• Korean journal of applied entomology
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• v.30 no.4
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• pp.258-264
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• 1991

Studies were carried out to investigate effects of temperature and photoperiod on diapause induction and of juvenile hormone III and 20-hydroxyecdysone treatment on diapausing adults of the alder leaf beetle, Agelastica coerulea Baly(Chrγsomelidae: Coleoptera). Its life cycle and ovarian development in adults were also observed. The beetle had one year life cycle with egg, larval, pupal and adult periods being 7-10, 19-21, 14-15 days and about 10 months, r respectively. All adults showed a diapause syndrome when the larvae were reared at $20^{\circ}C$ or $25^{\circ}C$ in combination of photoperiods of 16L/8D, 12L/12D, or 8L/16D. Their ovarioles did not s show any development of vitellogenesis before or during diapause and even when exposed at $15^{\circ}C$ after overwintering. When diapausing adults were treated with JH III they resumed feeding and laid several eggs and broke diapause condition temporally. But diapausing adults treated with 20-hydroxyecdysone did not show any response.

• Korean journal of applied entomology
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• v.34 no.4
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• pp.287-294
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• 1995

Studies were carried out to elucidate the efficacy of exogeneous 20-hydroxyecdysone treatment on terminating pupal diapause in the fall webworm. Hyphantria cunea Drury. And the difference was also investigated between normal adult development and post-diapause development after 20-hydroxyecdysone treatment. In the diapause termination rate of pupae treated with 20-hydroxyecdysone after storage for various periods at 16L:8D and $25\pm$$1^{\circ}C$, at the highest rate was observed from the group stored for the longest period and the lowest rate from those stored for 1.5 months. The time needed for adult emergence was inversely proportional to the chilling (at $0\pm$$1^{\circ}C$) period, and the longer its exposure period at low temperature, the higher its sensitivity to 20-hydroxyecdysone treatment. Pupal diapause duration was almost the same, regardless of storage period in the total darkness or at the photoperiod of 16L:8D, and also they successfully emerged to adult even without any experience at low temperature. The oxygen consumption rate in normally developing pupae showed nearly a typical U-form. But, that of diapausing pupae treated with 20-hydroxyecdysone slowly increased and jumped 14 days after the treatment. Pupal diapause began before formation of adult tissues, an a timing of adult tissue formation coincided with ascending timing of the metabolic rate in both normally developing pupae and diapausing pupae treated with 20-hydroxyecdysone. The diapausing pupae treated with 20-hydroxyecdysone was similar to normally developing pupae in band patterns of proteins from haemolymph or fat body.

• Journal of Bio-Environment Control
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• v.13 no.1
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• pp.56-60
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• 2004

The aphidophagous lady beetle, Harmonia axyridis, is induced to undergo reproductive diapause by low temperature treatment. The diapause of the adult beetle can be maintained without supplying the diet up to 5 months at $4^{\circ}C$. The diapause can be induced any time including during the summer, allowing the beetle to be supplied to the field for the control of aphids through the year. Fecundity and longevity after the reproductive diapause is though to be satisfactory enough for the control of aphids in the field, Methoprene, an analog of reproductive hormone of JH, increases the early fecundity of the beetle.

• Korean journal of applied entomology
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• v.29 no.4
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• pp.277-285
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• 1990

Laboratory and field studies were conducted to investigate the initiation and termination factors for pupal diapause in the Oriental tabacco budworm, Heliothis assulta Guenee. Diapause induction was dependent of photoperiod and temperature experienced by 4th and 5th instar larve. One hundred percent of pupal diapause was obtained when larvae were grown at 10L/14D or shorter and $20^{\circ}C$. But at $25^{\circ}C$ the maximum rate of diapause was only about 85% at 8L/16D, the shortest photoperiod tested in this experiment. Adults, eggs or pupae did not respond to diapause-inducing environmental conditions. The critical photoperiod was 12-12.5 hr at $25^{\circ}C$and 14-14.5 hr at $20^{\circ}C$. In the field-collected sample 100% of diapuse rate was observed on Sept. 20 and thereafter in Suwon and middle part of Korea. Cold temperature treatment was not necessary in the termination of pupal diapause, but accelerated adult development.

• Korean journal of applied entomology
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• v.49 no.2
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• pp.115-121
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• 2010

The bean bug, Riptortus clavatus Thunberg (Hemiptera: Alydidae), is a pest of soybeans and tree fruits. It enters reproductive diapause during winter. We studied the effect of different combinations of temperature, day length, and treatment period on the termination of diapause in R. clavatus using adult females collected in October and November 2006. Ovarian development was used to determine diapause termination. The treatments were: (1) HTLD; $25^{\circ}C$, 14L:10D treatment for 1, 2, 3 weeks and 30 days, (2) HTSD; $25^{\circ}C$, 10L:14D treatment for 1, 2, and 3 weeks, (3) LTLD; $8^{\circ}C$, 14L:10D treatment for 1, 2, and 3 weeks followed by HTLD for 3 weeks, and (4) LTSD; $8^{\circ}C$, 10L:14D treatment for 1, 2, and 3 weeks followed by HTLD for 3 weeks. The HTSD treatments did not affect ovarian development, and resulted in no significant difference in the number of mature eggs in ovaries or the percentage of diapause-terminated females compared to the control females before treatment. The percentage of females that terminated diapause was significantly higher in the HTLD treatment than in the HTSD treatment. The HTLD treatment for more than 14 days increased the percentage of diapause-terminated females, accelerated the development of the ovaries, and increased the number of mature eggs in ovaries. Compared with the HTLD or HTSD treatments, the LTLD or LTSD treatments followed by the HTLD treatment accelerated ovarian development and increased the number of ovipositing females. The pre-LTSD treatment for 1 week was enough to increase the number of eggs oviposited.

