담배거세미나방(Spodoptera litura), 열대거세미나방(Spodoptera frugiperda) 및 파밤나방(Spodoptera exigua) 은 광식성 해충이지만, 종특이적인 기주범위를 갖는다. 이들이 기주식물을 찾아가는 과정에 냄새감각이 어떤 역할을 하는지 알아보기 위해, 기주 및 비기주 식물에서 발산되는 46가지 휘발성 물질을 선정하여, 이들에 대한 나방 3종의 냄새반응을 GC-EAD(gas chromatography-electroantennogram detection)를 통해 확인하였다. 그 결과, 46가지의 식물유래화합물 중 9가지 물질이 3종의 나방 모두에서 냄새활성을 나타냈으며, 2가지 물질은 담배거세 미나방과 열대거세미나방에만 냄새활성을 나타냈고, 다른 몇 가지 물질은 담배거세미나방에만 냄새활성을 나 타냈다. 이 결과는 세 종 나방이 식물냄새물질 탐지를 위해 유사한 냄새감각세포를 가지며, 일부 종에서는 종특이 적인 냄새감각세포가 존재한다는 것을 보여준다. 이 결과를 바탕으로 냄새활성을 나타낸 물질들의 나방 3종에 대한 행동활성을 야외트랩실험을 통해 확인할 예정이다.

나방은 성페로몬에 대한 통신시스템이 잘 발달되어 있다. 동종의 암컷이 방출하는 성페로몬을 원거리에서 감지하여 암컷을 정확히 찾아가 교미할 수 있도록 하기 위해서, 수컷 나방은 고도로 발달된 성페로몬 감지 시스템을 갖고 있다. 이러한 시스템을 이용해서 수컷 나방은 페로몬 냄새 기둥(plume)을 따라 바람을 거슬러 비행하면서 간헐적으로 감지되는 페로몬 냄새가닥(odor filaments)을 추적하는 고정행동양식(stereotypic behavior)을 보인다. 일반적으로 여러 성분으로 구성되는 나방의 암컷 성페로몬은 그 조성이 종특이적(species-specific)이며, 비슷한 성분을 공 유하는 유사종들이 방출하는 성페로몬과 동종의 암컷이 방출하는 성페로몬을 정확히 구분하기 위해서 수컷 나방은 촉각에 여러 종류의 고도로 특 화된 페로몬 감각세포들을 갖고 있어서, 이들이 페로몬을 감지할 때 나오는 신경 신호들을 종합해서 동종의 페로몬을 인식하여 행동반응이 일어 나게 된다. 수컷 나방은 보통 동종의 페로몬 성분뿐만 아니라 유사종이 사용하는 페로몬 성분들을 특이적으로 감지하는 길항적(antagonistic) 냄 새감각세포들도 갖고 있어서 페로몬 식별력을 강화한다. 본 종설에서는 지금까지 보고된 수컷 나방의 페로몬 감지 시스템과 이와 연관된 수컷의 감각기 및 행동반응에 대한 연구 결과들을 정리하고, 이를 종합하여 앞으로의 연구 방향을 제시하고자 한다.

호박꽃과실파리(Bactrocera scutellata)는 박과 식물의 해충으로 기주식물을 찾아가는데 냄새 감각이 중요한 역할을 한다. 이들의 기주 식물인 단호박, 애호박, 노란호박 및 하늘타리의 냄새물질을 포집하여 이들 추출물에 대한 호박꽃과 실파리의 촉각과 작은턱수염의 냄새반응을 GC-EAD(Gas chromatography-electroantennographic detection) 및 GC-EPD (Gas chromatography-electropalpographic detection)를 이용하여 조사한 결과, 촉각과 작은턱수염에 존재하는 냄새감각세 포들에 강한 냄새활성을 나타내는 여러 물질들이 탐지되어, 촉각과 작은턱수염 모두 기주식물의 감지에 중요한 역할을 한다는 것을 보여주었다. 하지만, 촉각과 작은턱수염에 냄새활성을 나타내는 물질들의 종류는 서로 확연한 차이를 보여서 촉각과 작은턱수염이 기주식물의 냄새물질 탐지에 서로 다른 역할을 할 것이라는 사실을 나타내었다. 우리는 이들 냄새활성물질의 화학구조 동정을 진행하고 있으며, 이들의 구조가 밝혀지면 이들 물질의 호박꽃과실파리 에 대한 행동활성을 조사할 예정이다.

