Search

Many animals show altitudinal clines in size, shape and body colour. Increases in body size and reduction in the length of body appendices in colder habitats are usually attributed to improved heat conservation at lower surface-to-volume ratios (known as Bergmann’s and Allen’s rule, respectively). However, the patterns are more variable and sometimes reversed in small ectotherms that are affected by shortened growing seasons. Altitude can also affect colouration. The thermal melanism hypothesis predicts darker colours under cooler conditions because of a thermoregulatory advantage. Darker colours may also be favoured at high altitudes for reasons of UV protection or habitat-dependent crypsis. We studied altitudinal variation in morphology and colour in the colour-polymorphic meadow grasshopper Pseudochorthippus parallelus based on 563 individuals from 17 populations sampled between 450 and 2,500 m asl. Pronotum length did not change with altitude, while postfemur length decreased significantly in both sexes. Tegmen (forewing) length decreased in males, but not in females. The results indicate that while body size, as best quantified by pronotum length, was remarkably constant, extended appendices were reduced at high altitudes. The pattern thus follows Allen’s rule, but neither Bergmann’s nor converse Bergmann’s rule. These results indicate that inference of converse Bergmann’s rule based on measurements from appendices should be treated with some caution. Colour morph ratios showed significant changes in both sexes from lowland populations dominated by green individuals to high-altitude populations dominated by brown ones. The increase of brown morphs was particularly steep between 1,500 and 2,000 m asl. The results suggest shared control of colour in males and females and local adaptation along the altitudinal gradient following the predictions of the thermal melanism hypothesis. Interestingly, both patterns, the reduction of body appendices and the higher frequency of brown individuals, may be explained by a need for efficient thermoregulation under high-altitude conditions. [ABSTRACT FROM AUTHOR]

Bush crickets are a model group for testing hypotheses in sexual selection, but much of the information is based on laboratory observations on wingless or short-winged species, which may restrict their generality. Here we describe aspects of the mating behaviour of the long-winged European bush cricket Phaneroptera falcata (Poda, 1761). Both in the laboratory and the field, diel calling followed a normal, though slightly left-skewed distribution, peaking about three hours after sunset or lights-off. Under bright greenhouse conditions, when the light was suddenly switched off, calling occurred only after the onset of darkness. Decreasing light intensity may trigger the start of calling activity. In the field, calling decreased from midnight onwards, which may be related to a decrease in temperature. The sequence of events during copulation was identical in the laboratory and the field. However, in two of 14 copulations documented in the field, a pre-copulatory behaviour was observed that resembled the putative removal and ingestion of rival sperm. Previous suggestions that P. falcata (Poda) is monogamous are rejected on the basis of both laboratory and field results. In the laboratory males and females mated every 2.3 and 3.6 days, respectively. We introduce a simple way to calculate the average frequency of mating in the field, based on the observation that at any one time 3% of all the individuals are recorded mating and copulation lasts 15 min. We estimate that on average P. falcata (Poda) mates once per day. More generally, our results show it is important for evolutionary conclusions to measure behaviourial data in the field. [ABSTRACT FROM AUTHOR]

The potential for pheromone-based mating disruption of the Brassica pest Contarinia nasturtii was tested, both in small-scale plots with Brussels sprouts and in commercial-scale fields with either broccoli or cauliflower. Experiments in the small-scale plots used laboratory-reared insects released into a previously uninfested area, whereas large-scale experiments used a high natural population of C. nasturtii. Effectiveness of mating disruption was evaluated by the reduction of male captures in pheromone traps, and by reduction of crop damage caused by C. nasturtii. Dental cotton rolls (small-scale experiment) and polyethylene caps (large-scale experiment), containing 50 μg (2 S, 9S)-diacetoxyundecane, 100 μg (2 S,10 S)-diacetoxyundecane, and 1 μg (2 S)-acetoxyundecane, spaced 2 m apart, served as dispensers in the test plots. In both experiments, mean catches of C. nasturtii males in pheromone traps were reduced to near zero in treated plots, with control plots averaging 71 males/trap. In the large-scale experiments, no males were caught in pheromone traps over a period of 41 days after mating disruption was applied; one male was caught from days 42-60. In the small-scale trials, crop damage was reduced by 59 %, compared to the untreated control plot. In the large-scale experiments, damage was reduced on average by 91 %. This study shows successful field application of the mating disruption technique for control of a member of the dipteran family Cecidomyiidae, and demonstrates that pheromone-based mating disruption has potential for management of C. nasturtii populations. [ABSTRACT FROM AUTHOR]

