Latitudinal variation in the effects of winter temperature on egg hatching and larval development in Sympetrum frequens (Odonata: Libellulidae)

Unravelling the effect of climate variability on species biology has been one of the main goals of ecological studies. Environmental factors such as river discharge and temperature have being proposed as triggers of reproductive cycle in fish. In temperate climates, fish reproduction is affected mainly by temperature, while is influenced by flood pulses in large tropical rivers. We evaluated the influence of temperature and river discharge as triggers of Iheringichthys labrosus’ reproduction. We studied the following reproductive variables: gonadosomatic index (GSI), hepatosomatic index (HSI) and condition factor (K). Females of I. labrosus were examined in a time series of ten years along three sites located in Lower Uruguay River at the beginning (last week of November‐first week of December, spring) and by the end of the reproductive period (middle‐end of April, autumn). Generalised linear models detected a positive effect of mean winter temperature and site on the spring mature female GSI. Site was significant in addition to the interaction between temperature and site. Moreover, the effect of winter temperature was stronger than water discharge in triggering reproductive timing of I. labrosus, contrary to the model proposed for other species in tropical systems. Additionally, a literature review suggested a latitudinal gradient on reproduction, occurring earlier and prolonged with decreasing latitude (and increasing temperature). In this study, we stated the effect of temperature on the life history in a Neotropical fish using a multifaceted approach, particularly important in the current context of global climate warming.

Effects of winter temperatures, spring degree-day accumulation, and insect population source on phenological synchrony between forest tent caterpillar and host trees

The Influence Of Ultraviolet Irradiation Upon The Development And Infectivity Of Hookworm Larvae

Key message In apple, the overwintering bud appears hydraulically isolated from the parent stem. Spring budburst seems more related to a whole-shoot effect than to the water status of the individual bud during winter dormancy. Abstract The effects of winter temperatures, i.e., during dormancy, on shoot architecture are well known with bud- burst preferentially in the distal or the proximal part of the parent shoot in cold and mild winter conditions, respectively. However, the link with the overwintering bud water status is still scarcely documented. Our study was developed on four apple (Malus domestica Borkh.) cultivars covering a range of chilling requirements from low ('Condessa') to medium ('Granny Smith') and high ('Royal Gala', 'Starkrimson'), and maintained in either cold (1,428 h below 7.2 C) or mild (99 h below 7.2 C) fluctuating winter temperatures. Our aim was to analyze xylem conductance at the stem-to-bud junc- tion, and relative water content and water potential of the bud itself, for buds situated in the distal third of one-year-old shoots. From dormancy to the pre-budburst stage, xylem conductance at the stem-to-bud junction increased or decreased or did not show consistent changes depending on the cultivar and the winter temperature treatment. Whatever the cultivar, there were no significant trends across dates for the effects of winter temperatures on bud water potential and relative water content. Water potential had negative values, between -4.35 and -2.24 MPa, across cultivars and winter temperature treatments without a consistent relationship with actual spring budburst frequency. These results suggested that lateral buds were hydraulically isolated from the parent stem during winter until a few days before budburst. We discussed that the temperature-related spring budburst was likely more related to a whole-shoot effect mediated by hormonal, hydraulics and/or sugar signaling, than to the individual bud water status during dormancy.

Effects of winter temperatures on gypsy moth egg masses in the Great Lakes region of the United States

In Massachusetts, low winter temperatures delay the onset of flowering in black birch (Betula lenta L.), but not in gray birch (B. populifolia Marsh.). During the winter of 2006, male inflorescences and twigs of black birch had higher water contents than those of gray birch, and the inflorescences of black birch experienced greater frost kill than those of gray birch. Vessels diameters were greater in black than in gray birch, a difference associated with a higher incidence of winter xylem embolism, as indicated by reduced xylem hydraulic conductance. In both species, recovery of hydraulic conductance in twigs that survived the winter coincided with the development of root pressure. Frost kill to male inflorescences or associated damage to plant tissues may account for the difference between species in the effect of winter temperature on the time of first flowering. In a comparison of 24 birch species, sensitivity of the first flowering date to temperature was also correlated with water content in male inflorescences.

