Hot Summer Temperatures Research Articles

Towards SDG11: How Urban Greenery Can Help Us Build Sustainable Cities

In 2015, the United Nations launched 17 Sustainable Development Goals—efforts that should be taken to ensure the wellbeing of people and the planet by 2030. One of these goals aims to make cities sustainable by addressing environmental, social, and economic impacts to ensure cities are livable for future generations. This goal is important because more than half the world lives in cities now. Meeting the needs of many people in cities will not be easy, particularly with global problems like the hot temperatures experienced in cities, pollution, climate change, and food shortages. This is where urban greenery could help. Urban greenery includes the trees, parks, and other plants you see in cities. Greenery can help make our cities sustainable, providing benefits like cleaning the air, cooling the city in hot summer temperatures, and preventing flooding during heavy rains. Greener cities could make life better and healthier for everyone.

Vegetation composition and organic carbon content along right-of-ways on Interstate Highway 35 in Bexar County, Texas

Roadside habitat through major urban areas may offer remnant examples of natural grasslands. These habitats may be subjected to frequent as mowing and exposure to automobile emissions and runoff. This study was conducted on interstate highway right-of-ways in San Antonio, Texas, U.S.A. We compared the vegetation species and diversity, and the organic carbon of leaf litter, plants, and soils. Two non-native grasses accounted for 50.9% cover, while all native forbs and grasses accounted for only 9.8% cover. The mean biomass of non-native grasses was 4.5 times greater than that of all native species. Organic carbon content of leaf litter, plants, and soils was variable among the study sites, possibly due to management practices and a drought that occurred during the study. The mean organic carbon content in the upper 20 cm soil was 5.0 kg·C/m2 and organic carbon content was greater in the upper 10 cm than organic carbon in the 10.1 to 20 cm portion. Cynodon dactylon and Bouteloua curtipendula exhibited the greatest photosynthesis efficiency indicating these grasses are more adaptable to hot summer temperatures found in Central Texas. The organic carbon content along a major interstate was 13793 kg·C/ha for leaf litter, vegetation, and the upper 20 cm of the soil. We conclude that interstate highways provide habitat for some native species, but the vegetation along right-of-ways is dominated by two non-native grasses. It appears unlikely that roadside habitat can be restored to resemble native grasslands without large scale and costly restoration efforts.

High Growing Season Temperatures Limit Winter Recovery of Grapevines from Xylella fastidiosa Infection - Implications for Epidemiology in Hot Climates.

Management of widespread plant pathogens is challenging as climatic differences among crop-growing regions may alter key aspects of pathogen spread and disease severity. Xylella fastidiosa is a xylem-limited bacterial pathogen that is transmitted by xylem sap-feeding insects. Geographic distribution of X. fastidiosa is limited by winter climate, and vines infected with X. fastidiosa can recover from infection when held at cold temperatures. California has a long history of research on Pierce's disease and significant geographic and climatic diversity among grape-growing regions. This background in combination with experimental disease studies under controlled temperature conditions can inform risk assessment for X. fastidiosa spread and epidemic severity across different regions and under changing climate conditions. California's grape-growing regions have considerable differences in summer and winter climate. In northern and coastal regions, summers are mild and winters are cool, conditions which favor winter recovery of infected vines. In contrast, in inland and southern areas, summers are hot and winters mild, reducing likelihood of winter recovery. Here, winter recovery of three table grape cultivars (Flame, Scarlet Royal, and Thompson Seedless) and three wine grape cultivars (Sauvignon Blanc, Cabernet Sauvignon, and Zinfandel) were evaluated under temperature conditions representative of the San Joaquin Valley, an area with hot summers and mild winters that has been severely impacted by Pierce's disease and contains a large portion of California grape production. Mechanically inoculated vines were held in the greenhouse under one of three warming treatments to represent different seasonal inoculation dates prior to being moved into a cold chamber. Winter recovery under all treatments was generally limited but with some cultivar variation. Given hot summer temperatures of many grape-growing regions worldwide, as well as increasing global temperatures overall, winter recovery of grapevines should not be considered a key factor limiting X. fastidiosa spread and epidemic severity in the majority of cases.

