• Korean journal of applied entomology
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• v.44 no.3 s.140
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• pp.231-235
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• 2005

This study was conducted to obtain the optimal spray time for Pseudaulacaspis prunicota (Maskell) (Homoptera: Diaspididae) in early seaon in Jeju. Oviposition time of overwintered females and activity of hatched nymphs of P. prunicola were monitored, and the phenology data were compared with the outputs estimated by a degree-days model of P. pentagona (Targioni-Tozzetti)). Overwintered females of P. prunicola began to lay eggs from mid to late April, and the eggs started to hatch from early May followed by the active migration of the hatched nymphs during mid May. The phenological events of P. prunicola in early season were likely comparable with those of P. pentagona reported in southern Korea and in central Japan. A degree-day model, which predicts the proportion of >50% hatched egg batches of P. pentagona (y=1[exp(-(-a+bx))]; y, proportion; x, degree-days based on $10.5^{\circ}C$ from 1 January; a=-18.80 and b=0.073), accurately described the migration time of P. prunicola hatched nymphs. Thus, it is considered that the degree-day model can be used for predicting the optimal spray time for P. prunicola in early season.

• The Korean Journal of Ecology
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• v.18 no.4
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• pp.463-470
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• 1995

Anoplocnemis dallasi Kiritchencho is a sap-sucker which feeds on tips of amorpha fruticosa Linne in Korea. A. Dallasi had one generation a year and overwintered as the young adult stage. Most overwintered survivors emerged in early-mid May to late May. Known host plants were reviewed, and new host records were added. Females mainly laid eggs in linear single chain masses on leaves of Miscanthus sinensis var. purpurascens. Nymphs (except the non-feeding first instars) fed on young shoots. First instar nymphs clustered on leaves or shoots where they hatched, and, if disturbed, reformed aggregations soon. The second to the fifth instar nymphs migrate to the upper part of the shoot and congreagate on a partly expanded leaf. New adults firstly appeared in late August, remained on A.fruticosa, host plant, and fed on until mid October. The duration and survivorship curve, in laboratory rearing, of the egg and each nymphal stadium was determined.

• Korean journal of applied entomology
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• v.56 no.2
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• pp.97-105
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• 2017

An investigation was conducted to determine the characteristics of seasonal occurrences and effective insecticides for minimizing the occurrence of Pseudaulacaspis cockerelli in sweet persimmon orchards. Most of the nymphs or female scales that mated in mid-September overwintered on twigs, matured to lay eggs in the next spring in accordance with temperature increase, and survived till mid to late May to lay all of their eggs. Males mostly died after mating by the end of September, while the males on the fallen leaves died during the hibernating period. Egg laying in P. cockerelli showed differences in accordance with the weather conditions in each year. They laid eggs from mid-April to mid- or late May, with a peak in early or mid-May. A female was estimated to lay 160 eggs; eggs hatched a week later from the peak period of egg laying. In summer, egg laying started in early or mid-July and ended in mid- or late August, with a peak in late July or early August; a female laid approximately 130 eggs in summer. The estimated egg period was 4 days. The first generation nymph that hatched from the eggs laid by the overwintered female on twigs showed 10% occurrence on twigs and 90% on leaves. The first generation nymphs on twigs mostly developed into female scales. The occurrence of the second generation nymphs reached a peak on July 27, 2009; they lived on the twigs as their overwintering site from mid- or late August. The female and male scales on leaves developed at the similar rate as the first generation nymphs up to August. The occurrence of male scales indicated that the peak occurrence of nymphs was on August 12, 2009, male scales on August 27, and adults approximately on September 14, which showed steady relationship in the sequence of development from nymphs to adult males. Among the nymphs that occurred on the leaves on August 12, 75% of them emerged into male adults, mated, and died. Buprofezine+dinotefurn (20+15) WP treatment on June 9 and 16 resulted in 90.6% control of P. cockerelli, when mortality was checked 7 weeks after treatment.

