Efficiency of vibrational sounding in parasitoid host location depends on substrate density

Parasitoids of concealed hosts have to drill through a substrate with their ovipositor for successful parasitization. Hymenopteran species in this drill-and-sting guild locate immobile pupal hosts by vibrational sounding, i.e., echolocation on solid substrate. Although this host location strategy is assumed to be common among the Orussidae and Ichneumonidae there is no information yet whether it is adapted to characteristics of the host microhabitat. This study examined the effect of substrate density on responsiveness and host location efficiency in two pupal parasitoids, Pimpla turionellae and Xanthopimpla stemmator (Hymenoptera: Ichneumonidae), with different host-niche specialization and corresponding ovipositor morphology. Location and frequency of ovipositor insertions were scored on cylindrical plant stem models of various densities. Substrate density had a significant negative effect on responsiveness, number of ovipositor insertions, and host location precision in both species. The more niche-specific species X. stemmator showed a higher host location precision and insertion activity. We could show that vibrational sounding is obviously adapted to the host microhabitat of the parasitoid species using this host location strategy. We suggest the attenuation of pulses during vibrational sounding as the energetically costly limiting factor for this adaptatio

Ambient temperature affects mechanosensory host location in a parasitic wasp

Certain parasitic wasps (Ichneumonidae, Pimplinae) use self-produced vibrations transmitted on plant substrate to locate their immobile concealed hosts (i.e. lepidopteran pupae). This mechanosensory mechanism, called the vibrational sounding, depends both on physical cues of the environment and physical activity of the parasitoid and is postulated to depend on ambient temperature. We analysed the influences of temperature on vibrational sounding by choice experiments using plant-stem models with hidden host mimics in the temperate species Pimpla turionellae. The results show a significant effect of temperature on host-location activity and on the success of this process. Outside an optimum range, the performance of the wasps decreased both at low and high temperatures. Below 10°C and beyond 24°C, the wasps displayed (1) substantial reduction in responsiveness, i.e. proportion of females showing ovipositor insertions, (2) reduction of quantitative activity with ovipositor insertions in the individuals, and (3) reduced precision of mechanosensory host location. Nevertheless, female wasps were able to locate their host over a surprisingly broad range of ambient temperatures which indicates that the wasps are able to compensate for temperature effects on vibrational soundin

Implications of changes in seasonal mean temperature for agricultural production systems: three case studies

- The performance of dairy cows will suffer from elevated temperatures, reflecting the extent and uncertainty of projected warming in different scenarios, with a marked increase in heat stress for non-intervention scenarios (A1B and A2) toward the end of the century. This calls for the adoption of protective measures in the management of indoor and outdoor animal environments. - A substantial risk of a prolonged pest control season for the codling moth (an apple pest) is projected toward the end of the century for Northern Switzerland sites, and mid-century for the Ticino. Timely preventive programs are anticipated to represent a key ingredient of adaptation to changing risks from agricultural pests. - Results suggest that in the near future viticulture could benefit from increasing temperatures as a wider range of grape varieties could be grown. Toward the end of the century negative impacts from extreme temperatures are nevertheless expected to become important

Impact of Climate Change on Voltinism and Prospective Diapause Induction of a Global Pest Insect – Cydia pomonella (L.)

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 re-sampling 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 life-history 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

Design und Qualitätskontrolle der zahnmedizinischen Untersuchung in der NAKO Gesundheitsstudie [Design and quality control of the oral health status examination in the German National Cohort (GNC)]

