Wirkungen von Temperatur und Luftfeuchtigkeit auf die Embryonalentwicklung und das Eischlüpfen bei der SchildzeckeHyalomma marginatum Koch (Acari,Ixodidae)

Effect of temperature and relative humidity on embryonic development and egg hatch ofHyalomma marginatum Koch (Acari, Ixodidae) Effect of different temperatures (25, 30, 35, 40°C) and relative humidity (RH) levels (50, 75, 90%) on embryonic development and hatching ofHyalomma marginatum was investigated. The percentage of dead eggs and embryos, percentage of morphologically normal larvae, percentage of abnormally hatched larvae and percentage of larvae with morphological malformations were determined for each condition. Embryonic development and egg hatch proceeded at 25–35°C in all relative humidity levels tested. However 50% RH was unfavourable for these processes. The optimal conditions for larval development were found to be: temperature of 25–30°C and relative humidity of 75%. Under these conditions 72.7–87.8% of examined egg hatched into normal larvae.     

Temperature-dependent development of Sesamia nonagrioides

The effect of various constant temperatures on survival, development and adult longevity of Sesamia nonagrioides Lefébvre (Lepidoptera: Noctuidae) was studied under laboratory conditions. The following temperatures were tested: 14, 17, 21, 25 and 31 °C. The percentage of individuals that completed development at each temperature as well as the days needed for the emergence of the pupa and adult eclosion were measured. Adult longevity was estimated under the same conditions. Development time decreased significantly with increasing temperature within the range 14–25 °C. Survival was higher at medium temperatures (17–25 °C) in comparison with that at more extreme temperature regimens (14 and 31 °C). Egg and first larval instars were the stages where S. nonagrioides suffered the highest mortality levels at all temperatures. The highest survival was recorded with experimental individuals aging between the third and fifth larval instar. Thermal requirements of development (developmental thresholds, thermal constant, optimum temperature) of S. nonagrioides were estimated with application of linear and one nonlinear models (Logan I). Upper and lower developmental thresholds ranged between 31.2 and 36.2 and 7.0 and 10.3 °C, respectively. The optimum temperature for development (where maximum rate of development occurs) was estimated at between 28.1 and 30.3 °C. The thermal constant for total development was estimated at 1,000.0 degree-days. Adult longevity was also affected by temperature, as it was significantly reduced at higher temperatures (21–31 °C) compared to the lower ones (14 and 17 °C). This information would be useful in determining the critical temperatures which may affect the distribution of S. nonagrioides concerning potential climate change.     

Thermoperiodic effects on larval growth parameters of the Sesamia nonagrioides (Lepidoptera: Noctuidae)

The effect of five constant (10, 15, 20, 25 and 30°C) and the corresponding cycling (25:10, 27.5:12.5, 30:15, 32.5:17.5 and 35:20°C) temperatures at a photoperiod of 16:8 (L:D) h on the development and biometry (HCW, weight) of larva of Sesamia nonagrioides (Lef) Lepidoptera–Noctuidae were investigated. Larvae under both temperature treatments seemed to complete six instars. Final mean head capsule widths did not differ significantly between constant and cycling temperatures. Larval weights increased considerably through larval period under all temperature regimes. However, alternating temperatures were not shown to stimulate larval weight or head capsule widths compared with those of constant temperatures, although tended to result in shorter larval developmental periods. Results are discussed regarding development and seasonal biology of the species.     

Pupal diapause development and termination is driven by low temperature chilling in Bactrocera minax

Bactrocera minax is a major citrus pest in China, Bhutan, and India. It is univoltine and exhibits pupal diapause during winter. To better understand pupal diapause in this pest, we investigated pupal survival and pupal developmental duration under field and laboratory conditions. Specifically, we tested if pupal chilling was required for diapause development and termination. Nearly all mature larvae collected at the end of the citrus season entered pupal diapause. For pupae exposed in the field, natural chilling for less than 3 months resulted in more than 70 % mortality. However, exposure to winter conditions for 3 months or more both decreased pupal mortality and developmental duration when pupae were returned to the laboratory and held under constant temperature (25 °C). When pupae were gathered from the field in November and exposed to different chilling regimes in the laboratory, the chilling duration (30 vs 60 days) had significantly more impact on pupal survival than the specific chilling temperature (6, 8, 10, or 12 °C constant). However, both chilling duration and chilling temperature impacted on the pupal developmental duration, with longer chilling duration and higher temperatures decreasing pupal developmental duration. In conclusion, we demonstrated that pupal diapause development and termination in B. minax is strongly influenced by chilling conditions. Increasing cold exposure led to significantly and consistently faster adult eclosion and improved synchronization of adult emergence. This knowledge will help with the laboratory rearing of B. minax, an essential step in the long-term management of this pest.     

