The Effect of Predator Chemical Cue Age on Antipredator Behavior in the Wolf Spider Pardosa milvina (Araneae: Lycosidae)

The wolf spider, Pardosa milvina, exhibits reduced movement when detecting chemical cues (silk and excreta) from a larger wolf spider, Hogna helluo. We tested if cue age influenced Pardosa activity. Pardosa response was measured during 1-h trials using video-tracking equipment. Five treatments of predator cues were used: 5-day-old, 1-day-old, 1-h-old, and fresh cues and a control lacking predator cues. Pardosa moved significantly more slowly on substrates with fresh or 1-h-old cues compared to all other treatments and spent less time walking in all Hogna treatments relative to the control except with 5-day-old cues. Pardosa survived longer in the presence of Hogna with fresh compared to older cues. Prey may evaluate cue age as a measure of predation risk and grade antipredator behavior accordingly.     

Development,validation and reliability of the Chrononutrition Profile - Questionnaire

ABSTRACT

Chrononutrition, or the circadian timing of food intake, has garnered attention as a topic of study due to its associations with health (e.g. weight gain); however, a valid and reliable assessment of chrononutrition in daily life has not yet been developed. This paper details the development and initial reliability and validity testing of the Chrononutrition Profile – Questionnaire (CP-Q). The CP-Q assesses six components of chrononutrition that are likely to influence health (breakfast skipping, largest meal, evening eating, evening latency, night eating, and eating window). This questionnaire is designed to assess general chrononutrition behaviors and preferred timing of food intake. The CP-Q can be used as a sole evaluation of chrononutrition, and can also be utilized in conjunction with existing dietary measures to provide a comprehensive assessment of one’s eating behaviors. This measure offers health-care professionals, researchers, and stakeholders a cost-effective and comprehensive method of evaluating chrononutrition and identifying targets for health improvement.     

Host‐size decisions of female parasitoid wasps seeking hidden hosts

1. Choice of host size may play a critical role in parasitoid success, a task that takes on added complications when dealing with concealed hosts, but most such studies of insect behaviour have only taken place in the laboratory. 2. This study investigates the success of a wasp (Alabagrus texanus: Braconidae) in finding host caterpillars Herpetogramma theseusalis (Crambidae) of the most effectively handled size hidden in shelters, in both the field and the laboratory. 3. First, the study tested wasp preference and success in parasitizing large, middle‐sized and small caterpillars (> 5, 3–5, < 3 mm) presented in the open, one at a time, in the laboratory. The wasps attacked (inserted or attempted to insert their ovipositor) a higher proportion of middle‐sized (3–5 mm) caterpillars compared with either small (< 3 mm) or large (> 5 mm) caterpillars. Naïve wasps attacked large caterpillars more often than did experienced wasps. Wasps responded to increasing caterpillar size by increasing the number of legs used to pin their prey rather than by increasing handling time. 4. The frequencies of visits to shelters in the field containing a majority of either large or middle‐sized caterpillars were then compared, followed by a test providing the wasps with similar choices under controlled laboratory conditions. Wasps most frequently visited shelters containing a majority of middle‐sized caterpillars both in the field and under controlled laboratory conditions. 5. The combined results confirmed that the wasps can size‐select their hosts both in the field and in laboratory tests.     

An updated global data set for diet preferences in terrestrial mammals: testing the validity of extrapolation

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A system to simulate gas exchange in humans to control quality of metabolic measurements

We have developed a gas exchange simulation system (GESS) to assess the quality control in measurements of metabolic gas exchange. The GESS simulates human breathing from rest to maximal exercise. It approximates breath-by-breath waveforms, ventilatory output, gas concentrations, temperature and humidity during inspiration and expiration. A programmable motion control driving two syringes allows the ventilation to be set at any tidal volume (V _T), respiratory frequency (f), flow waveform and period of inspiration and expiration. The GESS was tested at various combinations of V _T (0.5–2.5 l) and f (10–60 stroke · min⁻¹) and at various fractional concentrations of expired oxygen (0.1294–0.1795); and carbon dioxide (0.0210–0.0690) for a pre-set flow waveform and for expired gases at the same temperature and humidity as room air. Expired gases were collected in a polyethylene bag for measurement of volume and gas concentrations. Accuracy was assessed by calculating the absolute and relative errors on parameters (error = measured−predicted). The overall error in the gas exchange values averaged less than 2% for oxygen uptake and carbon dioxide output, which is within the accuracy of the Douglas bag method. Accepted: 4 June 1998