• Korean journal of applied entomology
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• v.46 no.2
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• pp.281-286
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• 2007

Two hymenopteran egg parasitoid species, Gryon japonicum (Ashmead) (Scelionidae) and Ooencyrtus nezarae Ishii (Encyrtidae), were emerged from eggs of bean bug, Riptortus clavatus Thunberg (Heteroptera: Alydidae). The former parasitoid is first recorded in Korea. Brief morphological and biological characteristics, and parasitism on R. clavatus eggs are described.

• Korean journal of applied entomology
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• v.25 no.1 s.66
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• pp.37-40
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• 1986

We surveyed the IRRI farm to determine the extent of parasitization of yellow stemborer egg masses. The egg masses were randomly collected at weekly intervals from July to October 1984 from rice fields, 15-20 days after transplanting, and brought to the laboratory for collection of emerging parasites. Three species of hymenopterous parasitoids-Tetrasticus schoenobii, Telenomus rowani, and Trichogramma japonicum-were found from 700 egg masses. We introduced a method to calculate percent parasitism as based on parasite biology and behaviour. Among the three species, the combination of T. rowani and T. japonicum was the highest multiparasitization of yellow stem borer egg masses, and T. rowani, a solitary parasite had the highest number based on immature and adult stages counted. However, T. schoenobii may be the most efficient parasite because two to four host eggs are needed to complete the larval period, and it took $10{\sim}14$ days for one generation.

• Korean journal of applied entomology
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• v.44 no.2
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• pp.131-137
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• 2005

Seasonal occurrence of the egg parasitoid of bugs, Ooencyrtus nezarae (Hymenoptera: Encyrtidae), was monitored at soybean fields and university campus using traps baited with aggregation pheromone of bean bug, Riptortus clavatus, in Jinju, Gyeongnam province, Korea. The female O. nezarae captured at university campus in 2003 and 2004 was 317.5 and 103.4 times as many as males, respectively, and it was 12.6 times at soybean field in 2004. The female began to occur from late August, showing its peak around September 20 at soybean field in 2004. At university campus in 2003 and 2004, the female began to occur from mid or late August, and showed its peak early or mid September. At the two monitoring sites the catches of female sharply declined after October The E2HZ3H only showed attractiveness to O. nezarae, among three components of the aggregation pheromone of bean bug, (E)-2-hexenyl (Z)-3-hexenoate (E2HZ3H), (E)-2-hexenyl (E)-2-hexenoate (E2HE2H), and myristyl isobutyrate (MI). A mixture in a ratio of 20:20:10 or 16.7:16.7:16.7 of E2HZ3H:E2HE2H:MI attracted significantly more females than the mixture of 7:36:7 ratio did. This higher attractiveness of the former two blends may be attributed to the higher amounts of E2HZ3H in the blends.

• Korean journal of applied entomology
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• v.46 no.2
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• pp.275-280
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• 2007

This survey was conducted to illustrate insect pests and their natural enemies in soybean fields in Honam area. A total of 23 pest species in 13 families and 13 species of natural enemy were observed during 2002 to 2003. Delia platura, Medythia nigrobilineata, Spodoptera exigua and Aphis glycines occurred relatively with high population densities during the early growth stage of soybean. Dolycoris baccarum, Riptortus clavatus, Nezara antennata, Piezodorus hybneri and Halyomorpha halys began to occur between mid July to early August and lasted until the harvest time. Lepidopteran insect pests, Leguminivora glycinivorella, Pleuroptya ruralis, Scopula missaria, Macdunnoughia purissima and Spodoptera litura occurred significantly in late August in soybean field. Natural enemies of soybean insect pests observed in this survey were seven parasitoids, five predators, and an entomopahogenic fungus. Two egg parasitoid species for R. clavatus, two parasitoid species for P. ruralis, and five natural enemy species (including parasite, predator and entomopathogenic fungi) for either S. litura or A. glycines were identified, respectively. Among them two egg parasitoid species, Gryon japonicum and Ooenyrtus nezarae for R. clavatus, for and one parasitoid species for P. ruralis, that belong to Bethylidae, were new to Korea.

• Korean journal of applied entomology
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• v.19 no.2 s.43
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• pp.109-112
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• 1980

This study was carried out to investigate the distribution of egg parasitoids from green rice leafhopper, Nephotettix cincticeps Uhler, from the middle of August through the early September in southern rice cultural areas. The results were obtained as follow. 1. Four species of egg parasitoids, Gonatocerus sp. A and B, Paracentrobia andoi and Anagrus sp. are newly recorded from the eggs of green rice leafhopper. 2. Egg parasitism rates of Gonatocerus sp. were varied from $41.0\~73.9\%$ on an egg mass basis and from $29.7\~49.0\%$ on basis of egg. Percent parasitism rates by Paracentrobia andoi were $0\~9.7\%$ on an egg mass basis and from $2.1\~12.6\%$ on basis of egg. Gonatocerus sp. was dominant egg parasitoid in the parasitism rate than Paracentrobia andoi.

