• Korean journal of applied entomology
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• v.14 no.4 s.25
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• pp.215-219
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• 1975

The number of instars of pear sawfly larvae (Janus piri Okamoto) collected front field pear trees, were determined by measuring the width of head capsule, and the growth ratio in each instar was also studied. 1. The larval head width had six distinct peaks, which suggests that the larva of this insect passes six instars. 2. The head width tended to increase as the instars avdance, except in tile first and second instars. The coeffieient of variation decressed as the instars advanced. The growth ratio, which was similarly great in the first and second instars, decreased as the instars advanced. 3. Gains' and Campbell's formulae seemed to be more suitable than Dyer's for the determination of larval instars of this insect by the measurement of headwidth. 4. The larval instars could be inferred from the extent of damage to pear tree by this insect; that is the larvae in the second to fourth instars usually gave slight and invissible damage, while those in the fifth to sixth instars gave rapid and severe damage.

• Korean journal of applied entomology
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• v.28 no.2
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• pp.88-92
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• 1989

The Oriental tobacco budworm, Heliothis assulta (Guenee), larvae usually feed on the hot-pepper fruits and young tobacco leaves or buds in Korea. This experiment was conducted t(} compare their attraction to their host plants including fruits of the sweet-pepper and solanum uk kwang, besides the other two mentioned above. First instar larvae were most attracted to the hot-pepper fruits. Flowers or leaves of the hot pepper plants were not attractive either. When the hot-pepper fruits were compared for attractancy, based on developmental stages, relatively mature fruits, just before ripening, were the most attractive. Their extract with or without 10% ethanol also gave similar result to 1st instar larvae or 2~4 instar larvae, suggesting a possibility that there is an attractant(s) in the hot-pepper fruits.

• Korean journal of applied entomology
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• v.35 no.3
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• pp.249-253
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• 1996

In the laboratory study, the toxicities of chlorpyrifos-methyl, chlorpyrifos, etofenprox, etofenprox+PAF' and deltamethrin for different larval instars of S. litura decreased significantly as larvae aged. LCso values for chlorpyrifos- methyl and chlorpyrifos increased significantly from 3rd instar larvae, while those for etofenprox+PAP and deltamethrin-increased from 2nd instar larvae. In pot study, no significant differences in control efficacy were observed among each treated plots and over 90% control efficacy at 5 d after treatment was obtained in all of the treated plots, except treatment with deltamethrin. Therefore four insecticides excluding deltamethrin will be effective for controlling S. litura. However, it will be probably important to select appropriate insecticides and decide a proper time of treatment because the developmental stage is a significant factor in deciding insecticide efficacy because various developmental stages of the tobacco cutworm inhibit in fields.

• Korean journal of applied entomology
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• v.30 no.1
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• pp.54-57
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• 1991

The width of head capsule of the beet armyworm, Spodoptera exigua (Hubner), was measured on the 5th generation larvae reared with artificial diet. The mean widths of head capsule of each instar were: 1st, 0.246 mm; 2nd, 0.35 mm; 3rd, 0.546 mm; 4th, 0.809 mm; 5th, 1.242 mm; and 6th, 2.185 mm. The coefficient of variation (%) of each instar were: 1st, 8.6; 2nd, 9.5; 3rd, 15.1; 4th, 11.2; 5th, 12.0; and 6th, 12.9. The growth ratio of each instar were: 2nd, 1.43; 3rd, 1.55; 4th, 1.48; 5th, 1.54; and 6th, 1.76. The fitness(%) to Dyar's law of the measurement of head capsule width were: 1st, 94.7; 2nd, 98.3; 3rd, 98.7; 4th, 94.8; 5th, 94.6; and 6th, 92.2. When the logarithm of the width is plotted against the number of instars, the calculated regression line is highly significient (Log Y = -0.819 + 0.1872X, $r^2$ = $0.9977*{**}$) and Dyar's constant was 1.54.

