Peak Emergence Research Articles

Validation of degree day threshold for Delia platura first emergence in New York State

Seedcorn maggot (Delia platura) is a globally distributed agricultural pest that feeds on the germinating seeds of economically important crops, including corn and beans. The larvae cause underground damage, which can lead to stand loss. For decades, D. platura has been managed using insecticide-coated seeds, but following the ban on neonicotinoid-coated corn, soy, and wheat seeds in New York State, this practice will no longer be available. Degree day models have been used to predict the emergence of the overwintering generation of agricultural pests since the late 1900s. However, the terminology used in the literature to distinguish degree day thresholds for first emergence and peak emergence is unclear, and previous reports of a 360 degree day emergence threshold did not align with field observations. In 2023, we captured the first emergence at four sites, and in 2024, we monitored adult D. platura at 25 sites in New York State. We observed the first adult emergence between 52 and 197 accumulated degree days (98 ± 7 degree days, mean ± 1 SE) using a biofix of January 1st, confirming that in New York State, D. platura emergence is earlier than previously reported values. Additionally, we note adult activity during December 2023 and January 2024, suggesting that warming winters may impact our ability to predict pest emergence. We propose future models should incorporate both degree day information and other regionally specific factors known to impact pests, including farm management, soil conditions, and landscape composition, for more accurate predictions.

Monitoring the short-term biological response of environmental noise in real-life sleep conditions

A protocol is developed to measure the short-term biological response to environmental noise during sleep. It is designed as potential component in the Human Biomonitoring Program of the Flemish Government. The focus of the protocol is the user-friendliness and the use of non-invasive but accurate technology. The sensor boxes are deployed without third party support using a simple set of instructions. The setup includes simultaneous indoor and outdoor spectral noise monitoring to discriminate between indoor and outdoor disturbances. Actimetry and heart rate are monitored on-torso to detect potential arousals and awakenings. The data analysis is performed in a 10 second resolution and is based on the heart rate variability (HRV) of nine teenage subjects. The bedroom insulation is included using the difference between outdoor and indoor noise. The relevant biomarker is the HF/LF ratio, a HRV parameter related to the activation of the autonomous nervous system, shows significant correlation with the environmental noise. Peak emergence and augmented background noise also result in enhanced activation of the autonomous nervous system. This novel approach delivers an objective measure of the short-term biological effect of noise during sleep in real-life conditions. The affordability and low-invasive design allow large-scale deployment in future health studies.

Patterns of occurrence, phenology, and phylogeny of Phloeosinus punctatusLeConte(Coleoptera: Curculionidae, Scolytinae) in giant sequoia.

Here, we describe patterns of reproduction and flight phenology of putative Phloeosinus punctatus in giant sequoia groves and compare morphology and genotypes of beetles from sympatric giant sequoia (Sequoiadendron giganteum) and California incense-cedar (Calocedrus decurrens). Surveys conducted in 2022 revealed that numerous branches fall from giant sequoia crowns (on average ~30 branches/tree), with 20%-50% of trees per site shedding branches, depositing breeding material for beetles on the forest floor that subsequently becomes colonized. When noninfested branches cut from mature giant sequoias were placed at the ground surface, they were colonized by P. punctatus and produced an average of 28 beetles/kg branch. Climbing and examination of sequoia crowns in 2023 showed that 75% of mature trees across 11 groves showed evidence of adult beetle entrance holes in their crowns. In 2021, tests with sticky traps showed that beetles alighted on fallen branches from 20th May to 20th August (peak landing: 2nd July); a logistic model developed from emergence data in 2021 and 2022 predicts the emergence of F1 offspring from branches between 10th July and 1st September (peak emergence: 8th August). Beetles emerging from giant sequoia preferred to settle on giant sequoia, did not reproduce in incense-cedar, and diverged morphologically from beetles emerging from incense-cedar. However, phylogenetic analysis of three genes (28S, CAD, and COI) revealed no clear pattern of sequence divergence, suggesting a single species (P. punctatus) that colonizes both hosts, though cryptic speciation may not be detectable with standard barcoding genes. Ecological and potential management implications are discussed.