호박꽃과실파리, Bactrocera scutellata (Hendel) (Diptera: Tephritidae),는 호박 등 박과식물의 해충으로 야외 트랩실험을 통해 호박꽃과실파리 수컷이 cue lure와 raspberry ketone에 유인되는 것이 확인되었으며, 전자현미경 관찰을 통해 호박꽃과실파리의 촉각(antennae)과 작은턱수염(maxillary palps)에 각각 다른 형태의 냄새감각기들이 존재한다는 것을 확인하였다. 이 결과를 바탕으로 Bactrocera 속 과실파리들의 parapheromone 성분들인 cue lure, raspberry ketone, methyl eugenol, 및 zingerone 등의 물질들이 촉각과 작은턱수염 중 어떤 감각기관에 의해 감지되는지 알아보기 위해 이 물질들과 식물 냄새성분인 3-octanone에 대한 호박꽃과실파리의 eleltroantennogram (EAG) 및 electropalpogram (EPG) 반응을 측정하였다. 그 결과 cue lure 및 raspberry ketone은 작은턱수염에서 큰 EPG 반응을 보였으나 촉각에서는 EAG 반응을 나타내지 않았다. 이와는 대조적으로 호박꽃과실파리의 기주식물인 호박에서 방출되는 냄새 성분 중 하나인 3-octanone은 촉각에서 큰 EAG 반응을 나타내었으나 작은턱수염에서는 아주 작은 EPG 반응만을 나타내었다. 이러한 결과는 호박꽃과 실파리 수컷에 강한 유인력을 나타내는 cue lure와 raspberry ketone이 촉각이 아니라 작은턱수염에 존재하는 냄새감각세포들에 의해 감지된다는 것을 의미하며 이것은 호박과실파리 등 아직 강력한 유인제가 알려져 있지 않은 다른 과실파리류의 유인제 개발에 유용한 정보가 될 것이다.

Monitoring is an important component in the detection, surveillance and eradication of invasive insect pests. In particular, the availability of useful attractants and effective traps is critical in establishing a new surveillance program for quarantine pests. A powerful, species-specific attractant is desirable when precision early detection is needed. However, such an ideal attractant is not often available when the introduction of a new surveillance program is urgent. In reality, the combination of available monitoring means is adopted, which in turn requires the subsequent development of optimum monitoring strategy with these available means. Various species of fruit flies, belonging to the genus Bactrocera in particular, are serious threat to Korea, and developing systematic monitoring systems is needed against the invasion of the fruit flies. Effective male attractants, such as methyl eugenol and cue lure, and traps are currently available for some species such as B. dorsalis, B. tryoni, and B. carambolae. However, such attractants are yet to be developed for many other fruit fly species. The strong attraction of the striped fruit fly, B. scutellata, being present in large numbers in Korean fields to cue lure can be a potential obstacle in monitoring other species of fruit flies attracted to the same compound. Various attractants based on protein hydrolysates are also useful in monitoring fruit flies since they are attractive to both males and females of fruit flies. However, it is desirable to develop these protein-based baits into more species-specific attractants. Monitoring techniques for some important quarantine fruit flies are further discussed.

Electrophysiological responses of Queensland fruit fly, Bacterocera tryoni, were investigated to identify the olfactory receptor neurons (ORN) in the antennae and corresponding active volatile compounds, using the single sensillum recording technique and 52 test compounds including methyl methyl eugenol, cuelure and raspberry ketone. We found that different classes of olfactory sensilla and ORNs are present in the antennae of B. tryoni. Most of the ORNs appeared to have narrow response spectra, exhibiting specialized responses to one or a few volatile compounds among the 52 compounds tested. In this study, ORNs specialized for ammonia, nonanal, isopentanol, ethyl acetate, indole, phenol, 2,5-dimethylpyrazine and 2-coumaranone, respectively, have been identified. A class of ORNs exhibited highly specialized responses to methyl eugenol. A preliminary field trapping test conducted in New Caledonia to evaluate the behavioral activities of the olfactory active compounds indicated a blend of three synthetic compounds is attractive to female B. tryoni.

Four sympatric tortricid (Lepidoptera) species in New Zealand, Epiphyas postvittana (Walker), Planotortrix octo (Dugdale), Cydia pomonella (L.), and Cydia succedana (Denis and Schiffermüller), were studied for the morphology of antennal sensilla and the chemical communication systems using scanning electron microscopy (SEM), electro-antennogram (EAG), gas chromatography-electroantenno-detection (GC-EAD), single sensillum recording (SSR) and field tests. Antennal flagella of adult have four main types of olfactory sensilla (s.); s. trichodea, s. basiconica, s. auricillica, and s. coeloconica in the four species. The s. trichodea subtype I was longest and male-specific in all the species. The antennae of males of the four species showed characteristic higher EAG, GC-EAD and SSR responses to 12, 14-carbon acetates or alcohol. Some of the selected chemicals selected from the electrophysiological experiments caused significant antagonistic or agonistic activities to the sex pheromone of each species in the field. In this study, the four species showed distinct chemical communication systems according to sub-family, which possibly serve as a factor in species isolation.

