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Maeno KO, Piou C, Leménager N. Egg size-dependent embryonic development in the desert locust, Schistocerca gregaria. JOURNAL OF INSECT PHYSIOLOGY 2023; 145:104467. [PMID: 36528090 DOI: 10.1016/j.jinsphys.2022.104467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/26/2022] [Accepted: 12/11/2022] [Indexed: 06/17/2023]
Abstract
Phenotypic plasticity in body size is a product of modification of the developmental pathway. Although hatchlings of the desert locust, Schistocerca gregaria, show egg size-dependent plasticity in body size, it remains unclear how embryogenesis during egg development regulates final embryonic body size. To determine the developmental pathway causing body size variation at hatching, we examined egg and embryonic development at the early, middle, and late egg developmental stages in S. gregaria by comparing small and large eggs. Crowd-reared females produced larger eggs than isolated-reared females. The daily egg developmental rate was similar between small and large eggs: eggs dramatically absorbed external water after days 3 to 7 and nearly doubled the initial egg weight at the late stage of day 12. Morphological measurements of eggs and embryos at different days after oviposition revealed that large eggs were longer than small eggs throughout developmental stages. However, embryo length was similar between small and large eggs at the early stage (anatrepsis). Embryos begin to absorb yolk into their bodies after blastokinesis. The size of large-egg embryos increased significantly from the middle stage (katatrepsis) due to absorption of more yolk than small eggs. Egg length and embryo length were conspicuously larger in large eggs than in small eggs on day 12 of late katatrepsis. These results suggest that egg size did not influence the egg developmental rate and initial embryo size. Large eggs had more yolk and space, resulting in larger final embryos than small eggs. The amount of yolk and size of eggshells during katatrepsis could play a key role in determining hatchling body size in S. gregaria.
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Affiliation(s)
- Koutaro Ould Maeno
- Japan International Research Center for Agricultural Sciences (JIRCAS), Livestock and Environment Division, Ohwashi 1-1, Tsukuba, Ibaraki 305-8686, Japan.
| | - Cyril Piou
- CIRAD, UMR CBGP, INRAE, Institut Agro, IRD, Université Montpellier, F-34398 Montpellier, France
| | - Nicolas Leménager
- CIRAD, UMR CBGP, INRAE, Institut Agro, IRD, Université Montpellier, F-34398 Montpellier, France
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2
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Maeno KO, Piou C, Ghaout S. Allocation of more reproductive resource to egg size rather than clutch size of gregarious desert locust (Schistocerca gregaria) through increasing oogenesis period and oosorption rate. JOURNAL OF INSECT PHYSIOLOGY 2022; 136:104331. [PMID: 34838517 DOI: 10.1016/j.jinsphys.2021.104331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 08/24/2021] [Accepted: 11/19/2021] [Indexed: 06/13/2023]
Abstract
The desert locust, Schistocerca gregaria, shows a density-dependent reproductive trade-off by laying fewer but larger eggs in crowded conditions (gregarious phase) than in isolated conditions (solitarious phase). However, the physiological mechanisms controlling reproductive resource allocation remain unclear. We examined how egg production processes, including ovulation timing (i.e., oogenesis period), oocyte and ovarian growth rates, and oosorption rate (resorbing developing terminal oocytes), regulate reproductive outputs (egg biomass per clutch, egg size, and clutch size) during a reproductive cycle in S. gregaria by rearing them either under isolated or crowded conditions. We observed a common density-dependent negative correlation between egg size and clutch size, with no significant difference in egg biomass between the two rearing conditions. Dissection of female locusts after different days of oviposition revealed that the daily oocyte growth rate was almost similar between the two rearing conditions, but crowd-reared females ovulated later than isolated-reared ones, resulting in further oocyte growth in the former. Terminal oocytes were renewed by previous penultimate oocytes at the onset of a new reproductive cycle, and oosorption mainly occurred at an early stage in both rearing conditions; however, crowd-reared locusts displayed higher levels of oosorption compared to their isolated-reared counterparts. Crowding induced a high oosorption rate, resulting in a reduced clutch size and a prolonged oogenesis period, which in turn allowed oocytes to intake more yolk, which was probably recycled via oosorption. These results suggest that the length of the oogenesis period and oosorption rate are manipulated by maternal density, and these physiological modifications interactively regulate reproductive trade-off in S. gregaria.
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Affiliation(s)
- Koutaro Ould Maeno
- Japan International Research Center for Agricultural Sciences (JIRCAS), Livestock and Environment Division, Ohwashi 1-1, Tsukuba, Ibaraki 305-8686, Japan.
