Trichogramma is widely used in biological control of many Lepidoptera insect pests in the world. Although many species of host eggs, e.g. Sitotroga cerealela, Corcyra cephalonica, Ephestia kuehniella, Mamestra brassicae and even artificial host eggs are explored in mass production of Trichogramma, eggs dissected from the ovaries in female of Chinese (Oak) tussah moth (Antheraea pernyi) are still the most popular host eggs in China. Here I introduce technology processes of Trichogramma mass production that are popularly used in China, including: 1) selecting female cocoons from mixed sexes commercial cocoons, 2) cold storage of cocoons, 3) warming up the cocoons, 4) collecting female moths and dissecting ovaries, 5) separating, washing and drying host eggs, 6) multiplying Trichogramma with the host eggs, 7) producing Trichogramma products, i.e. the host egg cards, 8) storing Trichogramma under low temperatures, 9) releasing Trichogramma in the field. Nevertheless, problems are frequently encountered in these processes, e.g. high mortality of long-term storage and multiplying too many generations etc. To solve these problems and explore a method for long-term storage, we studied the diapause of T. dendrolimi in detail. We found that the optimal processes for diapause induction were exposing hosts for parasitization at 26℃ for 8 h before keeping them at 26℃ for another 40 h, and finally moving them into 10℃ for 4 weeks. The optimal processes for diapause termination were setting the diapause Trichogramma under 1℃ for two months and then exposing them at 26℃ until their emergence.

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.

옥수수 포장에서 발생하는 Trichogramma 속(genus) 조명나방 알기생벌의 종 (species) 분포를 조사하기 위해 홍천 외 7개 지역에서 6 ~ 8월에 수집된 알기생벌로 부터 핵내 리보솜 RNA 유전자의 ITS2(internal transcribed spacer 2) DNA 염기서 열 정보를 213 개 해독하였다. 종 구별을 위한 참고정보로서 GenBank 데이터베이 스에 등록되어 있고 종이 명확하게 확인된 Trichogramma 속 ITS2 염기서열 정보 를 58 종 총 404 개 확보하여 MEGA 5를 이용하여 국내에서 조사된 결과와 비교 분 석하였다. ITS2 DNA 염기서열 정보를 이용한 phylogenetic tree 결과들을 통해서 GenBank에 등록되어 있는 같은 종들이 여러 가지(branch)의 그룹에 흩어져 있어 일부 종들을 제외하고 명확한 구별이 어려웠다. 국내의 결과는 3 개의 가지(branch) 그룹으로 나눠졌으며 조명나방 알기생벌로 Trichogramma dendrolimi Matsumura 를 포함하여 최소한 3 개의 종이 있을 것으로 추정되었다. 앞으로 조명나방 알기생 천적을 이용한 생물적 방제 방법을 개발을 위해서는 명확한 종 동정이 되어야하며 그러기 위해서 수컷의 생식기에 관한 형태적 분석들이 필요할 것으로 보인다.

In Hymenoptera, thanks to its haplodiploid sex determination, arrhenotokous parasitoid females are able to control offspring sex ratio by determining whether to use sperm or not at the time of oviposition. However, the offspring sex ratio may also be influenced by the mating behavior of a male. When a male searches females, he will have more chances to encounter with other males in a high male density population than low male density population. If the male is competitive, the male can find females faster and may have longer copulation time, and eventually transfer more sperm than other males. In this study, we investigated mate searching time, copulation duration and offspring sex ratio as a function of the male density. Although the results show difference between searching time and copulation duration, they are not statistically significant. We will discuss the statistical consequence, male density dependent offspring sex ratio and its evolutionary implications.

