• Korean journal of applied entomology
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• v.60 no.1
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• pp.63-70
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• 2021

Two-spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae) is one of the major pests in apple orchards. TSSM was known to show different population dynamics depending on apple cultivars. We tested the host plant preference and fitness of TSSM on the leaves of 3 apple cultivars, Fuji, Tsugaru, and Hongro. TSSM showed higher behavioral preference to Fuji than Tsugaru and Hongro, and showed a higher fecundity in Fuji. The immature development of this mite was the shortest in Fuji and longest in Hongro. Total fecundities were not significantly different among cultivars, but daily fecundity was higher and longevity was lower in Fuji. Hongro was the less preferred cultivar for TSSM, and showed the lowest fitness by life table parameters. These results could explain the possible mechanisms of differential population dynamics among apple cultivars. Further study including diverse apple cultivars currently available in Korea could help to deploy time- and cultivar- specific IPM tactics.

• Korean journal of applied entomology
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• v.57 no.3
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• pp.143-149
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• 2018

The black pine bast scale (BPBS), Matsucoccus thunbergianae (Homoptera: Margarodidae), is one of the most serious insect pests of Japanese black pine (Pinus thunbergiana) in Korea. The density of BPBS varies by tree, branch, and location, making it difficult to monitor them. This study investigated to find a monitoring method for distribution and occurrence of BPBS on Japanese black pine using the yellow sticky trap. The density of male BPBS on sticky trap and nymphs from the branch of Japanese black pine was highly correlated in various surveyed sites. The number of male BPBS that attracted to the yellow sticky traps was higher in upper crown than the lower crown of P. thunbergiana but this was not statistically significant. The density of BPBS nymphs increases with the increase of the diameter of the branch, but the differences were not significant from 1 to 2.5 cm. BPBS was highly distributed in bottom-faced branch than the upper-faced branch of P. thunbergiana. Therefore, we suggest, the yellow sticky trap for the monitoring of BPBS and when examining the nymph density in branch, it is recommended that the bottom-faced branch of the 2-2.5 cm diameter branch be examined.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.3
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• pp.52-64
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• 2008

Aged sewage sludge with food waste leachate sludge or paper mill sludge was fed to earthworm (Eisenia fetida) populations and the effect of it on feeding and growth rate of earthworm population was investigated. Feeding rate of earthworm population on sewage sludge aged with food waste leachate sludge for 30 days was higher than that aged for 10 and 20 days. At 90 days after feeding, the density of earthworm population decreased regardless of aging period. And earthworm population growth to next generation was blocked by sewage sludge. The feeding rate and the density of earthworm population aged with paper mill sludge for 20 days were higher than that on sewage sludges aged for 10 and 30 days. Until 90 days after feeding, the density of earthworm population increased regardless of aging period of sewage sludge, however, since then decreased. There were comparatively higher feeding rate and growth rate of earthworm population on the sewage sludge which had been mixed with paper mill sludge and aged for 20 days, which rendered the probable pretreating method for vermicomposting sewage sludge.

• Research in Plant Disease
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• v.16 no.2
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• pp.109-114
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• 2010

The occurrence factors of Rice stripe virus (RSV) in Chungcheongbukdo were analyzed by investigating the viruliferous insect rate (VIR) of overwintered small brown plant hopper (SBPH), the population density of SBPH, the infection rate of natural host plants, and the occurrence rate of RSV on rice paddy fields at the 3 areas of Cheongwon, Jincheon, and Boeun in 2008 and 2009. The average VIR of overwintered SBPH was 0.0% in 2008 and 1.1% in 2009. From SBPH collected on early June in 2009, VIR was higher as 1.4% at Jincheon and 4.2% at Boeun than those of overwintered SBPH, and this higher VIR might relate stronlgy with the adult population of SBPH immigrated from China. The populations of SBPH at Cheongwon, Jincheon and Boeun in 2008 were 3.8, 7.5 and 20.8 Head/$m^2$, respectively. However, those of Cheongwon and Jincheon increased up to about two folds as 8.4 and 13.1 in 2009. No RSV was detected on the natural host plants including barley. The factors involved in RSV occurrence were affected negatively by the low VIR of overwintered SBPH, the low population of overwintered SBPH, the low infection rate of RSV on the natural host plants, and the clean cultivation environment in Chungcheongbukdo.

