The bean bug, Riptortus pedestris (Hemiptera: Alydidae), is a major pest of soybean and tree fruit in Korea. To protect crops, chemical insecticides have been widely used. However, the effects of insecticides is not only reduce the pest population but also change of pest behavior. In this study, we tested the effects of two insecticides, etofenprox (pyrethroid) and acetamiprid (neonicotinoid), on the behavior of R. pedestris. Two insecticides were diluted with water based on the conventional spray dose. After exposed to insecticide residue, adult R. pedestris was put individually into a clean petri dish with soybean. The behavior of R. pedestris was video-recorded for 16 hours. The frequencies of approaching to food and feeding were compared to the untreated control group. R. pedestris exposed to etofenprox made more frequent approaching to the food, but those exposed to acetamiprid made less frequent approaching compared to the control group. When compared to the control group, the feeding frequency of acetamiprid-exposed group was significantly reduced but etofenprox-exposed group showed more frequent feeding activity. In both treatments, the feeding probability, calculated by feeding frequency divided by approaching frequency, was reduced compared to the control. We conclude that acetamiprid may protect crops by reducing the frequency of R. pedestris to approach and feed on crops.

Seasonal abundance and distribution of mosquitoes and chigger mites are important for human populations. However, factors affecting the abundance and distribution of vector species are not well - understood. Furthermore, global climate change makes it difficult to predict the population dynamics of vector species. Therefore, it is important to monitor this vector species over a long period of time. In 2015, mosquitoes were collected from three potential mosquito habitats using black light trap and BG-Sentinel trap in Gyeongi-do in April through October. Also, we collected chigger mite using sherman live traps in Cheorwon, Gangwon-do in April, September and October. From the survey, we collected a total of 11,649 mosquitoes in three potential mosquito habitats, and a total of 3,656 chigger mites from 54 wild rodents. In the samples, dominant mosquito species were Aedes vexans nipponii (Species Ratio 70%), Culex pipens pallens (SR 9.8%) in Gyeonggi area and dominant chigger mite species was Leptotrombidium pallidium (SR 59%) in Cheorwon. The results of this study can serve as provide fundamental basis to develop effective management strategy under the global climate change environment.

Various techniques have been developed to monitor insect behavior in the field. Harmonic radar tagging is a promising method of tracking target insects because it can allow efficient detection of the insects with negligible effects on their behavior or physiology. However, availability of the light limits the effectiveness of the method as it is almost impossible to spot an insect in the dark. On the other hand, fluorescent-marking, when combined with strong light source, makes the organisms distinct at night in a non-destructive manner. Therefore, we conducted a field experiment to determine the effectiveness of the combination of the two methods. Riptortus pedestris (Fabricius) adults were marked with both harmonic radars and fluorescent paint. The marked insects were haphazardly arranged and pinned onto trees or the ground in the forest at night. Then, a group of paired researchers, one equipped with a harmonic radar and the other with a hand-held laser, attempted to find R. pedestris within 20 minutes. The detection rate showed a high variance ranging from 40% to 100%. Thus, with a proper training, harmonic radar system combined with fluorescent-marking can be a powerful technique to detect insects in the field. With these equipments, tracking insect behavior in the field will be more efficient in the dark.

Riptortus pedestris is a major agricultural pest in Korea. To manage this pest, it is necessary to understand the complete life history of R. pedestris. However, most studies have focused on the summer period when the pest attacks crops. Therefore, we conducted laboratory and field experiment to identify overwintering behavior of adult R. pedestris. First, we conducted two laboratory experiments to examine overwintering habitat preferences and spatial distribution of R. pedestris in the habitat. Second, we conducted field survey to characterize overwintering sites of R. pedestris in diverse landscapes. In the laboratory conditions, R. pedestris almost exclusively showed overwintering behavior in the leaf litter arena (63%) among the structures tested (rocks: 3%; rotten wood: 0%). And spatial distribution of R. pedestris showed solitary behavior in leaf litters. In the field, we located 12 individuals of overwintering adults from the urban areas, whereas no individuals were found from the high-elevation mountains and agricultural landscapes. Our results suggest that R. pedestris mainly use leaf litter as an overwintering structure, with solitary behavior, and low-elevation forested areas near urban landscapes seem to be more preferred overwintering sites.