• Korean journal of applied entomology
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• v.23 no.4 s.61
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• pp.233-236
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• 1984

Studies were conducted to investigate the effect of Carbofuran 3G on the density variation of rice pests and their natural enemies in case the insecticide was treated two times as compared with usual trials in paddy field. Even the two times application of Carbofuran 3G in the nursery boxes of machine transplanting and paddy water trials obtain same results to pests, small brown planthopper (Laodelphax striatllus), green rice leafhopper (Nephotettix cincticeps), brown planthorper (Nilaparvata lugens), white back planthopper (Sogotella furcifera), rice stem bore (Chilo suppressalis), rice stem maggot (Chlorops oryzae), rice thrips (cloethrips oryzae) as compared with usual trials. The density of natural enemies, spiders and egg parasite, Anagrus sp. of planthoppers in the two times application part of Carbofuran 3G increased 2.4 fold as compared with usual trials.

• Korean journal of applied entomology
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• v.23 no.4 s.61
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• pp.237-241
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• 1984

The trichogrammatidae ego parasite of the green rice leafhopper (GRLH), paracentrobia andoi, were investigated to know their parasitic activities after overwintering in the paddy banks and fallow fields, their seasonal variation and per cent parasitism in the paddy fields of Gyeongnam provincial O.R.D. at Jinju from 1982 to 1984. The parasitic activities of Paracentrobia andoi after overwintering in the Paddy banks in early Masch were high and tended to decrease remarkably since early April by moving to the fallow fields. The parasitic rate of paracentrobia andoi on GRLH was $21\%$ between late April and early May. the peak of egg laying period of GRLH. The per cent parasitism of the wasps in fallow fields was an average of $0\%$ in Gyeochang and Namji and $9.6-29.2\%$ in Namhae, Kimhae and Jinju. The parasitic activites of Paracentrobia andoi had three peakrs in paddy field, however, the highest peak was ovserved between mid- August and early October. The per cent egg parasitism of Paracentrobia andoi was an average of $16.5\%$ on second generation of Nepotettix cinctireps and $36.7\%$ on third generation of the leafhopper.

• Korean Journal of Agricultural Science
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• v.12 no.2
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• pp.253-259
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• 1985

This paper presents a natural enemy complex of plant and leafhoppers in rice plants and a relationship between the host insects and their natural enemies. Feeding preference of major paddy spiders have been tested. To date, 32 species of natural enemies of plant and leafhoppers have been recorded, including 30 species of parasites and predators (15 parasitoids, 14 predators and nematode) and 2 species of insect pathogens. Some of species have shown great potential for controlling plant-leafhoppers populations; parasites, Anagrus nr. flaveolus, Gonatocerus sp., Haplogonatopus atratus and paddy spiders. Pirata subpiraticus and Gnathonarium dentatum. Plant and leafhoppers-natural enemy relationship have been observed in different developmental stages of the host insects. Pirata sub-piraticus is the most active to searching the host insects and also prefered nymphs to adults.

• Korean journal of applied entomology
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• v.23 no.3 s.60
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• pp.158-165
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• 1984

These studies were carried out to investigate the bionomics of Gonatocerus sp. y (Hymenoptera: Mymaridae) , an egg parasite of the green rice leafhopper, Nephotettix cincticeps Uhler (Homoptera: Deltocephalidae) under laboratory and field conditions at Gyeongnam Provincial O.R.D. in Jinju from 1982 to 1983. The developmental period of each life stage was observed under four different temperature conditions from $15^{\circ}C\;to\;30^{\circ}C\;with\;5^{\circ}C$ increment. The development from egg to adult at 15^{\circ}C,\;20^{\circ}C,\;25^{\circ}C,\;and\;30^{\circ}C $ was completed in an average of 53, 25, 15, and 12 days and the females laid an average of 28, 48, 42, and 32 eggs respectively, with a maximum of 98. And most of the eggs were laid in the first two days after emergence. The time of adult emergence was determined under $25{\pm}1^{\circ}C$ condition. More than $76\%$ of the wasps emerged in the morning and the rest of them emerged in the afternoon. The average sex ratio between male and female was 1 : 5 when the wasps were developed from fertilized eggs. The longevity of female was greater than that of male when honey and water were provided as food, however, it was not when only water was supplied as food. The average longevities of females were 30 days at $15^{\circ}C$ and 15 days at $20^{\circ}C$ when honey and water were given as food. The peak precent parasitism of Gonatocerus sp. v on Nephotettix cincticeps in fallow fields was observed between late April and early May. The percent parasitism of the wasps In fallow fields was an average of 49\~59.9\% $ in Gyeochang, Namji and $23.2\~36\%$ in Namhae. The parasitic activities of the parasite had four peaks in paddy field, however, the highest peak was observed between late August and early September. The Percent e99 Parasitism of Gonatocerus sp. y was an average of $12.3\%$ on second the generation and $24.6\%$ of third genera lion of Nephotettix cinrticeps.

• Korean journal of applied entomology
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• v.48 no.1
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• pp.67-72
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• 2009

The kairomonal activity of the aggregation pheromones of Riptortus clavatus for the egg parasitoid, Gryon japonicum, were investigated in soybean field. The parasitism rate of G. japonicum gradually decreased when the distances between pheromone traps and egg sites were increased from 0 to 15 m. The active distance of pheromone source for parasitoid attraction was estimated to be ca. 15 m. Under field conditions, the parasitoid wasp population peaked during the late August and early September, and the parasitism rate increased when the number of pheromone traps was increased from one to three per $165\;m^2$. However, insecticide-treated plots, the level of parasitism recorded is relatively low. Sex ratios in field populations of G. japonicum were female-biased.