Using degree-day accumulations and host phenology for predicting larval emergence patterns of the olive psyllid, <Emphasis Type="Italic">Euphyllura phillyreae</Emphasis>

The olive psyllid, Euphyllura phillyreae Foerster is one of the most destructive pests on buds and flowers of olive tree (Olea europaea L.) in May when the olive growers cannot apply any insecticides against the pest. Temperature-dependent development of the psyllid was studied at constant temperatures ranged 16–26°C. A degree-day (DD) model was developed to predict the larval emergence using the weekly cumulative larval counts and daily mean temperatures. Linear regression analysis estimated a lower developmental threshold of 4.1 and 4.3°C and a thermal constant of 164.17 and 466.13 DD for development of egg and larva, respectively. The cumulative larval counts of E. phillyreae approximated by probit transformation were plotted against time, expressed as the sum of DD above 4.3°C, the starting date when the olive tree phenology was the period of flower cluster initiation. A linear model was used to describe the relationship of DDs and probit values of larval emergence patterns of E. phillyreae and predicted that 10, 50 and 95% emergence of the larvae required 235.81, 360.22 and 519.93 DD, respectively, with errors of 1–3 days compared to observed values. Based on biofix depends the development of olive tree phenology; the DD model can be used as a forecasting method for proper timing of insecticide applications against E. phillyreae larvae in olive groves.     

Temporal synchrony of Thaumetopoea processionea egg hatch and Quercus robur budburst

Field observations on egg hatch of Thaumetopoea processionea suggest that temporal asynchrony with Quercus robur budburst leads to starvation, retarded neonate development and mortality. However, T. processionea neonates are generally well adapted to variable between-tree and within-tree budburst phenology reflecting the species’ close bond to its host. They are able to withstand starvation periods of up to 3 weeks while searching extensively for suitable buds to feed on. Feeding and movements of young larvae frequently occur during daytime presumably taking advantage of higher day temperatures when night temperatures are below the species’ thermal threshold. Due to the specific adaptations, we assume precise temporal synchrony to play a minor role regarding its influences on T. processionea population dynamics. However, if hatching precedes budburst for more than 2–3 weeks, temporal asynchrony may become a significant mortality factor for the neonates particularly when other adverse events (e.g. unfavourable weather conditions) during that period are involved. Therefore, future studies should try to reveal further details of this interaction and focus on the impact of global warming on T. processionea—oak budburst synchronisation.     

Wirkungen zwischen Bacillus thuringiensis Berl. und Larven der Schlupfwespe Bracon brevicornis Wesm. in bzw. an den Raupen von Sesamia cretica Led. bei verschiedenen Temperaturen

Laboratory trials were undertaken to investigate the interactions which may occur when rearing the parasitoid,Bracon brevicornis on Sesamia cretica larvae after being injected with the pathogen,Bacillus thuringiensis under 5 constant temperatures. Bacillus-infected larvae ofS. cretica had detrimental effects on the parasitoid's progeny e. g. prolonged periods of both cocoon stage and total development at 20 or 25 °C; and decreased number of formed cocoons or produced adults at all tested temperatures. The most deleterious temperature for the parasitoid rearing under condition of the bacterial pathogen was 30 or 35 °C.     