Complex temperature mosaics across space and time in estuaries: implications for current and future nursery function for Pacific salmon

Water temperature is a key dimension of estuaries that can influence important biological processes including organismal growth, survival, and habitat use. For example, juvenile Pacific salmon rely on temperature-mediated growth opportunities in estuaries during seaward migration in the spring and summer. However, oncoming climate change is warming estuary temperatures and transforming growth potential. Yet, it is likely that estuary water temperatures are complex and dynamic across space and time. Here we investigated spatial and temporal patterns of water temperature across two contrasting estuaries on Vancouver Island, BC, and used these data to simulate juvenile Chinook salmon growth potential under both present conditions and a simplified scenario of climate warming. Summer temperatures were warmer and more spatially homogeneous across the Englishman River estuary relative to the Salmon River estuary. Within each system, temperature was variable across habitats and sites, appearing to be driven by a combination of local climate, river and ocean temperatures, tidal fluctuations, and habitat features. This shifting mosaic of temperatures generated a complex portfolio of growth opportunities for juvenile Chinook salmon. There were broad patterns of increasing growth potential across both systems as temperatures warmed in early summer. However, excessively hot late summer temperatures drove steep declines in growth potential across the Englishman River estuary, while positive trends continued through August in the Salmon River estuary. A simple climate change scenario revealed that estuaries and habitats may have differing vulnerabilities to increasing temperatures—with climate warming, favorable growth opportunities were even more constricted to early summer in the Englishman River estuary, but expanded across most habitats and times in the Salmon River estuary given lower baseline temperatures and higher habitat complexity. Collectively, this work underscores the importance of habitat complexity and local climate for maintaining diverse growth opportunities across estuaries, which may confer resilience to the nursery function of estuaries as temperature mosaics warm.

Multiperspective view of the 1976 drought–heatwave event and its changing likelihood

Abstract1976 was one of the most acute droughts in the UK, exceptional due to the compounding effects of low rainfall and hot summer temperatures. In this study, we provide a multiperspective view of the likelihood of a 1976‐like compound event occurring now and into the future. We find a high level of consistency in the messages emerging across a range of different approaches and climate modelling tools, from convection‐permitting climate projections to decadal hindcasts and global coupled‐model attribution ensembles. 1976 summer average temperatures remain, at the time of writing, amongst the highest on record, but with warming are becoming increasingly common. The nine‐month rainfall deficit to August 1976 was incredibly rare. Analysis here indicates that compound extremes like 1976 are expected to occur on time‐scales of hundreds to thousands of years in the present‐day climate, decreasing slightly into the future. The probability remains very small even if we account for favourable sea surface temperatures and atmospheric circulation that occurred in 1976. Similar but less severe events with a 1% chance of occurring in the present day are five times more frequent from the 2040s under RCP8.5. The occurrence of such compound events is significantly (up to an order of magnitude) higher than expected if temperature and rainfall extremes occurred independently. In general, differences in likelihood estimates between approaches can begin to be understood from how dependence between variables is handled, differences in bias correction, and different levels of conditioning (i.e., the probability given particular atmospheric or ocean states). The appropriate choice of conditioning very much depends on the question being asked and its unconscious use may lead to apparent contradictions. Parallels can be drawn between 1976 and the recent summer of 2022, and results here suggest that with hotter summers we should be prepared for more severe droughts like 1976 in the future.

Enhancing irrigation effectiveness in vineyards with innovative technologies

Enhancing irrigation effectiveness in vineyards with innovative technologies Professor Pete W. Jacoby, from Washington State University, walks us through enhancing irrigation effectiveness in vineyards with innovative technologies like automated irrigation. As growers worldwide struggle to sustain vineyard production during hot summer temperatures and limited water resources, emerging technologies in the form of electronic soil moisture sensors coupled with automated irrigation may provide some opportunities for consideration. Using soil moisture sensors can aid in irrigation scheduling to sustain crops such as wine grapes to avoid heat damage to vines and impacts on fruit yield ahead of visual effects on the vine.

