Energetics of Insect Diapause

Department of Entomology and Nematology, University of Florida, Gainesville, Florida 32611, USA.
Annual Review of Entomology (Impact Factor: 13.73). 01/2011; 56(1):103-21. DOI: 10.1146/annurev-ento-112408-085436
Source: PubMed


Managing metabolic resources is critical for insects during diapause when food sources are limited or unavailable. Insects accumulate reserves prior to diapause, and metabolic depression during diapause promotes reserve conservation. Sufficient reserves must be sequestered to both survive the diapause period and enable postdiapause development that may involve metabolically expensive functions such as metamorphosis or long-distance flight. Nutrient utilization during diapause is a dynamic process, and insects appear capable of sensing their energy reserves and using this information to regulate whether to enter diapause and how long to remain in diapause. Overwintering insects on a tight energy budget are likely to be especially vulnerable to increased temperatures associated with climate change. Molecular mechanisms involved in diapause nutrient regulation remain poorly known, but insulin signaling is likely a major player. We also discuss other possible candidates for diapause-associated nutrient regulation including adipokinetic hormone, neuropeptide F, the cGMP-kinase For, and AMPK.

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    • "Moths from investigated assemblage will undoubtedly increase their winter activity as a consequence of more periods with higher temperatures, as compared to insects in which dormancy is controlled hormonally and depends on the photoperiod. It must affect their reproductive success, as warmer winters reduce the energy reserves needed for post-winter reproduction (Hahn and Denlinger, 2011; Williams et al., 2012). "
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    ABSTRACT: The composition and seasonal dynamics of the moth assemblage active in a temperate deciduous forest of Central Poland in autumn and spring was studied in two seasons – 2007/2008 and 2008/2009. The standard light trapping method was used and, in addition, tree trunks were searched for resting moths. 42 species of moths from six families were found. The family Geometridae was predominant in terms of the numbers of individuals collected. Two geometrid species – Alsophila aescularia and Operophtera brumata – were defined as characteristic of the assemblage investigated. Late autumn and spring were richest in the numbers of species, whereas the species diversity was the lowest in mid-winter. Regression analysis showed that a temperature rise increased the species diversity of Geometridae but that rising air pressure negatively affected the abundance of Noctuidae.
    Journal of the Entomological Research Society 07/2015; 17(2):59-71. · 0.40 Impact Factor
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    • "Diapause is a programmed arrest of development that is controlled by endogenous physiological factors and may or may not involve depression of metabolism (Lees, 1955; Tauber and Tauber, 1976; Podrabsky and Hand, 1999; Denlinger, 2002; Reynolds and Hand, 2009; MacRae, 2010; Clegg, 2011; Hahn and Denlinger, 2011; Hand et al., 2011; Patil et al., 2013). Diapause typically precedes the onset of adverse environmental conditions, and production of diapausing embryos is often induced by environmental factors that offer reliable cues for predicting future conditions, such as photoperiod or food quality/availability. Depending on the developmental stage, diapause may be hormonally regulated and occur in response to signaling factors that come before the adverse period. "
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    ABSTRACT: Diapause is a programmed state of developmental arrest that typically occurs as part of the natural developmental progression of organisms that inhabit seasonal environments. The brine shrimp Artemia franciscana and annual killifish Austrofundulus limnaeus share strikingly similar life histories that include embryonic diapause as a means to synchronize the growth and reproduction phases of their life history to favorable environmental conditions. In both species, respiration rate is severely depressed during diapause and thus alterations in mitochondrial physiology are a key component of the suite of characters associated with cessation of development. Here, we use these two species to illustrate the basic principles of metabolic depression at the physiological and biochemical levels. It is clear that these two species use divergent molecular mechanisms to achieve the same physiological and ecological outcomes. This pattern of convergent physiological strategies supports the importance of biochemical and physiological adaptations to cope with extreme environmental stress and suggests that inferring mechanism from transcriptomics or proteomics or metabolomics alone, without rigorous follow-up at the biochemical and physiological levels, could lead to erroneous conclusions.
    Journal of Experimental Biology 06/2015; 218(12). DOI:10.1242/jeb.116194 · 2.90 Impact Factor
    • "Many insects survive low temperatures during winter in a state of diapause, an adaptation that affords protection from low temperatures and prevents insects from beginning the transition to the next stage (Hahn and Denlinger 2011). Early resumption of development may occur as climate changes, because earlier spring thaws are expected (Inouye 2008). "
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    ABSTRACT: Metamorphosis is an important developmental stage for holometabolous insects, during which adult morphology and physiology are established. Proper development relies on optimal body temperatures, and natural ambient temperature (Ta) fluctuations, especially in spring or in northern latitudes, could result in interruptions to development. It is unclear how low-Ta exposure may affect insects that are actively developing. To understand how suboptimal Ta may affect metamorphosing insects, we used the alfalfa leafcutting bee, Megachile rotundata (Fabricius), a solitary, cavity-nesting bee that spends its juvenile and pupal stages within a brood cell.Wecharacterized suites of physiological traits, rather than just using a singular parameter to determine effects of sublethal Ta stress. Metamorphosing M. rotundata were exposed to either constant or fluctuating low-Ta stress and compared to control bees allowed to develop normally. All bees survived and emerged as adults, but the constant low-Ta-stressed bees were affected most severely. Male constant low-Ta-stressed bees had decreased flight performance (lower metabolic rate, shorter flight bouts, decreased wing length), suggesting that the stress altered muscular or neurological development. Constant low-Ta-stressed bees also had altered activity levels, providing more support for the hypothesis that low-Ta stress causes longterm neurological defects. Exposure to fluctuating low Ta also delayed development time for both sexes; males had decreased adult life span, and both sexes had shortened wings. Together, these results provide evidence for a critical developmental window during metamorphosis and suggest that there may be severe implications for bees in the wild that are exposed to low-Ta stressors.
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