• Korean journal of applied entomology
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• v.34 no.1
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• pp.70-74
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• 1995

A study on seasonal changes in age structure and fecundity of Gryllotalpa africana Palisot de Beauvois was conducted in Suwon from 1991 through 194. It seemed that most of newly hatched nymphs emerge to adults in September and October, so have a life cycle a year, and some overwinter as nymphs and emerge to adults from August, so have a life cycle tow years. The mean number of eggs per cell was $36.00\pm$2.84 for egg cells laid in the laboratory, and $47.68\pm$4.35 for egg cells collected in the field. Mean and range of the numbers of egg cells produced per female were $1.17\pm$0.19 and 0~3.

• The Korean Journal of Pesticide Science
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• v.14 no.2
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• pp.157-163
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• 2010

This study was performed to investigate the hatching rate and eggs period until hatching in the laboratory against lantern fly, Lycorma delicatula eggs with different collecting date of eggs, and the susceptibility of 26 insecticides to the eggs, 1st and 2nd nymphs of Lycorma delicatula. The eggs of L. delicatula were increased the hatching rates as passed collecting date of eggs, and shorten in eggs period until hatching. By screening the susceptibility of 26 insecticides to the eggs, 1st, and 2nd nymphs, chlorpyrifos (312.5 ppm) showed the perfect inhibition effect of hatching against the eggs, however, the other insecticides did not show that effect. According to the collecting date of eggs, chlorpyrifos bioassayed the inecticidal effect with different concentration (625 ppm at double conc., 312.5 ppm at recommended conc., and 156.3 ppm at half conc.). The eggs collected from Apr. 20th 2010, were showed the inhibition effect of hatching over 94.5%, but the eggs collected from May 10th, 2010 were showed the inhibition effect of hatching as 86.7, 71.1, and 47.1%, respectively. However, hatched eggs were all killed perfectly within 24 hours. At recommended and half concentrations, the eggs collected from 15, May, are decreased the effect as 48.6%, 53.7%, respectively, and the mortality of eggs hatched also decreased as 61.0 and 22.0%, respectively, however, double concentrations did not show the changes. From the above results, it will be anticipate to show the higher mortality against the eggs of L. delicatula when treated chlorpyrifos until late-April.

• Korean journal of applied entomology
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• v.58 no.4
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• pp.381-387
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• 2019

From 2017 to 2019, the ovipositional and the developmental characteristics of Gampsocleis ussuriensis Adelung in the Buan area of Jeonbuk Province were examined. G. ussuriensis were mostly found in the weeded areas around the reservoir, where the adults first appeared in mid-July, showed up where by the early September, and overwintered in eggs. Nymphs appeared in early April to mid-July the next year. The nymphs hatched from early April and adults appeared after molting five times. The ovipositional period of G. ussuriensis was approximately 58 days. The total number of eggs per female was 124. The mean longevity of adults was 95.6 days for females and 84.8 days for males. Ovipositional mats were best with mixed Masato and Coco-Pitt at a ratio of 7:3. Developmental period of G. ussuriensis nymphs was 64.1 days at 24℃ and was longer than at different temperatures. The higher the temperature, the shorter the developmental period. The survival rate of nymphs was the best at 32℃ in 77.8%. The higher the density while rearing, the lower the survival rate, and the faster the development and molting velocity.