A New Perspective to Understand the Late Season Abundance of Delia antiqua (Diptera: Anthomyiidae): A Modeling Approach for the Hot Summer Effect.

The onion maggot, Delia antiqua (Meigen), is one of the most important insect pests to agricultural crops within Allium genus, such as onions and garlic, worldwide. This study was conducted to understand the seasonal abundance of this pest, with special reference to the hot summer effect (HSE), which was incorporated into the model of summer diapause termination (SDT). We assumed that hot summer temperatures arrested the development of pupae during summer diapause. The estimated SDT curve showed that it occurred below a high-temperature limit of 22.1 °C and peaked at 16 °C. Accordingly, HSE resulted in delaying the late season fly abundance after summer, namely impacting the third generation. In Jinju, South Korea, the activity of D. antiqua was observed to cease for more than two months in the hot summer and this pattern was well described by model outputs. In the warmer Jeju Island region, Korea, the late season emergence was predicted to be greatly delayed, and D. antiqua did not exhibit a specific peak in the late season in the field. The abundance patterns observed in Korea were very different from those in countries such as the United States, Canada, and Germany. These regions are located at a much higher latitude (42° N to 53° N) than Korea (33° N to 35° N), and their HSE was less intense, showing overlapped or slightly separated second and third generation peaks. Consequently, our modeling approach for the summer diapause termination effectively explained the abundance patterns of D. antiqua in the late season. Also, the model will be useful for determining spray timing for emerging adults in late summer as onion and garlic are sown in the autumn in Korea.

The Rate of Canopy Development Modulates the Link Between the Timing of Spring Leaf Emergence and Summer Moisture

AbstractShifts in phenological timing have important implications for ecosystem processes, with spring leaf emergence as a dominant control of carbon, water, and energy cycling. Phenological events are predominantly determined by weather and climate, therefore dynamic in time and sensitive to climate feedbacks. Improving our understanding of how ecosystems respond to changes in phenological timing will enhance our ability to assess summer soil water availability, since the timing of spring leaf emergence may lead to soil moisture deficits later in the growing season. We leveraged data from five AmeriFlux towers in central and eastern United States to investigate the extent spring leaf emergence (i.e., start of spring, SoS) influences rates at which forest canopies develop and how this impacts summer soil moisture (θJJA) variability. Our results indicate that ecosystem processes, specifically gross primary production (GPP) and evapotranspiration (ET), exhibit compensatory responses to varying leaf emergence; with delayed spring‐onset, the canopy developed more quickly, resulting in rapid GPP and ET increases, consistent across sites. Nonetheless, early SoS is a relatively good indicator for potential summer soil water deficits, particularly when it occurs together with meteorological conditions (i.e., lower‐than‐average precipitation, hot summer temperatures) that contribute to soil water deficits. When these meteorological conditions coincide with early SoS, θJJA deficits are exacerbated. To the extent that these extreme conditions occur more frequently under future climate scenarios, the dynamics of spring phenology and hydroclimate may play an increasingly important role in portending the likelihood of summer water deficits, which are projected to become more severe.