The α-proteobacterium Wolbachia is maternally inherited and is known to induce reproductive distortions in a wide range of insect taxa such as cytoplasmic incompatibility, feminization, male killing and parthenogenesis (PI). When a female is infected with PI-Wolbachia, she does not need a male to produce female offspring, because the female can produce female offspring via gamete duplication without the aid of sperm. However, in the parasitoid wasp Trichogramma kaykai species, Wolbachia infected parthenogenetic females still produce a fraction of male offspring. Offspring sex ratio for 10 days are different according to each T. kaykai isofemale line that is infected with PI- Wolbachia. This may be caused by complex interactions between Wolbachia and the host genetic backgrounds on converting sex of infected eggs.

Haplodiploid sex determination occurs in a wide range of animals, especially in Hymenoptera, where a fertilized egg develops into a diploid female and unfertilized into a haploid male. However, recent studies on diploid functional males in some wasps suggest that the simple addition of paternal gene by fertilization may not be enough to explain female offspring production in the sex determination system. Recently, activation of sex determination gene (tra) was found to have a pivotal role in determining the sex of Nasonia vitripennis. In N. vitripennis, tra is activated only on the paternal genome (i.e. sperm) not on the maternal counterpart (i.e. egg). Such parent specific activation of a gene is controlled by a epigenetic factor, DNA methylation. However, in Trichogramma kaykai, Wolbachia induces female offspring production without sperm. Therefore all female offspring are clonal to the maternal gene. This violates the role of activated sex determination gene (tra) from sperm in the wasp. We hypothesize that Wolbachia has an ability to activate the gene by demethylation. This hypothesis indicates that the target of sex ratio distorting endosymbionts may be an upstream gene. It will enhance our understanding of evolution of haplodiploid sex determination.

The α-proteobacterium Wolbachia pipientis infects a wide range of arthropods and filarial nematodes. Wolbachia is maternally inherited and is known to induce reproductive anomalies such as cytoplasmic incompatibility, feminization, male killing and parthenogenesis induction (PI). Trichogramma kaykai is a tiny wasp that parasitizes on lepidopteran eggs. When a female of the wasp is infected with PI-Wolbachia, the female produces female offspring via gamete duplication without the aid of sperm. As she ages, however, the fraction of male offspring increases. In this study, we investigated the effect of host genetic background on the expression of sex ratio between isofemale lines. Virgin females of six isofemale lines were allowed to lay eggs individually for 10 days. There was the positive relationship between female age and the offspring sex ratio. Furthermore, the sex ratio was significantly different among isofemale lines, implying that the host genetic background had an effect on the sex ratio. Based on the results, evolution of symbiosis in terms of sex ratio and future experimental design are discussed.

The Wolbachia bacterium is known to induce reproductive anomalies in various insect taxa such as cytoplasmic incompatibility, feminization, male killing and parthenogenesis. It is hypothesized that the degree of reproductive anomalies is dependent on the bacterial infection density. In this study, we attempted to test the hypothesis using the tiny egg wasp, Trichogramma kaykai that has served as the model system of parthenogenesis where an unfertilized egg develops into a female due to the bacterial infection. So far this is only found in haplodiploid organisms. The results show that 1) as mothers aged, they started producing male offspring, 2) the sex ratio was negatively correlated with the bacterial infection density, 3) female offspring were more than six times heavily infected with Wolbachia than male offspring in the species. In conclusion, female offspring production, parthenogenesis, is as a function of the Wolbachia bacterial density in this species.

The parasitism, development time, hatchability, and progeny production of Trichogramma chilonis(TC) females developed in eggs of Helicoverpa assulta (HAs), Cadra cautella (CC), and Helicoverpa armigera (HAr), repectively, were compared with those developed in reciprocal eggs at constant temperatures of 25±2℃ and relative humidity of 50～70% under 16L-8D. Developmental performances of TC reared in each of the three hosts on the following hosts(host tested) appeared differently, and were affected most by the size of the proceeding hosts and test host. Among the parameters parasitism and progeny production were affected more than others. Parasitism was significantly different between the treatments, lowest in CC-HAr(10.1±2.05%) and highest in HAr-HAs(47.0±2.09%), and the hatchability showed similar pattern. Development time as well was shortest in the CC-HAr where previous host is smallest and test host is biggest. The highest number of progeny production of TC was observed in HAr-HAs(93.9±6.87 wasps), and the lowest was CC-HAs(18.4±6.36 wasps).

