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Cécile Molinier, Céline M O Reisser, Peter Fields, Adeline Ségard, Yan Galimov, Christoph R Haag
Daphnia reproduce by cyclic-parthenogenesis, where phases of asexual reproduction are intermitted by sexual production of diapause stages. This life cycle, together with environmental sex determination, allow the comparison of gene expression between genetically identical males and females. We investigated gene expression differences between males and females in four genotypes of Daphnia magna and compared the results with published data on sex-biased gene expression in two other Daphnia species, each representing one of the major phylogenetic clades within the genus...
March 13, 2018: G3: Genes—Genomes—Genetics
Brent J Sinclair, Katie E Marshall
Temperate, polar and alpine insects generally do not feed over winter and hence must manage their energy stores to fuel their metabolism over winter and to meet the energetic demands of development and reproduction in the spring. In this Review, we give an overview of the accumulation, use and conservation of fat reserves in overwintering insects and discuss the ways insects modify fats to facilitate their selective consumption or conservation. Many insects are in diapause and have depressed metabolic rates over winter; together with low temperatures, this means that lipid stores are likely to be consumed predominantly in the autumn and spring, when temperatures are higher but insects remain dormant...
March 7, 2018: Journal of Experimental Biology
Robert B Srygley, Laura B Senior
An ongoing biological debate concerns the difference in trait expression in continuous versus cycling temperature regimes, but are even daily cycling temperatures sufficient to generate natural expression of traits? We compared embryonic development and the duration of diapause for Mormon cricket Anabrus simplex Haldeman (Orthoptera: Tettigoniidae) eggs incubated in a daily cycling temperature constant in both amplitude and thermoperiod with those in a cycling temperature that was patterned after natural fluctuations in ambient temperature...
March 1, 2018: Environmental Entomology
Andrzej Zawal, Aleksandra Bańkowska, Anna Nowak
Little research has been done on egg diapause and the embryonic development of water mites. The aim of this study was to check the impact of temperature and periods of light on hatching of larvae of Eylais extendens. Three batches of eggs which were spawned on 30 July were placed at one of three temperatures (4, 10 and 20 °C) and two periods of light (7 and 14 h per day). Egg hatching (both, percentage of hatched larvae and rate of hatching) was found to differ between 4 versus 10 °C and between 4 versus 20 °C, but not between 10 versus 20 °C...
March 5, 2018: Experimental & Applied Acarology
Jan Rozsypal, Martin Moos, Petr Šimek, Vladimír Koštál
Some insects rely on the strategy of freeze tolerance for winter survival. During freezing, extracellular body water transitions from the liquid to solid phase and cells undergo freeze-induced dehydration. Here we present results of a thermal analysis (from differential scanning calorimetry) of ice fraction dynamics during gradual cooling after inoculative freezing in variously acclimated larvae of two drosophilid flies, Drosophila melanogaster and Chymomyza costata. Although the species and variants ranged broadly between 0 and close to 100% survival of freezing, there were relatively small differences in ice fraction dynamics...
March 1, 2018: Journal of Experimental Biology
Maria Luiza S Mello, Benedicto de Campos Vidal, Jerome G Rozen
The larvae of the two distantly related nonsocial bees Ericrocis lata (Apidae) and Hesperapis (Carinapis) rhodocerata (Melittidae), which develop mostly under arid desert areas of North America, and that differ in that they either spin (E. lata) or do not spin (H. rhodocerata) protective cocoons before entering diapause, produce transparent films that cover the larval integument. To understand the nature of these films, their responses to topochemical tests and their characteristics when examined with fluorescence and high-performance polarization microscopy and microspectroscopy were studied...
February 2018: Microscopy and Microanalysis
M T Fountain, J Bennett, M Cobo-Medina, R Conde Ruiz, G Deakin, A Delgado, R Harrison, N Harrison
Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is a damaging pest of fruit. Reproductively diapausing adults overwinter in woodlands and remain active on warmer winter days. It is unknown if this adult phase of the lifecycle feeds during the winter period, and what the food source may be. This study characterized the flora in the digestive tract of D. suzukii using a metagenomics approach. Live D. suzukii were trapped in four woodlands in the south of England and their guts dissected for DNA extraction and amplicon-based metagenomics sequencing (internal transcribed spacer and 16S rRNA)...