Production of cuttings in response to stock plant temperature in the subtropical eucalypts, Corymbia citriodora and Eucalyptus dunnii

Propagation of subtropical eucalypts is often limited by low production of rooted cuttings in winter. This study tested whether changing the temperature of Corymbia citriodora and Eucalyptus dunnii stock plants from 28/23°C (day/night) to 18/13°C, 23/18°C or 33/28°C affected the production of cuttings by stock plants, the concentrations of Ca and other nutrients in cuttings, and the subsequent percentages of cuttings that formed roots. Optimal temperatures for shoot production were 33/28°C and 28/23°C, with lower temperatures reducing the number of harvested cuttings. Stock plant temperature regulated production of rooted cuttings, firstly by controlling shoot production and, secondly, by affecting the ensuing rooting percentage. Shoot production was the primary factor regulating rooted cutting production by C. citriodora, but both shoot production and root production were key determinants of rooted cutting production in E. dunnii. Effects of lower stock plant temperatures on rooting were not the result of reduced Ca concentration, but consistent relationships were found between adventitious root formation and B concentration. Average rooting percentages were low (1–15% for C. citriodora and 2–22% for E. dunnii) but rooted cutting production per stock plant (e.g. 25 for C. citriodora and 52 for E. dunnii over 14 weeks at 33/28°C) was sufficient to establish clonal field tests for plantation forestry.     

Temperature-dependent survival,development, and adult longevity of the koinobiont endoparasitoid <Emphasis Type="Italic">Venturia canescens</Emphasis> (Hymenoptera: Ichneumonidae) parasitizing <Emphasis Type="Italic">Plodia interpunctella</Emphasis> (Lepidoptera: Pyralidae)

The effect of various constant temperatures on survival, development, and adult longevity of Venturia canescens Gravenhorst (Hymenoptera: Ichneumonidae) parasitizing larvae of Plodia interpunctella Hübner (Lepidoptera: Pyralidae) was studied under laboratory conditions. The following temperatures were tested: 15, 17.5, 20, 22.5, 25, 27.5, 30, and 32.5°C. The percentage of parasitoids that completed development at each temperature as well as the days needed for the emergence of the parasitoid’s pupa and adult eclosion was measured. Adult longevity was estimated under the same conditions. Survival of V. canescens was significantly higher at 25 and 27.5°C compared to 17.5, 20, 30, and 32.5°C. No individual of V. canescens managed to complete development at 15°C. Overall, developmental time decreased significantly with increasing temperature within the range of 17.5–27.5°C. The lowest developmental time was observed at 27.5°C while the highest at 17.5°C. Upper and lower threshold temperatures for total development were estimated at 36.2 and 13.2°C, respectively. Optimum temperature for development and thermal constant were 30.6°C and 312.5 degree days, respectively. Adult longevity was also affected by temperature, as it was significantly reduced at higher temperatures compared to the lower ones. This information would be useful in determining the potential of using V. canescens as a biological agent in IPM programs, by optimizing mass rearing and release techniques of the parasitoid.     

Beziehungen zwischen dem Bakterium Serratia marcescens (Biz.) und der in den Raupen von Sesamia cretica. Led. (Lep., Tortricidae) sich entwickelnden Schlupfwespe Bracon brevicornis Wesm. (Hym., Braconidae)

Laboratory experiments were undertaken to study the interrelationships which may be detected when rearing the ectoparasitoid,Bracon brevicornis onSesamia cretica larvae after being injected with the bacterial pathogen,Serratia marcescens at five constant temperatures. Many effects detrimental to the parasitoid were found through rearing onSerratia-infected larvae ofSesamia e.g. decreased the deposited eggs especially at 35°C; reduced the formed cocoons and produced adults at all temperatures (15–35°C); and prolonged developmental, repriod especially at 20 or 25°C. Number of infected host larvae which allowed complete successful development for the parasitoid was significantly decreased especially at the extremes of temperatures.     

Determining suitability of thermal development models to estimate temperature parameters for embryonic development of <Emphasis Type="Italic">Sitona lepidus</Emphasis> Gyll. (Coleoptera: Curculionidae)

