Reproduction and dispersal pattern of egg parasitoids of Riptortus pedestris (Hemiptera: Alydidae) after installing pheromone traps plus non-viable host eggs

Bishwo Prasad Mainali,Un Taek Lim 한국응용곤충학회 2016 Journal of Asia-Pacific Entomology Vol.19 No.1

The aggregation pheromone of Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) has a kairomonal effect on its egg parasitoids. The addition of non-viable R. pedestris eggs to aggregation pheromone traps was suggested as a means to enhance reproduction of parasitoids attracted to pheromone traps and was found to enhance field parasitism. In this study, we tested if the eggs added to traps are indeed used by parasitoids for their reproduction. Spatial distributions of egg parasitism were assessed in a barley and a sesame field where non-viable host eggswere installed at four distances (8, 16, 24, and 32m) in two directions fromthe aggregation pheromone traps placed in the center of each field.While field parasitismincreased significantly over time, it decreasedwith distance fromtraps. Higher egg parasitismwas found up to 16mfrom the point of release in both barley and sesame fields. To compare temporal changes in parasitism, traps were also installed in another barley and another sesame field without adding host eggs. From regression slope comparisons, significant differences were found only in the sesame fields,where the parasitismrate on the last sampling date in the egg-released fieldwas higher than the comparison field by 80%. A higher male proportion was found near the trap installation point only for Gryon japonicum (Ashmead) (Hymenoptera: Platygastridae) in the sesame field. These findings suggest that supplemental host eggs in traps enhance field parasitismby increasing the reproduction and dispersion of field populations of parasitoids.

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.

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.

Evaluation of a newly developed aggregation pheromone trap of Riptortus pedestris (Hemiptera: Alydidae) to enhance parasitoid multiplication

Bishwo Prasad Mainali,Young-il Kim,Man-Woong Park,Un Taek Lim 한국응용곤충학회 2010 한국응용곤충학회 학술대회논문집 Vol.2010 No.10

In a previous study, aggregation pheromone trap added with refrigerated eggs of Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) in a netted pouch was found to enhance parasitism by its egg parasitoid Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) in soybean fields. However, the eggs released in the netted pouch would not be well exploited by the egg parasitoid due to reduced encounter of the eggs and elevated inter- or intraspecific competition among the parasitoids in clumped condition of released eggs inside the pouch. To solve this problem, new trap was developed with twelve separate cells for egg placement. Efficiency of this new trap was evaluated in a soybean field in Songcheon, Andong. Newly developed trap and formerly designed trap each with 180 refrigerated eggs were placed at a distance of 15-20m in the field. The released eggs were collected every week, and the experiment was replicated for three weeks. In addition, comparison was carried out by placing eggs in different density in the cell (120 in total per trap) for three weeks. Parasitism in newly developed trap (32-35%) was higher than that in the former trap (16-20%). Parasitism in the trap where eggs were released in six cells was the highest, followed by three cells, one cell, and eggs released in the pouch. From these findings, newly developed traps is better than previous design in enhancing the parasitism in soybean fields.

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.

Estimating optimum rate of chrysanthemum flower model traps to manage Frankliniella intonsa in strawberry greenhouse

Bishwo P. Mainali,Un Taek Lim 한국응용곤충학회 2008 한국응용곤충학회 학술대회논문집 Vol.2008 No.10

Chrysanthemum flower model trap (CFMT) developed to attract the flower thrips was evaluated for its optimal trap density that is required to manage the population of flower thrips in a strawberry greenhouse. CFMTs were installed in different rates per unit area (10m×5m), i.e., control (no trap), low (5 traps), medium (10 traps), and high (20 traps), in three different strawberry greenhouses at Namhoo, Andong. From each plot, 10 flowers were sampled every week from 16 May 2008 to 6 June 2008. Five traps were also randomly collected from each plot every week to record the number of flower thrips trapped. The seasonal number of both female and male thrips collected in the flowers was significantly lower in the plots with high density of traps compared to the control. In the plot with medium level of traps, less seasonal number of male F. intonsa were found in the strawberry flowers compared to the plot with low level of traps or control. When the numbers of thrips in the flowers were plotted against the numbers of thrips trapped in the CFMTs, significant correlation was found in female thrips only. However, there was no significant difference in seasonal number of male and female thrips trapped in the CFMTs randomly collected from the plots among the treatments. In conclusion CFMT used in medium or high density in the strawberry greenhouse reduced infestation of F. intonsa in the flowers and can be a good addition to integrated pest management tactics against anthophilous thrips.