Summer indoor queen banking as an alternative to outdoor queen banking practices

Honey bee queens are the most critical individuals of a complex eusocial society. Queen banking is the storage of queens individually in cages and placed in a colony to be cared for by worker bees. Queen producers bank excess queens as seasonal demand subsides in the summer to provide an on-demand supply to beekeepers. This approach, however, might be threatened by wildfires, decreased forage availability, and climate change. For this study, we compared current summer outdoor queen banking practices in northern California with banking in indoor temperature-controlled storage facilities to investigate the effectiveness of indoor storage as an alternative to outdoor storage in the summer. Treatments were separated into three groups: indoor queen banks, outdoor queen banks, and a set of unbanked control queens provided with three different stocking rates (50, 100, and 198 queens per bank). Queen quality parameters and survival data were assessed using laboratory and field assessment methods. We found no significant difference in queen quality parameters apart from the weight of indoor queens banked at the rate of 100, which were significantly lower than the other banking rates. Queens stored indoors had a significantly higher survival of 78 ± 1% than queens stored outdoors with a survival of 62 ± 3%. Indoor banking performed better in quality and survival as compared to outdoor queen banking. Therefore, queen banking has the potential to mitigate the valuable fall queen supply caused by rising hot summer temperatures.

Household mold exposure in association with childhood asthma and allergic rhinitis in a northwestern city and a southern city of China.

BackgroundThe prevalence of asthma and allergic diseases has increased rapidly in Chinese cities over the past decades. Few studies have examined the potential role of household mold in asthma and allergies in Chinese cities.MethodsA cross-sectional survey in 4,691 school-age children was performed in Lanzhou and Wuhan. The two cities represent distinct climate conditions, as Lanzhou, located in northwestern China, has dry and cold winter and relatively cool summer whereas Wuhan, located in central-southern China, has hot and humid summer and mild winter temperatures. Two schools were randomly selected from a suburb and an urban area of each city, respectively. Data were collected using a modified Chinese version of the American Thoracic Society (ATS) standard respiratory health questionnaire for children, regarding asthma, substance allergy, allergic rhinitis, presence of mold in residence, and household characteristics. Logistic regression models were applied to identify the odds ratios of childhood asthma and allergies with regard to mold.ResultsThe prevalence rates of asthma, substance allergy, allergic rhinitis, and mold, were all higher in Wuhan than in Lanzhou. We observed significant associations of household mold with increased prevalence for both asthma [odds ratio (OR) =2.399, 95% confidence interval (95% CI): 1.309–4.398], substance allergy (OR =1.729, 95% CI: 1.282–2.332) and allergic rhinitis (OR =1.969, 95% CI: 1.491–2.600), with spatial heterogeneity across urban versus suburban schools. The mold effect was modified by age group and breast-feeding status.ConclusionsAcross two climatically distinct cities, household mold exposure was significantly associated with an increased risk for asthma and allergies. Younger children and children from the suburbs were more likely to be affected by mold. Whether breastfeeding enhanced or weakened the mold effects were inconsistent across the cities and across the health outcomes.

Decreased Filter Run Volume Investigation Leads to an Unlikely Culprit

After a New York plant converted to biofiltration, staff initially thought hot summer temperatures, new procedures, and other factors were decreasing filter run volumes. But when the plant couldn't reach design‐rated capacity, an evaluation revealed a deposit obstructing the filter effluent valve.

Summer survival is a major limitation to interseeding Poaceae cover crops in Kentucky

AbstractInterseeding cover crops (CCs) may increase adoption in corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotations in areas with a limited establishment window after harvest. Interseeding could provide an additional use for grass varieties that have been developed from breeding programs. Interseeded CC species must survive through the summer, not cause yield loss in the main cash crop, and produce sufficient biomass to provision ecosystem services. We examined the potential of locally adapted forage grasses, most from the University of Kentucky's grass‐breeding program, as CCs interseeded in corn using field trials conducted over 2 yr (2016 and 2017) in Lexington and Princeton, KY. Grasses were drill‐interseeded when the corn was V5 or V6; density was measured through the summer and biomass measured the following spring prior to CC termination. Percent establishment was generally higher for the festulolium cultivars (× Schedolium braunii (K. Richt.) Stace [Schedonorus pratensis × Lolium perenne ssp. multiflorum]), one of the larger‐seeded entries. In all but one site‐year, most of the forage grass plants did not survive the summer, and biomass by the following spring was minimal. Tall fescue (Festuca arundinacea Schreb.) had the best summer survival in most site‐years though spring biomass prior to termination was less than 1700 lb acre−1 (1905 kg ha−1). Establishment of cool‐season interseeded CCs will remain a challenge in Kentucky due to hot summer temperatures. Future research on interseeding CCs in this region should focus on finding tolerant species as well as evaluating soil and crop management strategies to support interseeding CCs.