The clover root weevil, Sitona lepidus Gyll. is a pest of clovers (Trifolium spp.), particularly white clover (T. repens). Larva feeding severely impairs the capacity of white clover to fix atmospheric nitrogen, by attacking the nitrogen-fixing root nodules. Development of the egg stage was studied at six different constant temperatures ranging from 9 to 30°C to improve the basis for phenological forecasts. Development occurred over the entire range of temperatures, although hatching percentage at 30°C was only 24.4% compared to 90.1% at 28.5°C. Developmental time decreased with increase in temperature from 9 to 28.5°C but increased markedly at 30°C. At 28.5°C, the embryo development period was the shortest (10.35 days); whereas at 9°C, this parameter was the longest (55.08 days). Using linear regression, the lower threshold temperature was calculated 4.38°C and the thermal constant was 236.45 degree-days. The relationship between constant temperature and developmental rate was evaluated using nine models. The suitability of the models was evaluated based on eight indicators (R ², RSS, R _adj², AIC, BIC, AICC, W _j , and Z _i ). Of the nonlinear models, the Logan-6, Sharpe and DeMichele, and Lactin models were the most accurate at calculating t _opt of 27, 27.50, and 28°C, respectively. The results suggest that of the three models (Lactin, Briere, and Hilbert and Logan), that estimated critical temperatures, (t _min, t _opt, and t _max), Lactin gave the most suitable fit of data. This response of S. lepidus to temperature can be used for developing phonological models to predict the timing of egg hatch which are important for management programs targeting the weevil.     

Zur Biologie von Trogoderma variabile Ball. (Col. Dermestidae): Larvalentwicklung und Larvaldiapause

Larval development ofT. variabile under various environmental conditions is examined to estimate the potential damages in storehouses in Central Europe. Larvae develop between 21 and 37°C, lower temperatures considerably prolong the time of development: at 25° it lasts 48.3 days (♂ ♂) and 60.8 days (♀ ♀), at 30° 29.3 days (32.9 resp.), and at 35° 27.5 days (34.6 resp.). Female larvae on an average pupate after six larval instars, males after five. From this results the earlier pupation of the males. Isolated larvae do not pupate; they grow up to big and resistant dauerlarvae and possibly pass through a diapause of several years. Reared in groups larvae pupate promptly and diapause is terminated. Longevity, cold resistance and ability of starvation of dauerlarvae are examined. The results indicate that a development ofT. variabile in unheated rooms is possible. Because of the very slow development at lower temperatures economic important damages are unlikely.     

Factors influencing citrus fruit scarring caused by Pezothrips kellyanus

Kelly’s citrus thrips (KCT) Pezothrips kellyanus (Bagnall) (Thysanoptera: Thripidae) is a recently recorded cosmopolitan citrus pest, causing fruit scarring that results in downgrading of fruit. Due to the detrimental effects caused on fruits by KCT, we wanted to study some of the factors influencing fruit scarring. Specifically, the objectives were: (1) to determine the fruit development stage when citrus fruits are damaged by KCT and the population structure of KCT during this period, (2) to study the influence of temperature on intensity of damage, and finally, (3) to identify alternative host plants. KCT populations on flowers and fruitlets and alternate plant hosts were sampled in four citrus orchards from 2008 to 2010. The percentage of damaged fruits was also recorded. The exotic vine Araujia sericifera (Apocynaceae) was recorded as a new host for KCT. Thrips scarring started to increase at 350–650 degree-days (DD) above 10.2 °C, coinciding with a peak abundance of the second instar larval stages over all 3 years of the study. The maximum percentage of larval stages of KCT was observed in the 3 years at about 500 DD, a period which corresponds to the end of May or early June. Variation in the severity of fruit scarring appeared to be related to air temperature. Temperature likely affects the synchronisation between the peak in abundance of KCT larvae, and the period when fruitlets are susceptible to thrips damage. Temperature can also influence the survival and development of KCT populations in citrus and other host plants in the citrus agro-ecosystem.     

Untersuchungen zum Massenauftreten und Verhalten vonAlphitobius diaperinus Panz. (Coleoptera,Tenebrionidae) in Hühnermastbetrieben als Grundlage zur praxisgerechten Bekämpfung

A correlation betweenAlphitobius diaperinus generations and the rhythm of breeding the broilers and cleaning the poultry houses has been found. In the litter lots ofA. diaperinus larval instars can be observed. Approximately 13 days before the breeding of the broilers is completed the larvae start to leave the litter and search for hiding places for pupation in the walls of the buildings. The insects stay in these hiding places until the cleaning of the houses is finished. When the houses are prepared with new litter and higher temperatures for rearing the chickens are maintained, the beetles and larval instars leave the hiding places and continue their development, respectively laying eggs in the new litter. To prevent the insect emigration from the litter into the hiding places in the walls by temperature barriers the reactions of the adults and larvae to high temperature were tested. The results show that temperature barriers with more than 45°C only exceptionally can be overpassed by beetles and larvae.     