• Korean journal of applied entomology
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• v.61 no.3
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• pp.423-434
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• 2022

The two previously developed artificial diets (N4 and N6) used for rearing Spodoptera frugiperda (Noctuidae) larvae, were selected as highly-fit ones for rearing Mythimna loreyi larvae. Almost all biological characteristics were not significantly different between the colonies reared on the two diets at 25℃ and 15:9 h (light:dark) photoperiod. The developmental periods were 4.9-5.2 days for eggs, and 22.3-23.2 days for larvae. The pupal period and weight were different between the sexes in each diet colony. The pupal periods in females and males showed 12.6-12.8 days and 14.1-14.5 days, respectively. The pupal weights were ca. 345 mg for females and ca. 380 mg for males. The pupation and emergence rates were ca. 91-94%, and ca. 91-95%, respectively, without significant differences between the two colonies. The pre-oviposition and oviposition periods were 3.4 days and 4.7-4.8 days, respectively. The adult longevity was 8.2 days in females and 10.3-12.4 days in males. Total offsprings produced were found to be 724-847 larvae on an average with ca. 1,400 maximum larvae. In the life table analysis, the intrinsic rates of increases (0.1181 for N4 and 0.1253 for N6) were not significantly different between the two colonies. Individual differences in the larval instar number 5 and 6 were found within a diet colony. The ratios of 5-instar larvae were ca. 22% in N4 colony and ca. 7% in N6 colony. The larval period of 6-instar larvae was longer than that of 5-instar larvae. Width of head capsule in larvae varied from ca. 309 ㎛ for 1st instar to ca. 3,065 ㎛ for 6th instar. Body lengths measured from ca. 2.0 mm for 1st instar to ca. 29.1 mm for 6th instar. Larvae of M. loreyi and M. separata were found at the same time in a maize field during June and July, 2020.

• Korean journal of applied entomology
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• v.30 no.2
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• pp.130-130
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• 1991

현미를 사료로하여 네가지 정온도조정에서(25, 28, 34, 36$^{circ}C$ $pm$0.5$^{\circ}C$, RH 70%)에서 거짓쌀도둑(Tribilium castaneum Herbst)의 각 충태별 평균발육기간($\pm$SE)을 산출하였으며, 이를 기초로하여 발육임계온도를 추정하였다. 난의 평균발육기간은 각 온도에서 7.6$\pm$0.25, 4.8$\pm$0.10, 3.0$\pm$0.03, 2.5$\pm$0.09일, 유충에서 각각 53.3$\pm$1.49, 33.4$\pm$0.57, 30.6$\pm$0.70, 31.0$\pm$1.18일, 용에서 각각 12.1$\pm$0.17, 7.8$\pm$0.09, 5.0$\pm$0.07일로 산출되었으며, 난에서 성충우화시기까지의 전발육기간은 각각72.3$\pm$1.67, 46.0$\pm$0.05, 39.4$\pm$0.64, 38.7$\pm$1.15일로 산출되었다. 난과 용의 발육기간은 밀과 옥수수같은 다른 식이조건에서와 유사하였으나, 섭식을 하는 유충기의 발육은 밀보다 현미에서 상대적으로 지체되는 현상을 보였다. 한편 현미를 섭취했을 경우, 밀을 섭취했을 때 보다 발육중 치사율이 높아 밀에 비해 현미가 저급의 식물임을 보여주었다. 거짓쌀도둑 난, 유충 용 및 전발육기간의 저온발육임게온도는 각 충태 공히 20.0$^{\circ}C$로 산출되었으며, 유충과 전발육기간의 고온발육임계온도는 각각 40.2$^{\circ}C$와 41.9$^{\circ}C$로 추정되었다. 영기수는 온도에 상관없이 최빈치 7회를 나타냈지만, 온도의 상승에 따라 7회 이상 탈피하는 비율이 높아지는 경향을 보였다. 성비는 온도와 무관한 것으로 나타났다.

• Korean journal of applied entomology
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• v.9 no.2
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• pp.95-98
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• 1970

The results obtained are as follows. 1. The black-back Prominent has three to four generations in a year depending on the ecological conditions. The first adult appears from the middle of May to early June. 2. The average longevities of aduts were 5.8 days for the male and 5.9 days for female. 3. The period of eggs were about 4 days. 4. The larval period was about 17 2 days. 5. The pupal period was about 5 to 8 days. 6. The width of the head capsule ranged from 0.37mm for the 1st instar to 2.45mm for the last instar. 7. The larvae fed $95cm^2$ for the female and $60cm^2$ for the male in the laboratory condition. 8. The estimated number of the frass evacuated by the larvae were 682 in the laboratory and 663 in the field. 9. The sizes of the frass varied from 0.11mm to 2.46mm in length and 0,05mm to 2.92mm in diameter according to the larval instars. 10. The number of eggs in ovary were about 400. 11. This insect overwinters as a young larva.