• Korean journal of applied entomology
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• v.22 no.4 s.57
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• pp.262-270
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• 1983

The newly hatched nymphs of brown planthopper(BPH) were reared individually for two generations in test tubes, where young rice seedling was planted on agar solution, at $30^{\circ}C,\;25^{\circ}C\;and\;20^{\circ}C\;with\;95\%,\;75\%,\;65\%\;and\;35\%$ R.H. Effects of $30^{\circ}C$ on the development of BPH when compared with those of $25^{\circ}C$ are followings. Egg period, nymphal period, and adult longevity were shortened. Nymphal mortality was increased and the number of oviposited eggs was decreased. Hatchability was zero per cent because the eggs were either unfertilized or died before finishing the development. At the low temperature of $20^{\circ}C$, in comparision with $25^{\circ}C$, the developmental period of nymphs and eggs was considerably lengthened, and adult longevity was shortened, the number of oviposited eggs was decreased. The nymphal mortality was higher at high relative humidity $(above\;75\%\;RH)$ than that at low relative humidity $(under\;65\%\;RH)$. Under the condition of high relative humidities, the adult longevity was shortened, and the number of oviposited eggs was decreased.

• Korean journal of applied entomology
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• v.45 no.3 s.144
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• pp.381-383
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• 2006

The hatching rate of the eggs of Nannophya pygmaea Rambur, an endangered dragonfly species in Korea, was experimented in different temperature conditions ($10,\;15,\;20,\;25,\;and\;30^{\circ}C$) in laboratory. N. pygmaea eggs were collected from female adults inhabited a small wetland in Mungyong-si, Kyeongsangbuk-do, Korea, in July 2006. The hatching rate was evaluated from the number of hatched nymphs for the period of 100 days. As a result, the hatching rates were 83, 89, and 76% at $20,\;25,\;and\;30^{\circ}C$, respectively; however, eggs were not hatched at $10^{\circ}C\;and\;15^{\circ}C$ during the experiment period. The derived thermal threshold for egg hatching was $14.3^{\circ}C$, which is relatively higher than the values of other temperate dragonflies.

• Korean journal of applied entomology
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• v.18 no.2 s.39
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• pp.85-88
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• 1979

The cotton aphid, Aphis gossypii Glover, is known as the most important vectant vector of citrus tristeza virus, cucumber mosaic virus, potato virus Y and potato leafroll virus. This study conducted to investigate the life history of cotton aphid at Suweon, Korea$(Lat.37^{\circ}16'N,\;Long\;126^{\circ}59'E)$. The aphids were reared in small cages placed over twig of hibiscus and on the leaves of cucumber. The results obtained were summarized as follows: 1. Overwintering eggs hatched from mid to late April, with a hatching rate averaging seventy-nine percent. 2. The early-born progeny have 22 generations and the late-born progeny have 6 generations on hibiscus and cucumber from April to October. 3. The fundatrigeniae leave tile the primary host in late May to early June and migrate to the secondary hosts. 4. From early to mid Oct., the gynoparae migrate from the secondary hosts to the primary host. 5. The average length of life was about 29 days and they produced an average of 70 nymphs each. 6. The maximum number of aphids produced per female was 117 in the spring. 7. The developmental period ranged from 6 to 16 days (average 8 days), the reproductive period from 12.2 to 24.6 days (average 19 days). 8. The average number of nymphs produced by a female per dys was about 3.7, with a maximum number of 17.

• Korean journal of applied entomology
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• v.48 no.4
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• pp.423-429
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• 2009

Characteristics of habitat alteration and post-embryonic development of Paratlanticus ussuriensis were investigated in the mountain region of Bitanri, Yeongdong county, Chungcheongbuk-do from 2007 to 2009. Overwintered eggs under the ground in the hillside were hatched from late March to early April. The soil temperature during this season was $7{\sim}14^{\circ}C$. Young nymphs lived mainly at the hillside by eating oak tree leaves but the 3rd or 4th instars switched their habitat to orchards near the hillside in early May, which is the time for sprouting of peach leaves. Old nymphs developed into the adult stage at the orchards in late May and moved back to the hillside in late June. Duration of post-embryonic development from the first instar nymph to adult was 49.2 days after 7 moltings at $25^{\circ}C$. Female adults collected from the field had long ovipositor (26.2 mm) and were slightly longer in the body length, hind femur, tegmen and pronotum than those of males.