Studies on visual and olfactory response of western flower thrips (Thysanoptera: Thripidae)

Bishwo P. Mainali,Un Taek Lim 한국응용곤충학회 2008 한국응용곤충학회 학술대회논문집 Vol.2008 No.05

Frankliniella occidentalis Pergande (Thysanoptera: Thripidae) is economically important pest of various crops causing damage through direct feeding and transmitting tospoviruses. In a previous study differential responses of the thrips to various geometrical patterns of yellow sticky card were found. Therefore, in this study, we compared the behavioral responses of the thrips to visual and olfactory cues in cylindrical black box and Y-tube olfactometer, respectively. Multiple or pair wise choice tests were carried out among/between six geometrical patterns of yellow color paper and artificial flowers. The thrips preferred circular shape to other geometrical patterns in multiple choice test. In pair wise choice test between three geometrical patterns, i.e., circular, rectangle, and modified circular, and artificial strawberry flowers, the thrips showed preference to the yellow artificial flower than any other cues. The thrips resided on the yellow artificial flower almost 4 times more than other patterns. In Y-tube olfactometer test, higher number of the thrips chose the arm with p-anisaldehyde and artificial flower compared to the arm with only the artificial flower. Higher number of the thrips also chose the arm containing both visual and real flower odor as compared to arm with the only real flower odor. The potentials and application of these results in the development of attraction traps for the thrips management have been discussed.

Released eggs of Riptortus pedestris (Hemiptera: Alydidae) enhances parasitism in Agakong field

Bishwo P. Mainali,Un Taek Lim 한국응용곤충학회 2010 한국응용곤충학회 학술대회논문집 Vol.2010 No.05

Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) causes losses in several crops in Korea. Release of non-viable refrigerated eggs of R. pedestris is known to enhance natural parasitism by Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) and Gryon japonicum (Ashmead) (Hymenoptera: Scelionidae) in soybean fields. In this study, we conducted an experiment of cage-exclusion design to verify the former results in more manipulative approach in a soybean field. Agakong field (45×26 m2) located at Songcheon, Andong was divided into 15 plots (10×6 m2) with each experimental arena of 3×2 m2 in the center. There were three treatments: (1) release of refrigerated eggs of R. pedestris, (2) release of refrigerated eggs with one time spray of thiamethoxam, and (3) untreated control. A fine mesh cloth with iron poles was used to encircle the arenas. Refrigerated eggs of R. pedestris were released (100/arena) twice before sampling. One-day old eggs of R. pedestris were released (60/arena) in all the experimental arenas at an interval of 6 days, and 30 eggs from each were collected to record parasitism. We found no significant difference in the eggs and nymphs population of R. pedestris among the treatments. However, adult density was significantly reduced in the treated plots during final two sampling days compared to the control. We found significantly higher parasitism by G. japonicum on the eggs collected from treated plots (9-25%) compared to the control plots (1-9%). It is verified that releasing non-viable eggs of R. pedestris help to enhance natural parasitism in soybean field.

Evaluation of different leguminous seeds as food sources for the bean bug Riptortus pedestris

Bishwo P. Mainali,김현주,윤영남,오인석,배순도 한국응용곤충학회 2014 Journal of Asia-Pacific Entomology Vol.17 No.2

This studywas conducted to determine the effects of six different leguminous seeds (cowpea,white kidney bean,soybean cultivars Cheongja and Daepung, mung bean, and azuki bean) on the life history traits of the bean bugRiptortus pedestris (F.) (Hemiptera: Alydidae). The total developmental time from the first instar nymph toadult ranged from 18 to 25 d; R. pedestris fed with white kidney beans were the slowest to develop. In addition,bugs fed with white kidney beans had the highest mortality (93%) and the shortest longevity (18 d). R. pedestrisfedwith cowpeas, soybeans, or azuki beans had high reproductive success, with the highest egg hatching successrecorded in bugs fed cowpeas. The results suggest that cowpea may be a beneficial food source for the developmentand reproduction of bean bugs.