The pupal parasitoid Pimpla turionellae (L.) uses self-produced vibrations transmitted on the plant substrate, so-called vibrational sounding, to locate immobile concealed pupal hosts. The wasps are able to use vibrational sounding reliably over a broad range of ambient temperatures and even show an increased signal frequency and intensity at low temperatures. The present study investigates how control of body temperature in the wasps by endothermic mechanisms may facilitate host location under changing thermal environments. Insect body temperature is measured with real-time IR thermography on plant-stem models at temperature treatments of 10, 18, 26 and 30 °C, whereas behaviour is recorded with respect to vibrational host location. The results reveal a low-level endothermy that likely interferes with vibrational sound production because it occurs only in nonsearching females. At the lowest temperature of 10 °C, the thoracic temperature is 1.15 °C warmer than the ambient surface temperature whereas, at the high temperatures of 26 and 30 ° C, the wasps cool down their thorax by 0.29 and 0.47 °C, respectively, and their head by 0.45 and 0.61 °C below ambient surface temperature. By contrast, regardless of ambient temperature, searching females always have a slightly elevated body temperature of at most 0.30 °C above the ambient surface temperature. Behavioural observations indicate that searching females interrupt host location more frequently at suboptimal temperatures, presumably due to the requirements of thermoregulation. It is assumed that both mechanisms, producing vibrations for host location and low-level endothermy, are located in the thorax. Endothermy by thoracic muscle work probably disturbs signal structure of vibrational sounding, so the processes cannot be used at the same time. [ABSTRACT FROM AUTHOR]

Certain ichneumonid parasitoids (Hymenoptera) use self-produced vibrations transmitted on plant substrate, so-called vibrational sounding, to locate their immobile concealed pupal hosts. An ambient temperature dependency with higher frequencies and intensities at higher temperatures is postulated because signals are of myogenic origin. Here, temperature influence on vibratory signals is analysed in the temperate parasitoid Pimpla turionellae under different thermal conditions using plant-stem models to elicit host-searching behaviour. Signals are measured with laser Doppler vibrometry and analysed for time parameters and frequency components applying fast-Fourier transformations. The results reveal an unexpected effect of ambient temperature on signals produced by the female wasps. Although average values of time parameters (pulse trains, pulse train periods, inter pulse duration) are unchanged by ambient temperature, the frequency parameters show an inverse thermal effect. Within the temperature range tested (8–26 °C), decreasing temperature leads to significantly higher frequency and intensity of the self-produced vibrations in the temperate species. This inverse thermal effect may be explained by a temperature-coupled signal production in the frequency domain to compensate negative low-temperature effects on the mechanoreceptors by increased muscle activity. The option of heterothermy to produce signals reliably during vibrational sounding under low temperature is also discussed. [ABSTRACT FROM AUTHOR]

Parasitoid host location in nature is facilitated by simultaneously using different information sources. How multisensory orientation on the same spatial scale is influenced by environmental conditions is however poorly understood. Here we test whether changes in reliability of cues can cause parasitoids to alter multisensory orientation and to switch to cues that are more reliable under extreme temperatures. In the ichneumonid wasp Pimpla turionellae, multisensory use of thermally insensitive vision and thermally sensitive mechanosensory host location by vibrational sounding (echolocation on solid substrate) was investigated with choice experiments on plant-stem models under optimum temperature (18°C), at high- (28°C) and low-temperature limits (8°C) of vibrational sounding. Temperature affected relative importance of vibrational sounding whereas visual orientation did not vary. At 18°C, parasitoids used visual and vibrational cues with comparable relative importance. At 8 and 28°C, the role of vibrational sounding in multisensory orientation was significantly reduced in line with decreased reliability. Wasps nearly exclusively chose visual cues at 8°C. The parasitoids switch between cues and sensory systems depending on temperature. As overall precision of ovipositor insertions was not affected by temperature, the parasitoids fully compensate the loss of one cue provided another reliable cue is available on the same spatial scale. [ABSTRACT FROM AUTHOR]