Whiteflies (Hemiptera: Aleyrodidae) and thrips (Thysanoptera: Thripidae) are major pests on greenhouse crops including sweet pepper (Capsicum annuum L.) in South Korea. To manage this pest complex effectively, it is fundamental to understand population dynamics and spatial distributions of the pests. In this study, we conducted visual counting and used yellow sticky traps to monitor whitefly and thrips populations in sweet pepper greenhouse (6 × 28 m). The survey was conducted every two weeks over two months. A total of 84 traps were set up at 20cm from the plant top canopy and spaced 1m apart from each other. Leaves were selected randomly from the middle plant canopy for visual counting at the same sampling locations. The trap data indicate that the numbers of whiteflies and thrips increased from 5.50 ± 0.34 to 168.51 ± 14.95 and from 52.40 ± 1.67 to 158.42 ± 7.44 (mean ± SE) per trap, respectively, over the two-month observation period. In general, the spatial distributions of these pests aggregated near the greenhouse entrance with significant positive correlation between the densities of the two species (r = 0.74, P = 0.02). However, the results of visual counting were completely different; either species was rarely found on leaves, even when the trap catches were relatively high at the same locations. That is, there was no correlation between visual counting and sticky trap data sets. The current study will serve as a fundamental step to develop reliable and effective management programs for greenhouse sweet pepper.

Sweet pepper (Capsicum annuum L.) is one of the leading export greenhouse crops in South Korea. Sweetpotato whitefly, Bemisia tabaci Gennadius is one of the major pests on greenhouse pepper. This pest is conventionally managed by synthetic insecticide application, however this management tactic causes the overuse of toxic compounds and the resistance of whiteflies to insecticides. Therefore, the development of environment-friendly natural insecticides is vitally important. In this study, we evaluated the efficacy of three newly-screened insecticidal compounds for B. tabaci (Biotype Q) in laboratory. The insecticidal effects of the compounds were assessed with adult B. tabaci using leaf disc arena established in petri dish. Among the three compounds tested, JS408, a plant extract from Perilla sp., showed significant insecticidal effects on B. tabaci in one hour causing 90% mortality. However, JA408 caused phytotoxicity on sweet pepper leaf resulting in browning dead spots. The new plant-extract JA408 has promising potential as natural insecticidal compound for B. tabaci, but further study must resolve the phytotoxicity issue. Moreover, insecticidal effect should be evaluated under field conditions.

Mosquitoes are vectors of many human diseases such as Japanese encephalitis, vivax malaria, west nile fever, dengue fever and yellow fever. However, factors affecting the abundance and distribution of mosquitoes are not well-understood. Moreover, the global climate change makes it even more difficult to address and predict the population dynamics of mosquitoes. Therefore, it is important to monitor this medically-important pest throughout landscapes over a long period of time. This study was conducted as a part of the nation-wide surveillance program to monitor insect vectors. In 2015, mosquitoes were collected using black light traps and BG-Sentinel traps in Gyeonggi-do at every two weeks from April to September. Three types of potential mosquito habitats were selected for surveillance: urban area (Suwon), cattle shed (Yongin) and wild bird refuge (Gwangju). Among the three habitats, female mosquitoes were first caught on April 4 by BG-Sentinel trap in the urban area. The highest density of female mosquitoes in the traps was recorded in July in the urban area (134 ± 84 per trap); the highest density was observed in June in the cattle shed (2473 ± 1319) and wild bird refuge (21 ± 15) (mean ± SE). The dominant mosquito species were Culex pipens pallens (91%), Aedes vexans nipponii (79%) and Anopheles sinensis (33%) in the urban area, cattle shed and wild bird refuge, respectively. The results of this study indicate that female mosquitoes were most abundant in the cattle shed habitat type. It is also noteworthy that the dominant mosquito species varied among the habitat types surveyed. This nation-wide monitoring program for medical pests will provide fundamental basis to develop effective management strategy under the global climate change environment.