Drivers of moth phenology in England and Wales

Climate change has led to changes in the phenology of Lepidoptera species. While phenological shifts have been previously measured for moth species in England and Wales, the drivers of these shifts are not well known. Here, we use data from the National Moth Recording Scheme and the Garden Moth Scheme to investigate the drivers of phenology in 149 moth species over a 50 year period from 1970 to 2019. We investigate whether there have been phenological shifts in adult emergence using three phenology metrics: First Emergence (FE), Peak Emergence (PE), and Emergence Standard Deviation (ESD) in relation to life history traits and temperature. Overwintering stage had a significant impact on moth phenology, so we analysed species that spend the winter as eggs, larvae or pupae separately. Overall phenological changes were different depending on overwintering stage category and phenological measure, with the rate of phenological shifts increasing with later overwintering life stages in response to both temperature and year. The overwintering stage larva was the only one impacted by diet, with those that feed on woody hostplants emerging ~ 17 days later than species with herbaceous hostplants. These results indicate that species that either overwinter in earlier life stages or have woody hostplants may be less adaptable to climate change, and thus should be the targets of conservation efforts.

Maggots cannot live on meat meal alone: production parameters for mass rearing of the ovoviviparous blowfly, Calliphora dubia (Diptera: Calliphoridae).

This study determined a cost-effective larval diet for rearing Calliphora dubia Macquart for use as a potential managed pollinator in Australia. This fly has potential as a pollination species to support honey bees (Apis mellifera). Larvae of C. dubia were reared mostly in meat meals with varying amounts of either whole egg powder, whole eggs (+ shell), bran flakes, skimmed milk powder, brewer's yeast, or poultry oil. This was done from an economic and production perspective to support commercial rearing. Several laboratory-based studies determined the growth and output from various ingredient combinations. Larvae fed 90% meat meal and 10% whole egg powder developed rapidly through to pupation with a high pupation rate, adult size, and percent adult emergence. Given the high cost and difficulty in sourcing whole egg powder, media comprising mostly meat meals with the addition of bran flakes and whole eggs also supported rapid larval development, pupation rate, and adult emergence. The ideal amount of media/larvae was 0.5 g/larvae to support high pupation rates and adult emergence. Adult eclosion occurred over 4-5 days, even when larvae were laid and fed within 1 h on ample media. Commercial mass rearing would then require daily cohorts of larvae to ensure peak adult fly emergence over 1-2 days for release into a crop. Mass-rearing C. dubia should use meat meal as the base ingredient with bran flakes and whole eggs added and fed at 0.5 g of media/larvae. Based on the current media ingredient costs, rearing 1-m adult C. dubia would cost just over $500 (US$342).

Seasonal prevalence of the invasive rusty-spotted longhorn beetle, Apriona swainsoni (Coleoptera: Cerambycidae), adults in Fukushima Prefecture, Japan

AbstractInvasive longhorn beetles are serious pests of tree stands worldwide. The rusty-spotted longhorn beetle, Apriona swainsoni (Hope) (Coleoptera: Cerambycidae: Lamiinae), is native to continental Asia, where it is a significant pest of legume trees. Its invasion into non-native ranges and damage to the local legume tree, Maackia amurensis, were first reported from Fukushima Prefecture, Japan, in 2021. This study investigated the biology of A. swainsoni in relation to adult emergence in Japan. Preliminary observations confirmed that A. swainsoni larvae create planned emergence holes on the host surface in late May. By exploiting these planned emergence holes, the adult emergence period was investigated in a field promenade of M. amurensis during the summer of 2022 and 2023. The researchers plugged the holes and recorded plug removal, resulting in the observation of 60 and 227 putative emergence events in respective years, with the majority occurring in early to mid-July. Further, during the summer of 2022, a periodic field survey of adult emergence was conducted, obtaining eight adults. Furthermore, a supplementary survey using infested logs maintained in a field cage demonstrated that the emergence period does not differ between sexes and the male-to-female ratio is one:one. Our results suggest that control efforts to suppress A. swainsoni adults in the field, such as insecticide spraying, should be prioritized in the relatively short, peak emergence period. This work indicates that the plug survey is useful for detecting the emergence period.

