Bo Yoon Seo

Attraction of the invasive Halyomorpha halys in its native Asian range to traps baited with semiochemical stimuli

The brown marmorated stink bug, Halyomorpha halys, is considered a serious invasive species capable of causing significant agricultural and nuisance problems. Researchers in the USA recently identified the two-component H. halys aggregation pheromone from populations in North America and found that when it is combined with the pheromone synergist methyl decatrienoate (MDT), it resulted in reliable, season-long captures of H. halys throughout the USA. However, no study has assessed whether H. halys populations in the native range are attracted to and can also be reliably captured by the combination of these stimuli. In this study, our goal was to evaluate the response of H. halys adults, nymphs, and non-target organisms to traps baited with the aggregation pheromone, MDT alone, or in combination at three locations in the native range. Traps baited with combined stimuli reliably captured the greatest numbers of H. halys adults and nymphs, and traps baited with either lure treatment caught a unique community of non-target organisms. In addition, Plautia stali was cross-attracted to the H. halys aggregation pheromone. Overall, we demonstrate that the pheromone-based tools developed in the USA may be used for worldwide detection and surveillance programs for H. halys and P. stali.

Monitoring of Mythimna separata Adults by Using a Remote-sensing Sex Pheromone Trap

We desinged and evaluated a remote-sensing sex pheromone trap for real-time monitoring of Mythimna separata (Lepidoptera: Noctuidae), a migratory insect in Korea. The system consisted of a modified cone-trap with a sex pheromone lure, a sensing module based on light interruption, a signal transmission module based on code division multiple access, a main electronic board for system control, a power supply based on a solar collector, a stainless steel-pole supporting the system, and a signal collection and display system based on an internet web page. The ratio (>92%) of the actual number of insects to the signal number in the remote-sensing trap was improved by sensing only within a limited period at night on the basis of the insect`s circadian rhythm, control of signal sensitivity on the basis of sensing software programming, 1-h interval for signal transmission, and adjustment of the signal transmission program. The signal occurrence pattern in the remote-sensing trap was conclusively similar (correlation coefficient, >0.98) to the actual pattern of adult occurrence in the trap. The result indicated that the remote-sensing trap based on the attraction of the sex pheromone lure for M. separata has a promising potential for practical use. Occurrence of M. separata adults was observed several times in 2011 and 2012, and the peaks were sharp.

Detectability of Halyomorpha halys (Hemiptera: Pentatomidae) by portable harmonic radar in agricultural landscapes

Abstract Harmonic radar technology enhances capability to track the movement of individual small insects under field conditions. To maximize the capacity of this technology, it is necessary that radar tags must be securely attached to insects and that the tags remain functional when subjected to mechanical stress. In this study, a series of experiments was carried out to test an improved harmonic radar tag designed to be more resistant to mechanical stresses and to establish that a portable harmonic radar system can effectively detect adult Halyomorpha halys Stål (Hemiptera: Pentatomidae) on various structures in different landscapes. The functional resistance of radar tags to ∼1-m free falls on a hard surface was improved significantly by reinforcing the adhesive bond between the radar transponder and the radar wire by application of cyanoacrylate glue. This measure did not affect the detectability of radar tags, and it significantly increased the resistance of radar tags against random mechanical impacts inflicted on the insects and tags. The success rates of locating radar-tagged H. halys were compared among different landscapes, including a mowed grasscovered plot (250 m2), a mature peach tree plot (50 m2), and an unmanaged hedgerow (50 m2). The success rates were > 90% in all landscapes tested. There was no significant difference in the search time needed to locate tagged adults. In general, it took less than 2 min to detect and recover H. halys. The success rates of locating radar-tagged H. halys were also compared among different locations within mature fruit trees. There was no significant difference in the success rates between the inner third (87%) and the outer third of the host tree canopy (100%). However, a significantly longer period of time was required to locate H. halys in the inner canopy (372 s ± 95 SE) compared with the outer canopy (148 s ± 39 SE). When H. halys were concealed in the lower, middle and upper thirds of the outer tree canopy, the success rates of locating tagged adults were consistently 95% or greater at all canopy heights with no significant difference in search times needed to locate tagged adults. The results of this study provide context for researchers to reliably use this radar system in the field to study the dispersal biology of H. halys.