| | - Cyril Piou
- CIRAD, UMR CBGP, INRAE, Institut Agro, IRD, Université Montpellier, F-34398 Montpellier, France; Ibn Zohr University, Agadir, Morocco; Centre National de Lutte Antiacridienne (CNLAA), Aït-Melloul, BP 125, Inezgane, Agadir, Morocco
| | - Saïd Ghaout
- Centre National de Lutte Antiacridienne (CNLAA), Aït-Melloul, BP 125, Inezgane, Agadir, Morocco
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Hou L, Wang X, Yang P, Li B, Lin Z, Kang L, Wang X. DNA methyltransferase 3 participates in behavioral phase change in the migratory locust. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2020; 121:103374. [PMID: 32283278 DOI: 10.1016/j.ibmb.2020.103374] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 03/06/2020] [Accepted: 03/31/2020] [Indexed: 06/11/2023]
Abstract
DNA methylation plays important roles in the behavioral plasticity of animals. The migratory locust, Locusta migratoria, displays striking density-dependent phenotypic plasticity that can reversely transit between solitarious and gregarious phases. However, the role and the mechanism through which DNA methylation is involved in locust phase change remain unknown. Here, we investigated the expression levels of three DNA methyltransferase genes and their roles in the regulation of locust phase changes. All three Dnmt genes, namely, Dnmt1, Dnmt2 and Dnmt3 showed high expression levels in the brains of gregarious locusts. By contrast, only Dnmt3 transcript rapidly responded to population density changes, decreasing during the isolation of gregarious locusts and steadily increasing upon the crowding of solitarious locusts. Dnmt3 knockdown significantly reduced the phase-related locomotor activity, rather than the attraction index, in gregarious and crowded solitarious locusts. Transcriptome analysis showed that Dnmt3 knockdown upregulated the genes related to metabolism and transporting activity and downregulated those associated with oxidative stress response. The expression level of the phase-core transcriptional factor, hormone receptor HR3, was significantly suppressed in the brain after Dnmt3 knockdown. Moreover, there was significant overlap in the differentially expressed genes between Dnmt3 RNAi and HR3 RNAi data sets, suggesting HR3 may act as key transcriptional factor mediating Dnmt3-controlled gene expression profiles in locust brains. These findings suggest that Dnmt3 transcription is involved in locust behavioral transition, implying the possible roles of DNA methylation in phase-related phenotypic plasticity in locusts.
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Affiliation(s)
- Li Hou
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xuesong Wang
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Pengcheng Yang
- Beijing Institutes of Life Science, Chinese Academy of Science, 1 Beichen West Road, Chaoyang District, Beijing, 100101, China
| | - Beibei Li
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Zhe Lin
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Le Kang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China; Beijing Institutes of Life Science, Chinese Academy of Science, 1 Beichen West Road, Chaoyang District, Beijing, 100101, China.
| | - Xianhui Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China.
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Maeno KO, Piou C, Ghaout S. The desert locust, Schistocerca gregaria, plastically manipulates egg size by regulating both egg numbers and production rate according to population density. JOURNAL OF INSECT PHYSIOLOGY 2020; 122:104020. [PMID: 32035952 DOI: 10.1016/j.jinsphys.2020.104020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 12/21/2019] [Accepted: 02/06/2020] [Indexed: 06/10/2023]
Abstract
Egg-size adjustment is one of the important plastic life-history traits for animals living in heterogeneous environments. The adaptive investment hypothesis predicts that mothers should increase progeny size according to certain cues predicting adverse future conditions of their offspring. However, reproductive resources are limited, and females have to simultaneously reduce egg number to allocate more resources to increase size. It remains unclear how single individuals alter egg size and number according to temporally heterogeneous environments. In the present study, we examined how desert locusts, Schistocerca gregaria, plastically alter egg size and number according to population density. We also investigated the trans-generational maternal effects on progeny characteristics as well as their own maternal physiological response (oviposition interval). Females kept in crowded conditions laid significantly larger and heavier eggs by reducing clutch size (number of eggs per egg pod) compared to isolated females, suggesting the existence of a reproductive trade-off between the two traits. The crowding-forced isolated females induced concerted changes not only in egg size but also in egg number tending towards those characteristics of gregarious control, implying that single individuals showed trade-off when egg size was increased. Double-blind testing confirmed the rapid crowding effects on egg size. Females also responded to crowding by extending the oviposition interval. As the oviposition interval extended, egg size increased, but clutch size decreased. Eggs from crowding-forced isolated females began to produce gregarious-phase type hatchlings (large and black) instead of solitarious-phase type ones (small and green). These results suggested that S. gregaria plastically manipulate egg size by regulating egg numbers and egg production rate, and indicated the presence of trans-generational maternal effects on progeny phase.
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Affiliation(s)
- Koutaro Ould Maeno
- Japan International Research Center for Agricultural Sciences (JIRCAS), Livestock and Environment Division, Ohwashi 1-1, Tsukuba, Ibaraki 305-8686, Japan; Laboratory of Insect Ecology, Graduate School of Agriculture Kyoto University Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Cyril Piou
- CIRAD, UMR CBGP, F-34398 Montpellier, France; Centre National de Lutte Anti-acridienne (CNLAA), Aït-Melloul, BP 125, Inezgane, Agadir, Morocco; Ibn Zohr University, Agadir, Morocco
| | - Saïd Ghaout
- Centre National de Lutte Anti-acridienne (CNLAA), Aït-Melloul, BP 125, Inezgane, Agadir, Morocco
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Maeno KO. Comments/arguments to: Re-examination of the maternal control of progeny size and body color in the desert locust Schistocerca gregaria: Differences from previous conclusions (by Yudai Nishide and Seiji Tanaka - 2019 - Journal of Insect Physiology xx, xxx). JOURNAL OF INSECT PHYSIOLOGY 2019; 114:158-159. [PMID: 30910453 DOI: 10.1016/j.jinsphys.2019.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Affiliation(s)
- Koutaro Ould Maeno
- Japan International Research Center for Agricultural Sciences (JIRCAS), Ohwashi 1-1, Tsukuba, Ibaraki 305-8686, Japan.