• Korean journal of applied entomology
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• v.24 no.1 s.62
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• pp.11-14
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• 1985

Some experiments were conducted to evaluate the aphidivorous activity of coccinellid beetle, Harmania axyridis Pallas. Experiments were carried out using with laboratory reared beetles and two aphid species(Aphis gossypii and Myzus persicae). Factors referred in the study of aphidivorous activity were the age of beetle, aphid species, temperatreu and illumination time. The aphidivorous activity was greatly different in relation to aphid species, developmental stages of the beetle, and the temperature. The 3rd and 4th instar larvae consumed more aphids than the 1st and 2nd instar larvae. Though the beetles consumed more number of cotton aphid, total weight of aphids consumed the more or less the same. Aphidivorous activity of the 1st to 4th instar larvae increased with a rise in temperature and adult activity was relativel high at $20^{\circ}C$ and low at $15^{\circ}C\;and\;30^{\circ}C$. The aphidivorous activity of the beetles was not influenced by the illumination period under the conditions given in this experiments, however, seem to require further study.

• Korean Journal of Environmental Biology
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• v.32 no.2
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• pp.112-117
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• 2014

Predation efficiency and preference of the hydrophilid water beetle, Hydrochara affinis (Coleoptera: Hydrophilidae), larvae on two mosquito species, Culex pipiens molestus and Ochlerotatus togoi, were tested under laboratory conditions. Experiments were conducted in a transparent cylindrical plastic container (diameter, 100 mm; height, 40 mm; water level, 15 mm) for 24 hours (16 h, light; 8 h, dark) at $25^{\circ}C$. The predation efficiency of H. affinis on mosquito larvae was investigated under various prey conditions (1, 2, 4, 8, 16, 32, 64, and 128 larvae) with five replicates. Further, in order to investigate the prey preference on two mosquito species, each 32 larvae of C. pipiens molestus and O. togoi were provided simultaneously for the first instar larva of H. affinis with 5 replicates. As a result, the predation curves of H. affinis on two mosquito species were logarithmic; and the number of consumed prey increased as the number of predator instars were increased. As predicted from the predation curves, the estimated maximum number of C. pipiens molestus and O. togoi consumed by a third instar larva of H. affinis per a day was 926 and 304 larvae, respectively. As predicted from the Holling's disk equation, the differences in consumed prey number between predator instars and prey species were caused by handling time rather than attack rate. Handling time decreased rapidly as the predator larvae grew, and that of O. togoi was twice longer than that of C. pipiens molestus.

• Korean journal of applied entomology
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• v.59 no.3
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• pp.185-202
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• 2020

The diapause induction season in Ostrinia furnacalis (Lepidoptera: Crambidae) was estimated in Suwon. Three batches of adult generations were observed, the first one from early May to early July, the second from early or mid-July to early or mid-August, and the third from mid-August to October. In outdoor larval rearing, colony rearing occurring from mid-July to mid-August produced both non-overwintering and overwintering larvae, whereas late-reared colonies produced only overwintering larvae. Larvae collected during July and August in maize fields produced both non-overwintering and overwintering larvae, whereas late-collected larvae produced only overwintering larvae. The results indicated that O. furnacalis has a bi- or trivoltine complex life cycle in this area. In the laboratory, when larvae of all instars within 9 h after molting were first treated to a diapause induction condition (11:13 h = light:dark photoperiod and 20℃), almost all larvae were induced to diapause. However, when similar treatments were conducted age-specifically for the 5th instar larvae, diapause induction rates in 3- and 4-day-old larvae of the 5th instar decreased. In contrast, when larvae were subjected to the diapause induction treatment only during the periods from the hatching stage to the 2nd, 3rd, and 4th instar, almost all larvae were not induced to diapause. The results suggest that the early age of the 5th larval instar is the last stage for sensitivity to diapause induction stimuli. In the diapause-induced larvae, hemolymph trehalose content increased and body supercooling points dropped, compared with those in non-diapause larvae.