Can Maruca vitrata (Lepidoptera: Crambidae) Over-winter in Suwon Area?

Maruca vitrata is a main insect pest against crops of Vigna species (V. angularis and V. radiata) and Sesbania sesban in Fabaceae, but the life cycle of the insect is unclear in Korea. In order to know over-wintering possibility, its stage of the insect, over-wintering entry season, and the first adult emergence season of the next year, we investigated over-wintering rates of the insect in outdoor conditions in Suwon (37o16 ́N 126o59 ́E 35ASL). In all colonies which the rearing for larvae, pupae and eggs started after mid-September, adults did not emerge within the year, and all insects died before next June. In several trials for over-wintering of larvae and pupae in soil, all insects died, too. Larvae stored during specified periods at low temperatures (10 and 13°C) did not emerge. From the results, it was postulated that M. vitrata does not have an adaptability to temperature below zero, and cannot over-winter in Suwon area.

A PCR Method to Distinguish Matsumuraeses phaseoli from M. falcana Based on the Difference of Nucleotide Sequence in the Mitochondrial Cytochrome c Oxidase Subunit I

The two closely related major leguminous crop pests in Korea, Matsumuraeses phaseoli and M. falcana (Lepidoptera: Tortricidae) have very similar morphological characters, which occasionally give rise to a failure in distinguishing between the two. In this study, we report an easy PCR-SSP method to distinguish between them, with a sequence specific primer set (P-SF2, F-SF3, and C-SR3) based on single nucleotide mismatch in 3` terminal base of a primer, which is found in the mitochondrial cytochrome c oxidase subunit I DNA (mtCOI). Through application of this method, each species may be clearly identified in terms of its PCR band size and pattern, only one band (245 bp) for M. falcana and one (409 bp) or two bands (409 bp & 245 bp) for M. phaseoli.

Development of Matsumuraeses phaseoli (Lepidoptera: Tortricidae) Reared on an Artificial Diet under Outdoor Conditions and Its Over-wintering Stage

Matsumuraeses phaseoli is one of the main pests that attack the flowers and pods of red bean (Vigna angularis) and mungbean (Vigna radiata) in Korea. To elucidate the developmental characteristics and over-wintering stage of M. phaseoli, several stages of the insect were observed through artificial rearing under outdoor conditions in Suwon (37°16′N 126°59′E 35ASL), Korea. In colonies in which neonate larvae were reared at about 2-week intervals for more than a year, the developmental period from larva to adult emergence became longer from spring to summer, but shorter from summer to autumn; aestivation was not observed during the summer season. The colony in which rearing started on Oct 8, 2008 over-wintered as pupae and emerged in late April next year with a survival rate of 6%. However, the colony in which the rearing started on Oct 23, 2008 over-wintered as mature larvae, pupated in late April, and emerged in early and mid-May with a survival rate of 2%. When the fifth instar larvae were transferred outside from the laboratory (25°C, 15L:9D) between November and February, no larvae could survive during the winter season. Some newly laid eggs and newly emerged adults could not hatch and could not survive, respectively, in outdoor conditions in November and December. These results suggest that neonate larvae of M. phaseoli that hatch in October can over-winter as late larvae or pupae in Suwon, Korea.

Molecular Identification of Trichogramma (Hymenoptera: Trichogrammatidae) Egg Parasitoids of the Asian Corn Borer Ostrinia furnacalis, Based on ITS2 rDNA Sequence Analysis

