Diapause hormone terminates larval diapause in the bamboo borer, Omphisa fuscidentalis (Hampson)

Phakamas Subta,Suphawan Suang,Panuwan Chantawannakul,Manaporn Manaboon 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.3

The larvae of the bamboo borer (Omphisa fuscidentalis Hampson) maintain a diapause state for approximately nine months. However, changes in the ecdysteroid titer lead to the termination of larval diapause when juvenile hormone analogue (JHA) is applied. The hormonal mechanisms that terminate larval diapause are still unknown. Recently, it was found that the O. fuscidentalis diapause hormone and pheromone biosynthesis activating neuropeptide genes (Ompfu-DH-PBAN) were expressed during the development of both larvae and pupae and during the late larval diapause. This result suggested that diapause hormone (DH) might be involved in the termination of larval diapause. Thus, our study aims to determine the effect of DH on diapause termination in the bamboo borer. The response of diapausing larvae to DH was assayed using the synthesized O. fuscidentalis diapause hormone (Ompfu-DH). After injection with different concentrations of DH (25, 50 and 100 ng/larvae), nearly half of the individual larvae (approximately 45%) became completed or incompleted pupae within 30 days. The mean days of pupation in larvae injected with 25, 50 and 100 ng DH were 26.81 ± 17.86, 26.30 ± 16.45 and 25.30 ± 16.12, respectively. The hemolymph ecdysteroid titer in Ompfu-DH injected-larvae was significantly higher 10–15 days after Ompfu-DH injection and reached a maximum before the formation of the pupal cuticle. These results indicate that Ompfu-DH terminates larval diapause in O. fuscidentalis by increasing the ecdysone in hemolymph, reflecting a new role of DH in the regulation of larval diapause in this species.

Molecular characterization and functional analysis of two trehalose transporter genes in the cabbage beetle, Colaphellus bowringi

Li Jia-Xu,Cao Zhen,Guo Shuang,Tian Zhong,Liu Wen,Zhu Fen,Wang Xiao-Ping 한국응용곤충학회 2020 Journal of Asia-Pacific Entomology Vol.23 No.3

The trehalose, major blood sugar in insects, enhances stress resistance of diapausing individuals in adverse environment and provides an energy source for reproduction. Trehalose transporters (TRETs) play an important role in transport of trehalose from trehalose-producing tissues, e.g. fat body, to trehalose-consuming tissues. Although studies have shown that trehalose contributes to diapause and reproduction, the function of TRETs in these processes remains unclear. In this work, we cloned two TRET genes, TRET1a and TRET1b, from the cabbage beetle Colaphellus bowringi, which is capable of entering reproductive diapause under long-day conditions. We also analyzed the expression profiles of these two genes and investigated their potential roles in diapause and reproduction. The results suggested that both TRET1a and TRET1b belong to sugar-transporter and major facilitator superfamilies. Interestingly, TRET1a was highly expressed in the fat bodies of diapause-destined (DD) females but TRET1b was predominantly expressed in the ovaries of non-diapause-destined (NDD) females. Hormonal induction indicated that juvenile hormone induced TRET1b but repressed TRET1a at transcriptional levels. Methoprene-tolerant and Krüppel homolog 1 mediated the JH-suppressed TRET1a expression but were not involved in the regulation of TRET1b expression by JH. RNAi of TRET1a in DD females elevated the trehalose content in the fat bodies and suppressed the expression of a couple of genes related to stress resistance, which is a critical diapause trait. Knockdown of TRET1b in NDD females reduced the trehalose content in the ovaries but had no apparent effect on the ovary development and yolk deposition. These data suggest that TRET1a and TRET1b could regulate the trehalose content in specific tissues and may play potential roles in reproductive diapause in the females of C. bowringi. Introduction Diapause is a survival strategy for many insects in adapting to adverse environmental conditions (Tauber and Tauber, 1976; Tougeron, 2019). Diapause is a dynamic successive process that consists of diapause induction, preparation, initiation, maintenance, termination, and post-diapause quiescence (Kostal, 2006). Insects accumulate enormous nutrients such as sugars and lipids to enter diapause during diapause preparation phase (Hahn and Denlinger, 2007, 2011). The trehalose is the major hemolymph sugar in insects. The sugar not only provides source of energy but also protects proteins and cellular membranes from dehydration, desiccation, heat, cold, and oxidation (Elbein et al., 2003; Li et al., 2002; Richards et al., 2002; Wyatt and Kalf, 1957; Yancey, 2005; Zhu et al., 2008). Therefore, trehalose can play roles in reproduction and diapause by mediating energy supply and stress tolerance, respectively (Kamei et al., 2011; Lu et al., 2019; Xu et al., 2009).

