Lower developmental threshold
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Threshold intensities for elicitation of movements and of epileptic afterdischarges by rhythmic stimulation of the sensorimotor cortex were estimated in 90 rats with implanted electrodes. Four age groups were studied--animals 12, 18, 25 and 90 days old. Both thresholds exhibited significantly higher values for adult animals in comparison with all groups of young pups. Whereas no differences were found among the rat pups in thresholds for movements accompanying stimulation, epileptic afterdischarges demonstrated a lower threshold in 18-day-old in comparison with 25-day-old animals. The development of cortical excitability is rather complicated and deserves further studies.
- MeSH
- elektrická stimulace MeSH
- elektroencefalografie * MeSH
- elektrofyziologie MeSH
- epilepsie patofyziologie MeSH
- krysa rodu Rattus MeSH
- mozková kůra patofyziologie MeSH
- potkani Wistar MeSH
- senzorické prahy MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The postmortem interval (PMI) estimation, in cases where the body was discovered in an advanced stage of decomposition, is predominantly based on entomological evidence. However, very few forensically important species are sufficiently known in detail to allow a practical application. One of them is the carrion beetle, Necrophila (Calosilpha) brunnicollis (Kraatz, 1877). Its development from egg to adulthood was studied under a range of ecologically relevant constant temperatures to find parameters of thermal summation models. Developmental sexual dimorphism and the presence of developmental rate isomorphy were investigated. Herein we present the lower developmental thresholds and sum of effective temperatures for all developmental stages of N. brunnicollis (egg, first-third larval instar, postfeeding stage, and pupae). We did not find any evidence of developmental sexual dimorphism nor was the presence of developmental rate isomorphy confirmed. Our results present the first thermal summation model of the East Asian carrion beetle that can be used for the PMI estimation.
- Klíčová slova
- Silphinae, developmental rate, forensic entomology, sexual dimorphism, thermal summation model,
- MeSH
- brouci růst a vývoj MeSH
- forenzní entomologie metody MeSH
- kukla růst a vývoj MeSH
- larva růst a vývoj MeSH
- mrtvola MeSH
- posmrtné změny MeSH
- sexuální faktory MeSH
- teoretické modely MeSH
- teplota MeSH
- zvířata MeSH
- zvláštnosti životní historie MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
When the proportion of total developmental time spent in a particular developmental stage does not change with temperature, an organism shows "rate isomorphy." This is the case only if the lower developmental threshold is the same for all developmental stages. In this study, the incidence of rate isomorphy in seven species of mites and 342 species from 11 insect orders (some represented by several populations) was determined. Whether a species shows rate isomorphy or not was determined over a range of temperatures where the relationship between the rate of development and temperature is linear. Proportion of total developmental time spent in a particular stage was plotted against temperature and the existence of rate isomorphy inferred from a zero change in proportion. Rate isomorphy was detected in 243 (57%) of 426 populations. In the rest of the cases, rate isomorphy was violated by deviations in the proportion of time spent in a stage by an average of 0.2% (range 4.5E-06% to 2.8%) at the mean of the range of temperatures of all the data sets (11 degrees C). The violations occurred most frequently at the extremes of the linear phase, which is attributed to methodical biases, mortality at low temperatures, or too coarse an estimate of developmental time at high temperatures. Similarly, a meta-analysis also revealed an overall prevalence of rate isomorphy. Consequently, in insect and mite species, all the developmental stages appear to have the same population-specific lower developmental threshold. The existence of rate isomorphy could be of great practical importance, for example, in the timing of life-history events and in determining preadult thermal requirements. There are also indications that it may act as a phylogenetic constraint.
- Publikační typ
- časopisecké články MeSH
There is a controversy about whether the thermal constants, lower developmental threshold, rate of development and corresponding degree days required for development, change when a species is reared under different developmental conditions. We present a more precise way of measuring these constants using the linear relationship between the rate of development and temperature. First we use the equation proposed by Ikemoto and Takai (2000) to determine the linear phase of development and then a generalised linear model having a different variance at low and high temperatures, specific for each condition, to estimate the parameters of the linear relationship. Using this method, we show that providing the difference in food quality is sufficiently great, an aphidophagous ladybird develops significantly faster and starts developing at a significantly lower temperature on a good than on a poor quality diet. Adaptive significance of the thermal constants not remaining constant is discussed in terms of a trade-off between growth and rate of development, when temperature and food quality varies.
