by two egg parasitoids, respectively. As a result, R. pedestris population collected in March and April did not reproduce, and fecundity and proportion of reproduced females were the highest in August. But, neither hatchability nor parasitism rate of R. pedestris eggs show significant difference among the sampling months. In conclusion, R. pedestris starts to reproduce from May, and fecundity reaches highest on August. No change in egg quality was found among the study periods.

진딧물 기생봉인 목화면충좀벌과 진디면충좀벌의 기주를 목화진딧물과 복숭아혹진딧물로 하여 15, 20, 25, 30℃에서 사육하면서 기주섭식수, 기생수, 우화율, 성비, 발육기간을 조사하였다. 목화진딧물이 기주일 때 15℃, 25℃에서 목화면충좀벌의 기주섭식수(5.4, 9.7마리)가 진디면충좀벌(2.0, 2.9마리)보다 많았으며 복숭아혹진딧물이 기주일 때 2종 기생봉 간 기주섭식수의 차이는 없었다. 목화진딧물에 기생한 목화면충벌의 기생수가 15℃에서 11.1마리, 30℃에서 21마리로 진디면충좀벌의 기생수(7, 12.3마리)보다 많았으며 복숭아혹진딧물에 기생시켰을 때는 20℃와 25℃에서 목화면충좀벌의 기생수(12.1, 17.1마리)가 진디면충좀벌(6.1, 10마리)보다 더 많았다. 목화진딧물을 기주로 했을 때 30℃에서 목화면충좀벌의 우화율(83.3%)이 진디면충좀벌(69.4%)보다 높았으며 복숭아혹진딧물에서는 우화율 차이가 없었다. 목화진딧물에서 사육했을 때 진디면충좀벌의 암컷비율이 15℃에서 75.2%, 30℃에서 73.9%로 목화면충좀벌의 암컷비율(19.5, 48.6%)보다 높았으며 복숭아혹진딧물에서 사육했을 때는 목화면충좀벌의 암컷비율이 15℃에서 65.3%, 25℃에서 90.0%여서 진디면충좀벌의 암컷비율(34.4, 78.8%)보다 높은 것을 알 수 있었다. 목화진딧물에서 2종 기생봉간 산란에서 우화까지의 발육기간의 차이는 없었고 복숭아혹진딧물에서는 20℃에서 목화면충좀벌의 발육기간(19.9일)이 진디면충좀벌(16.5일)보다 길었다.

Ooencyrtus nezarae Ishii and Gryon japonicum (Ashmead), egg parasitoids of Riptortus pedestris (Fabricius), coexist despite direct competition for host eggs. As asymmetrical pattern of seasonal occurrence, i.e., more G. japonicum during spring-summer and more O. nezarae during summer-fall, has been reported, host resource partitioning may occur in temporal scales. To test this hypothesis, we demonstrated the interspecific competition between the two species by measuring parasitism in nine combinations of host densities and exposure times. To reflect gregarious-solitary dichotomy, three O. nezarae and one G. japonicum mated females were used in each experiment. O. nezarae was better competitor when exposure time was longer than 1 day irrespective of host densities. Parasitism rate and progeny emergence of O. nezarae was 1.6-2.8 and 4.7-7.3 times higher than G. japonicum. O. nezarae has higher potential rate of increase than G. japonicum due to gregariousness, and be more successful in larval competition inside multiparasitized host egg as it acts as a facultative hyperparasitoid. Although G. japonicum was more effective in host finding (as they showed relatively higher per capita parasitism and progeny emergence), their progeny suffered high mortality from the larval competition with O. nezarae. These results may explain the asymmetrical occurrence pattern in the field.

Aggregation pheromone of Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) has kairomonal effect on its egg parasitoids. Thus, inclusion of non-viable host eggs of R. pedestris to aggregation pheromone trap was suggested to propagate parasitoids attracted in the trap. In this study, spatial and temporal distribution of egg parasitoids were investigated in sesame fields in Songcheon, Andong where aggregation pheromone traps were installed with non-viable host eggs. Parasitism changes were assessed after collecting non-viable host eggs released at distances of 8, 16, 24, and 32 m from the trap. Higher egg parasitism and adult emergence was found up to 16 m from the point of release. Parasitism increased over time, but decreased with distance. For the comparison of change in temporal parasitism, traps were installed without host eggs in another sesame field. Parasitism rate in sesame field without host eggs increased by 13%, whereas, in the field with host eggs, the parasitism increased up to 44%. These findings suggest that host eggs attached to the pheromone traps help the parasitoids propagate and disperse.

Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) and Gryon japonicum (Ashmead) (Hymenoptera: Scelionidae) are major egg parasitoids of Riptortus pedestris (Fabricius) (Hemiptera: Alydidae), a mobile pest on several crops in Korea and Japan. We compared the sensitivity of the two parasitoids to different temperature and relative humidity (RH) conditions to understand their phenological relations. Less than 6 hours old naïve female adult O. nezarae and G. japonicum were individually kept in 50 ml tubes without food and water sources. The tubes were placed in three humidity conditions (50-55, 70-75, and 90-95% RH) in desiccators. These desiccators were then maintained at 20, 25, and 30°C. In each temperature and RH combination 75-76 individuals were assessed for the mortality every 8 hours. G. japonicum was found to survive longer (37-116 hours) in all the temperature and RH combinations than O. nezarae (31-103 hours). Both the two parasitoids survived better in higher RH in all temperatures. The reduced sensitivity to lower humidity by G. japonicum compared to O. nezarae may explain the earlier occurrence of G. japonicum in the spring. The relations with seasonal occurrence of the two parasitoids were discussed.

To understand microhabitat distribution of insect pest is important for developing timely management tactics. We investigated within plant distribution of Riptortus clavatus Thunberg (Hemiptera: Alydidae) eggs and its’ parasitism by egg parasitoids such as Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) in soybean fields. Sampling was carried out to determine the most preferred oviposition site (upper leaf surface, under leaf surface, pod and stem) in different varieties of soybean (Daewon, Cheongja, Taegwang, Daepung, Seomoktae, Seoritae) in Andong, 2007 and 2008. Parasitism was recorded only in 2008. In seasonal total, proportion of R. clavatus eggs deposited within soybean plant was significantly higher on under leaf surface (70-97%) followed by upper leaf surface, pod, and stem (2-29%, 0-8% and 0-2%, respectively) depending on varieties of soybean. In seasonal total, parasitism rate by O. nezarae was significantly higher on the eggs collected from under leaf surface (61%) followed by eggs collected from upper surface of the leaves (43%), pods (7%) and stem (33%). In conclusion, R. clavatus prefer upper leaf surface the most as a oviposition substrate in soybean, and highest parasitism by O. nezarae on the host eggs was also found on upper leaf surface.

Trissolcus nigripedius Nakagawa and Telenomus gifuensis Ashmead (Hymenoptera: Scelionidae) are solitary egg parasitoids of Dolycoris baccarum L. (Hemiptera: Pentatomidae), a polyphagous seed-sucking bug of agricultural crops. Field examinations revealed that the two parasitoids are the most common species, but only a single species emerge from a host egg mass. To explain this observation we tested two hypotheses of interspecific host discrimination and asymmetry in competitive interaction between the two parasitoids. When provided with host eggs pre-parasitized by each other, both Tr. nigripedius and Te. gifuensis parasitized 94 and 100% of the host eggs without interspecific host discrimination, respectively. Interestingly, from the multiparasitized eggs irrespective of oviposition sequence, progeny of Te. gifuensis always survive better than Tr. nigripedius. Te. gifuensis is superior in immature competition probably due to shorter egg incubation period, hence progeny of Te. gifuensis become first instar faster than that of Tr. nigripedius. However, adult Tr. nigripedius is always superior competitor in possessing and guarding the host eggs even after oviposition against Te. gifuensis. Therefore, the asymmetry in competitive interaction between Tr. nigripedius and Te. gifuensis may explain the emergence of a single species from a host egg mass in the field in spite of no interspecific host discrimination.