February 22, 2018: Insect Molecular Biology
Josiah T Wagner, Param Priya Singh, Amie L Romney, Claire L Riggs, Patrick Minx, Steven C Woll, Jake Roush, Wesley C Warren, Anne Brunet, Jason E Podrabsky
BACKGROUND: The annual killifish Austrofundulus limnaeus inhabits ephemeral ponds in northern Venezuela, South America, and is an emerging extremophile model for vertebrate diapause, stress tolerance, and evolution. Embryos of A. limnaeus regularly experience extended periods of desiccation and anoxia as a part of their natural history and have unique metabolic and developmental adaptations. Currently, there are limited genomic resources available for gene expression and evolutionary studies that can take advantage of A...
February 20, 2018: BMC Genomics
N Pokhrel, E Ben-Tal Cohen, O Genin, M Ruzal, D Sela-Donenfeld, Y Cinnamon
Storing eggs at low temperature prior to incubation is common practice in the broiler hatchery industry; however, prolonged storage (beyond 7 d) is known to increase early embryonic mortality and reduce chick quality and performance. To better understand the basis of this mortality, we previously published milestone criteria to evaluate morphological and cellular properties of the freshly laid embryo. Using these criteria, in the present study we checked the effects of storage at 18°C and 12°C for up to 28 d on hatchability and chick quality...
February 14, 2018: Poultry Science
Maria Cuenca Cambronero, Luisa Orsini
Long-term studies enable the identification of eco-evolutionary processes that occur over extended time periods. In addition, they provide key empirical data that may be used in predictive modelling to forecast evolutionary responses of natural ecosystems to future environmental changes. However, excluding a few exceptional cases, long-term studies are scarce because of logistic difficulties associated with accessing temporal samples. Temporal dynamics are frequently studied in the laboratory or in controlled mesocosm experiments with exceptional studies that reconstruct the evolution of natural populations in the wild...
January 19, 2018: Journal of Visualized Experiments: JoVE
Angela E Douglas
In Focus: Mushegian, A. A., Walser, J. -C., Sullam, K. E., & Ebert, D. (2018). The microbiota of diapause: How host-microbe associations are formed after dormancy in an aquatic crustacean. Journal of Animal Ecology, 87, 400-413. All animals are colonized by micro-organisms, most of which are benign or beneficial. Where do these micro-organisms come from? Theory predicts that micro-organisms which are transmitted vertically from parent to offspring are especially likely to be beneficial to the host, while horizontally acquired micro-organisms are opportunistic and more variable in their impact on host performance...
March 2018: Journal of Animal Ecology
Michael R Kearney, John Deutscher, Jacinta D Kong, Ary A Hoffmann
The phenological response is among the most important traits affecting a species' sensitivity to climate. In insects, strongly seasonal environments often select for a univoltine life-cycle such that one seasonal extreme is avoided as an inactive stage. Through understanding the underlying mechanisms for univoltinism, and the consequences of its failure, we can better predict insect responses to climate change. Here we combine empirical data and simulation studies to investigate the consequences of an unusual diapause mechanism in a parthenogenetic matchstick grasshopper, Warramaba virgo, from arid southern Australia...
February 13, 2018: Integrative Zoology
Jia Yuan, Wenbo Deng, Jeeyeon Cha, Xiaofei Sun, Jean-Paul Borg, Sudhansu K Dey
Embryo implantation is central to pregnancy success. Our previous understanding is limited by studying this phenomenon primarily in two dimensions. Here we employ 3D visualization, revealing that epithelial evaginations that form implantation chambers (crypts) consistently arise with preexisting glands, suggesting direct access of glands to embryos within the chamber. While the lobular domains of the glands become more developed, the ductal regions continue to elongate and progressively stretch following implantation...