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Nishide Y, Tanaka S. Re-examination of the maternal control of progeny size and body color in the desert locust Schistocerca gregaria: Differences from previous conclusions. JOURNAL OF INSECT PHYSIOLOGY 2019; 114:145-157. [PMID: 30685482 DOI: 10.1016/j.jinsphys.2019.01.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 09/13/2018] [Accepted: 01/18/2019] [Indexed: 06/09/2023]
Abstract
The desert locust shows conspicuous phase polyphenism of various traits in response to crowding conditions. Gregarious females lay larger eggs that produce black hatchlings, whereas solitarious females lay smaller eggs that produce green hatchlings. Previous studies have shown that changes in egg size and hatchling body color occurred easily in the laboratory upon exposure of the female parent to crowding or isolation for as few as 2 days. Based on these observations, these studies concluded that female adults perceive crowding stimuli with their antennae and require light for perception of the stimuli, with contact chemicals present on the integument of sexually mature males that are responsible for the crowding effect. We undertook this study to identify the chemical structures of the reported contact substances, which remain unknown to date. However, we could not reproduce the main results reported in the aforementioned studies and found that egg size and hatchling body color did not alter easily, even after crowding or isolation of the female parent for 2 days or longer. We were not able to observe a change in the progeny crowding characteristics by stimulating the antennae of female adults through either physical contact with male adults or using hexane extracts of their body surfaces. Similarly, the importance of light for gregarization or solitarization was also ruled out. These results indicate that some of the conclusions of previous studies should be reconsidered.
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Affiliation(s)
- Yudai Nishide
- National Institute of Agro-biological Sciences at Ohwashi, Ohwashi 1-2, Tsukuba, Ibaraki 305-8634, Japan
| | - Seiji Tanaka
- National Institute of Agro-biological Sciences at Ohwashi, Ohwashi 1-2, Tsukuba, Ibaraki 305-8634, Japan.
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Werner MS, Claaßen MH, Renahan T, Dardiry M, Sommer RJ. Adult Influence on Juvenile Phenotypes by Stage-Specific Pheromone Production. iScience 2018; 10:123-134. [PMID: 30513394 PMCID: PMC6279967 DOI: 10.1016/j.isci.2018.11.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 11/15/2018] [Accepted: 11/15/2018] [Indexed: 12/14/2022] Open
Abstract
Many animal and plant species respond to population density by phenotypic plasticity. To investigate if specific age classes and/or cross-generational signaling affect density-dependent plasticity, we developed a dye-based method to differentiate co-existing nematode populations. We applied this method to Pristionchus pacificus, which develops a predatory mouth form to exploit alternative resources and kill competitors in response to high population densities. Remarkably, adult, but not juvenile, crowding induces the predatory morph in other juveniles. High-performance liquid chromatography-mass spectrometry of secreted metabolites combined with genetic mutants traced this result to the production of stage-specific pheromones. In particular, the P. pacificus-specific di-ascaroside#1 that induces the predatory morph is induced in the last juvenile stage and young adults, even though mouth forms are no longer plastic in adults. Cross-generational signaling between adults and juveniles may serve as an indication of rapidly increasing population size, arguing that age classes are an important component of phenotypic plasticity.
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Affiliation(s)
- Michael S Werner
- Department of Evolutionary Biology, Max Planck Institute for Developmental Biology, Tübingen 72076, Germany
| | - Marc H Claaßen
- Department of Evolutionary Biology, Max Planck Institute for Developmental Biology, Tübingen 72076, Germany
| | - Tess Renahan
- Department of Evolutionary Biology, Max Planck Institute for Developmental Biology, Tübingen 72076, Germany
| | - Mohannad Dardiry
- Department of Evolutionary Biology, Max Planck Institute for Developmental Biology, Tübingen 72076, Germany
| | - Ralf J Sommer
- Department of Evolutionary Biology, Max Planck Institute for Developmental Biology, Tübingen 72076, Germany.
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8
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Tan S, Wang Y, Liu P, Ge Y, Li A, Xing Y, Hunter DM, Shi W. Increase of Albinistic Hosts Caused by Gut Parasites Promotes Self-Transmission. Front Microbiol 2018; 9:1525. [PMID: 30042753 PMCID: PMC6048391 DOI: 10.3389/fmicb.2018.01525] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 06/19/2018] [Indexed: 11/24/2022] Open
Abstract
Paranosema locustae is a gut parasite that has been applied widely in the control of grasshoppers in many parts of the world. Usually, P. locustae is transmitted horizontally via passive modes under natural conditions but in the current study, a positive transmission strategy of P. locustae was demonstrated. First, infection by P. locustae resulted in the cuticula of infected Locusta migratoria nymphs to become lighter in color: normally only a small proportion of locusts are pale with most either being partly or mostly black; but locusts infected with P. locustae became pale. And it was found that the change to pale occurred even among uninfected black and partly black nymphs reared with infected locusts. The eumelanin of the thorax and abdomen of infected individuals decreased significantly, as did the level of dopamine. In addition, there was a decrease in phenol oxidase activity and the expression of henna and pale, which are involved in the synthesis of cuticle melanin, decreased. What is the ecological significance of this increase in light-colored hosts caused by P. locustae? We discovered that light-colored locusts were more susceptible to the microsporidian pathogen than dark-colored individuals were, because of their weaker melanization. Phenol oxidase activity in pale locusts was lower than that of black locusts, but the serpin expression level of pale locusts was higher than that of black individuals. When examined for infection, it was found that initially uninfected nymphs had picked up P. locustae infections indicating that infections are readily passed from one pale locust to another. The infection rate of healthy locusts reared with light-colored locusts infected with P. locustae was 100% which was more than with black-colored ones. The increase in albinistic locusts clearly promoted the prevalence of P. locustae in the total population. In conclusion, these results elucidated a new strategy of positive self-transmission in P. locustae. Importance: Mother Nature always grants wisdom to her creatures and feeds them carefully. This wisdom is particularly apparent in the relationships between two interacting species. In this study, our team focused on the interaction between L. migratoria and P. locustae. In a previous study, it was found that L. migratoria isolate infected individuals, reducing avoiding the spread of P. locustae, in a previous study. The solitary, pale individuals infected by P. locustae were left behind as locust groups marched ahead, leading to a kind of behavioral immunity in the insects. Here, we reported that P. locustae promotes pigmentation loss in L. migratoria, causing a larger proportion of light-colored individuals, and these lighter individuals which possessed weaker immunity against pathogens. This strategy is advantageous to P. locustae, as it promotes its propagation and spread. These extraordinary abilities of L. migratoria and P. locustae have accumulated over millennia of years of interaction.