Abstract: This study used an explorative, individual-based model to evaluate the influences of (1) plant architecture, i.e. dwarf versus standard trees, (2) the use of hail nets, and (3) insect behaviour on the phenology of the codling moth, Cydia pomonella (Lepidoptera: Tortricidae), a major pest in apple orchards worldwide. Body temperatures of the different codling moth stages were approximated by microhabitat temperatures, behavioural response to temperature, and biophysically modelled temperature increments due to absorption of solar radiation. Results indicate a significant influence of habitat parameters on the phenology of the codling moth. Under the simulated conditions, adults appeared up to 6 days earlier in dwarf trees than in standard trees, and up to 5 days later in trees covered with hail nets than in trees without them. In contrast, thermoregulation behaviour, which is documented for the larval and adult stages, appeared to be of relatively low influence on the insect''s overall phenology. Model validation using reported pheromone trap catches of male moths agreed with the simulated appearance dates of adults of the overwintered generation. Simulated and observed appearance dates did not deviate when habitat temperature was used, but deviated considerably when standard air temperature was used as driving variable. Considering habitat and behaviour will help to improve current phenology models for the codling moth. [Copyright &y& Elsevier]

Several parasitic wasps of the Pimplinae (Ichneumonidae) use self-produced vibrations transmitted through plant substrate to locate their concealed immobile hosts (lepidopteran pupae) by reflected signals. This mechanosensory mechanism of host location, called vibrational sounding, depends on the physical characteristics of the plant substrate and the wasp’s body and is postulated to depend on ambient temperature. Adaptations of two parasitoid species to thermal conditions of their habitats and the influence of temperature on the trophic interaction during host location are investigated in the tropical Xanthopimpla stemmator (Thunberg) and compared with the temperate Pimpla turionellae (L.). Plant-stem models with hidden host mimics are offered to individual wasps under defined temperature treatments and scored for the number and location of ovipositor insertions. Significant effects of temperature are found on host-location activity and its success. The tropical species possesses an optimum temperature range for vibrational sounding between 26 and 32 °C, whereas the performance decreases both at low and high temperatures. The temperate species reveals substantial differences with respect to performance at the same thermal conditions. With increasing temperature, P. turionellae shows a reduced response to the host mimic, reduced numbers of ovipositor insertions, and decreased precision of mechanosensory host location. In the tropical X. stemmator, the female wasps are able to locate their host with high precision over a broad range of ambient temperatures, which suggests endothermic thermoregulation during vibrational sounding. Environmental physiology may therefore play a key role in adaptation of the host location mechanism to climatic conditions of the species’ origin. [ABSTRACT FROM AUTHOR]