February 9, 2018: Nature Communications
Dóra Nagy, Gabriele Andreatta, Stefano Bastianello, Ane Martín Anduaga, Gabriella Mazzotta, Charalambos P Kyriacou, Rodolfo Costa
The fruit fly Drosophila melanogaster survives thermally stressful conditions in a state of reproductive dormancy (diapause), manifested by reduced metabolic activity and arrested ovarian development in females. Unlike insects that rely primarily on photoperiodic stimuli to initiate the diapause program, in this species dormancy is regulated by low temperature and enhanced by shorter photoperiods. Overwintering phenotypes are usually studied under simple laboratory conditions, where animals are exposed to rectangular light-dark (LD) cycles at a constant temperature...
February 1, 2018: Journal of Biological Rhythms
Luis Leal, Venkat Talla, Thomas Källman, Magne Friberg, Christer Wiklund, Vlad Dincă, Roger Vila, Niclas Backström
In temperate latitudes, many insects enter diapause (dormancy) during the cold season, a period during which developmental processes come to a standstill. The wood white (Leptidea sinapis) is a butterfly species distributed across western Eurasia that shows photoperiod-induced diapause with variation in critical day-length across populations at different latitudes. We assembled transcriptomes and estimated gene expression levels at different developmental stages in experimentally induced directly developing and diapausing cohorts of a single Swedish population of L...
February 7, 2018: Molecular Ecology
Shinya Komata, Chung-Ping Lin, Teiji Sota
Female-limited Batesian mimicry may have evolved because of stronger predation pressure on females than on males, but some physiological costs of mimicry may also hinder the evolution of mimicry in males. In Papilio memnon, which possesses a female-limited Batesian mimicry polymorphism, two alleles at the doublesex (dsx) locus strictly control female phenotypes. To examine whether there are physiological costs associated with mimetic genotypes in the juvenile stage, we compered mortality, juvenile growth and development, and the resultant adult characteristics among three dsx genotypes (HH, Hh, hh) at a constant temperature (25°C) and two differing day lengths (LD 14:10 and LD 12:12; the latter might induce pupal diapause) by crossing individuals heterozygous (Hh) for the dsx allele...
February 2, 2018: Journal of Insect Physiology
H-M He, H-J Xiao, F-S Xue
Increasing evidence has demonstrated that the environmental conditions experienced by parents can shape offspring phenotypes. Here, we examined the effects of the photoperiod and temperature experienced by parents on the incidence of diapause in their progeny in the cabbage beetle, Colaphellus bowringi, using three experiments. The first experiment examined parental diapause incidence under different photoperiods at 25°C and the incidence of diapause in progeny from both non-diapausing and diapausing parents under the same rearing conditions...
February 5, 2018: Bulletin of Entomological Research
Joelle K Lemmen-Lechelt, Tyler J Wist, Maya L Evenden
Volatile chemicals produced by plants mediate host location, mate-finding and oviposition behavior in insects. State-dependent response to plant cues allows for timing of foraging, mating and oviposition on ephemeral host plants or plant parts. Caloptilia fraxinella is a herbivorous specialist on the foliage of ash trees (Fraxinus). Adults are long-lived and undergo a nine-month reproductive diapause over the fall and winter. Mating and oviposition occur in the spring when volatile chemicals released by ash leaves mediate host location...
February 3, 2018: Journal of Chemical Ecology
Hideto Yoshimura, Yoshihiro Y Yamada
Independent-founding paper wasps constitute a major group of primitively eusocial insects, and when caste-fate determination occurs in temperate species of these wasps, particularly regarding whether it occurs before or after emergence, remains unclear. No critical morphological differences occur between potential queens of the next generation (often called gynes) and workers in primitively eusocial insects. The gynes of temperate species are characterized by diapausing, and the nutrients available during the larval stage have often been believed to determine caste fate...
January 24, 2018: Die Naturwissenschaften
Don Yu, Neal Madras, Huaiping Zhu
We develop a temperature-driven abundance model for West Nile virus (WNV) vector species, Culex pipiens and Culex restuans. Temperature-dependent response functions for mosquito development, mortality, and diapause were formulated based on results from available laboratory and field studies. Numerical results compared to observed mosquito trap counts from 2004-2016 demonstrate the ability of our model to predict the observed trend of the mosquito population over a single season in the Peel Region, Ontario. The model has potential to be used as a real-time mosquito abundance forecasting tool with applications in mosquito control programs...
January 20, 2018: Journal of Theoretical Biology
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