Biochemical Changes during Embryonic Diapause in Domestic Silkworm, Bombyx mori L. (Lepidoptera: Bombycidae)

Singh, Tribhuwan,Saratchandra, Beera Korean Society of Sericultural Science 2002 International Journal of Industrial Entomology Vol.5 No.1

Ecophysiologically diapause represents a syndrome of physiological and biochemical characteristics, all of which ensure survival during a long period of dormancy. Since, silkworm enters diapause as embryo at the early embryonic stage, the duration of egg life depends on the duration of embryonic diapause. The nature of diapause in silkworm, Bombyx mori, is primarily determined by genetic characters and endocrinologicnl mechanisms, mediated by environmental factors such as temperature and photoperiod. Hibernating potency value besides nucleic acid and carbohydrate metabolism, production and utilization of sorbitol are also equally responsible for induction, initiation, determination, maintenance and termination of diapause. Embryonic diapause in Bombyx moir, induced by active secretion of sub-oesophageal ganglion is attributed to hormonal system and metabolic adjustment, which serves to bring about a new physiological state. Metabolic conversion of trehalose to glycogen at induction, glycogen to sorbitol at initiation and sorbitol to glycogen at termination of diapause is correlated and in each metabolic shift a key enzyme becomes active in response to hormonal and environmental stimulation. An attempt has been made in this review article to discuss briefly the nature of embryonic diapause, influence of various factors on diapause nature, hormonal mechanism of diapause besides biochemical composition of egg, nucleic acid and carbohydrate metabolism, production and utilization of sorbitol in relation to induction, determination, maintenance, initiation and termination of diapause in the silkworm, Bombyx mori.

Enhancing bio-suppression of Parthenium hysterophorus L.: Diapause in Zygogramma bicolorata Pallister and its manipulation through insulin-like peptides (ILPs)

R.K. Gupta,Salil Gupta,K. Bali,K. Srivastava 한국응용곤충학회 2010 Journal of Asia-Pacific Entomology Vol.13 No.4

In-depth investigations on diapause behaviour of Z. bicolorata revealed that the adults entered diapause at any time from August to December and that the number peaked (42.00%) during the last half of November. The percentage of adults entering diapause increased with a decrease in day length. Weight of diapausing adults was significantly higher than weight of non-diapausing adults. The percentage of adults undergoing diapause at 30 °C was significantly lower than those undergoing diapause at 15 and 25 °C. The percentage of adults burrowing increased with increasing moisture. In silty soil and soil with high organic matter, 46.7%and 49.2% of adults entered diapause, respectively, whereas in sandy soil, only 23.5% of adults entered diapause. When newly emerged beetles were exposed to 5 μg of human insulin 30/70, a significantly lower percentage of treated adults underwent diapause compared to untreated adults under both feeding and no feeding conditions. Insulin treatment also influenced the emergence period from diapause (93.92±1.73 days), percent emergence (81±1.54%) and fecundity/month (512.7±25.38 eggs) of Z. bicolorata in treated adults as compared to untreated adults (109.05±2.2, 74.00±1.82 and 438.3±19.33 eggs,respectively). However, there was no significant impact of insulin on adult longevity. These findings are of great utility in the biological suppression of Parthenium as it will enhance the effectiveness of this beetle through manipulation of diapause.