• The Korean Journal of Pesticide Science
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• v.4 no.2
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• pp.50-55
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• 2000

Occurrence, Injury aspects and control effect of some chemicals were investigated on tomato in plastic house from 1997 to 1998. Adults trapped by yellow sticky trap and sweeping net were increased from late May abruptly. Survey of population densities by yellow sticky trap was more clear than sweeping net. Damaged leaves were found out all the year round in continuous cropping fields and rate of damaged leaves was below 20% in early April and increased gradually up to 80% level after late May. Otherwise, damaged leaves were appeared from 6 weeks after transplanting in first growing field and then damaged leaves was 80% level in spring culture. In autumn culture, rate of damaged leaves was maintained 80% level from transplanting to harvesting date regardless of cultivation years. Number of adults was trapped from late May and peak was late June but mature larva was $6{\sim}8$ individuals in spring culture. In autumn culture, adult and larval densities was maintained high for 3 weeks after transplanting but begun to decrease from 4 weeks(early September). Chlorfenapyr EC, cyromazine WP and abamectin EC could suppress larval populations of Liriomyza trifolii effectively.

• Journal of Sericultural and Entomological Science
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• v.51 no.2
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• pp.89-94
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• 2013

The aim of the present study is to investigate food consumption, hatching periods, adult mortality, the mean number of hatchlings and ovipositional trend of Gryllus bimaculatus De Geer. The rearing and experiments were conducted in the rearing room ($28{\pm}2^{\circ}C$, $60{\pm}10%$RH). As the adult rearing density increased from 50 to 400, it did not affect the average daily food consumption of adult crickets which was $0.067{\pm}0.008$ g a day. However, the daily radish consumption decreased from 0.128 to 0.068 g per day. 95.8% of eggs hatched by the sixth day after the beginning of hatching. The average mortality of the adults gradually increased, and reached 93.9% by the 8th week. Total number of hatchlings per female was $172.2{\pm}10.6$ ($mean{\pm}SD$) in 200 females rearing cages, which was noticeably less than $248.8{\pm}17.8$ ($mean{\pm}SD$) in 100 females rearing cages. Sex ratio of the crickets given in the rearing cages did not affect both the number of hatchlings and ovipositon rate. Oviposition rate periodically fluctuated as progressed, and it reached 81.5% of the total oviposition by the $3^{rd}$ week since the beginning of ovipoisiton.

• Korean journal of applied entomology
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• v.58 no.4
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• pp.291-297
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• 2019

Since Metcalfa pruinosa was first reported in Koera, it has continually caused damage to sweet persimmon orchard in southern part of Korea. Metcafa pruinosa exist not only in farmland but also in forest areas, and are difficult to control due to the influx of individuals from near forest. M. pruinosa has been occurred in orchard and its surroundings because of various host range. Thus, it has been difficult to decide spatial range and control time for efficient management. In this study, occurrence and dispersal pattern of M. pruinosa in persimmon orchard were surveyed using clear sticky traps, and spatial patterns were analyzed with SADIE(Spatial Analysis by Distance IndicEs), based on location information at sticky traps. Spatial association between survey time was also analyzed to identify when the spatial pattern changed. In sweet persimmon orchard, M. pruinosa mainly dispersed in mid to late May, when the first instar hatches, and in August, emerging season of adult. The first instar nymphs hatched in mid-May were randomly distributed in orchard, but distribution was changed to aggregative pattern after dispersed surroundings of orchard. Adults showed random distribution pattern after immigration to orchard again. These tendency was also observed in density change at orchard and its surroundings, and matched to actual density of M. pruinosa in sweet persimmon trees.