Comprehensive evaluation of the resistance to shoot shriveling before and after sprouting in different varieties of Ping’ou hybrid hazelnut

IntroductionThe hybrid hazelnut is an important fruit tree species known for its high productivity and disease resistance. However, during the growth process of hybrid hazelnuts, issues such as branch withering and bud wrinkling have attracted significant attention. These phenomena severely impact the normal development and yield of the plants. This study aimed to investigate the relationship between the resistance to shoot emergence and physiological changes in six hazel tree varieties by comprehensively analyzing their resistance to shoot emergence.MethodSix widely cultivated hazelnut hybrid varieties were selected for physiological measurements and field surveys using one-year-old branches and buds as test materials. The resistance to shoot emergence of different hazel tree varieties was evaluated through correlation analysis, principal component analysis, and membership function evaluation.ResultsThe results showed that the length and width of hazel buds gradually increased while the thickness first increased and then decreased before and after bud burst. The carbohydrate levels of the ‘Dawei’, ‘Pingou 110’, and ‘84–237’ varieties were significantly higher than those of other varieties. The content of reducing sugars and starch in hazel buds generally increased and then decreased during the bud burst process, while α-amylase activity showed a decreasing trend followed by an increasing trend. The antioxidative enzyme activity of ‘Dawei’ was significantly higher than that of other varieties on different sampling dates. The soluble protein content, POD enzyme activity, and CAT enzyme activity of hazel buds for the six varieties gradually decreased. The moisture content of ‘Pingou 210’ shoots was significantly higher than that of other varieties during the peak emergence period. The correlation analysis results showed that the bud burst rate of hazel trees was positively correlated with the length, width, thickness, reducing sugar content, starch content, POD enzyme activity, CAT enzyme activity, and shoot moisture content, while it was negatively correlated with α-amylase activity and relative conductivity of shoots. Through a comprehensive evaluation using correlation analysis, principal component analysis, and membership function analysis, the resistance to shoot emergence of the six hazel tree varieties was ranked in the following order: ‘Dawei’, ‘Pingou 110’, ‘84–237’, ‘Pingou 210’, ‘Yuzhui’, and ‘Liaozhen 3’.DiscussionThis study fills a research gap regarding the physiological changes of hazelnuts before and after sprouting, and provides theoretical guidance for further research on the anti-withering ability of hazelnut trees.

Exploiting asynchronous host-parasitoid emergence distributions to optimise insecticide applications and protect beneficial insects– a case study using the citrus gall wasp Bruchophagus fellis (Hymenoptera: Eurytomidae)

The citrus gall wasp (CGW), Bruchophagus fellis (Girault) (Hymenoptera: Eurytomidae), is a serious pest of citrus in southern Australia. Severe infestations can result in yield loss and a reduction in fruit size. Several parasitoid species attack CGW, with Megastigmus brevivalvus (Girault) (Hymenoptera: Torymidae) (MBV) being the dominant species. Both CGW and MBV are univoltine and adult wasps emerge from galls in the spring. Median emergence of MBV lags behind that of CGW by 2–3 weeks. We modelled the effect of spray timing for foliar-applied, non-systemic insecticides on the relative exposures of CGW and MBV based on their emergence distributions and estimated the optimal spray timing that maximises the control of CGW while minimising the impact on MBV. Three temporal emergence distribution scenarios for the two species and 28 periods of residual insecticide activity were considered in the investigation. The results showed that the optimal spray timing was always before the peak emergence of CGW. Depending on the residual activity of the insecticide, the optimal spray date pre-dated the peak emergence of CGW by 1–24 days, with longer lead times for insecticides with longer residual activity. By contrast, the optimal spray date varied little across the different emergence scenarios, suggesting that the results apply over a wide range of locations and seasons. A single insecticide application at the optimal timing may not guarantee satisfactory control of CGW. When the residual activity of the insecticide is short, multiple applications with a combined residual activity of 16 days are needed to ensure insecticide contact with ≥90% of all CGW that emerge in a season.

Adult Emergence and Morphometrics of Chinese Citrus Fly, Bactrocera minax (Enderlein) (Diptera: Tephritidae) in Nepal