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Affiliation(s)
- Shuqian Tan
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
| | - Yang Wang
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
| | - Pingping Liu
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
| | - Yang Ge
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
| | - Aomei Li
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
| | - Yongjie Xing
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
| | | | - Wangpeng Shi
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
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Dushimirimana S, Damien D, Hance T. Polyandry as a Signal of Phase Shift in Female Desert Locust Schistocerca gregaria. FUTURE FOODS 2017. [DOI: 10.5772/67938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Little CJ, Chapuis MP, Blondin L, Chapuis E, Jourdan-Pineau H. Exploring the relationship between tychoparthenogenesis and inbreeding depression in the Desert Locust, Schistocerca gregaria. Ecol Evol 2017; 7:6003-6011. [PMID: 28808560 PMCID: PMC5551105 DOI: 10.1002/ece3.3103] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 05/05/2017] [Accepted: 05/10/2017] [Indexed: 12/14/2022] Open
Abstract
Tychoparthenogenesis, a form of asexual reproduction in which a small proportion of unfertilized eggs can hatch spontaneously, could be an intermediate evolutionary link in the transition from sexual to parthenogenetic reproduction. The lower fitness of tychoparthenogenetic offspring could be due to either developmental constraints or to inbreeding depression in more homozygous individuals. We tested the hypothesis that in populations where inbreeding depression has been purged, tychoparthenogenesis may be less costly. To assess this hypothesis, we compared the impact of inbreeding and parthenogenetic treatments on eight life-history traits (five measuring inbreeding depression and three measuring inbreeding avoidance) in four laboratory populations of the desert locust, Schistocerca gregaria, with contrasted demographic histories. Overall, we found no clear relationship between the population history (illustrated by the levels of genetic diversity or inbreeding) and inbreeding depression, or between inbreeding depression and parthenogenetic capacity. First, there was a general lack of inbreeding depression in every population, except in two populations for two traits. This pattern could not be explained by the purging of inbreeding load in the studied populations. Second, we observed large differences between populations in their capacity to reproduce through tychoparthenogenesis. Only the oldest laboratory population successfully produced parthenogenetic offspring. However, the level of inbreeding depression did not explain the differences in parthenogenetic success between all studied populations. Differences in development constraints may arise driven by random and selective processes between populations.
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Affiliation(s)
- Chelsea J Little
- Department of Aquatic Ecology Eawag: Swiss Federal Institute of Aquatic Science and Technology Dübendorf Switzerland
| | | | | | - Elodie Chapuis
- IRD, CiradUniv Montpellier, IPME Montpellier France.,UMR PVBMT CIRAD Saint-Pierre La Réunion France
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11
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Ernst UR, Van Hiel MB, Depuydt G, Boerjan B, De Loof A, Schoofs L. Epigenetics and locust life phase transitions. ACTA ACUST UNITED AC 2015; 218:88-99. [PMID: 25568455 DOI: 10.1242/jeb.107078] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Insects are one of the most successful classes on Earth, reflected in an enormous species richness and diversity. Arguably, this success is partly due to the high degree to which polyphenism, where one genotype gives rise to more than one phenotype, is exploited by many of its species. In social insects, for instance, larval diet influences the development into distinct castes; and locust polyphenism has tricked researchers for years into believing that the drastically different solitarious and gregarious phases might be different species. Solitarious locusts behave much as common grasshoppers. However, they are notorious for forming vast, devastating swarms upon crowding. These gregarious animals are shorter lived, less fecund and transmit their phase characteristics to their offspring. The behavioural gregarisation occurs within hours, yet the full display of gregarious characters takes several generations, as does the reversal to the solitarious phase. Hormones, neuropeptides and neurotransmitters influence some of the phase traits; however, none of the suggested mechanisms can account for all the observed differences, notably imprinting effects on longevity and fecundity. This is why, more recently, epigenetics has caught the interest of the polyphenism field. Accumulating evidence points towards a role for epigenetic regulation in locust phase polyphenism. This is corroborated in the economically important locust species Locusta migratoria and Schistocerca gregaria. Here, we review the key elements involved in phase transition in locusts and possible epigenetic regulation. We discuss the relative role of DNA methylation, histone modification and small RNA molecules, and suggest future research directions.