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.

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,

Evaluation of chrysanthemum flower model trap to attract two Frankliniella thrips (Thysanoptera: Thripidae)

Bishwo Prasad Mainali,임언택 한국응용곤충학회 2008 Journal of Asia-Pacific Entomology Vol.11 No.3

Frankliniella occidentalis Pergande and F. intonsa Trybom (Thysanoptera: Thripidae) are anthophilous insect pests of many crops worldwide. We evaluated a flower model trap mimicking the chrysanthemum flower as a new method to attract the thrips in the laboratory and a strawberry greenhouse. Both choice and no-choice tests in the laboratory showed that the chrysanthemum flower model trap attracted significantly more adult F. occidentalis and F. intonsa compared to yellow sticky trap. Up to 4.1 times more of F. occidentalis and 5.4 times more of F. intonsa were caught in the flower model trap in the strawberry greenhouse. The flower model trap would be a good addition to the integrated thrips management, although at present it is more expensive than the yellow sticky trap. Frankliniella occidentalis Pergande and F. intonsa Trybom (Thysanoptera: Thripidae) are anthophilous insect pests of many crops worldwide. We evaluated a flower model trap mimicking the chrysanthemum flower as a new method to attract the thrips in the laboratory and a strawberry greenhouse. Both choice and no-choice tests in the laboratory showed that the chrysanthemum flower model trap attracted significantly more adult F. occidentalis and F. intonsa compared to yellow sticky trap. Up to 4.1 times more of F. occidentalis and 5.4 times more of F. intonsa were caught in the flower model trap in the strawberry greenhouse. The flower model trap would be a good addition to the integrated thrips management, although at present it is more expensive than the yellow sticky trap.

Use of flower model trap to reduce the infestation of greenhouse whitefly on tomato

Bishwo Prasad Mainali,임언택 한국응용곤충학회 2008 Journal of Asia-Pacific Entomology Vol.11 No.2

Flower model trap (FMT) made from artificial yellow chrysanthemum flower coated with sticky material was originally developed to attract anthophilous Frankliniella thrips species. During evaluation of the FMT in a strawberry greenhouse, it was also found to attract higher number of greenhouse whitefly, Trialeurodes vaporariorum Westwood (Homoptera: Aleyrodidae), compared to the conventional yellow sticky trap. The color cue exhibited by the petals and/or geometrical pattern of the flower models might have tempted the whitefly to land on them. Therefore, we assessed the potential of the FMT as a novel pest management tactic for T. vaporariorum. In laboratory comparison test in an acryl cage, the FMT captured adult whiteflies 1.8 times more than did the yellow sticky trap. Installation of 80 FMTs in a 500 m2 commercial tomato greenhouse significantly reduced the adult population of T. vaporariorum. Sooty mold infestation was also reduced by 85% on the greenhouse fruits. Similarly less sooty mold infestation was found on the harvested tomato fruits from the trap-equipped greenhouse. Although no significant reduction in the nymphal population of T. vaporariorum was observed, the FMT employed with timely installation and replacement could be another useful greenhouse tomato pest management tactic for T. vaporariorum. Flower model trap (FMT) made from artificial yellow chrysanthemum flower coated with sticky material was originally developed to attract anthophilous Frankliniella thrips species. During evaluation of the FMT in a strawberry greenhouse, it was also found to attract higher number of greenhouse whitefly, Trialeurodes vaporariorum Westwood (Homoptera: Aleyrodidae), compared to the conventional yellow sticky trap. The color cue exhibited by the petals and/or geometrical pattern of the flower models might have tempted the whitefly to land on them. Therefore, we assessed the potential of the FMT as a novel pest management tactic for T. vaporariorum. In laboratory comparison test in an acryl cage, the FMT captured adult whiteflies 1.8 times more than did the yellow sticky trap. Installation of 80 FMTs in a 500 m2 commercial tomato greenhouse significantly reduced the adult population of T. vaporariorum. Sooty mold infestation was also reduced by 85% on the greenhouse fruits. Similarly less sooty mold infestation was found on the harvested tomato fruits from the trap-equipped greenhouse. Although no significant reduction in the nymphal population of T. vaporariorum was observed, the FMT employed with timely installation and replacement could be another useful greenhouse tomato pest management tactic for T. vaporariorum.