Plant architecture of apple trees in commercial orchards was rapidly changed from traditional tall trees to dwarf trees to optimize yield and fruit quality. Additionally, hail nets are widely used to prevent yield loss by hail. These changes are expected to considerably influence the orchard microclimate and thus the developmental rates of pest insects in apple. However, these relationships have not yet been fully elucidated. The present study was conducted over the seasonal cycle to investigate the influence of plant architecture and hail nets on the habitat temperatures of the codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), in apple, Malus domestica Borkh. (Rosaceae). Within the canopies, leaf area index (LAI) and global site factor (GSF) were quantified using hemispherical photography. Temperature was analysed for the main habitats of the different codling moth stages, i.e., air within the canopy, bark of tree stems, and apple fruit. In dwarf trees, LAI was lower, leading to a higher GSF than in tall trees. Hail nets did not influence LAI and GSF. Results for dwarf trees compare as follows with those for tall trees: Average air temperatures within the canopy were 0.7 °C higher during daytime, whereas 0.4 °C lower at night. Mean surface temperatures of bark were 0.9 °C higher on sunny and 0.4 °C on overcast days. Mean surface temperatures of apple fruits were 1.8–2.7 °C higher on sunny days, but 0.6 °C cooler on overcast days. The effect of hail nets was confined to a reduction of the air temperature within the canopy by approximately 0.2–0.8 °C. Bark and apple surface temperatures were not significantly affected. Based on the temperature differences in the habitats considered, the calculated development of the codling moth in dwarf trees was on average 3 days faster than in tall trees. The calculations imply a negligible effect of hail nets on codling moth development. [ABSTRACT FROM AUTHOR]

The thermoregulation behaviour of the adult codling moth, Cydia pomonella, is investigated in the laboratory using temperature gradient experiments. Unmated males and females are tested at dawn when moths typically move to resting sites. Mated females are tested during oviposition over a complete diurnal cycle. Temperature strongly affects microhabitat selection in adult moths. Unmated males and females prefer to rest at the low-temperature ends of temperature gradients between 15 and 32 °C. Relative humidity does not influence the thermal response in unmated females, whereas males show a less distinct temperature selection under high humidity. By contrast to unmated moths, ovipositing females prove to be highly thermophilous (i.e. they deposit the highest proportions of their eggs in the zones of highest temperatures of gradients between 15 and 36 °C). This striking discrepancy in thermal response of females between their premating and oviposition period is likely to reflect an adaptation to different selection pressures from the thermal environment. Unmated moths may benefit from low temperatures by a longer lifespan and crypsis within the tree canopy, whereas the choice of warmer oviposition sites by mated females will favour a faster development of eggs. [ABSTRACT FROM AUTHOR]

The selection of habitats with favourable temperature by the apple blossom weevilAnthonomus pomorum(L.) is investigated in a temperature gradient arena with a range of approximately 0–15 °C. Single female and male weevils are tested in the arena 2, 4 and 6 days after termination of diapause, during photophase and during scotophase. During photophase, weevils of both sexes choose the warmest part of the temperature gradient arena, irrespective of the time elapsed after diapause. During scotophase, high temperature is favoured by male weevils, as well as by females 2 and 4 days after diapause. However, 6 days after termination of diapause, females show no thermal preference in the temperature gradient arena during scotophase, indicating that thermal choice of femaleA. pomorumin the scotophase changes with time after the termination of diapause. The results suggest that both sexes benefit from thermoregulation by habitat choice during photophase when the weevils are flight active and colonize apple trees. [ABSTRACT FROM AUTHOR]

The thermoregulation behaviour of the codling moth,Cydia pomonella, is investigated in temperature gradient experiments with larvae feeding within apples, and with mature larvae searching for cocooning sites. Feeding larvae appear to prefer the apple hemisphere with a higher temperature (i.e. they build larger cavities in the radiated, warmer part of the fruit). The proportion of larval cavities in the warmer hemisphere is positively related to increasing apple temperature on that side, as well as to the temperature difference between the warm and the cool fruit hemisphere. The mechanism in feeding larvae can be termed as cryptic basking because, during microhabitat selection, the caterpillars exploit temperature differences that are caused explicitly by incident solar radiation. Fifth-instar larvae in search of cocooning sites show no temperature preference within the large gradient offered (9–29 °C), with no difference between males and females. During larval development, the insect changes its thermoregulation behaviour in response to a possible shift in benefits of an elevated body temperature with respect to environmental conditions. Both the thermoregulation behaviour and such a shift of behavioural response should be respected when simulating body temperatures of the species. [ABSTRACT FROM AUTHOR]