A commercial egg parasitoid, Trichogramma sp. Nabis101, was released into agricultural cultivating areas in Korea due to its wide host spectrum against insect pests. Moreover, an application technique has been recently developed to enhance its control efficacy by mixture treatment with a microbial control agent. Despite its expansion of commercial availability, any genetic identification on this commercial strain was not determined. Also, to meet inconsistent demands from consumers, the live parasitoids need to be stored without significant loss of their survival and parasitic activity. This study determined nucleotide sequence of internal transcribed spacer (ITS) of the wasp species. The identified ITS sequences indicate that this wasp species is most similar to T. brasiliensis. Optimal storage condition of this wasp required young parasitized stage at 10℃. Under these conditions, survival, sex ratio, longevity, and parasitic behavior were not much impaired for 5 weeks.

배추좀나방은 비닐하우스 등 시설재배가 늘어남에 따라 십자화과 채소의 연중재배가 이루어지면서 경제적인 피해가 심한 농작물 해충 중 하나이다. 이 해충은 세대기간이 짧고 화학농약의 집중살포로 인해 저항성이 빠르게 발달 되어 방제가 어렵고 미생물제제인 B.t에 대해서도 저항성이 보고되고 있는 실 정이다. 최근 이러한 문제해결과 친환경적 방제를 위하여 천적의 이용이 증가 하고 있지만, 천적과 미생물제제를 동시에 이용하여 종합적 해충방제를 하기 위한 시도들과 그에 따른 방제효과에 대한 정보들이 미흡한 실정이다. 따라서 배추좀나방 방제를 위해 이용되는 천적인 조명알벌의 기생율과 국내에서 시 판중인 B.t 약제의 혼합 처리시 방제효과에 대한 기초 자료를 얻고자 실험을 실시하였다. 배추좀나방에 이용되고 있는 천적 중 알에 기생하는 조명알벌과 B.t 생물농 약 T제품을 투입시기를 달리하여 처리 후 조명알벌의 기생율과 배추좀나방 유충 생존율, 피해엽수 등을 조사하여 각각의 처리와의 방제효과를 비교하고 자 하였다. B.t 약제를 처리 후 천적을 투입하였을 때 이전보다 좋은 방제효과 를 나타내었는데, 이와같이 혼합처리를 통한 배추좀나방 모든 발육단계의 동 시방제를 통하여 보다 효과적이고 안정적인 친환경방제를 할 수 있을 것으로 기대된다. 추후 대표적인 농업해충인 파밤나방과 거세미나방에 대한 조명알벌 의 기생율과 배추 포장실험을 통하여 보다 효과적인 방제방법을 연구할 계획 이다.

Due to internal feeding behavior, the oriental tobacco budworm, Helicoverpa assulta (Guenée), infesting hot pepper has been regarded to be effectively controlled by targeting egg and neonate larval stages just before entering the fruits. This study aimed to develop an efficient biological control method focusing on these susceptible stages of H. assulta. An egg parasitoid wasp, Trichogramma evanescens Westwood, was confirmed to parasitize the eggs of H. assulta. A mixture of Gram-positive soil bacterium, Bacillus thuringiensis subsp. kurstaki, and Gram-negative entomopathogenic bacterium, Xenorhabdus nematophila ANU101, could effectively kill neonate larvae of H. assulta. A sex pheromone trap monitored the occurrence of field H. assulta adults. The microbial insecticide mixture was proved to give no detrimental effects on immature development and adult survival of the wasp by both feeding and contact toxicity tests. A combined treatment of egg parasitoid and microbial pesticide was applied to hot pepper fields infested by H. assulta. The mixture treatment of both biological control agents significantly decreased the fruit damage, which was comparable to the chemical insecticide treatment, though either single biological control agent did not show any significant control efficacy. This study also provides morphological and genetic characters of T. evanescens.