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Affiliation(s)
- Ulrich R Ernst
- Functional Genomics and Proteomics Lab, KU Leuven, Naamsestraat 59, bus 2465, B-3000 Leuven, Belgium
| | - Matthias B Van Hiel
- Functional Genomics and Proteomics Lab, KU Leuven, Naamsestraat 59, bus 2465, B-3000 Leuven, Belgium
| | - Geert Depuydt
- Functional Genomics and Proteomics Lab, KU Leuven, Naamsestraat 59, bus 2465, B-3000 Leuven, Belgium
| | - Bart Boerjan
- Functional Genomics and Proteomics Lab, KU Leuven, Naamsestraat 59, bus 2465, B-3000 Leuven, Belgium
| | - Arnold De Loof
- Functional Genomics and Proteomics Lab, KU Leuven, Naamsestraat 59, bus 2465, B-3000 Leuven, Belgium
| | - Liliane Schoofs
- Functional Genomics and Proteomics Lab, KU Leuven, Naamsestraat 59, bus 2465, B-3000 Leuven, Belgium
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12
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Chen B, Li S, Ren Q, Tong X, Zhang X, Kang L. Paternal epigenetic effects of population density on locust phase-related characteristics associated with heat-shock protein expression. Mol Ecol 2015; 24:851-62. [DOI: 10.1111/mec.13072] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 01/02/2015] [Accepted: 01/07/2015] [Indexed: 12/28/2022]
Affiliation(s)
- Bing Chen
- State Key Laboratory of Integrated Management of Pest Insects and Rodents; Institute of Zoology; Chinese Academy of Sciences; Beijing 100101 China
| | - Shaoqin Li
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory; College of Plant Science and Technology; Huazhong Agricultural University; Wuhan 430070 China
| | - Qiang Ren
- State Key Laboratory of Integrated Management of Pest Insects and Rodents; Institute of Zoology; Chinese Academy of Sciences; Beijing 100101 China
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory; College of Plant Science and Technology; Huazhong Agricultural University; Wuhan 430070 China
| | - Xiwen Tong
- State Key Laboratory of Integrated Management of Pest Insects and Rodents; Institute of Zoology; Chinese Academy of Sciences; Beijing 100101 China
| | - Xia Zhang
- Beijing Institute of Life Sciences; Chinese Academy of Sciences; Beijing 100101 China
| | - Le Kang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents; Institute of Zoology; Chinese Academy of Sciences; Beijing 100101 China
- Beijing Institute of Life Sciences; Chinese Academy of Sciences; Beijing 100101 China
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13
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Chen Q, He J, Ma C, Yu D, Kang L. Syntaxin 1A modulates the sexual maturity rate and progeny egg size related to phase changes in locusts. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2015; 56:1-8. [PMID: 25446392 DOI: 10.1016/j.ibmb.2014.11.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Revised: 10/24/2014] [Accepted: 11/03/2014] [Indexed: 06/04/2023]
Abstract
The migratory locust (Locusta migratoria) exhibits clear phenotypic plasticity depending on its population density. Previous studies have explored the molecular mechanisms of body colour, behavior, immunity, and metabolism between high population density gregarious (G) and low population density solitarious (S) locusts. However, the molecular mechanisms underlying differences in reproductive traits remain unknown. G locusts reach sexual maturation much faster and lay larger eggs compared with S locusts. The traits of G locusts decreased significantly with isolation, whereas those of S locusts increased with crowding. Analysis of gene expression in female adults indicated that syntaxin 1A (Syx1A) was expressed significantly higher in G locusts than in S locusts. After silencing Syx1A expression in G locusts by RNA interference (RNAi), their sexual maturity rate and progeny egg size changed towards those of S locusts. Similarly, increment in the traits of S locusts with crowding was blocked by Syx1A interference. Changes in the traits were also confirmed by decrease in the level of vitellogenin, which is regulated by Syx1A. In conclusion, plasticity of the sexual maturity rate and progeny egg size of G and S locusts, which is beneficial for locusts to adapt to environmental changes, is regulated by Syx1A.
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Affiliation(s)
- Qianquan Chen
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Jing He
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Chuan Ma
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; Beijing Institutes of Life Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Dan Yu
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Le Kang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; Beijing Institutes of Life Sciences, Chinese Academy of Sciences, Beijing 100101, China.
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14
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Maeno KO, Piou C, Ould Babah MA, Nakamura S. Eggs and hatchlings variations in desert locusts: phase related characteristics and starvation tolerance. Front Physiol 2013; 4:345. [PMID: 24363645 PMCID: PMC3850081 DOI: 10.3389/fphys.2013.00345] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 11/08/2013] [Indexed: 11/21/2022] Open
Abstract
LOCUSTS ARE GRASSHOPPER SPECIES THAT EXPRESS PHASE POLYPHENISM modifying their behavior, morphology, coloration, life history and physiology in response to crowding. Desert locusts, Schistocerca gregaria, epigenetically modify progeny quality and quantity in response to crowding. Gregarious (crowded) females produce larger but fewer progeny than do solitarious (isolated) ones. The variability of progeny quality within single egg pod and the reasons why gregarious progeny have a better survival rate than solitarious ones remains unclear. This study investigated 1) the effects of rearing density on the variation in egg size within single egg pods 2) the starvation tolerance of hatchlings from mothers with different phases and 3) the physiological differences in hatchling energy reserve. Isolated females produced smaller but more eggs than did crowded ones. The variation in egg size within egg pods was greater in the latter than in the former. A negative relationship between egg size and number of eggs per egg pod was observed for both groups. Under starvation conditions, gregarious hatchlings survived significantly longer than solitarious ones. Among the solitarious hatchlings, the survival time was longer with increased hatchling body size. However, small individuals survived as long as large ones among the gregarious hatchlings. The percentage of water content per fresh body weight was almost equal between the two phases, before and after starvation. In contrast, the percentage of lipid content per dry body weight was significantly higher in gregarious hatchlings than in solitarious ones before starvation, but became almost equal after starvation. These results demonstrate that female locusts not only trade-off to modify their progeny size and number, but also vary progenies' energy reserves. We hypothesize that gregarious females enhance their fitness by producing progeny differently adapted to high environmental variability and particularly to starvation conditions.