Chinese citrus fly, Bactrocera minax is a destructive and univoltine pest of citrus fruits. Geographical altitudinal gradients as well as prevailing climate affect the biology and ecology of insect. Hence, this study aimed to ascertain the effect of altitude on the adult emergence and morphological variations in various ecological settings of Ramechhap district of Nepal from February to June 2021 in citrus orchard. Six altitude ranges were selected in 50 m distance from 1200 to 1500 m above sea level (masl), ranging from 1201-1250 masl, 1251-1300 masl, 1301-1350 masl, 1351-1400 masl, 1401-1450 masl and 1451-1500 masl. The peak adult emergence periods were the 2nd, 3rd, 4th week of April in 1201-1250 masl, 1251-1300 masl, 1301-1350 masl, respectively, followed by 1st, 2nd and 3rd week of May in 1351-1400 masl, 1401-1450 masl, 1451-1500 masl, respectively. Morphometrics of Chinese citrus fly such as weight, length and width of pupa and adult were almost similar to the species collected in various altitudes. The average body length of male Chinese citrus fly adult was 11.58± 0.112 mm while female was 15.57± 0.076 mm. The average wingspan of male was 20.71± 0.285 mm while that of female was 23.14± 0.156 mm. The longevity of adult Chinese citrus fly species increased with increase in altitude. This information could be useful to design an appropriate management plan of Chinese citrus fly in various altitudinal gradients of Nepal.

Effects of yellow and green light stress on emergence, feeding and mating of Anomala corpulenta Motschulsky and Holotrichia parallela Motschulsky (Coleoptera: Scarabaeidae)

Light is one of the key environmental factors for insects to survive. Artificial light sources different from natural environmental light can cause light stress in insects. Yellow and green light stress can interfere with the diurnal rhythm of nocturnal moths and their mating, oviposition, and adult longevity. The scarabaeid beetles Anomala corpulenta Motschulsky and Holotrichia parallela Motschulsky are widely distributed, and they are very harmful underground pests. In order to clarify the effects of light stress on their behaviors, individuals of both species were exposed to yellow light (565-585 nm) and green light (525-545 nm), with different light intensity gradients of yellow light in a laboratory setting. The short-term light stress treatment of A. corpulenta and H. parallela was carried out at night. The number of beetles emerging per half an hour was recorded, and mating pairs and feeding activity in 24 h were counted. The results showed that yellow and green light stress significantly changed the rhythm and reduced the rate of beetle emergence in the two beetle species investigated. Also, the peak emergence activity was delayed and the feeding and mating activities were significantly reduced. When treated with different intensities of yellow light, it was found that the rate of emergence of A. corpulenta under 10 lx was close to the control groups. The rate of emergence in H. parallela was significantly lower than the control groups before 0:00, in the 60 lx and 110 lx treatment groups, but after 0:00, the emergence rate of H. parallela was significantly higher in the 60 lx and 110 lx treatment groups than other treatments. However, the emergence rhythms in the three light intensity treatment groups are basically the same as in the control groups. The feeding amount and mating beetles in the three light intensity treatment groups were significantly lower than in the control groups. There were no significant differences in the three treatments. The results show that light stress above 10 lx significantly interferes with the behavioral activities of the two beetle species, investigated. This study provides a new approach for a light control technology for nocturnal beetle pest species. Keywords: yellow and green light, Anomala corpulenta Motschulsky, Holotrichia parallela Motschulsky, emergence rhythm, feeding, mating DOI: 10.25165/j.ijabe.20231601.7639 Citation: Jiang Y L, Huang Q Y, Wei G S, Gong Z J, Li T, Miao J, et al. Effects of yellow and green light stress on emergence, feeding and mating of Anomala corpulenta Motschulsky and Holotrichia parallela Motschulsky (Coleoptera: Scarabaeidae). Int J Agric & Biol Eng, 2023; 16(1): –.

Emergence and Reproductive Rhythm of Clostera anastomosis (Lepidoptera: Notodontidae)

Abstract Clostera anastomosis L. (Lepidoptera: Notodontidae) is a serious defoliator of poplar, Populus spp., trees in China. To establish a baseline of information for possible ecological management of this pest, we studied its emergence, courtship, mating, and oviposition behaviors in the laboratory at 27 ± 1°C and 60 ± 10% relative humidity under a 14:10-h (light:dark) photoperiod. Under these conditions, peak emergence of female adults occurred in the sixth day after pupation, and peak emergence of males was in the seventh day after pupation. Emergence for both sexes occurred throughout the day. Courtship behavior began at the sixth hour of scotophase, reaching peak activity between the 10th hour of scotophase and the first hour of photophase. The courtship and mating success rate were highest for 1-d-old females, and then gradually decreased with age until no mating was observed after females were 4 d old. With 1-d-old females, mating was only observed from the seventh hour of scotophase to the first hour of photophase, with peak activity at 0.5 h after the onset of photophase. Oviposition primarily occurred within 3 d after mating, with 49.8% of the eggs being deposited during the first day after mating. These results demonstrate that there are distinct circadian rhythms in adult emergence and subsequent reproductive behavior of C. anastomosis, thus providing a basis for development of monitoring and management strategies of this pest.