• Korean journal of applied entomology
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• v.39 no.4
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• pp.251-258
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• 2000

These studies were conducted to investigate the prey consumption and suppression of cotton aphid and green peach aphid by Chrysopa pallens Ramber as a predator. The 3$^{rd}$ instar of C. pallets fed on 29.8, 77.9, 133.6, and 155.7 individuals of apterous Aphis goussypii Glover a day at 17,22, 27, and 32$^{\circ}C$, respectively. A preovipositing female fed on 73.1 individuals, ovipositing female on 86.6 individuals, and adult male on 69.7 individuals of apterous Myzus persicae (Sulzer) a day at the 27$^{\circ}C$. The functional response curve of the larvae and adults of C. pallens to the densities of A. gossypii indicated Helling’s Type II: the consumption of prey by the C. pallens increased with the prey density but the consumption rate decreased. The attack rate of 3rd instar of C. pallens was the highest among the 2nd instar, 3$^{rd}$ instar, adult male and adult female, and handling time was the shortest. The critical ratio of the predator vs. the prey to effectively suppress the population of A. gossypii by releasing C. pallets eggs was 1 : 4 on red pepper and egg plant, and 1 : 3 on cucumber. Release of second larval stave of C. pallens at the ratio of 1 : 30 of the predator vs. the prey controlled satisfactorily A. gossypii on red pepper, and 1 : 20 on cucumber and tomato. The three-times introduction of the eggs of C. pallens was as effective as four applications of insecticides from mid-June to late September.r.

• Korean journal of applied entomology
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• v.18 no.1 s.38
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• pp.15-21
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• 1979

To determine the population regulation mechanism of the Green rice leafhopper (Nephotettix cincticeps Uhler), the responses of the population increase to initial densities and the effect of host conditions and temperatures during developmental period were investigated. In the out door experiment, the increasing ratio of population density of this pest was reduced as initial density increased and this density-dependent effect was differ in accordance with host condition. Host conditioning through feeding resulted in reduction in numbers of eggs produced and it seemed to be affected by some inhibiting materials secreted by the pest during feeding. though the direct effect of feeding can't be excluded. The population growth was related with population density and host stage. Thus in late planted units, the host stage was favourable to the growth of population at low initial insect density but unfavourable at relatively high initial insect density and in early planted units, vice versa. The temperature during developmental stages definitely affected the determination of sex ratio of adult population and reduced numbers of eggs produced. The most favourable temperature to the population increase was $290^{\circ}C$, and at high temperature, $33^{\circ}C$, severe reduction of fecundity was shown ana it seemed to be caused by the simple reduction in numbers of eggs produced.

• Korean journal of applied entomology
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• v.34 no.3
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• pp.249-255
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• 1995

These experiments were conducted to investigate the life history and the seasonal fluctuation of population density of tea red spider mite, Tetranychus kanzawai Kishida and to observe its natural enemies in the southern area. Under field-cage conditions, tea red spider mite occurred 11~12 generations. The average periods from egg to adult emergence were 8.7~13.1 days in summer and 12.6~24.9 days in spring and autumn. The average longevities of adults were 15.5~21.9 days in summer and 25.1~31.6 days in spring and autumn. The average number of eggs laid per female were 45.1 in summer and 52.6 in spring and autumn. Tea red spider mite population showed two peaks during April-June, and appeared third or forth peak during October-November. The density of all the stages was the lowest in July through August. Tea red spider mites stayed at lower parts of tea plants in March but they moved to upper parts in April though June, and they again moved to lower parts after autumn. Tea red spider mite overwintered as all stages. Adults were the dominant overwintering stage during this stage. The surveyed natural enemies of the tea red spider mite were 7 species including Amblyseius longispinosus (Evans), A. eharai Amitei et Swirski, Anystis baccarun (L), Agistemus fleschneri Summers, Orius sauteri Poppius, Oligota yasumatsui Kistner and Scolothrips sp.