For the biological control of the greenhouse whitefly, aphids, American leaf-miners, Encarsia formosa, Aphidius colemani, Diglyphus isaea, and Dacnusa sibirica were used as biological control factors. Otherwise, many kinds of environment friendly agricultural materials were also used in the kindly environment friendly fanning. For testing the toxicity of environment friendly agricultural materials against to insect parasitoids as biological control factors, 61 environment friendly agricultural materials were selected by using methods and periods with insect parasitoids in the greenhouses. Environment friendly agricultural materials were sprayed to mummies and adults of E. formosa and A. colemani, and adults of Diglyphus isaea and Dacnusa sibirica in laboratory condition. Emergence rates were checked during 12 days after spray to mummies of E. formosa and A. colemani, and survival rates were at 24 and 48 hours after viral test for adult parasitoids, with 10% sugar solution. Emergence rates of E. formosa mummies were inhibited by sprayed the fungicidal environment friendly agricultural material (FEFAM) E and the environment friendly agricultural materials contained molybdenum (EFAMMo) G as 0.4 and 2.7%, respectively. E. formosa adults were not survived in vial for 48hours after sprayed and dried with the environment friendly agricultural materials contained plant extract (EFAMPE) J and the EFAMMo C. The environment friendly agricultural materials contained microelements (EFAMMEs) B and EFAMPE H, environment friendly agricultural materials contained useful soil microorganisms (EFAMSMs) H, FEFAM A and FEFAM D were recorded low survival rates of E. formosa adults with 6.7, 13.3, 13.3, 20.0 and 20.0, respectively. In case of the spraying environment friendly agricultural materials to mummies of A. colemani there were low emergence rate from mummies to adults as around 20s % with water spraying as control. A. colemani adults were not survived in vial with EFAMMo C. EFAMPE J, EFAMPE F, EFAMPE H, EFAMSM H were recorded low survival rates under 20% as 6.7, 13.3, 13.3 and 13.3, respectively. D. isaea and D. sibirica adults were not survived in vial with EFAMPE J. EFAMMo C was 53.3% of survival rates in 48 hours vial tests. D. isaea and D. sibirica were not affected by environment friendly agricultural materials compared with E. formosa and A. colemani.

An analysis of Lysiphlebus Foerster species reared from various field-collected aphid species determined the presence of probably trans-palearctic L. fabarum (Marsh.), L. testaceipes (Cress.) which is an accidentally introduced and established immigrant from North America, and L. koraiensis Stary sp. n., a native species of presumably broader distribution. Both parthenogenetic and biparental populations of L. fabarum were identified in Korea.

솔잎혹파리가 새로운 지역에 침입하여 극심한 피해를 일으킨 후 회복하는 과정에서 솔잎혹파리와 천적 기생봉의 상호작용을 분석하였다. 솔잎혹파리 확산 선단지 26개 지점에서 1975년부터 1997년까지 조사된 솔잎혹파리 충영형성율, 기생봉 밀도 및 기생율 자료를 분석한 결과, 솔잎혹파리 침입초기인 1975년의 충영형성율은 평균 34.8% 이었으나 1980년 이후 크게 감소하여 밀도가 안정화되었다. 기생봉의 기생율은 침입초기에는 1.9%로서 낮았으나 시간이 진행됨에 따라 기생율이 증가하여 솔잎혹파리에 의한 피해가 만성적으로 발생하는 1990년대에는 12% 이상으로 크게 증가하였다. 충영형성율과 기생봉 미도와의 관계는 초기에는 서로 상관성이 매우 낮았으나 솔잎혹파리의 침입후 약 10년 이후에는 충영형성율 증가에 따라 기생봉의 밀도도 점근적으로 증가하는 양상을 나타내었다. 또한 충영형성율에 따른 기생율도 초기에는 명확한 경향성이 없었지만 솔잎혹파리 침입 10년 후에는 보다 명확한 밀도역의존적 특성을 나타내었다. 이러한 결과는 솔잎혹파리와 기생봉의 상호작용이 설정되어 있지 않지만 침입 후 약 10년경부터 기주-기생자간의 전형적인 상호작용 양상을 보이며, 기생봉의 밀도조절 능력은 솔잎혹파리 피해가 많은 발생초기에는 미약하지만 솔잎혹파리 밀도가 낮은 피해회복지역에서는 높은 밀도조절 능력을 가지고 있다는 것을 제시하였다.