The general positive effect of warmer winters on the abundance of small-sized zooplankton in the following spring and early summer has been reported from different parts of the Baltic Sea, but the mechanism of this link is not clear. Although causal links cannot be deduced with confidence from observational data, sufficiently detailed analyses can nevertheless provide insights to the potential mechanisms. We present an example of such an analysis, scrutinizing the effects of winter and spring hydroclimate on the abundance of small-sized dominant calanoid copepods (Eurytemora affinis and Acartia spp.), using data from 2080 zooplankton samples collected over 55 years (1957–2012) from a shallow coastal habitat (Pärnu Bay, Gulf of Riga) in the Baltic Sea. Our results indicated that the milder winters brought about higher abundances, and reduced seasonality of small-sized copepods, whereas ambient sea surface temperature (SST) mostly affected the relative abundance of adult stages. The sliding window correlation tests revealed temporal shifts in the effects of controlling variables: with the continuous increase in SST, the effect of winter temperature on the abundance of Acartia spp. weakened. In contrast, E. affinis was consistently affected by SST, but the effect of winter temperature was more pronounced during the period of on average colder winters.

Two pyrethroids, deltamethrin (D) and alphacypermethrin (AC), have been used as commercial products for tick control worldwide. However, the effects of sublethal doses of these compounds on various tick species and their developmental stages have not been fully explored yet, although such knowledge could contribute to a more effective application of both pyrethroids and simultaneous reduction of their costs and undesirable side effects, including the harmful impact on other organisms and environmental contamination. This study investigates the effect of sublethal concentrations of D and AC applied to engorged females on the fecundity, development of eggs and larvae, and the number of offspring in the Ixodes ricinus (L.) tick, which is the most important vector of tick-borne diseases of humans in Europe. After detachment from rabbit’s skin, fully engorged I. ricinus females were treated with 20 μl of pyrethroid solutions at five concentrations from 0.01562 to 0.25% and kept at 28 °C and 75% relative humidity. The impact of the pyrethroids on maturation and development of eggs as well as development of larvae was assessed based on parameters of the preoviposition and oviposition periods and the course of embryogenesis and egg hatch. The investigations have shown that both tested acaricides reduce the reproductive rate in I. ricinus females by inhibition of egg development and disturb embryonic development and larval hatch. Females did not lay eggs at concentrations higher than 0.0625% AC and 0.125% D. The lower concentrations of both pyrethroids disturbed or inhibited the embryogenesis and egg hatch in I. ricinus.

Frontiers Events is a rapidly growing calendar management system dedicated to the scheduling of academic events. This includes announcements and invitations, participant listings and search functionality, abstract handling and publication, related events and post-event exchanges. Whether an organizer or participant, make your event a Frontiers Event!

Lantern fly(Lycorma delicatula) is a major invasive pest that causes withering symptom of agricultural crops by sucking tree sap and sooty mold symptom by producing honeydew. This study was conducted to investigate the occurrence pattern of lantern fly in grape orchards in Gyeonggi area and the effect of winter temperature on L. delicatula egg survival during 2010 to 2013. In Gyeonggi areas, overwintered L. delicatula eggs began to hatch from early May and nymphs peaked in mid May. Adults emerged from late July and laid eggs until early November. The survival of L. delicatula eggs during overwintering was largely affected by winter temperatures. The relationship between the number of days below a threshold temperature (x) in January and the survival rate of overwintering L. delicatula eggs (y) was using linear regression model. The best model selected by the lowest RSS (residual sum of square) between predicted and actual survival was y = -1.0486 x + 94.496 (R 2 = 0.7067) with –11°C of threshold temperature. These results should be helpful to conduct L. delicatula management programs, since the results provided relivable prediction for the winter survival of L. delicatula eggs and the phenology of egg hatch in the spring.

<p>Objectives: to update the still quoted 25-year-old finding that a drop in winter temperature by 1 ºC below its mean is associated with 8,000 excess winter deaths in England and Wales.</p> <p>Methods: time-series regression of excess winter deaths between 1950/1 and 2011/12 on mean outside temperature, influenza and pneumonia deaths and a secular trend.</p> <p>Results: we find that a 1 ºC decrease in winter temperature below its mean is associated with 5,100 excess winter deaths. Excess winter mortality has been falling on average by approximately 580 deaths per year.</p> <p>Conclusions: Our revised estimates should supersede Curwen and Devis’s in academic and official publications. Notwithstanding there has been some mitigation in the effects of winter temperature on mortality over the last 60 years, excess winter mortality - given its magnitude- should still be a major source of public health concern in England and Wales.</p>

The effect of temperature on egg development of the apple sawfly Hoplocampa testudinea Klug was studied under controlled conditions. Based on a linear model describing the relationship between temperature and developmental rates a thermal threshold of 6.9 °C and a thermal constant of 85 day‐degrees were established. The experimental results were used to expand and parameterise an existing phenology model to include egg development and hatching of first instar larvae. The model thus became a valuable forecasting tool not only for adult emergence and the optimal monitoring period but also for egg hatch and the best timing of control measures against first instar larvae. The model was validated by comparing predictions with independent observations on egg‐laying and subsequent hatching of first instar larvae under semi‐field conditions.