- Klíčová slova
- Degree days, Food quality, Linear phase of development, Lower developmental threshold, Menochilus sexmaxculatus, Propylea dissecta,
- MeSH
- brouci růst a vývoj MeSH
- dieta MeSH
- Hemiptera růst a vývoj MeSH
- vysoká teplota * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
In animals that do not regulate their body temperature by the production of heat, the proportion of the total developmental time spent in a particular developmental stage does not change with temperature. In the quasi-linear region of the relationship between developmental rate and temperature, all of the developmental stages appear to have the same species-specific lower developmental threshold. This trait, which is called developmental isomorphy, constrains developmental adaptations of ectotherms to their environments and facilitates the precise timing of life-history events.
- MeSH
- bezobratlí růst a vývoj MeSH
- biologické modely * MeSH
- časové faktory MeSH
- obojživelníci růst a vývoj MeSH
- regresní analýza MeSH
- ryby růst a vývoj MeSH
- teplota * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- metaanalýza MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
Two values of thermal requirements, the lower developmental threshold (LDT), that is, the temperature at which development ceases, and the sum of effective temperatures, that is, day degrees above the LDT control the development of ectotherms and are used in phenology models to predict time at which the development of individual stages of a species will be completed. To assist in the rapid development of phenology models, we merged a previously published database of thermal requirements for insects, gathered by online search in CAB Abstracts, with independently collected data for insects and mites from original studies. The merged database comprises developmental times at various constant temperatures on 1,054 insect and mite species, many of them in several populations, mostly pests and their natural enemies, from all over the world. We show that closely related species share similar thermal requirements and therefore, for a species with unknown thermal requirements, the value of LDT and sum of effective temperatures of its most related species from the database can be used.
- MeSH
- biologické modely MeSH
- druhová specificita MeSH
- hmyz růst a vývoj MeSH
- roztoči růst a vývoj MeSH
- teplota MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Noise-exposed rat pups provide a model of early deprivation of sensory input to the central auditory system, allowing the study of developmental neuroplasticity. Our previous results have demonstrated that a brief exposure of rats to broadband noise (125 dB SPL 8 min, 14th postnatal day) at the onset of hearing resulted in an altered intensity perception and frequency discrimination in adulthood despite normal hearing thresholds. In this study, we assessed the gap-detection ability and possible presence of tinnitus- and hyperacusis-like behavior in adult rats after the same neonatal acoustic trauma, using measurements of the acoustic startle response (ASR) in quiet and noisy environments and its prepulse inhibition by gaps in noise (gap-PPI). A significant deficit in the ability to detect gap was observed in the exposed rats when 55 dB SPL broadband noise was used as background. An increase of noise intensity to 65-75 dB SPL led to strengthening of the gap-PPI in exposed animals, which approached the gap-PPI values of control animals at these levels. Behavioral signs of tinnitus (gap detection deficits in 10 kHz narrow band noise) were found in 25% of exposed rats. An increased sensitivity to continuous noise was manifested in all exposed rats by suppression of the ASR at significantly lower background noise levels than in the controls. This effect was particularly pronounced in rats with tinnitus-like behavior. Our results indicate that neonatal acoustic trauma, producing only a transient threshold shift, may produce permanent abnormalities in suprathreshold auditory functions and the development of tinnitus and hyperacusis-like behavior.