Higher Subseasonal Predictability of Extreme Hot European Summer Temperatures as Compared to Average Summers

AbstractSummer temperatures in the last decades were increasingly characterized by persistent extremes, and there is evidence that this trend will continue in a warming climate. The exact timing of these extremes is less well known, and it is therefore crucial to consider their subseasonal predictability. We compare the prediction of summer 2m‐temperature extremes in Europe with the prediction of average events for four subseasonal forecasting systems. We find higher prediction skill for warm extremes as compared to average events, with some regional dependence. The same is not true for cold extremes, indicating an asymmetry in the processes causing opposite summer temperature extremes. The forecast skill is strongly increased by the most severe and persistent events in the analyzed period. We hypothesize that the enhanced warm extreme skill is related to persistent flow patterns and land‐atmosphere interaction. This could have implications for potentially enhanced predictability in a warming climate.

Can hot temperatures limit disease transmission? A test of mechanisms in a zooplankton–fungus system

Abstract Thermal ecology theory predicts that transmission of infectious diseases should respond unimodally to temperature, that is be maximized at intermediate temperatures and constrained at extreme low and high temperatures. However, empirical evidence linking hot temperatures to decreased transmission in nature remains limited. We tested the hypothesis that hot temperatures constrain transmission in a zooplankton–fungus (Daphnia dentifera–Metschnikowia bicuspidata) disease system where autumnal epidemics typically start after lakes cool from their peak summer temperatures. This pattern suggested that maximally hot summer temperatures could be inhibiting disease spread. Using a series of laboratory experiments, we examined the effects of high temperatures on five mechanistic components of transmission. We found that (a) high temperatures increased exposure to parasites by speeding up foraging rate but (b) did not alter infection success post‐exposure. (c) High temperatures lowered parasite production (due to faster host death and an inferred delay in parasite growth). (d) Parasites made in hot conditions were less infectious to the next host (instilling a parasite ‘rearing’ or 'trans‐host' effect of temperature during the prior infection). (e) High temperatures in the free‐living stage also reduce parasite infectivity, either by killing or harming parasites. We then assembled the five mechanisms into an index of disease spread. The resulting unimodal thermal response was most strongly driven by the rearing effect. Transmission peaked at intermediate hot temperatures (25–26°C) and then decreased at maximally hot temperatures (30–32°C). However, transmission at these maximally hot temperatures only trended slightly lower than the baseline control (20°C), which easily sustains epidemics in laboratory conditions and in nature. Overall, we conclude that while exposure to hot epilimnetic temperatures does somewhat constrain disease, we lack evidence that this effect fully explains the lack of summer epidemics in this natural system. This work demonstrates the importance of experimentally testing hypothesized mechanisms of thermal constraints on disease transmission. Furthermore, it cautions against drawing conclusions based on field patterns and theory alone. A free Plain Language Summary can be found within the Supporting Information of this article.

Effect of climate on tree growth in the Pampa biome of Southeastern South America: First tree-ring chronologies from Uruguay