The paternal sex ratio (PSR) chromosome is considered as an extremely selfish genetic element. It has only been found in the two hymenopteran insects- Nasonia and Trichogramma- with haplodiploid sex determination. When an egg is fertilized by sperm bearing PSR, the paternal genome is destroyed by PSR soon after fertilization resulting in haploid restoration and the egg develops into a male with only the maternal genome and PSR itself. Recently PSR is paid much attention, since it may be used for controlling haplodiploid pests. PSR can be successfully transferred from its natural host, T. kaykai to the novel host, T. deion. In the two hosts another sex ratio distorter, Wolbachia, is found. Wolbachia is a cytoplasmically inherited bacterium that induces parthenogenesis in this genus resulting in female offspring production without fertilization. The transmission efficiency of PSR in T. deion is lower than that in T. kaykai and is negatively influenced by the Wolbachia infection. The results show that 1) there is a negative host genetic background effect on the transmission of PSR in the novel host, 2) the transmission efficiency becomes even lower, when PSR males are infected with Wolbachia. The results imply that complex interactions among the bacterium, PSR and the species specific genetic background.

산누에나방의 알에 대하여, 광주기를 각각 달리하였을 때 송충알벌의 산란수, 기생률, 그리고 우화율에 미치는 영향을 조사하였다. 그리고 16L:8D 광주기 조건에서 24시간 동안에 인공기주에서의 산란경향과 우화수를 조사하였다. 송충알벌의 산란수는 서로 다른 기주조건에서 기주를 처음 접한 후 날짜가 지나면서 감소하였다. 서로 다른 광조건(16L, 12L, 18L)에서 자연기주인 산누에나방의 알에 대한 산란수는 첫째날 기주당 산란수가 각각 10.7(16:8LD), 20.5(12:12LD), 19.6(8:16LD)개이었고, 그 후 급격히 감소하여 일차별로 10일 동안 16:8LD에서 13.7, 64.4, 25.5, 18.5, 14.6, 12.3, 1.3개로 조사되었다. 한편 인공기주에 대한 산란수는 16:8LD 광조건에서 1일재 가장 낮아 42.1%, 그후 2일과 3일째에 63.5%, 80.5%로 일차별로 증가한데 비하여 인공기주에서는 급격히 감소하여 1일쨍에 84.6%, 그후 2일과 3일째는 각각 52.2, 16.8%로 조사되었다. 인공기주에서의 시간대별 우화수 조사는 암조건에서 명조건으로 바뀌는 05:00시에서 06:00시 사이에 평균 61.2개체로 13.9%를 차지하여 비교적 높게 나타났다.

담배나방의 각태별 발생소장을 조사하여 정확한 방제적기를 알고자 Black light-trap 및 실수조사로 조사하여 다음과 같은 결과를 얻었다. (1) 성충은 연3회 발생하며 5월하순부터 월동용에서 우화하여 제일회는 6월하순-7월상, 중순, 제2회는 8월중, 하순, 제3회는 9월 중, 하순이었다. (2) 란은 7월초순부터 계속 증가하다가 8월하순-9월초에 최감기를 보여주었다. 그러나 회수는 뚜렷치 않았다. (3) 유충은 3회발생으로 회수가 뚜렷치 않고 7월초부터 발견되며 7월하순-8월초순에 최감기를 보이고 10월중순까지도 계속 볼 수 있었다. (4) 란기생봉의 기생율은 시기적으로 차이가 있으나 란의 밀도와 기생율과는 관계가 있으며 9월하순까지 평균 의 기생율을 보였다. (5) 란 1위에 기생하는 기생봉수는 1-4마리이고 그 빈도는 1마리의 기생이 , 2마리의 기생이이었다.