• Korean journal of applied entomology
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• v.60 no.4
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• pp.449-462
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• 2021

We analyzed the effects of temperature on the survival, development, and reproduction of the non-diapause Asian corn borer, Ostrinia furnacalis (Lepidoptera: Crambidae). A 16:8 h light:dark photoperiod was supplied to the non-diapause stages of O. furnacalis. The insects were raised on an artificial diet at seven constant temperatures between 15 and 35℃ for immature stages, and eight temperatures between 13 and 33℃ for the adult stage. The survival rate of eggs exceeded 70% at all temperatures, whereas survival of larvae was as low as 7.4% at 15℃. The developmental periods of the immature stages decreased with increasing temperature, but the larval period did not decrease further at 35℃. The pupal weight increased with increasing temperature, but the female weight decreased at 35℃. Variations with different last larval instars within the colonies at different temperatures were observed. Adults produced offspring at all tested temperatures. Adult longevity and the pre-oviposition and oviposition periods decreased with increasing temperature, but the pre-oviposition period increased at 33℃. Total fecundity exceeded 400 viable eggs at 22℃ and 31℃. The mean daily fecundity during the oviposition period and the mean daily fecundity on the day of oviposition increased with increasing temperature, but decreased at 33℃. Daily fecundity sharply increased at earlier adult ages and slowly decreased thereafter. The simulated oviposition frequency was greatest at 22℃. The lower developmental threshold temperatures were estimated to be the lowest at 9.7℃ for the first instar larva and the highest at 14.7℃ for the 5th to last instar larval stage, using a linear model.

• Korean journal of applied entomology
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• v.26 no.3 s.72
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• pp.139-144
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• 1987

This study was carried out to investigate the incidence and termination of pupal diapause in the fall webworm, Hyphantria cunea Drury. Larvae obtained from overwintered pupae were reared on Morus alba leaves at $25{\pm}1^{\circ}C$ with the relative humidity of 60% or higher in a laboratory. The critical photoperiod for pupal diapause initiation is between 14hrs and 14hrs & 30 minutes at $25{\pm}10^{\circ}C$. The developmental period of larvae was shorter under longer photoperiod at $25{\pm}1^{\circ}C$. In nature. diapause termination seems to begin in late December. The diapausing pupae did not emerge at all when they were transferred to a favorable environment before the time.

• Korean journal of applied entomology
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• v.32 no.2
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• pp.139-150
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• 1993

This study was conducted to investigate the effect of 20-hydroxyecdysone on diapausing pupae of Hyphantna cunea. Treatment of 20-HE at the dosage of 5 $\mu$ g or higher/g live weight terminated diapause in about 50% of Hyphantna cunea pupae treated, and some malformed adult emerged at dosages of 10 or 12.5 $\mu$g of 20-hydroxyecdysone/g live wt. The maximum concentration of 20-hydroxyecdysone in the whole body of normally developing pupae was about 3.2 $\mu$g/g on the 6th day after pupation, and in that of diapausing pupae treated with 20 -HE about 4.1 $\mu$g/g on the 6th day after the treatment. But diapausing pupae showed a low level( 1.7 $\mu$g/g) of maximum 20-HE concentration. In diapausing pupae treated with 20- HE, glycongen content was lower than in normally developing pupae, but the changing pattern was similar to that observed in normally developing pupae. Glucose(and/or sorbitol) and trehalose content of 20-HE-injected pupae reached the maximum value on the 6th day after the injection, which were higher than those of normally developing pupae. The amount of soluble haemolymph proteins was lower but the total soluble protein content of haemolymph-rernoved whole body was higher in 20-HE-injected pupae than that in normally developing pupae.

• Korean journal of applied entomology
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• v.44 no.4 s.141
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• pp.265-270
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• 2005

Seasonal occurrence of the stink bug Piezodorus hybneri (Gmelin) (Heteroptera: Penta-tomidae) was monitored at a soybean field and the campus of Gyeongsang National University, Gyeongnam. Korea, in which host plants are less available for the bug with aggregation pheromone traps of Riptortus clavatus Thunberg (Heteroptera: Alydidae) in 2004. At soybean field, P. hybneri began to be attracted to traps from June 28, earlier than flowering stage of soybean plants. Number of P. hybneri attracted increased sharply after October 11. At the campus the bugs were not attracted to traps from March 21 to October 5, but began to be attracted since October 11. Difference in the occurrences in the two sites may suggest that the stink bug immigrates actively into soybean field to find host plant. P. hybneri that had been attracted to traps since October 11 was assumed to be diapausing adults emigrating to hibernation sites. There was no difference between sexes in trap catches. The fact that P. hybneri was attracted from June to late November may suggest that the aggregation pheromone of R. clavatus was attractive to both non-diapausing and diapausing adults of P. hybneri. The aggregation pheromone traps, when baited with 16.7+16.7+16.7 mg or 7+36+7 mg of (E)-2-hexenyl (Z)-3-hexenoate, (E)-2-hexenyl (E)-2-hexenoate, and myristyl isobutyrate, attracted significantly higher number of both sexes of P. hybneri adults than the live male traps baited with ten R. clavatus males and hexane control.

• 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.