Annual patterns of occurrence of Riptortus pedestris (Hemiptera: Alydidae) and its egg parasitism in a field where a series of crops cultivated

Bishwo P. Mainali,Youngkeun Yi,Un Taek Lim 한국응용곤충학회 2011 한국응용곤충학회 학술대회논문집 Vol.2011 No.05

From our previous studies in a farm in Songcheon, Andong where a series of crops was cultivated in 2008 and 2009, occurrence patterns of Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) and its egg parasitism by Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) and Gryon japonicum (Ashmead) (Hymenoptera: Scelionidae) were reported. With an objective to verify the trend of the occurrence pattern, a year long monitoring of R. pedestris and its egg parasitism was continued in 2010 in the same location where barley, sesame, and soybean were cultivated in series. We placed four aggregation pheromone traps added with 50 refrigerated eggs of R. pedestris each along the perimeter of the field from 11 April to 31 October. Weekly occurrence patterns of R. pedestris and its parasitism in 2010 were generally similar to the patterns of previous years. Riptortus pedestris population first appeared in the last week of April, peaked after the third week of August, and declined in October. Parasitism by G. japonicum was recorded up to 64% in July, 2010 which was much higher than previous years. This study verifies that G. japonicum is the first colonizer that appears as early as May and remains active until September. Ooencyrtus nezarae, however, starts to occur late from the last week of August and exist in the field until October.

Quality assessment of refrigerated eggs of Riptortus pedestris (Hemiptera: Alydidae) stored at different temperature and relative humidity regimens

Bishwo P. Mainali,Youngkeun Yi,Un Taek Lim 한국응용곤충학회 2011 한국응용곤충학회 학술대회논문집 Vol.2011 No.10

Periodical release of non-viable refrigerated eggs of Riptortus pedestris (Fabricius) has been found to enhance field parasitism level in soybean fields. However, optimum refrigeration conditions required for the eggs in order to preserve its quality to ensure effective level of parasitism for a longer period has been rarely reported. We assessed optimum environment condition for refrigeration of the eggs using three different temperatures (2, 6, and 10℃) and relative humidities (RH) (high, medium and low). Eggs of R. pedestris were refrigerated at nine combinations of temperature and relative humidity for 30 consecutive days. Those eggs were taken out and after 8 days, mated female Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) were individually exposed to the eggs, and their development, emergence, and sex ratio were examined. Number of eggs parasitized was highest (5.9) on eggs stored at 6℃ and high RH. Significantly higher male proportion was recorded in the eggs stored at 10℃. However, RH had no effect on the sex ratio. For both male and female, development time was the least on host eggs stored at 2℃ and high RH. Adult emergence was recorded highest from the eggs stored at 2℃ followed by 6℃ and at high RH. In conclusion, eggs refrigerated below 6℃ at high RH condition maintained better quality of R. pedestris eggs for the parasitization by O. nezarae.

Performance evaluation of Ooencyrtus nezarae (Hymenoptera: Encyrtidae) on eggs of bean bugs reared on different food sources

Bishwo P. Mainali,Soon-Do Bae,Hyun-Ju Kim,Young-Nam Yoon,Yeong-Hoon Lee,In-Hee Park,Hang-Won Kang 한국응용곤충학회 2015 한국응용곤충학회 학술대회논문집 Vol.2015 No.04

Riptortus pedestris (F.) (Hemiptera: Alydidae) attacks several leguminous crops and its reproductive success is found to be affected by the leguminous host types. Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) is an egg parasitoid of R. pedestris and its quality attributes depend on the host egg quality. We, thus, investigated the performance of O. nezarae on eggs of R. pedestris fed on different leguminous seeds. Eggs collected from R. pedestris female adults obtained from rearing on one of the four hosts such as soybean, adzuki bean, mung bean, and cowpea seeds were exposed as a batch (n=15) to a single 4 to 5 day-old mated female O. nezarae. The eggs exposed were collected after 24 h. Number of parasitized eggs, sex ratio, development times, and adult emergence were recorded. The maximum number of eggs parasitized by O. nezarae were the eggs of mung bean fed R. pedestris. Eggs produced from the adzuki bean fed bugs had the lowest parasitization. There was no difference recorded in the developmental time of parasitoids emerged from the eggs of R. pedestris fed on different legumes. Proportion of male O. nezarae was highest on the eggs of cowpea seed fed adult bugs (26%); the lowest of that was found on the eggs of mung bean fed bugs (22.4%). Ooencyrtus nezarae can successfully parasitize eggs of R. pedestris regardless of hosts food sources. However, eggs of mung bean fed R. pedestris, among the tested legumes, were found to be of the best quality for reproductive success of O. nezarae.

