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Impaired hatching exacerbates the high CO₂ sensitivity of embryonic sand lance Ammodytes dubius
Rising oceanic partial pressure of CO₂ (pCO₂) could affect many traits in fish early life stages, but only few species to date have shown direct CO₂-induced survival reductions. This might partly be because species from less CO₂-variable, offshore environments in higher latitudes are currently underrepresented in the literature. We conducted new experimental work on northern sand lance Ammodytes dubius, a key forage fish on offshore Northwest Atlantic sand banks, which was recently suggested to be highly CO₂-sensitive. In 2 complementary trials, we produced embryos from wild, Gulf of Maine spawners and reared them at several pCO₂ levels (~400−2000 μatm) in combination with static (6, 7, 10°C) and dynamic (10→5°C) temperature treatments. Again, we consistently observed large, CO₂-induced reductions in hatching success (−23% at 1000 μatm, −61% at ~2000 μatm), and the effects were temperature-independent. To distinguish pCO₂ effects during development from potential impacts on hatching itself, some embryos were switched between high and control pCO₂ treatments just prior to hatch. This indeed altered hatching patterns, consistent with the CO₂-impaired hatching hypothesis. High CO₂ also delayed the day of first hatch in one trial and peak hatch in the other, where later-hatched larvae were of similar size but with progressively less endogenous energy reserves. For context, we extracted seasonal pCO₂ projections for Stellwagen Bank (Gulf of Maine) from regional ensemble simulations, which indicated a CO₂-induced reduction in sand lance hatching success to 71% of contemporary levels by 2100. The species’ unusual CO₂ sensitivity has large ecological and scientific ramifications that warrant future in-depth research.
Journal Article
Life-history traits of Aedes aegypti (Linnaeus) distributed across a latitudinal range of 23 °N–6 °S
The growth and associated traits of Aedes aegypti (L.) mosquitoes may adapt and evolve in response to the costs associated with body size in relation to latitudinal variation. We analyzed the life-history traits and energy reserves of field-collected mosquitoes from Taiwan, Thailand, and Indonesia along a latitudinal range spanning from 23°N to 6°S. A U-shaped relationship between body size and latitude was observed. Our study demonstrated the role of latitudinal temperature variations in determining the body size patterns of Ae. aegypti. Notably, the body size of the northern populations (from Taiwan) was significantly larger than those of the tropical populations from Thailand and Indonesia. Models have demonstrated that regional precipitation levels may contribute to body trait variations in certain high-latitude populations in Thailand. However, Indonesian populations have high development rates and large body sizes, indicating the involvement of other physiological traits in determining mosquito body size. The reproductive output of the adult females in this study was positively correlated with body size, but our measure of longevity did not covary significantly with the body size. By contrast, the reproductive output of mosquito-tested populations was in inverse proportion to longevity. Additionally, the mean teneral glycogen levels in the Indonesian and Thai populations were 2.5 times higher than those in theTaiwanese populations. The Indonesian and Thai populations had low mean generation and doubling times, resulting in a high intrinsic rate of increase compared with that of the Taiwanese populations, despite the Taiwanese populations having the highest net reproduction rate. Graphical Abstract
Journal Article
Biological toxicity of Ruta graveolens essential oil against three species of diptera Drosophila melanogaster, Culex pipiens and Culiseta longiareolata
Background & objectives: Recently, the use of biodegradable and environment friendly plant-based bioinsecticides has received a great deal of attention from researchers to control insect disease vectors. The aim of this research is to determine the larvicidal efficacy of Ruta graveolens essential oil against third instar larvae of two species of mosquito (Culex pipiens and Culiseta longiareolata) and a biological model Drosophila melanogaster.
Methods: Culiseta longiareolata and Culex pipiens larvae were collected from untreated areas located in Tebessa and Drosophila melanogaster, the wild strain collected from rotten apples in the Tebessa region. Ruta graveolens essential oil has been tested at different concentrations between 2.5μ/mL and 140μL/mL against third instar larvae of the three species under standard laboratory conditions according to the recommendations from the Word Health Organization. The effects were examined on mortality, growth and the main components (proteins, carbohydrates, lipids).
Results: The essential oil showed larvicidal activity with LC50 and LC90 values (10.85μL/mL, 70.95μL/mL and 39.4μL/mL), (26μL/mL, 144.5μL/mL and 89.57μL/mL) against third instar larvae of Drosophila melanogaster, Culex pipiens and Culiseta longiareolata respectively. In addition, it disrupted the growth and several morphological malformations were observed. It also affected growth and the main components (proteins, carbohydrates, lipids).