Maternal control of cold and desiccation tolerance in eggs of the band-legged ground cricket Dianemobius nigrofasciatus in relation to embryonic diapause

Shin G. GOTO,Kengo DOI,Shin NAKAYAMA,Hideharu NUMATA 한국곤충학회 2008 Entomological Research Vol.38 No.1

Cold and desiccation tolerance was investigated in the eggs of the band-legged ground cricketDianemobius nigrofasciatus in relation to embryonic diapause. Diapause eggs were more tolerant to both desiccation and cold than non-diapause eggs. In addition, diapause-destined eggs on day zero (0-12 h after being laid) already showed high tolerance to these stresses before entering diapause. This clearly indicates that stress tolerance, like diapause, is controlled by photoperiod, but is not directly associated with diapause itself. Because the acquisition of stress tolerance predates the onset of diapause, it is plausible that diapause programming during some period before the onset of diapause is involved in the acquisition of stress tolerance. Weights and sizes were nearly identical in short-day and long-dayeggs until day five. Sorbitol, a major sugar alcohol in eggs of D. nigrofasciatus, was accumulated at the same level in short-day and long-day eggs on days zero and five. These results indicate that the surface-to-volume ratio as well as the accumulation of sugar alcohol is not involved in the acquisition of stress tolerance. Maternal factors are clearly involved in the acquisition of stress tolerance in D. nigrofasciatus eggs, but the physiological mechanisms underlying the tolerance are still unclear.

Temperature effects on embryonic development of Paratlanticus ussuriensis (Orthoptera: Tettigoniidae) in relation to its prolonged diapause

Hea-Son Bang,이경열,심재경,정명표,김명현,강기경,이덕배 한국응용곤충학회 2011 Journal of Asia-Pacific Entomology Vol.14 No.3

Paratlanticus ussuriensis eggs overwinter by entering diapause, which can be prolonged to more than 1 year depending on environmental conditions. To determine temperature effects on diapause duration of P. ussuriensis eggs, the rates of embryonic development and hatching were compared at various temperatures conditions by measuring embryonic stages and egg weights. Most eggs stayed in a very young stage (blastoderm formation, stage 4) when reared at 15 and 20 °C, 10–30% eggs developed into middle or late stages when reared at 25 °C, and most embryos developed fully (stage 23/24) when reared at 30 °C. Egg weight at 30 °C was 1.5 times higher than those reared at 20 °C. Chilling induced hatching in embryos at stage 23/24. Chilling caused stage 4 embryos to develop into stage 24, but they failed to hatch in response to a second warm period. Thus, P. ussuriensis eggs can overwinter either as young embryos (initial diapause) or as fully-developed embryos (final diapause). Eggs that experience an initial diapause overwinter again the second year in a final stage diapause. The post-diapause period was shorter when embryos overwintered in a final stage diapause. The hatching rate was highest in a temperature range of 7.5–15 °C. Our results suggest that temperature is an important environmental factor for the control of prolonged diapause in P. ussuriensis and initial diapause plays an important role in the control of its life cycle.

Differential metabolism of juvenile hormone III between diapause and non-diapause of Aspongopus chinensis Dallas (Hemiptera: Dinidoridae) revealed by transcriptome sequencing

Wu Youfang,Tian Ying,Tan Jun,Zhao Shuai,Zhou Wenzhen,Luo Rui,Guo Jian-Jun 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.2

Aspongopus chinensis Dallas, 1851 is an important insect resource with a long utilization history as traditional Chinese medicine and food owing to its various health benefits, including anti-cancer, anti-bacteria, and anticlotting properties. However, the long period of reproductive diapause during the overwintering stage has limited the broad utilization and artificial cultivation of A. chinensis. Diapause is largely regulated by juvenile hormones. Therefore, understanding the relationship between juvenile hormone metabolism and A. chinensis diapause may provide useful insight for developing genetic engineering strategies to regulate diapause. We identified differentially expressed genes in diapause and non-diapause adults of A. chinensis by transcriptome sequencing. A total of 336,230,260 clean reads were assembled into 80,769 unigenes. Overall, 3,524 differen tially expressed genes were identified, including 2,174 down-regulated and 1,350 up-regulated genes in diapause adults. Among these differentially expressed genes, 22 were significantly enriched in the JH III metabolismrelated pathway based on Kyoto Encyclopedia of Genes and Genomes analysis. These results provide insight into the molecular-level mechanism of diapause regulation and highlight new targets for preventing diapause to improve A. chinensis cultivation and productivity.