BACKGROUND: Caries and periodontitis are highly prevalent worldwide. Because detailed data on these oral diseases were collected within the framework of the German National Cohort (GNC), associations between oral and systemic diseases and conditions can be investigated. OBJECTIVES: The study protocol for the oral examination was designed to ensure a comprehensive collection of dental findings by trained non-dental staff within a limited examination time. At the mid-term of the GNC baseline examination, a first quality evaluation was performed to check the plausibility of results and to propose measures to improve the data quality. MATERIALS AND METHODS: A dental interview, saliva sampling and oral diagnostics were conducted. As part of the level‑1 examination, the number of teeth and prostheses were recorded. As part of the level‑2 examination, detailed periodontal, cariological and functional aspects were examined. All examinations were conducted by trained non-dental personnel. Parameters were checked for plausibility and variable distributions were descriptively analysed. RESULTS: Analyses included data of 57,967 interview participants, 56,913 level‑1 participants and 6295 level‑2 participants. Percentages of missing values for individual clinical parameters assessed in level 1 and level 2 ranged between 0.02 and 3.9%. Results showed a plausible distribution of the data; rarely, implausible values were observed, e.g. for measurements of horizontal and vertical overbite (overjet and overbite). Intra-class correlation coefficients indicated differences in individual parameters between regional clusters, study centres and across different examiners. CONCLUSIONS: he results confirm the feasibility of the study protocol by non-dental personnel and its successful integration into the GNC's overall assessment program. However, rigorous dental support of the study centres is required for quality management

Sexual harassment in heterogeneous landscapes can mediate population regulation in a grasshopper

Population regulation has been related to differences in the quality among habitats, which mediate differences in vital rates such that in poor habitats reproductive rates are lower than those in high-quality habitats. The spatial distribution of animals in such habitats depends on their preferences and the degree to which individuals have a free choice of a particular habitat. The identified mechanisms that lead to a particular spatial distribution and eventually to regulation mainly include foraging-related interference, for example, ideal free distribution, or simple selection of available high-quality habitats, that is, site-dependent habitat selection. However, in insect species these mechanisms might not be applicable, but density-dependent habitat selection still occurs. We therefore suggest a mechanism that refers to the nearly universal observation that matings also bear fitness costs. Although these costs have been investigated on the individual level in many insect species, their consequences for population dynamics have not yet been addressed. In the grasshopper species Stenobothrus lineatus, females in a nonreceptive mating status escape sexually approaching males by undirected jumps. By including such avoidance behavior in a spatially-explicit simulation model, we investigated its potential to result in progressive use of low-quality habitats at increasing population densities. In particular, we show that (1) such behavior changes habitat selection, (2) altered habitat selection results in population regulation, and (3) the degree of habitat heterogeneity influences regulation such that (4) heterogeneous habitats show fine-tuned regulation and homogeneous habitats tend to support large fluctuations. [KEYWORDS: habitat quality ; habitat use ; individual interactions ; mating behavior ; spatial simulation model ; Stenobothrus lineatus]

Perception of Chromatic cues during host location by the pupal parasitoid Pimpla turionellae (L.) (Hymenoptera: Ichneumonidae)

Chromatic and achromatic plant cues are expected to be particularly important for parasitoids of endophytic pupal hosts, because these stages do not feed and therefore avoid volatile emission caused by plant tissue damage. Endophytic feeding can cause discoloration or desiccation, leading to changes in color and/or brightness of infested plant parts that may be visually detected by parasitoids. The role of color cues in the host-finding behavior of parasitoids is poorly understood, and the visual system of most parasitoid species has not yet been investigated. We studied color discrimination ability and innate color preferences in the pupal parasitoid Pimpla turionellae (L.) (Hymenoptera: Ichneumonidae) during location of concealed hosts. Responses to combinations of yellow and blue bands of different reflectance intensities were investigated on cylindrical models of plant stems. The parasitoid’s reaction to these chromatic cues was evaluated by scoring the number of ovipositor insertions into the colored bands. Female parasitoids discriminated blue from yellow irrespective of total reflectance and inserted their ovipositors significantly more often into the blue area. True color vision is demonstrated for the examined species, and responses to chromatic cues are discussed in relation to their importance for host location in parasitoids. Results of this study and of our previous work suggest that P. turionellae uses contrasts (chromatic or achromatic) rather than specific color characteristics in visual host location. [KEYWORDS: pupal parasitoid, host location, vision, wavelength discrimination, chromatic contrast]