Differential Scanning Calorimetry Material Studies: Benzil Melting Point Method for Eliminating the Thermal History of DSC

How to eliminate the thermal history present in differential scanning calorimetry, this question has been widely concerned. Benzil has a serious thermal history that is not well eliminated by conventional thermal history methods. Herein, using benzil as a target, we developed a freeze-gradient temperature rate heating up method to eliminate the thermal history of DSC. Compared with the conventional method, this method avoids the introduction of new thermal histories by new crystalline forms that may appear during the cooling crystallization process. The results show that the peak shape of the melting peak is sharper and the peak emergence position is closer to the theoretical melting point after the elimination of the thermal history by the freeze-gradient heating up method. Based on this method, we optimized other factors to establish a complete method for the determination of melting point by DSC, analyzed the uncertainty of the method, and obtained an extended uncertainty of 0.19°C for DSC in this method. The validation results show that the p-nitrotoluene of the melting point reference substance was 52.64°C, which is within its reference value of (52.53 ± 0.20) °C, showing that this method is reliable. This study provides a reference for other thermal analysis methods to eliminate thermal history.

Observations on the biology of the Flores weevil, Floresianus sordidus Hustache in northern New Zealand

ABSTRACT Flores weevil (Floresianus sordidus Hustache, 1939 (Coleoptera, Curculionidae)) is now common in northern areas of the North Island of New Zealand. Historic records and new field data were investigated to learn more of the biology, seasonality, and likely pest status of the weevil. Laboratory studies were undertaken on its feeding preferences and the impact of host plant on oviposition and survival. Flores weevil adults were found to be absent in pastures from November to February and started emerging in early autumn (March), with peak emergence in April and May. Adults preferred feeding on broad-leaved plants and did not feed on perennial ryegrass (Lolium perenne L.). Mean longevity of field-collected adults in the laboratory ranged from 20 days, when provided ryegrass, to 62 days on plantain (Plantago lanceolata L.). Eggs were laid in batches of up to 20 eggs. Most eggs were laid by weevils feeding on red clover (Trifolium pratense L.) and the least by those provided ryegrass. Dissections showed ryegrass-fed weevils retained mature eggs in their ovaries. First instar larvae were found to feed on soil organic matter, whereas second and third instar larvae fed on roots. Host plant had no significant effect on larval survival or development of these stages.

Complexation of Anthocyanin-Bound Blackcurrant Pectin and Whey Protein: Effect of pH and Heat Treatment.

A complexation study between blackcurrant pectin (BCP) and whey protein (WP) was carried out to investigate the impact of bound anthocyanins on pectin–protein interactions. The effects of pH (3.5 and 4.5), heating (85 °C, 15 min), and heating sequence (mixed-heated or heated-mixed) were studied. The pH influenced the color, turbidity, particle size, and zeta-potential of the mixtures, but its impact was mainly significant when heating was introduced. Heating increased the amount of BCP in the complexes—especially at pH 3.5, where 88% w/w of the initial pectin was found in the sedimented (insoluble) fraction. Based on phase-separation measurements, the mixed-heated system at pH 4.5 displayed greater stability than at pH 3.5. Heating sequence was essential in preventing destabilization of the systems; mixing of components before heating produced a more stable system with small complexes (<300 nm) and relatively low polydispersity. However, heating WP before mixing with BCP prompted protein aggregation—producing large complexes (>400 nm) and worsening the destabilization. Peak shifts and emergence (800–1200 cm−1) in infrared spectra confirmed that BCP and WP functional groups were altered after mixing and heating via electrostatic, hydrophobic, and hydrogen bonding interactions. This study demonstrated that appropriate processing conditions can positively impact anthocyanin-bound pectin–protein interactions.