Tree-ring research in the highland tropics and subtropics represents a major frontier for understanding climate-growth relationships. Nonetheless, there are many lowland regions – including the South American Pampa biome – with scarce tree ring data. We present the first two tree-ring chronologies for Scutia buxifolia in subtropical Southeastern South America (SESA), using 54 series from 29 trees in two sites in northern and southern Uruguay. We cross-dated annual rings and compared tree growth from 1950 to 2012 with regional climate variability, including rainfall, temperature and the Palmer Drought Severity Index – PDSI, the El Niño Southern Oscillation (ENSO) and the Southern Annular Mode (SAM). Overall, ring width variability was highly responsive to climate signals linked to water availability. For example, tree growth was positively correlated with accumulated rainfall in the summer-fall prior to ring formation for both chronologies. Summer climate conditions were key for tree growth, as shown by a negative effect of hot summer temperatures and a positive correlation with PDSI in late austral summer. The El Niño phase in late spring/early summer favored an increase in rainfall and annual tree growth, while the La Niña phase was associated with less rainfall and reduced tree growth. Extratropical climate factors such as SAM had an equally relevant effect on tree growth, whereby the positive phase of SAM had a negative effect over radial growth. These findings demonstrate the potential for dendroclimatic research and climate reconstruction in a region with scarce tree-ring data. They also improve the understanding of how climate variability may affect woody growth in native forests – an extremely limited ecosystem in the Pampa biome.

Water Distribution System Failure Risks with Increasing Temperatures.

In the coming decades, ambient temperature increase from climate change threatens to reduce not only the availability of water but also the operational reliability of engineered water systems. Relatively little is known about how temperature stress can increasingly cause hardware components to fail, quality to be affected, and service outages to occur. Changes to the estimated-time-to-failure of major water system hardware and the probability of quality noncompliance were estimated for a modern potable water system that experiences hot summer temperatures, similar to Phoenix, AZ, and Las Vegas, NV. A fault tree model was developed to estimate the probability that consequential service outages in quantity and quality will occur. Component failures are projected to have a percent increase of 10-101% in scenarios where peak summer temperature has increased from 36 to 44 °C, which create the conditions for service outages to have a percent increase of 7-91%. Increased service outages due to multiple pumping unit failures and water quality noncompliances are the most notable concerns for water utilities. The most effective strategies to prevent temperature-related failures should focus on monitoring and correcting chlorine residual and disinfection byproduct concentration, and on cooling pumping unit motors and electronics.

Seasonal physiological responses to heat in an alpine range-restricted bird: the Cape Rockjumper (Chaetops frenatus)

Hot, dry summer conditions impose physiological stress on endotherms, yet we have a poor understanding of how endotherms seasonally adjust their costs of thermoregulation under hot conditions. We determined whether seasonal phenotypic plasticity in evaporative cooling capacity at high temperatures explained how the range-restricted Cape Rockjumper (Chaetops frenatus; hereafter ‘Rockjumper’), copes with hot and dry summer temperatures of the temperate mountain peaks of southwest South Africa. We measured evaporative water loss (EWL), resting metabolic rate (RMR), and body temperature at high air temperatures (30–42 °C) of individuals from a wild population of Rockjumpers during winter and summer (n = 11 winter, 4 females, 7 males; n = 10 summer, 6 females, 4 males). We found Rockjumper evaporative cooling in summer imposes higher EWL (i.e. greater water costs) compared to winter, although an accompanying lack of change in RMR resulted in increased summer cooling efficiency. These patterns are similar to those observed in species that inhabit regions where summer temperatures are routinely high but the species are not water stressed. Our findings indicate that avian seasonal physiological adjustments to heat can be diverse. Further seasonal studies on thermoregulation in response to heat will greatly improve our knowledge of the functional value of traits such as evaporative cooling efficiency and heat tolerance and how they contribute to the physiological stress organisms experience in heterogenous environments.

The Relationships among Actual Weather Events, Perceived Unusual Weather, Media Use, and Global Warming Belief Certainty in China

Abstract Previous research revealed that if individuals personally experience an unusual weather event as a result of global warming (vs no personal experience), they may hold higher belief certainty that global warming is happening and hence develop more favorable attitudes toward mitigation actions. However, much of the previous research focused on self-reported personal experience and global warming beliefs using cross-sectional surveys; reverse causality is thus possible. Based on weather records and survey data, the present research examined whether actual weather events can influence one’s perceptions of unusual weather and belief certainty. Severe Typhoon Fitow 2013, but not hot summer temperatures, directly predicted the Chinese perceived experience of unusual weather and indirectly predicted their belief certainty and attitudes toward mitigation behavior. However, the effects were relatively small. Possible explanations and implications for environmental education are discussed.