Efficacy of low temperatures for the control of all life stages of <Emphasis Type="Italic">Plodia interpunctella</Emphasis> and <Emphasis Type="Italic">Liposcelis bostrychophila</Emphasis>

The insecticidal effect of low temperatures for the control of all life stages of two stored-product insects, Plodia interpunctella and Liposcelis bostrychophila, was evaluated under laboratory conditions. The temperatures tested were 0, ??5, ??10 and ??15 °C, and, at these temperatures, the insects were exposed for 2, 4 and 8 h and also for 1, 2, 3 and 7 days. Regarding P. interpunctella, the most cold-tolerant life stage was larvae, given that 2 days of exposure were needed for complete (100%) mortality at ??10 °C. Moreover, all larvae were dead at ??15 °C even after 2 h of exposure. Eggs of P. interpunctella were susceptible to cold, as mortality was complete after 7, 1 day, 2 and 2 h at 0, ??5, ??10 and ??15 °C, respectively. L. bostrychophila was by far less susceptible than P. interpunctella. For this species, adults were still alive even after 7 days at ??10 °C, while complete mortality was achieved only after 1 day at ??15 °C. Eggs of L. bostrychophila were the most cold-tolerant life stage, as survival was observed even after 3 days at ??15 °C. The results of the present study provide the first data set on which all life stages of P. interpunctella and L. bostrychophila are evaluated for their susceptibility to cold treatments in a standardized series of exposures and temperatures. These results are expected to further encourage the “real world” application of cold treatments for the disinfestation of durable stored-products.     

Über den Einfluß der Temperatur auf die Entwicklung und Vermehrung des Bekreuzten Traubenwicklers,Lobesia botrana Den. et Schiff. (Lepid., Tortricidae)

By breeding grape moth,Lobesia botrana Den. et Schiff., in laboratory conditions the effect of constant temperatures on the growth and reproduction of the pest was investigated. On the basis of collected data the sum of effective temperatures for every stage of growth as well as the threshold temperature for the growth were calculated. For the embryonic development the temperatures are 74,0°C±2,3°C and 8,8°C; for the larval development in males 384,6°C±30,1°C and 7,3°C, in females 362,3°C±20,9°C and 9,4°C; for the chrysalis stage in males 162,1°C±23,5°C and 7,1°C, in females 151,5°C±24,0°C and 9,1°C. The sums of effective temperatures of the particular growth stages were completed by their quantil values (Q₃₀, Q₅₀, Q₇₅, Q₉₅). The threshold temperature for the life of moths was set up as 11,0°C in males and 12,8°C in females. The reproduction activity in the majority of females begins at temperatures above 15°C. The effect of the temperature on the actual fertility has proved to be significant. The optimal temperatures for the oviposition are within the range of 20,0°C–27,0°C. The relation between the actual fertility and temperature is at these temperatures determined by the regression line equation Y=?5,75·X+293. Temperatures below or above the limits of this interval are less favourable for the oviposition because they lead to a decreasing of actual fertility. The limit temperature (15°C) of reproduction activity in the majority of females is considered to be the lowest extreme temperature for the oviposition.     

Effects of temperature on the growth of a Japanese willow (Salix gilgiana Seemen)

The effects of temperature on the growth characteristics of a Japanese willow (Salix gilgiana Seemen) were studied with respect to dry matter production, wood anatomy and the net photosynthetic rates of leaves. Clonal materials were grown in natural-light rooms (phytotrons) at 30°C/25°C, at 25°C/20°C or at 20°C/15°C (day/night: 12 h/12 h), respectively. The elongation rate of shoots from the beginning of June to the end of July was approximately 22 cm per week under the three different sets of conditions. The shoots reached approximately 3 m in height after 4 months of growth. Total dry matter production and dry weights of stems did not differ very much among the three sets of temperature conditions after 9 months of growth. The dry weight of leaves increased at high temperatures while that of roots decreased. The number of vessels increased significantly at 30°C/25°C and 25°C/20°C, whereas the diameters of vessels and fibers, and the double wall thickness of fibers did not vary markedly under all three temperature regimes. The net photosynthetic rate and the respiration rate in mature leaves were highest at 30°C/25°C, and both activities increased with increases in growth temperature. The increase in the photosynthetic rate was much smaller than that in the respiration rate. Individual plants had been completely adapted to the respective growth temperatures, as judged from the decrease in the photosynthetic rate after the transfer to different temperatures. Part of this work was reported at the 102nd Annual Meeting of the Japanese Forestry Society (Nagoya, Japan, 1991). This work was supported by Grants-in-Aid (Integrated Research Program for Effective Use of Biological Activities to Create New Demand) from the Ministry of Agriculture, forestry and Fisheries of Japan (BRP 97-IV-B-10).     