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Affiliation(s)
- Koutaro O. Maeno
- CIRAD, UMR CBGPF-34398 Montpellier, France
- The Mauritanian Desert Locust Centre, Centre National de Lutte AntiacridienneNouakchott, Mauritania
| | - Cyril Piou
- CIRAD, UMR CBGPF-34398 Montpellier, France
| | - Mohamed A. Ould Babah
- The Mauritanian Desert Locust Centre, Centre National de Lutte AntiacridienneNouakchott, Mauritania
| | - Satoshi Nakamura
- Japan International Research Center for Agricultural SciencesTsukuba, Japan
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15
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Harano KI, Tanaka S, Watari Y, Saito O. Phase-dependent locomotor activity in first-stadium nymphs of the desert locust, Schistocerca gregaria: effects of parental and progeny rearing density. JOURNAL OF INSECT PHYSIOLOGY 2012; 58:718-725. [PMID: 22387425 DOI: 10.1016/j.jinsphys.2012.02.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 02/20/2012] [Accepted: 02/20/2012] [Indexed: 05/31/2023]
Abstract
This study examined the effects of parental and progeny rearing density on locomotor activity of 1st-stadium nymphs of the desert locust, Schistocerca gregaria, using an actograph. Progeny obtained from solitarious (isolated-reared) or gregarious (crowd-reared) locusts were reared in isolation or in a group of 30 nymphs. Crowding after hatching had a slight influence on mean activity shortly after the start of measurements, but no clear effect was detected until day 2, when maximum activity during the 6-24 h of observation was significantly higher than that of the nymphs kept in isolation. On the other hand, the effects of parental rearing density on locomotor activity manifested at all ages examined (0-2 days old). Progeny of gregarious locusts showed consistently higher activity than those of solitarious locusts. In newly hatched nymphs, the effect of parental rearing density was explained by variation in body size at hatching, one of the phase-dependent characteristics. Hatchling body color was also correlated with locomotor activity and body weight. Similar levels of locomotor activity were exhibited when green, solitarious and black, gregarious nymphs were similar in body weight. These results suggested that parental rearing density indirectly influences locomotor activity in the progeny shortly after hatching by affecting their body size as eggs or hatchlings.
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Affiliation(s)
- Ken-ichi Harano
- Locust Research Laboratory, National Institute of Agro-biological Sciences at Ohwashi, Tsukuba, Ibaraki 305-8634, Japan.
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16
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Tanaka S, Harano KI, Nishide Y. Re-examination of the roles of environmental factors in the control of body-color polyphenism in solitarious nymphs of the desert locust Schistocerca gregaria with special reference to substrate color and humidity. JOURNAL OF INSECT PHYSIOLOGY 2012; 58:89-101. [PMID: 22075390 DOI: 10.1016/j.jinsphys.2011.10.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 10/06/2011] [Accepted: 10/10/2011] [Indexed: 05/31/2023]
Abstract
This study re-examines the effects of environmental factors including substrate color, humidity, food quality, light intensity and temperature on the green-brown polyphenism, black patterning and background body color of solitarious (isolated-reared) nymphs of Schistocerca gregaria. All individuals reared in yellow-green or yellow containers became green morphs, whereas those reared in white, ivory-colored, blue, grey, brown, zinc-colored and black containers produced brown morphs in similar proportions. The intensity of black patterns was negatively correlated with the brightness of the substrate color of the containers. Humidity, which previous studies claimed controls green-brown polyphenism in this species, exerted no significant influence on either the green-brown polyphenism or the black patterning. Food quality also had little effect on body color. High temperature tended to inhibit darkening. The background body color on the thorax was greatly influenced by the substrate color of rearing containers and a close correlation was found between these two variables, indicating that, in contrast to what has been suggested by others, this species exhibits homochromy to match the body color to the substrate color of its habitat. Similar responses were observed in another strain, although some quantitative differences occurred between the two strains examined. Based on these results, a new model explaining the control of body-color polyphenism in this locust is proposed and the ecological significance of black patterns in solitarious nymphs is discussed.
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Affiliation(s)
- Seiji Tanaka
- Locust Research Laboratory, National Institute of Agro-biological Sciences at Ohwashi, Tsukuba, Ibaraki 305-8634, Japan.
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17
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Linksvayer TA, Kaftanoglu O, Akyol E, Blatch S, Amdam GV, Page RE. Larval and nurse worker control of developmental plasticity and the evolution of honey bee queen-worker dimorphism. J Evol Biol 2011; 24:1939-48. [PMID: 21696476 DOI: 10.1111/j.1420-9101.2011.02331.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Social evolution in honey bees has produced strong queen-worker dimorphism for plastic traits that depend on larval nutrition. The honey bee developmental programme includes both larval components that determine plastic growth responses to larval nutrition and nurse components that regulate larval nutrition. We studied how these two components contribute to variation in worker and queen body size and ovary size for two pairs of honey bee lineages that show similar differences in worker body-ovary size allometry but have diverged over different evolutionary timescales. Our results indicate that the lineages have diverged for both nurse and larval developmental components, that rapid changes in worker body-ovary size allometry may disrupt queen development and that queen-worker dimorphism arises mainly from discrete nurse-provided nutritional environments, not from a developmental switch that converts variable nutritional environments into discrete phenotypes. Both larval and nurse components have likely contributed to the evolution of queen-worker dimorphism.
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Affiliation(s)
- T A Linksvayer
- School of Life Sciences, Arizona State University, Tempe, AZ, USA.
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18
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Maeno K, Tanaka S, Harano KI. Tactile stimuli perceived by the antennae cause the isolated females to produce gregarious offspring in the desert locust, Schistocerca gregaria. JOURNAL OF INSECT PHYSIOLOGY 2011; 57:74-82. [PMID: 20888831 DOI: 10.1016/j.jinsphys.2010.09.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 09/24/2010] [Accepted: 09/24/2010] [Indexed: 05/29/2023]
Abstract
Maternal determination of progeny body size and coloration in the desert locust, Schistocerca gregaria, depends on the crowding conditions experienced during the short sensitive period that occurs two to six days before the deposition of the egg pod. Solitarious (isolated-reared) females produce relatively small eggs that yield solitarious green hatchlings but, females that are exposed to crowded conditions during the sensitive period, produce larger eggs that yield the dark-colored hatchlings characteristic of gregarious forms. The present study aimed to determine the stimuli influencing the maternal determination of progeny characteristics as well as the site at which such stimuli are perceived. By exposing isolated female adults to various combinations of visual, olfactory and tactile stimuli from a crowd of other adults, we found that no crowding effects could be elicited without tactile stimulation. Coating of various body surfaces with nail polish followed by exposure to crowding stimulation suggested that female adults perceive crowding stimuli with their antennae. This finding was supported by another experiment in which the antennae were either removed or covered with wax before the isolated females were exposed to crowded conditions. Neither serotonin nor an antagonist of its receptor affected the density-dependent maternal determination of progeny characteristics when injected into isolated or crowded female adults.
