• Korean journal of applied entomology
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• v.48 no.2
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• pp.221-227
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• 2009

Temperature effects on diapause termination of Paratlanticus ussuriensis eggs were studied by measuring embryonic development and hatching rates at various conditions of indoor chilling and overwintering temperatures. Diapausing eggs of P. ussuriensis did not hatch at continued incubation at $25^{\circ}C$ and even after chilling for once at either $5^{\circ}C$ or $10^{\circ}C$ for 30, 45 and 60 days. In addition, double chillings at $5^{\circ}C$ with a 90 days interval at $25^{\circ}C$ did not induce hatching of diapausing eggs. However, double chillings at $10^{\circ}C$ induced hatching at 3.6${\sim}$26.7%. When eggs were incubated at $25^{\circ}C$ after chilling for once at $5^{\circ}C$ for various periods, those weights were not changed but those chilled at $10^{\circ}C$ gradually increased to approximately 1.5 times. When 60-days-old eggs were artificially deposited under the soil at three different mountain sites in September 2007, the hatching rates of the first-overwintered eggs were 11.3, 3.5 and 4.1% and those of the second-overwintered eggs were 25.1, 21.6 and 0.4% at Hoepori, Bitanri and Hwasanri, respectively. Most eggs were hatched from mid-March to mid-April but little bit earlier in southern regions. During the hatching period soil temperatures in three tested locations were around 8 to $12^{\circ}C$. In overall, diapausing eggs of P. ussuriensis were greatly influenced by chilling temperature conditions and those repeated cycles, and may required overwintering for one or two times to hatch for the post-embryonic development.

• Journal of Sericultural and Entomological Science
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• v.28 no.2
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• pp.35-37
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• 1986

To reduce the number of rearing season required for preservation of multivoltine silkworms which do not produce diapause eggs, the optimal egg stage, temperature, and period of cold storage were examinede using hatchability as an indicator of viability. Multivoltine silkworm starains MR, SPT, and HM were used in the study. 1. The hatchability of multivoltine silkworm eggs (MR and STP) preserve at 5$^{\circ}C$ for 30 days was 80% for the eggs chilled from 2 days after oviposition but less 5% for those chilled from 7 days after ovipostion. 2. When 2 day-old eggs of multivoltine silkworm (HM) were preserved between -2.5$^{\circ}C$ to 7.5$^{\circ}C$ for 15 to 60 days, $0^{\circ}C$ and 2.5$^{\circ}C$ showed the highest hatchability with 91% at 30 days and 61% at 60 days storage, respectively. 3. From these results, it can be concluded that by preserving 2 day-old eggs at 2.5$^{\circ}C$ for 50 to 60 days, rearing seasons required for preservation of the multivoltine silkworm can be reduced to half per year.

• Development and Reproduction
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• v.25 no.4
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• pp.269-277
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• 2021

Effects of water temperature and hormones on ovarian development of conger eel in Korea were investigated. Ovarian development was analyzed by measuring gonadosomatic index (GSI) and oocyte diameter with histological methods. At rearing water temperatures of 12℃, 14℃, and 16℃, GSI value increased from 3.66 at the start of the experiment to 7.44, 8.82, and 7.34 at the end of the experiment, respectively. At rearing water temperatures of 12℃, 14℃, and 16℃, egg diameter increased from 245.11-300.25 ㎛ at the start of the experiment to 377.62-480.27 ㎛, 396.72-498.54 ㎛, and 382.29-475.69 ㎛ at the end of the experiment, respectively. Follicular oocyte development revealed that primary yolk globule stage observed from January to March. It entered to secondary yolk globule stage in April and remained at the same stage until July. As a result of examining effects of three hormones (human chorionic gonadotropin (HCG), luteinizing hormone releasing hormone analogue (LHRHa), and salmon pituitary extraction (SPE) on ovarian development, HCG was found to be the most effective one. The progress from diapause of the secondary yolk globule stage to migratory nucleus stage of oocytes could be induced by treating fish with HCG at 1,000 IU/kg. The effect of hormone treatment on ovarian development of conger eel in Korea was the most effective at water temperature of 14℃.