Improving Weed Management Based on the Timing of Emergence Peaks: A Case Study of Problematic Weeds in Northeast USA

We reviewed the timing of the peak rate of emergence for 15 problematic weed species as well as ways to use this knowledge to improve control. Much of the previous literature modeled emergence based on growing-degree-days. For these models, we input average temperature data from several zones of Northeast USA. Within species, model-predicted peak emergence in the warmest and coolest zones differed by an average of 39 days. Also within species, there was some variation between models, likely reflecting different conditions in study locations and population-level differences that will need to be addressed in future modelling efforts. Summarizing both observed and modelled results, emergence typically peaked early-season for barnyardgrass, Canada thistle, common lambsquarters, common ragweed, giant foxtail, large crabgrass, perennial sowthistle, and smooth crabgrass. Emergence typically peaked mid-season for hairy galinsoga, mouseear chickweed, and red sorrel. Emergence typically peaked late-season for annual bluegrass. Several species emerged in a protracted manner, including common chickweed, quackgrass, and redroot pigweed. With this improved knowledge, farmers may target key problematic species of a particular field in several ways. Weed seedling control efforts can be timed at the highest densities or most vulnerable phenological stage. Residual herbicides and suppressive mulches can be timed to maximize effectiveness prior to their breakdown. And if management flexibility allows, crop selection and associated planting dates may be adjusted to improve crop competition or facilitate seedbank depletion through timely bare fallow periods. Such improvements to weed management based on timing of emergence will likely become even more impactful as predictive model reliability continues to improve.

Effect of age, daily rhythm and mating on pheromone titres and trapping of Glyphodes pyloalis (Lepidoptera, Crambidae)

AbstractGlyphodes pyloalis (Lepidoptera, Crambidae) is an important pest of mulberry trees in China, and current methods for accurate population monitoring and control of this pest are lacking. The sex pheromone of G. pyloalis in China was re‐identified as E10, E12, Z14‐hexadecenyl acetate (E10E12Z14‐16:Ac) and tentatively E10, E12, E14‐hexadecenyl acetate (E10E12E14‐16:Ac). The emergence began 2 h before the dark period, and the peak emergence was 3 h into scotophase. Analysing the female moth's age from 1–9 days revealed that the titre of sex pheromone E10E12Z14‐16:Ac and E10E12E14‐16:Ac did not change statistically, and the ratio remained constant at 7.19 ± 1.12. The titre of pheromone had a significant circadian rhythm, increasing at 2 h after darkness, peaking at 6–8 h before decreasing, but it was still detected after 4 h into photophase. Mating of G. pyloalis occurred mainly at night, with the highest rate during 3 h into scotophase, which was earlier than the temporal pattern of pheromone titres. 18.1% of unfed moths mated immediately after eclosion during the scotophase. This was lower than what is seen in 1–3‐day‐old moths but similar to 4‐day‐old moth. Mating can occur on the same day after emergence, primarily within 1–4 days. Female moths can release pheromone again 48 h after mating, but the ratio of E10E12Z14‐16:Ac and E10E12E14‐16:Ac was reduced to 5.1 ± 0.73. The trapping of male moths in the field showed a significant circadian rhythm, but significant differences in pheromone trapping in Sichuan Gongxian, Zhejiang Chun'an and Haining, and Jiangsu Wujiang were observed. At the same location, the circadian rhythm of moth trapping showed differences between generations. The trapping of the overwintering generation occurred mostly in the early period of scotophase, while other generations were caught slightly later. Our results contribute to effective pheromone trapping for monitoring and mass trapping to better control G. pyloalis populations.

Spatiotemporal patterns of emergence phenology reveal complex species‐specific responses to temperature in aquatic insects