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Affiliation(s)
- Koutaro Maeno
- Locust Research Laboratory, National Institute of Agrobiological Sciences at Ohwashi (NIASO), Tsukuba, Ibaraki 305-8634, Japan
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Maeno K, Tanaka S. Epigenetic transmission of phase in the desert locust, Schistocerca gregaria: determining the stage sensitive to crowding for the maternal determination of progeny characteristics. JOURNAL OF INSECT PHYSIOLOGY 2010; 56:1883-1888. [PMID: 20709069 DOI: 10.1016/j.jinsphys.2010.08.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 08/06/2010] [Accepted: 08/06/2010] [Indexed: 05/29/2023]
Abstract
Desert locust female adults respond to crowded conditions by changing progeny characteristics such as egg size, clutch size (no. of eggs per pod), hatchling body size and coloration. This study was conducted to determine the stage sensitive to crowding in this locust. Reproductively active females reared in isolation increased egg size and decreased clutch size and the proportion of green hatchlings after exposure to crowded conditions (in which each female was kept with four male adults). These changes depended not only on the timing of exposure to crowded conditions during the reproductive cycle but also on the length of the exposure. By varying the time and length of the exposure, it was found that crowding had no influence on progeny characteristics during the last two days of egg development at 31 °C and that there was a four-day sensitive stage before this period. The sensitive stage coincided with the time when the affected oocytes were 1.5-4mm long, while the sensitivity to crowding appeared to be constant over the sensitive stage. The larger the magnitude of the increase in egg size after exposure to crowding, the smaller the proportion of green hatchlings (and the larger the proportion of gregarized dark hatchlings); there was a sigmoidal relationship between the two variables. Based on these results, we propose a model for determining the stage sensitive to crowding in both the female parent and the oocytes.
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Affiliation(s)
- Koutaro Maeno
- Locust Research Laboratory, National Institute of Agrobiological Sciences at Ohwashi (NIASO), Tsukuba, Ibaraki 305-8634, Japan
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20
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Tanaka S, Maeno K. A review of maternal and embryonic control of phase-dependent progeny characteristics in the desert locust. JOURNAL OF INSECT PHYSIOLOGY 2010; 56:911-918. [PMID: 20493874 DOI: 10.1016/j.jinsphys.2010.05.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2010] [Revised: 05/13/2010] [Accepted: 05/13/2010] [Indexed: 05/29/2023]
Abstract
Hatchlings of the desert locust, Schistocerca gregaria, display phase polyphenism in body coloration and size. This phenomenon has been found to be maternally controlled and two different mechanisms have been proposed to explain the underlying process. One mechanism claims that a water-soluble pheromonal factor secreted by gregarious female adults into the foam plugs of egg pods induces darkening in their progeny. The other mechanism states that hatchling body coloration is pre-determined in the ovaries and that no foam factor is involved in this phenomenon. This mechanism was supported by the observation that hatchling melanization was not prevented by the early washing or separation of eggs, which should have removed the pheromonal factor from the eggs and produced green hatchlings according to the other mechanism. This paper reviews the latest findings related to this phenomenon with special reference to reproductive cycles and genetic differences. The close relationships between egg size and the degree of melanization in hatchlings may provide strong evidence against the possible involvement of the pheromonal factor, because egg size is determined in the ovarioles. Furthermore, the absence of "solitarizing" effects of early washing and separation on hatchling melanization was also confirmed in different genetic strains. A hypothesis proposed by others that such effects occur only in eggs from the first reproductive cycle was tested and rejected. Based on these and other results, a model to explain the mechanisms underlying the maternal control of progeny characteristics and embryonic control of melanization in the hatchling was proposed.
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Affiliation(s)
- Seiji Tanaka
- Locust Research Laboratory, National Institute of Agrobiological Sciences at Ohwashi, Tsukuba, Ibaraki 305-8634, Japan.
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21
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Maeno K, Tanaka S. Is juvenile hormone involved in the maternal regulation of egg size and progeny characteristics in the desert locust? JOURNAL OF INSECT PHYSIOLOGY 2009; 55:1021-1028. [PMID: 19699747 DOI: 10.1016/j.jinsphys.2009.08.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Revised: 08/14/2009] [Accepted: 08/14/2009] [Indexed: 05/28/2023]
Abstract
The role of juvenile hormone (JH) in the maternal regulation of progeny characteristics was examined in the desert locust, Schistocerca gregaria. Female adults of this species are known to produce smaller but more eggs when reared in isolation than do those reared in a group. Eggs laid by isolated females develop green hatchlings typical of solitarious forms, whereas those laid by the latter produce black hatchlings typical of gregarious forms. Topical application of a juvenile hormone analog (JHA), fenoxycarb, or implantation of corpora allata (CA) taken from the migratory locust, Locusta migratoria, caused crowded S. gregaria females to deposit smaller eggs, but did not have a significant effect on the number of eggs per egg pod except at high doses of JHA. The production of smaller eggs by treated and untreated crowded females was closely associated with earlier deposition of the egg pods and shorter oviposition intervals. However, neither JHA application nor CA implantation influenced the progeny characteristics in actively reproducing aged females under crowded conditions, while untreated control females started producing smaller and more eggs upon transfer to isolated conditions. These results may suggest that JH is not directly involved in the maternal regulation of phase-dependent progeny characteristics.