• Journal of Sericultural and Entomological Science
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• v.5
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• pp.25-38
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• 1965

I. Breeding of tussah silkworm(preliminary report). The preliminary examination for bleeding has been carried out since 1963 in tussah silkworms. 1) The strain(l-MG-B)of the heaviest silk quantity was the green silkworm and brown cocoon in univoltine, and the strains(2-G-B, 2-MG-B) of the heaviest silk quantity were also the green silkwom and brown cocoon in bivoltine in both spring and fall in 1965. 2) It looks like the voltinism, the body color and the cocoon color have reached to pure line up to 1965. II. Best place for the winter of tussah pupa. This work was aimed to find out good ways for the winter of tussah pupa. 1) The hatch of bivoltine was better than that of univoltine. 2) The cocoons covered with the leaves were good in the emergence of moth. 3) The cocoons which were kept at natural temperature till the first emergence of moths would show bad in both hatch and emergence. 4) If some of the pupae kept under natural condition were controled at proper temperature for a few days, hatch and laying eggs were best. 5) The best places for the winter were the egg storage and the rearing room. III. Relation between incubation temperature and voltinism. 1) When the tussah pupa are kept at natural temperature during winter, the moths do not come out of the pupa. 2) There is no difference between about 18$^{\circ}C$ and about 25$^{\circ}C$ during incubation in hatching ratio. 3) The tussah silkworms of univoltine in mortality are stronger than that of bivoltine. 4) There is not any relation between voltinism and high or low temperature for pupa and eggs. IV. Induced mutation by gamma-ray and neutron in tussah silkworm. This work was carried out in order to induce the mutation by treating the pupa or the eggs of tussah silkworm with gamma my and neutron. The results obtained are as follows. 1. Though the whole pupa treated with neutron become moths, the moths have no ability to copulate each other. The only moths emerged from pupa treated with neutron, 4000${\gamma}$ are able to lay all un-fertilized eggs, some of which have a hole on the surface and nothing of contents. 2. The non-diapause eggs are treated with neutron in spring, but the hatching ratio is 50∼60 percent, but the whole eggs treated with gamma ray are never hatched. 3. The sensitivity of the pupa to neutron is weaker than that of the eggs. 4. The hatching ratio is in direct proportion to the gamma ray dose. 5. Author find out a new mutant which is excellent in the cocoon quality, so he will do the progeny test next hear.

• Korean journal of applied entomology
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• v.46 no.2
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• pp.295-302
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• 2007

We investigated starvation of hatching larvae, occasional artificial hatching and incubation method to establish year-round rearing of the wild silkmoth, Antheraea yamamai. In the test of starvation of hatching larvae for brushing at a time, the survival rate of the fourth instar of larvae starved for 1 day after hatching in $25^{\circ}C\;and\;5^{\circ}C$ was 83.3% and 96.0%, respectively. The result represents that the survival rate is high at low temperature during starvation. In the occasional artificial hatching test for multi-times rearing of A. yamamai, the useful hatchability is high at $5^{\circ}C$ in case of preserving eggs for 2 months from incubation time, and at both $2.5^{\circ}C\;and\;0^{\circ}C$ in case of over 6 months. A new incubation method with pre-incubation at $15^{\circ}C$ and 24 D photoperiod showed high hatchability about 80% for only 2 days compared with hatching for 5-6 days in traditional incubation method with the preservation at $25^{\circ}C$.

• Korean journal of applied entomology
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• v.24 no.3 s.64
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• pp.151-156
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• 1985

Apple leaf miner(ALM), Phyllonorycter ringoniella(Matsumura), occurs $4{\sim}5$ generations a year in Suweon; adult emergence peaks being in mid April, early June, early July, mid August, and mid September with the highest one in the 4th generation. Numbers of days required to complete the development(egg to adult emergence) were different with oviposited dates; 43days for late May, $32{\sim}37$ days for June to July, and 39days for early August. ALM larvae oviposited after late August did not emerge and went into diapause. Sites of the infested leaf on the shoot seemed to be somewhat different with the ALM generations; the preferred leaf sites being the 1st-6th leaf for the 1st, the 4th-9th for the 2nd, the 4th-18th for the 3rd or 4th, and the terminal leaves of the first growth shoot or the leaves of the secondary shoot for the 5th generation. Parasites of three families emerged from the mines of ALM in Suweon. The encyrtid (Holcothorax testaceipes Ratzelburg) occurs 4 generations and the eulophids 5 generations a year. A small number of the braconid(Apanteles sp.) occcrred only in September.