Antennal olfactory receptor neurons (ORNs) for pheromone and plant volatile compounds were identified and characterized in Sitona lepidus and S. discoideus, using the single sensillum recording technique with five pheromone-related compounds and 40 host and non-host plant volatile compounds. Different types of olfactory sensilla containing specialized ORNs were identified in these weevils. Different types of sensilla housed ORNs specialized for pheromone-related compounds, 4-methyl-3,5-heptanedione or one or more of four stereoisomers of 5-hydroxy-4-methyl-3-heptanone. In addition to the pheromone-related ORNs, several types of olfactory sensilla contained ORNs responsive to plant volatile compounds. Most of the ORNs showed high specificity to specific volatile compounds although some of the active compounds showed overlapping response spectra in the ORNs across different types of sensilla. Our study indicates that both S. lepidus and S. discoideus have species-specific set of highly sensitive and selective ORNs for pheromone and plant volatile compounds. The behavioral implication of these findings is discussed.

Sensory system of insect is important for their fitness in the environment. Riptortus pedestris (Hemiptera: Alydidae) is a major pest of bean plants and some fruit trees in Korea, Japan, China, and South Asian countries. This study was conducted to investigate morphology and distribution of antennal sensilla of R. pedestris, using scanning electron microscopy. Antennae of R. pedestris was 11 and 9.84 mm in length in male and female, respectively, and consists of four segments; scape, pedicel, flagellum 1 and 2 (F1 and F2). Five types of sensilla (s.) trichodea, four types of s. basiconica, two types of s. chaetica, and one type of s. coeloconica were preliminary identified in both sexes of adult R. pedestris, based on their size, shape, presence of socket and surface structure. Three types of trichoid sensilla, four types of basiconic sensilla, one type of chaetic sensilla and coeloconic sensilla had numerous pores along the surface of the sensilla, suggesting their olfactory function. Eight types of sensilla (3 trichoid, 2 basiconic, a chaetic and a coeloconic) showed a distinct socket structure at the base of each sensillum. Different types of sensilla showed different distribution along the antennal segments. Two types of trichoid sensilla and two types of basiconic sensilla were distributed on scape, pedicel and F1 flagella subsegment. However, the distribution of eight other types of sensilla was limited to one of two flagella subsegments.

Phytophagous insects detect volatile compounds produced by host and non-host plants, using species-specific sets of olfactory receptor neurons (ORNs). To investigate the relationship between the range of host plants and the profile of ORNs, single cell recordings were carried out to identify ORNs and corresponding active compounds in female Uraba lugens (Lepidoptera: Nolidae), an oligophagous eucalypt feeder. Based on the response profiles to 39 plant volatile compounds, 13 classes of sensilla containing 40 classes of ORNs were identified in female U. lugens. More than 95% (163 out of 171) of these sensilla contained 16 classes of ORNs with narrow response spectra, and 62.6% (107 out of 171) 18 classes of ORNs with broad response spectra. Among the specialized ORNs, seven classes of ORNs exhibited high specificity to 1,8-cineole, (±)-citronellal, myrcene, (±)-linalool and (E)-β-caryophyllene, major volatiles produced by eucalypts, while nine other classes of ORNs showed highly specialized responses to green leaf volatiles, germacrene D, (E)-β)-farnesene and geranyl acetate that are not produced by most eucalypts. We hypothesize that female U. lugens can recognize their host plants by detecting key host volatile compounds, using a set of ORNs tuned to host volatiles, and discriminate them from non-host plants using another set of ORNs specialized for non-host volatiles. The ORNs with broad response spectra may enhance the discrimination between host and non-host plants by adding moderately selective sensitivity. Based on our finding, it is suggested that phytophagous insects use the combinational input from both host-specific and non-host specific ORNs for locating their host plants, and the electrophysiological characterization of ORN profiles can be used for predicting the range of host plants in phytophagous insects.

In insects, the sense of smell is a complex and highly sensitive modality, governing essential decisions such as choice of food and oviposition sites. Plants emit substantial amounts of volatile organic compounds (VOCs), and the characteristic scent represents a dynamic communication channel. Understanding this odor-mediated system is critically important in the habitat management and in the largest view of the conservation biological control. Here we suggest that the fitness of the egg parasitoid ,an important biological control agent of the green vegetable bug may be improved through the understanding of chemical communication in the biological control system. Initially, the attractiveness of four flowering plant species, chosen from apanelofplants based on the longevity of the eggparasitoid on these plants, to T. basalis was assessed, which indicated significant behavioral attraction of T. basalis to the buckwheat flowers. Subsequently, and GC-MS analysis were carried out to identify the olfactory-active VOC semanated from buck wheat, demonstrating that the antennalol factory receptor neurons of T. basalis were responsive to some aliphatic acids as well as a few common plant volatiles. In behavioral bioassays using synthetic formulation based on the chemical and electrophysiological analysis, T. basalis exhibited significant behavioral attraction to the synthetic blend at optimum dose. The findings, in a wider perspective, form the basis for further improvement of the use of the companion plants that may increase the insects’ communities’ ability to persist in an environment.