Tissue-specific variation of heat shock protein gene expression in relation to diapause in the bumblebee Bombus terrestris

김백근,심재경,김동우,권용정,이경열 한국곤충학회 2008 Entomological Research Vol.38 No.1

Diapause-associated expression patterns of heat shock protein genes (hsp) were determined in the queen of the bumblebee Bombus terrestris, a pollination insect. Partial cDNA sequences of three hsp genes -shsp, hsc70 and hsp90- were obtained, and the deduced amino acid sequences were found to be highlyhomologous with corresponding hsp of hymenopteran insects. Using northern hybridization, the transcript level of each gene was compared in six stages relating to diapause: pre-mating, post-mating, chilling for 1, 2 and 3 months, and postchilling. The transcript level was also compared in four tissues of adult queens: brain, thoracic muscle, gut and ovary. The transcript levels of the three hsp genes changed at various rates in relation to diapause, and each pattern was highly tissuespecific. Overall patterns of hsc70and hsp90 expression were similar in each tissue. The shsp level in the brain was downregulated after 1 month chilling, but its level in the ovary was upregulated during a long chilling period; levels in muscle and gut did not change in relation to diapause. The levels of both hsc70 and hsp90 in muscle were gradually upregulated in late diapause and postdiapause stages, but levels in the ovary were downregulated during the chilling period, while levels in the brain and gut did not change in relation to diapause. Our results show that the three hsp genes were differentially regulated in stage- and tissue-specific manners throughout diapause, and suggest unique physiological roles for these genes in relation to diapause in each tissue of queen bumblebees.

The effect of temperature and light conditions on diapause induction in a Korean population of Neoseiulus womersleyi Schicha (Acari: Phytoseiidae)

Si Yong Kim,이준호,정철의 한국응용곤충학회 2010 Journal of Asia-Pacific Entomology Vol.13 No.2

To determine the condition for diapause induction of a Korean population of Neoseiulus womersleyi,combinations of constant temperatures (14, 16, 18, 20 and 25 °C) and photoperiods (0, 8, 10, 12, 14, 16 and 24 h photophase) were used from egg to adult emergence. Diapause induction was determined by reproductive cessation of adult females. Lower temperature and shorter photophase resulted in higher diapause induction. Critical photophases for diapause induction were 10 and 12 h at 18 and 16 °C,respectively. Diapause-induced N. womersleyi adult females consumed significantly fewer eggs of the twospotted spider mite, Tetranychus urticae, than non-induced females. Field monitoring of N. womersleyi showed that there was no egg-bearing female after 282 Julian date, while a model estimated complete diapause induction at 288 Julian date. Diapause of this predatory mite occurred approximately 2 weeks before diapause of its main prey, T. urticae, in Korean apple orchards. Further study perspectives are discussed relative to the spider mite biological control system in fruit orchards.

cDNA Cloning of Heat Shock Proteins and their Expression in the Ussur Brown Katydid, Paratlanticus ussuriensis

Jae-Kyoung Shim,Kyeong-Yeoll Lee,Hea-Son Bang 한국응용곤충학회 2011 한국응용곤충학회 학술대회논문집 Vol.2011 No.10

Diapause duration of Paratlanticus ussuriensis is prolonged as an egg that enter both initial and final diapause stgaes. Environmental conditions, such as temperature, can modify the duration of initial diapause. Eggs enter initial diapause at 20℃, but continued early embryonic development at 30℃. Final diapause at a fully developed embryonic stage is obligatory regardless of temperature conditions. To determine temperature effects on initial diapause mechanism of P. ussuriensis eggs, we compared weights, DNA and RNA amounts of eggs incubated at either 20℃ or 30℃ for 50 days after oviposition. We identified small heat shock protein (shsp), heat shock protein 90 (hsp90) and three heat shock protein 70 (hsp70a, hap70b, hsp70c) genes of P. ussuriensis and determined those expression levels at different temperature conditions. The levels of shsp, hsp70a, hsp70b and hsp90 was not detectable until 20 days after oviposition at both temperature conditions, but highly increased at 50 and 60 days when incubated at 30℃. In contrast, hsp70c level was rapidly peaked at 20 days after oviposition, which is the time of initial diapause entrance. We analysis of temperature sensitivity of P. ussuriensis eggs. Hsp70a is expressed after the first cold treatment of mature eggs. Hsp70b is highly expressed just before hatching. Both shsp and hsp70c was highly expressed at the heat shock condition into immature egg stage. Our results suggest that high temperature breakdown initial diapause and one hsp gene, such as hsp70c, may be involved into the mechanism of initial diapause of P. ussuriensis eggs.