AbstractAimClimate change is broadly affecting phenology, but species‐specific phenological response to temperature is not well understood. In streams, insect emergence has important ecosystem‐level consequences because emergent adults link aquatic and terrestrial food webs. We quantified emergence timing and duration (within‐population synchronicity) of insects among streams along a spatiotemporal gradient of mean water temperature in a montane basin to assess the sensitivity of these phenological traits to heat accumulation from mid‐winter through spring emergence periods.LocationSix headwater streams in the Lookout Creek basin, H.J. Andrews Experimental Forest, Oregon, USA.MethodsWe collected emerging adults of four abundant insect species twice weekly throughout spring for 6 consecutive years. We fit Gaussian models to the empirical temporal distributions to characterize peak emergence timing (mean) and duration (days between 5th and 95th percentiles) for each species/stream/year combination. We then quantified relationships between degree‐day accumulation and phenological response.ResultsOnly one of the four species (a caddisfly) showed a simple response of earlier emergence timing in both warmer streams and years. One stonefly had lengthy emergence periods resulting in substantial phenological overlap between warmer and cooler streams/years. Interestingly, two species (a mayfly and a stonefly) responded strongly to temporal (interannual) temperature differences but minimally to spatial differences, indicating that emergence was nearly synchronous among streams, within years. These two species had among‐stream differences approaching 500 degree‐days from mid‐winter to peak emergence. Conversely, duration of emergence was more strongly associated with spatial than temporal differences, with longer duration in lower‐elevation (warmer) streams.Main conclusionsEmergence phenology has species‐specific responses to temperature likely driven by complex cues for diapause or quiescence periods during preceding life cycle stages. We hypothesize a trade‐off between complex phenological response that synchronizes emergence among heterogeneous sites and other traits such as adult longevity and dispersal capacity.

Effects of sand burial depth on Xanthium spinosum seed germination and seedling growth

In desert habitats, sand burial is an important factor affecting germination of plant seeds and seedling growth. Xanthium spinosum has strong adaptability in arid desert areas, and is a common malignant invasive plant in Xinjiang, China. The effects of different sand burial depths on seed germination, seedling emergence, growth and biomass allocation were studied to provide a scientific basis for further control of X. spinosum. Six sand burial depths (1, 2, 3, 5, 7 and 9 cm) were established to explore the response of X. spinosum seed germination and seedling growth to sand burial. The first emergence time, peak emergence time, emergence rate, seedling growth height, biomass and biomass distribution of X. spinosum seeds was significantly different at sand burial depths (P < 0.05). The X. spinosum seeds had the highest emergence rate (71.5%) at 1 cm sand burial and the maximum seedling height (7.1 cm). As sand burial depth increased, the emergence rate and seedling height gradually decreased. Emergence rate (12.25%) and seedling height (2.9 cm) were lowest at 9 cm sand burial. The root length at 9 cm depth (13.6 cm) was significantly higher than that at other sand depths (P < 0.05). The sand burial depth affected the biomass accumulation and distribution of X. spinosum. As sand burial depth increased, the root biomass and rhizome ratio increased, and the most deeply buried seedlings allocated more biomass for root growth. The optimal sand burial depth for seed germination and seedling growth of X. spinosum was 1–3 cm, and high burial depth (5–9 cm) was not conducive to the germination and growth of X. spinosum seedlings. For prevention and control of X. spinosum, we suggest deeply ploughing crops before sowing to ensure X. spinosum seeds are ploughed into a deep soil layer.

Influence of road traffic noise peaks on reading task performance and disturbance in a laboratory context

The influence of fluctuating road traffic noise on perceived disturbance during a reading task as well as on performance, inside a living room with closed windows, is presented in this paper. Sixteen 2-min sound sequences were created combining two variables: the number of events (four levels varying from one to four car pass-bys) and the peak emergence above the background noise (four levels with a 5 dB(A) step) keeping limited variations ofLAmax, 1s. The noise impact was evaluated through a reading task of texts synchronized with the sound sequences, for participants classified into fast or slow readers, and sensitive or non-sensitive to noise. The comprehension rate of the texts decreases as the background sound level increases. The reading speed decreases during the rising front of a peak, and goes back to its former regular reading speed during the descending front of the peak. This slowdown during the rising front reaches 14% for slow readers. The declared disturbance is higher for slow readers compared to fast readers, and higher for noise sensitive persons compared to non-sensitive persons. The influence of the acoustic indicators on the reading disturbance is very small compared to the influence of personal factors. There is even no influence of the number of events on this disturbance.

Long-term noise interferometry analysis in the northeast Pacific Ocean.

Long-term noise interferometry analysis is conducted over six years of data using two hydrophones on the Ocean Observatories Initiative Cabled Array. The two hydrophones are separated by 3.2 km and are bottom-mounted at 1500 m. We demonstrate the ability of ambient noise interferometry to reliably detect multi-path arrivals in the deep ocean from bottom-mounted hydrophones. An analysis of the multi-path arrival peak emergence is presented, as well as long-term trends of the signal-to-noise ratio of the arrival peaks. Last, we show that long-term ambient noise interferometry provides the opportunity for monitoring directional, coherent ambient sound such as the fin whale chorus.