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Affiliation(s)
- Koutaro Maeno
- Locust Research Laboratory, National Institute of Agrobiological Sciences at Ohwashi (NIASO), Tsukuba, Ibaraki, Japan
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Maeno K, Tanaka S. The trans-generational phase accumulation in the desert locust: morphometric changes and extra molting. JOURNAL OF INSECT PHYSIOLOGY 2009; 55:1013-1020. [PMID: 19631213 DOI: 10.1016/j.jinsphys.2009.07.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Revised: 07/09/2009] [Accepted: 07/10/2009] [Indexed: 05/28/2023]
Abstract
To understand the underlying trans-generational phase accumulation, a classical morphometric characteristic, the F/C ratio (F, hind femur length; C, maximum head width), of adult desert locusts (Schistocerca gregaria) was monitored over eight consecutive generations. Adult F/C ratios, which are larger in solitarious locusts than in gregarious ones, were negatively correlated to the darkness of body color at hatching. Two successive generations were required for a complete shift from the gregarious (crowd-reared) to the solitarious (isolated-reared) phase and vice versa in the laboratory. That is (1) female adults needed to be exposed to crowded (or isolated) conditions so that their hatchlings would become large (or small) and dark (or green) in color, and (2) the hatchlings then needed to be exposed to crowded (or isolated) conditions for their entire nymphal stage. Solitarious locusts exhibited extra molting that influenced the F/C ratio in the adult stage, but did not exert significant influences on the trans-generational changes in this trait because the incidence was low. The incidence of extra molting was negatively correlated with nymphal survival rates. The morphometric trans-generational changes may be explained without assuming any accumulating internal factor.
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Affiliation(s)
- Koutaro Maeno
- Locust Research Laboratory, National Institute of Agrobiological Sciences at Ohwashi (NIASO), Tsukuba, Ibaraki, Japan
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Maeno K, Tanaka S. Artificial miniaturization causes eggs laid by crowd-reared (gregarious) desert locusts to produce green (solitarious) offspring in the desert locust, Schistocerca gregaria. JOURNAL OF INSECT PHYSIOLOGY 2009; 55:849-854. [PMID: 19505472 DOI: 10.1016/j.jinsphys.2009.05.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Revised: 05/29/2009] [Accepted: 05/29/2009] [Indexed: 05/27/2023]
Abstract
The mechanism underlying the phase-dependent polyphenism in hatchling body coloration was studied by testing for a possible causal relationship with egg size in the desert locust, Schistocerca gregaria. Crowd-reared (gregarious) females typically produce large, black offspring, whereas females reared in isolation (solitarious) deposit small, green offspring. We first tested for possible genetic differences in the role of egg foam by washing or separating eggs from two strains of locust. No solitarizing effect was found in either of the strains tested, supporting a previous finding, using another laboratory strain, to show that the hatchling body coloration and size are pre-determined in the ovary of the mother and no egg foam factor is involved in the control of the hatchling body coloration. Topical application of fenoxycarb, a juvenile hormone analog (JHA), and implantation of extra corpora allata (CA), taken from Locusta migratoria, caused gregarious female adults of S. gregaria to produce small eggs. Some eggs laid by CA-implanted females produced green hatchlings. All large eggs chosen among those deposited by gregarious females produced black hatchlings. When eggs were either kept on dry filter paper at nearly saturated relative humidity during embryogenesis or pricked with a needle so that some egg yolk was squeezed out, some produced small, green hatchlings. These results suggested that the amount of egg yolk or the availability of yolk material may determine the body coloration of hatchlings.
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Affiliation(s)
- Koutaro Maeno
- Locust Research Laboratory, National Institute of Agrobiological Sciences at Ohwashi (NIASO), Tsukuba, Ibaraki 305-8634, Japan
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Maeno K, Tanaka S. Phase-specific developmental and reproductive strategies in the desert locust. BULLETIN OF ENTOMOLOGICAL RESEARCH 2008; 98:527-534. [PMID: 18590599 DOI: 10.1017/s0007485308006044] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Locusts modify developmental and reproductive traits over successive generations depending on the population density. A trade-off between developmental rate and body size and between progeny size and number is often observed in organisms. In this study, we present evidence that this rule is evaded by desert locusts, Schistocerca gregaria Forskål, which often undergo outbreaks. Under isolated conditions, large hatchlings, typical of the gregarious forms, grow faster but emerge as larger adults than do small hatchlings typical of the solitarious forms, except for some individuals of the latter group that undergo extra molting. Under crowded conditions, large and small hatchlings grow at a similar rate, but the former become larger adults than the latter. Small hatchlings show a trade-off between development time and body size at maturation, but this constraint is avoided by large hatchlings. Phase-specific, as well as body size-dependent, differences are also detected in reproductive performance. As adult body size increases, females of a solitarious line produce more but slightly smaller eggs, whereas those of a gregarious line produce more and larger eggs. Total egg mass per pod is larger in gregarious forms than in solitarious forms. A trade-off between egg size and number is shown by a solitarious line but not by a gregarious line that produces relatively large eggs with similar numbers of eggs per pod. These results suggest that phase transformation involves not just a shift of resource allocation but also an enhanced capability expressed in response to crowding.
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Affiliation(s)
- K Maeno
- Laboratory of Insect Life Cycles and Physiology, National Institute of Agrobiological Sciences at Ohwashi, Tsukuba, Ibaraki, Japan
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