Effects of combining releases of non-viable host eggs with insecticide application on Riptortus pedestris population and its egg parasitoids

Bishwo P. Mainali,Sangwon Kim,임언택 한국응용곤충학회 2012 Journal of Asia-Pacific Entomology Vol.15 No.2

Our previous study demonstrated that the release of refrigerated non-viable eggs of Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) enhanced parasitism rates in soybean fields but did not result in the reduction of R. pedestris populations. This study was further conducted using an open-cage exclusion design in a soybean field in order to evaluate the compatibility of combining releases of non-viable host eggswith a single pre-harvest application of insecticide for the control of R. pedestris. Refrigeratedeggs of R. pedestris were released twice in treatment plots, and fresh (b1 day old) eggs of R. pedestris were deployed in all experimental arenas,every 6 days, for host resource and measurement of field parasitism. The releases of host eggs did not reduce the number of R. pedestris in any life stage except the adult stage on two sampling dates. However, parasitism by Gryon japonicum (Ashmead) (Hymenoptera: Scelionidae) was higher in treated plots (9–25%) than in the control plots (1–9%). Statistical significant reduction was not found in the pest population, but parasitism rates significantly increased. Pesticide application did not reduce the bug population but did affect the parasitoids population. Pest management tactics, using both artificially deployed host eggs and insecticide, are discussed. © Korean Society of Applied Entomology, Taiwan Entomological Society andMalaysian Plant Protection Society,

Dispersal Pattern of Egg Parasitoids of Riptortus pedestris in Sesame Field Where Aggregation Pheromone Traps we Installed with Non-viable Host Eggs

Bishwo P. Mainali,Un Taek Lim 한국응용곤충학회 2012 한국응용곤충학회 학술대회논문집 Vol.2012 No.05

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.

Flower model trap helps to reduce thrips infestation on red pepper in field

Bishwo P. Mainali,Eunmok Kim,Un Taek Lim 한국응용곤충학회 2010 한국응용곤충학회 학술대회논문집 Vol.2010 No.05

Chrysanthemum flower model trap developed by modifying an artificial yellow chrysanthemum flower was reported to be more attractive to flower thrips than a commercial yellow sticky trap. The installation of the traps (20 traps per 50 m2 plot), especially, reduced the seasonal populations of Frankliniella intonsa Trybom (Thysanoptera: Thripidae) on strawberry flowers in greenhouse by 82% compared to the untreated control. In this study, we tested if the installation of the flower model traps can reduce thrips population on a red pepper field located in Seokdong, Andong. The pepper field was treated two times with pesticides during the period of experiment. The traps were installed in plant canopy at different densities (0, 5, 10, 20 traps) in 20 plots (3×5 m2 each) using a completely randomized design. Population of thrips was examined on the collected pepper flowers from 1 July to 29 July in 2009. Thrips found on the flowers were all F. intonsa. Significance effect of treatment and sampling date was found from repeated-measure analysis of variance. The highest density of traps significantly reduced female and male F. intonsa population by 60% and 46% compared to the control, respectively. However, no difference in immature population was found among the treatments. These results indicate flower model trap can be an additional tool for the management of flower thrips on field red pepper.

Developmental Rate of Halymorpha halys (Hemiptera:Pentatomidae) Fed on Different Food Sources

Bishwo P Mainali,Soon-Do Bae,Hyun-Ju Kim,Young-Nam Yoon,In-Seok Oh 한국응용곤충학회 2013 한국응용곤충학회 학술대회논문집 Vol.2013 No.04

The brown marmorated stink bug Halyomorpha halys Stål (Hemiptera: Pentatomidae), is native to Korea, Japan, and China. H. halys is one of the major polyphagous pentatomids with a wide host range encompassing ornamental shrubs, trees, and cultivated crops such as millet, sesame, soybean, apple, yuzu, pear, cherry, and peach and inflicting losses of several crops in Korea. However, study on dietary importance of these hosts on the development rate of H. halys is sparse. We evaluated fruits of apple and orange with or without soybean plus peanuts as food sources to investigate development rate, mortality and fecundity of the stink bug. Not apple but orange only diet could support development up to adult stage but with higher mortality. First instars were found to molt into second instars without feeding. The longest time H. halys took to develop was in its fifth instar. Overall shortest developmental period (39.82) days was recorded on those fed on orange+soybean and peanut whereas those fed on orange only diet had longest development period (78.92 days). Generational mortality of those fed on diets consisting of soybean and peanuts ranged from 43 to 53%. Those only fed on water could not develop into third instars. H. halys could not develop into fourth instar in apple only diet. However, on orange only diet 20% H. halys could emerge as adults. Fecundity was measured for the first day of oviposition per female. Fecundity was recorded highest (28 eggs) on orange+soybean and peanut diets. The results suggest that H. halys require leguminous seeds in order to develop fully and lay fertile eggs.