Seed viability, germination and seedling emergence of the critically endangered stem succulent, Adenium swazicum, in South Africa

The regeneration ecology of many southern African threatened plant species is poorly understood. Temperature is considered the most important environmental factor governing seed germination. The germination temperature requirements of the critically endangered stem succulent, Adenium swazicum, were determined under controlled conditions, together with tetrazolium staining protocol tests to assess seed viability. The effects of soil medium, watering levels, depth of sowing and shading on germination/seedling emergence were also determined at the Lowveld National Botanical Garden (LNBG). Germination/seedling emergence was compared under nursery conditions within (Skukuza Nursery in Kruger National Park) and outside (LNBG) the natural distribution range of A. swazicum. The germination of viable seeds ranged 96.5–100% for a broad range of temperatures from 20 to 35°C as well as for 30/20°C (light/dark) alternating temperature. No germination was recorded at 5°C and 10°C, and relatively limited germination at 15°C (42.9%) and 40°C (15.4%). These results were modelled using a Generalized non-linear model, with a binomial error and a logit link function, best-fit models were second-order polynomials (i.e., quadratic). Mean Germination Time ranged from 2 to 6days among temperature treatments. Tetrazolium together with germination results for the 20−35°C temperatures showed moderate to high seed viability across populations and between years within the same population. Seedlings readily emerged irrespective of soil media (3 types) or planting depth (surface, 5 and 10mm) but higher emergence occurred under more frequent watering. Seedlings emerged equally well under sun or shade conditions, but only subsequently survived in the shade. Despite lower temperatures recorded during October/November 2010 at LNBG (outside range: 27.2±0.9°C) compared to Skukuza (within range: 32.6±0.9°C), final germination/seedling emergence was high at both locations (LNBG: 82%; Skukuza: 94%). Together with field observations, this study shows that (a) seed germination is rapid and with high percentages after being cued by warm to hot summer temperatures, a period when rainfall is also at its highest, and (b) that seedling recruitment depends on the availability of suitably shaded microsites. This is the first study on the regeneration ecology of an Adenium sp. and will aid both in situ and ex situ conservation of A. swazicum.

Temperature-dependent age-specific demography of grapevine moth (Lobesia botrana) (Lepidoptera: Tortricidae): jackknife vs. bootstrap techniques

Grapevine moth, Lobesia botrana (Lep. Tortricidae) is a key pest of grape in Iran and other vineyards of the world. In this study, eight constant rearing temperatures (5, 10, 15, 20, 25, 30, 32 and 35 ± 1 °C) along with 60 ± 10% RH and a 16:8 (L:D) h photoperiod were chosen for demographic studies of the grapevine moth. Immature stages were unable to develop when reared at 5 and 35 °C, and the progeny moths were unable to successfully mate at 10, 15 and 32 °C. The overall developmental time of juveniles decreased at 30 °C (from 320.7 ± 3.4 d at 10 °C to 34.2 ± 0.2 d) followed by an increase to 42.5 ± 0.6 d at 32 °C. Based on values of the stable population growth parameters, the temperature of 25 °C was found to be optimal for propagation of grapevine moth. The highest values of the intrinsic rate of increase, gross and net reproductive rates were 0.0719 d −1, 55.5 and 23 females per generation, respectively, at 25 °C. Since jackknife and bootstrap estimates of mean and standard error were mainly similar, both methods may equally be used for uncertainty estimates. Our data suggest that cold storage of grapes will help to control grapevine moth infestations and damage. In many grape growing regions of Iran, the first generation is expected to cause damage. It is expected since our reproductive life table analysis suggests that the hot summer temperatures may restrict pest development during subsequent generations.