- Klíčová slova
- Acoustic startle, Acoustic trauma, Gap detection, Hyperacusis, Rat, Tinnitus,
- MeSH
- chování zvířat * MeSH
- hluk škodlivé účinky MeSH
- hyperakuze etiologie psychologie MeSH
- krysa rodu Rattus MeSH
- nedoslýchavost z hluku psychologie MeSH
- neuroplasticita MeSH
- poruchy sluchu etiologie psychologie MeSH
- potkani Long-Evans MeSH
- sluchový práh * MeSH
- těhotenství MeSH
- tinnitus etiologie psychologie MeSH
- úleková reakce MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- mužské pohlaví MeSH
- těhotenství MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The effects of phenytoin on threshold intensities of stimulation were studied in cortical epileptic afterdischarges (ADs) in 12-day-old and adult rats with implanted electrodes. Stimulation of the sensorimotor cortical area induced movements directly related to the stimulation as well as EEG afterdischarges (ADs) of the spike-and-wave type and of the limbic type. Rat pups exhibited lower thresholds for stimulation-bound movements and spike-and-wave ADs than adult animals. On the contrary, the limbic type of ADs was elicited with lower current intensity in adult than in immature rats. Phenytoin increased the threshold for stimulation-related movements only in adult rats, whereas threshold intensities for spike-and-wave ADs were increased and thresholds for limbic type of ADs remained uninfluenced in both age groups. The age-dependent effect on stimulation-related movements might be due to a maturation of connectivity in the motor system or to developmental changes in the voltage-gated sodium channels as the main target of phenytoin action.
- MeSH
- antikonvulziva farmakologie MeSH
- elektrická stimulace MeSH
- elektroencefalografie MeSH
- elektrofyziologie MeSH
- epilepsie patofyziologie MeSH
- fenytoin farmakologie MeSH
- krysa rodu Rattus MeSH
- limbický systém fyziologie MeSH
- modely nemocí na zvířatech MeSH
- mozková kůra účinky léků patofyziologie MeSH
- potkani Wistar MeSH
- věkové faktory MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- antikonvulziva MeSH
- fenytoin MeSH
Low temperatures play an important role in arthropods because they affect both the individual and population development of all physiological and behavioural activities. Manipulation with low temperatures is a primary nonchemical pest control method. For stored product and food industry practitioners, a knowledge of pest thermal requirements, in particular threshold temperatures at which development and other activities of a particular pest species cease, is of crucial importance. This review presents summary data regarding the lower temperature thresholds of 121 species of stored product and food industry pests from six arthropod taxa (Acari, Coleoptera, Lepidoptera, Psocoptera, Diptera, and Blattodea). In particular, this review collected and summarized information regarding the lower development thresholds, lower population thresholds, lower acoustic or respiratory thresholds, lower walking and flying thresholds and lower trap capture thresholds for flying and walking arthropods. The average lower development threshold (LDT) differed among orders: the lowest was reported for Acari (6.8 °C) and Diptera (8.1 °C), followed by Lepidoptera (11.3 °C) and Psocoptera (13.8 °C), and the highest was reported for Coleoptera (14 °C) and Blattodea (15 °C). An exclusion-function was established showing the percentage of pest species (n = 112) that were developmentally suppressed (excluded) due to temperatures reaching the LDT in the range of decreasing temperatures from 25 °C to 0 °C. We scaled various temperature thresholds from the lowest to highest temperature as follows: the walking threshold, the trap capture threshold for walking insects, the lower development threshold, lower population threshold, lower flying threshold and the lower trap capture threshold for flying pests. Important pest species were identified for which information regarding the lower temperature threshold is missing, or for which the information is too variable and should be refined in future research.
- Klíčová slova
- development, flying, forensic entomology, individual, pest management, populations, respiration, temperature, thresholds, walking,
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
We tested whether two basic thermal requirements for insect development, lower developmental thresholds, i.e. temperatures at which development ceases, and sums of effective temperatures, i.e. numbers of day degrees above the lower developmental thresholds necessary to complete development, differ among insect species that proved to be successful invaders in regions outside their native range and those that did not. Focusing on species traits underlying invasiveness that are related to temperature provides insights into the mechanisms of insect invasions. The screening of thermal requirements thus could improve risk-assessment schemes by incorporating these traits in predictions of potentially invasive insect species. We compared 100 pairs of taxonomically-related species originating from the same continent, one invasive and the other not reported as invasive. Invasive species have higher lower developmental thresholds than those never recorded outside their native ranges. Invasive species also have a lower sum of effective temperatures, though not significantly. However, the differences between invasive and non-invasive species in the two physiological measures were significantly inversely correlated. This result suggests that many species are currently prevented from invading by low temperatures in some parts of the world. Those species that will overcome current climatic constraints in regions outside their native distribution due to climate change could become even more serious future invaders than present-day species, due to their potentially faster development.