Interpretation & conclusion: The essential oil affected growth and energy reserves for all three species. The results indicated that the essential oil of Ruta graveolens has good potential as a source of natural larvicides.
Journal Article
Rapid evolution of Ophraella communa cold tolerance in new low-temperature environments
Low winter temperatures severely stress newly arriving insect species. Adaptive evolutionary changes in cold tolerance can facilitate their establishment in new environments.
Ambrosia artemisiifolia
, a noxious invasive plant, occurs throughout China.
Ophraella communa
, a biological control agent of
A. artemisiifolia
, mainly occurs in southern China. However, in 2012, it established populations in Beijing (39.98°N, 115.97°E) following introduction from Laibin (23.62°N, 109.37°E), implying cold adaptation. The mechanisms underlying its rapid evolution of cold tolerance remain unknown. We investigated the levels of cryoprotectants and energy reserves in adult
O. communa
from two latitudes. In high-latitude insects, we found high trehalose, proline, glycerol, total sugar, and lipid levels; five potential genes (
Tret1a
,
Tret1b
,
Tret1-2
,
P5CS
, and
GST
), responsible for regulating cold tolerance and involved in trehalose transport, proline biosynthesis, and glutathione S-transferase activation, were highly expressed. These hybridisation changes could facilitate cold temperature adaptation. We demonstrate the genetic basis underlying rapid adaptation of cold tolerance in
O. communa
, explaining its extension to higher latitudes. Thus, specialist herbivores can follow host plants by adapting to new temperature environments via rapid genetic evolution.
Journal Article
Market madness : a century of oil panics, crises, and crashes
\"In Market Madness, Dr. Blake Clayton, a Wall Street stock analyst and former Oxford researcher, draws on a century's worth of statistical data to offer a revolutionary new look the history of oil and future of energy. The culmination of a multi-year study, he shows how generational fears about an imminent, irreversible shortage of oil punctuate the history of oil since its earliest days. He explores the conditions in which oil supply fears arise, gain popularity, and eventually wane, and shows how important such stories can be in affecting financial markets. He links these episodes to the behavioral concept of irrational exuberance and new era economic thinking, first popularized by Nobel Laureate Yale economist Robert Shiller, to show how unfounded pessimism affects the market for oil and other exhaustible resources. Acknowledging the significant geological and structural changes the oil market has undergone over the last century, the book does not dismiss today's shortage fears out of hand, but asks what they reveal about how commodity markets function and what that means for investors and public officials. Clayton argues that the lessons to be learned from this history are the need for quality data about US and global oil reserves, the importance of clear communication from public officials about energy markets and resources, and the value of transparency in commodities markets. While these measures will not eliminate volatility and unpredictability in energy markets, he writes, they would mitigate unnecessary price spikes and improve investor and government decision-making. The book addresses popular debates in economics and finance on how mass beliefs affect financial markets while also offering a colorful narrative history for general readers about the dramatic booms and busts of the American oil industry\"-- Provided by publisher.
Book
Analysis of fatty acids to examine larval and settlement biology of the Caribbean spiny lobster Panulirus argus
Spiny lobsters have an extended pelagic larval development in oceanic waters, ending in a non-feeding post-larva that swims to coastal habitats to settle and molt to a benthic juvenile. The accumulation of energetic reserves by larvae is thought to be challenging, especially in tropical waters. We examined changes in fatty acid (FA) composition of the tropical Caribbean spiny lobster Panulirus argus for successive developmental stages sampled across the shelf and off the eastern Yucatan Peninsula, Mexico. Final-stage larvae accumulate considerable lipid reserves (26 ± 2.8% SD of dry weight), mostly saturated FAs (65.4 ± 2.1% of total FAs). Proportions of the FAs 14:0, 15:0, and 16:1n-7 tended to decrease from final larvae to settled juveniles, consistent with their use as a key energy source, although the dominant energy sources in all developmental stages were 16:0 and 18:0. In contrast, the percentages of 20:4n-6 (arachidonic acid) and 20:5n-3 (eicosapentaenoic acid) tended to increase with development, consistent with being conserved. Bacterial and flagellate FA markers dominated in final-stage larvae, indicating a microbial loop foodweb as the source of lipid reserves. Such foodwebs are characteristic of the oligotrophic waters in which the larvae of both sub-tropical and temperate spiny lobsters species are also found. Similarities in the accumulation and use of FAs between the tropical P. argus and spiny lobsters from cooler regions of the world suggest that their extended larval period is a means of acquiring sufficient energy reserves whilst feeding in oligotrophic oceanic waters.
Journal Article