The significance of the apple blossom weevil, Anthonomus pomorum L. (Coleoptera: Curculionidae), as a potential threat to apple, Malus domestica Borkh., has increased over the past two decades in many regions of Europe. The apple blossom weevil immigrates into orchards and colonises apple trees in early spring. Females deposit single eggs into closed blossom buds, which leads to capped blossoms. This study was designed to test the suitability of transparent shelter traps for the surveillance of colonisation under different population pressures, and to assess the quantitative relationship between number of weevils caught and: (1) absolute injury, expressed as number of infested buds, as well as (2) relative injury, expressed as a percentage of infested buds relative to all buds on the tree. The findings with the new shelter traps were contrasted to results from limb jarring. Numbers of weevils caught with the transparent shelter trap were positively correlated with absolute injury, as well as with relative injury across the five study sites, whereas weevil counts with limb jarring were not correlated with absolute injury, but only with relative injury. Our data validate the transparent shelter trap as a method for accurately monitoring the course of spring colonisation of A. pomorum and demonstrate its potential for predicting injury by the weevils to blossom buds. In contrast, the significance of limb jarring for monitoring both the time course of colonisation and subsequent injury is limited. The significant linear relationship between the number of weevils caught in shelter traps and the relative injury allows for predictions of potential damage before oviposition takes place, i.e., early enough for an insecticide application where necessary. [ABSTRACT FROM AUTHOR]

Investigates the response of Pimpla turionellae towards plant stem models with shades of gray on a white substrate. Demonstration that the absolute amount of achromatic contrast is the critical parameter for visual host location; Increased ovipositor insertion activity due to increased contrast.

Based on the model system of Brussels sprouts [ Brassica oleracea var. gemmifera (Brassicaceae)], the herbivore cabbage white caterpillar, Pieris brassicae (L.) (Lepidoptera: Pieridae), and the parasitoid wasp, Cotesia glomerata (L.) (Hymenoptera: Braconidae), the influence of plant damage type, and damage duration were assessed on plant volatile emission and subsequent recruitment of natural antagonists of the herbivore. Plants were damaged by three methods for a period of either 3 or 8 h: herbivore damage (HD), progressive mechanical damage, and final mechanical damage inflicted in a single event. Wind-tunnel bioassays evaluated whether the mode of damage affected female parasitoid oriented flight. After both periods of damage, all treatments were highly significantly preferred by naïve C. glomerata to undamaged control plants. After 3 h, herbivore-damaged plants were significantly preferred to plants with final damage (FD). Most remarkably, following 8-h damage, the parasitoid preferred both herbivore-damaged and progressively damaged plants to plants with FD and did not significantly discriminate between herbivore and progressively damaged plants, thus indicating a similarity in plant response to herbivore and progressive mechanical damage. In addition to wind-tunnel bioassays, emitted plant volatiles were collected and analysed by thermal desorption gas chromatography/mass spectrometry, following 3 and 8 h of damage in order to correlate volatiles released from different damage types with the attraction of the parasitoid. Differences in volatile profiles from all damage types were similar following both 3 and 8 h of damage, with only ( Z)-3-hexenyl acetate found to be emitted in significantly higher quantities by final mechanical damage compared with HD after 3 h. In conclusion, the plant's response to progressive mechanical damage was more similar to HD than final mechanical damage deployed at a single point in time, irrespective of damage duration, and C. glomerata did not significantly discriminate between progressive damage and HD. [ABSTRACT FROM AUTHOR]

In bush-crickets, males produce a calling song to announce their presence to females. Females ready to mate respond either by a phonotactic approach or signal their presence acoustically by establishing a kind of duet. This duetting behaviour is typical of phaneropterid bush-crickets, of which many species in Europe are flightless. In the long-winged genus Phaneroptera, the females also respond acoustically to the male calling song, which is quite similar in the three west European species in this genus. After acoustical contact, however, the behaviour of males and females of the three species differ markedly. In P. nana, males and females engage in a duet in which the female responds to each syllable of the male song (and he approaches her). In P. falcata, the female only responds to certain elements of the male song that are produced at long intervals. However, after her response the male does not change its song or its position, but often increases its singing activity (and the female approaches him). In P. sparsa the female only responds to particular, very complicated and soft elements of the male song, which are typically repeated at intervals of several to many minutes. After hearing the response, the male drastically changes its song by producing only the soft elements. These parts of the song contain syllables with a unique spectral composition and others that may threaten eavesdropping rivals. In this species both sexes probably move towards each other during mate localization. At present, we can only speculate about the adaptive nature of the different strategies. [ABSTRACT FROM AUTHOR]