The anthelmintic potential of methanol and aqueous extracts of G. senegalensis in vitro against the egg hatch and larval development of C. elegans Bristol N2 (susceptible to ivermectin) and C. elegans DA1316 (ivermectin resistant strain) was evaluated.. The eggs and larvae were incubated in aqueous and methanol extracts of the stem bark of G. senegalensis with the serial concentrations of 0.2, 0.4, 0.6, 0.8, 1.0 and 2.0 mg/ml. Methanol extracts of G. senegalensis which inhibited above 80% egg hatch in both strains of C. elegans were moderately effective whereas the aqueous extracts were ineffective. Both aqueous and methanol extracts which recorded up to 90% inhibition of larval development against C. elegans DA1316, as well as C. elegans Bristol N2, were considered effective. However, methanol extract proved more efficient than the aqueous extract against larval development as well as egg hatch in both strains of C. elegans (P 0.05). Therefore, extract from G. senegalensis can be use against ivermectin resistant parasitic nematodes. Guiera senegalensis may be used as a natural source of lead compounds to produce anthelmintic drugs. Cytotoxicity test should be conducted before the extracts are tested in vivo on the infected ruminant animals. Keywords: Activity, anthelminitic, Caenorhabditis elegans , egg hatch, G. senegalensis , larval development

Anopheles gambiae Giles sensu stricto (Diptera: Culicidae) egg development and its relation to environmental parameters is an understudied aspect of vector biology. Although several studies have illustrated the dramatic effects of temperature on egg development, egg hatching dynamics remain unclear. The objective of this study was to expose An. gambiae eggs to various temperatures for different lengths of time and determine the impact on egg development and hatching count. Batches of mosquito eggs (n = 30 eggs/replicate) were incubated under moist conditions at temperatures of 12, 22, 27, 33, and 42 degrees C for intervals of 1, 3, 7, and 10 days. After that, they were flooded with distilled water at 27 degrees C, and hatching counts were observed for up to 7 days. Mosquito eggs held at 22 and 27 degrees C had the highest overall mean hatching count. During early incubation periods, eggs held at 33 degrees C had hatching counts comparable to 22 and 27 degrees C, but counts decreased drastically during later incubation periods. Temperatures of 12 and 42 degrees C reduced mosquito egg viability, because few eggs hatched in these temperature regimes. Other experiments revealed that during early embryonic development, temperature had a major effect on the developing embryo, while later in embryonic development it had no dramatic effect. Microscopic observation of the An. gambiae embryo showed that extreme low and high temperatures affected the normal development of the embryo. A regression model was developed to describe the effect of incubation temperature and incubation period on egg hatching counts, which demonstrated that the optimum temperature for egg hatching ranges from 24 to 30 degrees C, irrespective of incubation period. The interaction between temperature and time period may have implications for dry-season survival and climate-based models of malaria risk.

IntroductionThe present trial aimed to investigate invitro anthelminthic activities of selected tropical tanniferous plant extract on egg hatchability and larval development inhibition of Haemonchus contortus in sheep. In view of that, three tropical tanniferous plants Rhus glutinosa, Syzygium guineensa and Albizia gumifera, were selected based on their relative high content of condensed tannins.MethodsIn this study, eggs were collected from artificially infected with H. contortus. Then the egg was directly subjected to invitro assay with these condensed tannin-enriched extracts using egg hatchability assay and inhibition of larval development assay.ResultsThe result showed that extracts from all three tropical tanniferous plants demonstrated statistically significant (P < 0.05) dosedependent inhibition of both egg hatchability and larval development. According to IC50 and IC90 values, the condensed tannin-enriched extracts inhibiting egg hatching and larval development most potently were Rhus glutinosa followed in descending order of activity by Syzygium guineensa and Albizia gumifera.DiscussionThe result of this study showed that these condensed tanninenriched extracts were effective in inhibiting egg hatchability as well as larval development. Therefore, condensed tannin might be recommended as one of the options for the control of H. contortus in sheep.