Threshold temperatures and degree-day estimates for development of post-dormancy larvae of <Emphasis Type="Italic">Monochamus galloprovincialis</Emphasis> (Coleoptera: Cerambycidae)

Developmental thresholds and thermal requirements for development of post-dormancy larvae of Monochamus galloprovincialis (Olivier) (Cerambycidae; Monochamini) were studied at ten constant temperatures ranging from 7 to 35°C. The relationship between temperature and development duration in days was linear between 15 and 30°C (r ²  = 0.98). The lower threshold for development was determined to be 12.2 ± 0.8°C and an average of 822 degree-days (DD) above that value was required for 50% adult emergence under laboratory conditions. The rate of larval development decreased above 30°C and the lethal upper threshold was between 32 and 35°C. Degree-day rate summation was initiated in the first of March and model predictions were validated with records of field emergence for the years 2001 to 2004. The modified sine wave predicted median emergence with an average error of 3.8 days from emergences in the field and a zero-day difference for two of the years. Model predictions were always within 10% of actual observed emergences. Predictions for early emergences (cumulative percentiles 1 and 10) were less accurate than predictions for median and late emergencies. The results suggest that a simple linear method driven by air temperatures can predict the emergence of M. galloprovincialis with sufficient accuracy to improve the pest management programmes currently implemented on the pine wilt disease affected zone in Portugal.     

Developmental threshold temperature and effective accumulative temperature of pupae and eggs of <Emphasis Type="Italic">Holcocerus hippophaecolus</Emphasis>

In order to understand the occurrence and the developmental regularity of seabuckthorn carpenterworm (Holcocerus hippophaecolus) and predict its population density, the developmental threshold temperature (C) and effective accumulative temperature (K) of the carpenterworm pupae and eggs were analyzed under the conditions of constant and variable temperatures. The results show that the values of C and K of the carpenterworm pupae are (12.1±0.2) °C and (295.2±4.1) day-degrees at constant temperatures, and (15.5±0.4) °C and (202.4±13.1) day-degrees at variable temperatures. However, the values of C and K of the eggs at variable temperatures are (16.7±0.8) °C and (101.5±12.6) day-degrees. The differences of developmental threshold and effective accumulative temperature under the conditions of constant and variable temperatures of the carpenterworm pupae accord with the developmental regularity of most insects in nature. By comparing five different constant temperatures, the conclusion is that the optimum developmental temperature of the pupae is 21 °C when both the pupation of the mature larvae and the eclosion of the pupae are very accordant. Moreover, the percentage of eclosion is over 90%. The average developmental durations of the carpenterworm pupae and eggs are 31 and 16 d at variable temperatures.     

Frost hardiness gradients in shoots and roots of picea mariana seedlings

Frost hardiness of tissues along the length of the stem and the root was investigated in first‐year black spruce (Picea mariana (Mill.) B.S.P.) seedlings. Frost hardiness of 1 cm long stem and root segments was evaluated based on Index of Injury, calculated from post‐freezing electrolyte leakage. Frost hardiness was tested approximately weekly beginning seven weeks after seedlings were transferred from an 18 to a 10 h photoperiod, both at day/night temperatures of 26°C/16°C. Trees were transferred to temperatures of 10°C day and 5°C night at a 10 h photoperiod after a further 18 days. Frost hardiness was greater at the terminal bud and least at the root tips. Although shoots were generally more frost hardy than roots, differences in hardiness along the stem and root axes were gradual, rather than abruptly differing at the shoot‐root interface. All tissues, including root tips, increased in frost hardiness after conditioning for 18 days under short photoperiods (10 h) and warm temperatures (26?C/16°C, day/night). Under cold temperatures (10°C/5°C, day/night) all tissues, excepting the root tips, tolerated — 16°C with little subsequent electrolyte leakage.