In bush-crickets, males produce a calling song to announce their presence to females. Females ready to mate respond either by a phonotactic approach or signal their presence acoustically by establishing a kind of duet. This duetting behaviour is typical of phaneropterid bush-crickets, of which many species in Europe are flightless. In the long-winged genus Phaneroptera, the females also respond acoustically to the male calling song, which is quite similar in the three west European species in this genus. After acoustical contact, however, the behaviour of males and females of the three species differ markedly. In P. nana, males and females engage in a duet in which the female responds to each syllable of the male song (and he approaches her). In P. falcata, the female only responds to certain elements of the male song that are produced at long intervals. However, after her response the male does not change its song or its position, but often increases its singing activity (and the female approaches him). In P. sparsa the female only responds to particular, very complicated and soft elements of the male song, which are typically repeated at intervals of several to many minutes. After hearing the response, the male drastically changes its song by producing only the soft elements. These parts of the song contain syllables with a unique spectral composition and others that may threaten eavesdropping rivals. In this species both sexes probably move towards each other during mate localization. At present, we can only speculate about the adaptive nature of the different strategies. [ABSTRACT FROM AUTHOR]

Highlights: [•] High levels of fruit phenolics enhance agroecosystem resilience to invasive pests. [ • ] Locally-grown apple cultivars were resistant to Anastrepha ludens attack. [•] Resistant cultivars could act as population sinks for invading or expanding pests. [•] Locally-grown apple cultivars should be kept as gene reservoirs for plant breeding. [ABSTRACT FROM AUTHOR]

Abstract: Crop protection in general and apple crop protection in particular often rely on pesticides, although several alternative pest management measures are available. In this context European agricultural policy requires the implementation of Integrated Pest Management (IPM) by 2014. Within IPM, more than one strategy can be practiced but selecting the most sustainable strategy is difficult because it requires simultaneous assessment of multiple environmental and economic aspects or attributes. Here, we introduce the SustainOS methodology for sustainability assessment of orchard systems, and we evaluate its usefulness in a case study involving four crop protection strategies in apple orchards of five European regions. SustainOS is an iterative, multi-attribute approach for defining and rating the sustainability of crop protection strategies in comparative studies. It consists of a transparent system-description tool including context, target, and crop protection parameters. The parameters are used as input data for life cycle assessment, environmental risk assessment, and full-cost calculations. The various results from these quantitative assessments are used to generate a multi-attribute rating with respect to ecological and economic sustainability. We demonstrate how the quantitative results can be translated into rating classes. By applying the SustainOS methodology, we show that the ecological sustainability for all five regions can potentially be improved by implementing alternative crop protection measures currently available. We also report that, by increasing yield, yield stability, and fruit quality, implementation of IPM can improve the economic situation of apple growers. Because of its transparency, SustainOS facilitated the collaborative development and comparison of crop protection strategies for sustainable orchard systems by an international network of agronomists, economists, and environmental scientists. [Copyright &y& Elsevier]