Currently, the management of Riptortus pedestris (Hemiptera: Alydidae) relies mainly on insecticide application in most crop productions. However, there have been very few detailed studies concerning the potential behavioral effects of sublethal dose of insecticide. This study was conducted to address sublethal effects of five insecticides on the mobility of R. pedestris. Adult R. pedestris were individually exposed to dry residue of insecticides for 4 hours in laboratory. Tested insecticides were fenitrothion (organophosphate), etofenprox (pyrethroid), bifenthrin (pyrethroid), acetamiprid (neonicotinoid) and dinotefuran (neonicotinoid). After the exposure, vertical climbing ability and flight capacity of survived R. pedestris were evaluated and compared to water-treated control. First, the mortality of R. pedestris after the 4-h insecticide exposure was as follows: 10% for fenitrothion, 3.4% for dinotefuran, 3.4% for acetamiprid, 0% for etofenprox and 0% for bifenthrin. The vertical mobility of R. pedestris was affected differently by insecticides tested. Acetamiprid resulted in decrease (37%) in the vertical mobility, whereas dinotefuran caused increase (153%) in the ability compared to the control. There was no effect by three other insecticides on the vertical mobility. In general, tested insecticides did not affect the flight capacity of R. pedestris compared to untreated individuals. However, etofenprox resulted in increase (230%) in the flight capacity. The results of this study indicate that insecticide-treated but survived R. pedestris can show similar or even increased mobility compared to untreated individuals. This should be considered in designing insecticide application programs against of R. pedestris.

R. pedestris is a major insect pest in agricultural production, especially on soybean and tree fruit, in Korea. Currently, the management of this pest relies mainly on insecticide application in most commodities. However, the chemical controls cause numerous environmental problems. To develop sustainable management tools, it is fundamental to understand the basic biology and ecology of R. pedestris. However, the overwintering ecology of this pest is virtually unknown. In this study, we surveyed diverse landscapes including high elevation mountains soybean fields and there neighboring forests to find and characterize the overwintering sites of R. pedestris. In the field, we sampled leaf litters from 1㎡ grids to locate overwintering R. pedestris. The samples were taken every 100m altitude in the mountain areas or every 50m distance in the flat landscapes. Overwintering R. pedestris were found from 6 samples out of 137 samples. All overwintering R. pedestris were located from forested areas adjacent to urban landscapes in Seong-Nam si, Gyeong-Gi Do. Interestingly, no overwintering R. pedestris was found from in the samples collected from high elivation mountains including Yeon-In, Song-Ni, Chi-Ak, Ga-Ya, Wol-Chul. likewise, no overwintering individual was found from soybean fields and their neighboring forested areas. With caveat that the data were collected only for 1 year, our results support that R. pedestris overwinters solitary resulting in low detection rates from the samples. Given that R. pedestris typically disperse into cultivated crops with high densities, it is important to better understand environmental factors affecting the presence or absence of overwintering R. pedestrris in diverse landscapes. The knowledge would be essential to develop sustainable monitoring and management programs for this economically important pest in Korea.

The use of radar systems for entomological research offers new opportunities that allow continuous tracking of individual insects in natural settings. In particular, harmonic radar systems can be applied for small animals such as insects because the radar tag does not rely on battery power, allowing them to be light weight. To apply this technology, it is essential to develop procedures to securely attach radar tags on target insects and thereafter demonstrate no adverse effects of radar tag attachment on insect survivorship and behaviors. In this study, we developed procedures to securely attach harmonic radar tags on adult Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) and verified there were no detectable adverse effects of radar tagging on R. pedestris survivorship and walking or flight capacity. With the radar technique, future studies will focus on understanding dispersal capacity and pattern of R. pedestris in diverse landscapes. This will help enhance monitoring and management programs for this pest.