ABSTRACT: To identify the species of Trichogramma occurring in the corn fields of Korea as egg parasitoids of Ostrinia furnacalis, we sequenced the full-length of ITS2 nuclear rDNA from 112 parasitoids collected during this study. As a reference to distinguish species,we also retrieved full-length ITS2 sequences of 60 Trichogramma species from the NCBI GenBank database. On the basis of the size an d3′terminal sequence pattern of the ITS2 sequences, the Trichogramma samples collected in this study were divided into three groups (K-1,-2, and -3). Evolutionary distances ( d) within and between groups based on ITS2 sequences were estimated to be ≤0.005 and ≥0.080,respectively. In the net average distance between groups or species, the d value between K-1 and T. ostriniae , K-2 and T. dendrolimi , andK-3 and T. confusum was the lowest, with values of 0.016, 0.001, and 0.002, respectively. In the phylogenetic tree, K-1 and K-2 were clustered with T. ostriniae and T. dendrolimi , respectively. However, K-3 was clustered with three different species, namely, T. confusum, T. chilonis, and T. bilingensis. NCBI BLAST results revealed that parasitoids belonging to K-1 and K-2 showed 99% identity with T. ostriniae and T. dendrolimi , respectively. Parasitoids in K-3 collected from Hongcheon showed 99-100% identity with T. confusum and T.chilonis, and one parasitoid in K-3 collected from Gochang had 98% identity with T. bilingensis , T. confusum , and T. chilonis . On the basisof these results, we infer that the species of Trichogramma collected in this study are closely related to T. ostriniae (K-1) and T. dendrolim i(K-2). However, it was not possible to distinguish species of K-3 using the ITS2 sequence alone.Key words: Ostrinia furnacalis, Zea mays, Trichogramma, ITS2, Molecular phylogenetic tree초 록: 옥수수 포장에서 발생하는 Trichogramma 속 조명나방 알기생벌의 종 분포를 조사하기 위해 채집된 알기생벌로부터 핵내 ITS2 DNA 전체 염기서열 정보를 해독하였다. 그리고 종 구별을 위한 참고정보로 NCBI GenBank 에 등록된 Trichogramma 속 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. confusum 과 d 값이 각각 0.016, 0.001, 0.002 로 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% identity 를 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.검색어: 조명나방, 옥수수, Trichogramma , ITS2, 분자계통수*Corresponding author: seoby@korea.krReceived February 14 2014; Revised June 9 2014Accepted July 1 2014

Development of an Emergence Model for Overwintering Eggs of Metcalfa pruinosa (Hemiptera: Flatidae)

The temperature-dependent development of Metcalfa pruinosa overwintering eggs was investigated at ten constant temperatures (12.5, 15, 17.5, 20, 22.5, 25, 27.5, 30, 32.5, and , Relative Humidity 20~30%). All individuals collected before April 13, 2012 failed to develop into first instar larvae. In contrast, some individuals that were collected on April 11, 2013 successfully developed when reared under temperature regimes. The developmental duration was shortest at (13.3 days) and longest at (49.6 days) in the fourth collected colony (April 26 2013). Developmental duration decreased with increasing temperature up to and development was retarded at high-temperature regimes (). The lower developmental threshold was and the thermal constant required to complete egg overwintering was 252DD. The Lactin 2 model provided the best statistical description of the relationship between temperature and the developmental rate of M. pruinosa overwintering eggs (

The Temperature-Dependent Development of the Parasitoid Fly, Exorista Japonica (Townsend) (Diptera: Tachinidae)

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Eclosion and Mating Behavior of Matsumuraeses phaseoli (Matsumura) (Lepidoptera: Tortricidae)

Exorista japonica is one of the major natural enemies of noctuid larvae, Mythimna separata and Spodoptera litura. The examined parasitoid was obtained from host species M. separata, collected at Gimje city and identified by DNA sequences (partial cytochrome oxidase I, 16S, 18S, and 28S). For purposed of this study, laboratory reared S. litura served as the host species for the development of the E. japonica. The developmental period of E. japonica immature stages were investigated at seven constant temperatures (16, 19, 22, 25, 28, 31, 34±1°C, RH 20∼30%). Temperature-dependent developmental rates and development completion models were developed. E. japonica was successfully developed from egg to adult in 16∼31°C temperature regimes. Developmental duration was the shortest at 34°C (8.3 days) and the longest at 16°C (23.4 days) from egg to pupa development. Pupal development duration was the shortest at 28°C (7.3 days). Total immature-stage development duration decreased with increasing temperature, and was the shortest at 31°C (16.3 days) and the longest at 16°C (45.4 days). The lower developmental threshold was 7.8°C and thermal constant required to complete total immature-stage development was 370.4 degree days. Among four non-linear temperature-dependent developmental rate models, Briere 1 model had the highest adjusted R-squared (0.96). The distribution model of development completion for total immature stage development of E. japonica was well described by all model (  =0.90) based on the standardized development duration. These results of study would be necessary not only to develop population dynamics model but also to understand fundamental biology of E. japonica.