Monthly weather forecasts (MOFCs) were shown to have skill in extratropical continental regions for lead times up to 3 weeks, in particular for temperature and if weekly averaged. This skill could be exploited in practical applications for implementations exhibiting some degree of memory or inertia toward meteorological drivers, potentially even for longer lead times. Many agricultural applications fall into these categories because of the temperature-dependent development of biological organisms, allowing simulations that are based on temperature sums. Most such agricultural models require local weather information at daily or even hourly temporal resolution, however, preventing direct use of the spatially and temporally aggregated information of MOFCs, which may furthermore be subject to significant biases. By the example of forecasting the timing of life-phase occurrences of the codling moth (Cydia pomonella), which is a major insect pest in apple orchards worldwide, the authors investigate the application of downscaled weekly temperature anomalies of MOFCs for use in an impact model requiring hourly input. The downscaling and postprocessing included the use of a daily weather generator and a resampling procedure for creating hourly weather series and the application of a recalibration technique to correct for the original underconfidence of the forecast occurrences of codling moth life phases. Results show a clear skill improvement of up to 3 days in root-mean-square error over the full forecast range when incorporating MOFCs as compared with deterministic benchmark forecasts using climatological information for predicting the timing of codling moth life phases. [ABSTRACT FROM AUTHOR]

Global warming will lead to earlier beginnings and prolongation of growing seasons in temperate regions and will have pronounced effects on phenology and life-history adaptation in many species. These changes were not easy to simulate for actual phenologies because of the rudimentary temporal (season) and spatial (regional) resolution of climate model projections. We investigate the effect of climate change on the regional incidence of a pest insect with nearly worldwide distribution and very high potential for adaptation to season length and temperature - the Codling Moth, Cydia pomonella. Seasonal and regional climate change signals were downscaled to the hourly temporal scale of a pest phenology model and the spatial scale of pest habitats using a stochastic weather generator operating at daily scale in combination with a resampling approach for simulation of hourly weather data. Under future conditions of increased temperatures (2045-2074), the present risk of below 20% for a pronounced second generation (peak larval emergence) in Switzerland will increase to 70-100%. The risk of an additional third generation will increase from presently 0-2% to 100%. We identified a significant two-week shift to earlier dates in phenological stages, such as overwintering adult flight. The relative extent (magnitude) of first generation pupae and all later stages will significantly increase. The presence of first generation pupae and later stages will be prolonged. A significant decrease in the length of overlap of first and second generation larval emergence was identified. Such shifts in phenology may induce changes in life-history traits regulating the life cycle. An accordingly lifehistory adaptation in photoperiodic diapause induction to shorter day-length is expected and would thereby even more increase the risk of an additional generation. With respect to Codling Moth management, the shifts in phenology and voltinism projected here will require adaptations of plant protection strategies to maintain their sustainability. [ABSTRACT FROM AUTHOR]

The walnut husk fly, Rhagoletis completa Cresson (Diptera: Tephritidae), has recently invaded Switzerland, Austria, Germany, and France, probably crossing the alpine divide after its initial introduction into Italy. Here, the susceptibility of 36 walnut [ Juglans regia L. (Juglandaceae)] cultivars to attack by R. completa was studied in an experimental orchard in Switzerland. Walnut cultivars differed significantly in infestation rates; cultivars that produced large, heavy fruit harboured significantly more larvae than cultivars that produced smaller fruit. Pupal weight was significantly influenced by cultivar, but not by any of the physical properties that we measured. For individual fruit within a cultivar, pupal weight was weakly related to fruit weight and infestation level. Adult longevity was correlated with pupal weight and appeared to be favoured in flies that developed in large-fruit cultivars. The longevities of adults recovered from different cultivars differed significantly. The shortest longevity was recorded for flies recovered from Geisenheim 1049 (39.2 ± 2.80 days) and the longest for flies recovered from Sheinovo (68.8 ± 21.75 days). Differences in diapause length were also highly significant and varied between 167 ± 5.1 (Esterhazy III) and 257.4 ± 8.21 days (Mayette). These results suggest that (1) across and within cultivars, walnut husk flies prefer to infest (i.e., they develop better in) large, heavy fruit, and (2) offspring that develop in large fruit are likely to accrue fitness advantages over the offspring of females using smaller fruit. Our results provide the basis for subsequent studies on resource defence by males, as they enable a prediction of which type of fruit males should defend more vigorously. [ABSTRACT FROM AUTHOR]