Non-preferred Condition Research Articles

Sub-optimal host plants have developmental and thermal fitness costs to the invasive fall armyworm.

The fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith) is a global invasive pest of cereals. Although this pest uses maize and sorghum as its main hosts, it is associated with a wide range of host plants due to its polyphagous nature. Despite the FAW's polyphagy being widely reported in literature, few studies have investigated the effects of the non-preferred conditions or forms (e.g., drought-stressed forms) of this pest's hosts on its physiological and ecological fitness. Thus, the interactive effects of biotic and abiotic stresses on FAW fitness costs or benefits have not been specifically investigated. We therefore assessed the effects of host plant quality on the developmental rates and thermal tolerance of the FAW. Specifically, we reared FAW neonates on three hosts (maize, cowpeas, and pearl millet) under two treatments per host plant [unstressed (well watered) and stressed (water deprived)] until the adult stage. Larval growth rates and pupal weights were determined. Thermal tolerance traits viz critical thermal maxima (CTmax), critical thermal minima (CTmin), heat knockdown time (HKDT), chill-coma recovery time (CCRT), and supercooling points (SCPs) were measured for the emerging adults from each treatment. The results showed that suboptimal diets significantly prolonged the developmental time of FAW larvae and reduced their growth rates and ultimate body weights, but did not impair their full development. Suboptimal diets (comprising non-cereal plants and drought-stressed cereal plants) increased the number of larval instars to eight compared to six for optimal natural diets (unstressed maize and pearl millet). Apart from direct effects, in all cases, suboptimal diets significantly reduced the heat tolerance of FAWs, but their effect on cold tolerance was recorded only in select cases (e.g., SCP). These results suggest host plant effects on the physical and thermal fitness of FAW, indicating a considerable degree of resilience against multiple stressors. This pest's resilience can present major drawbacks to its cultural management using suboptimal hosts (in crop rotations or intercrops) through its ability to survive on most host plants despite their water stress condition and gains in thermal fitness. The fate of FAW population persistence under multivariate environmental stresses is therefore not entirely subject to prior environmental host plant history or quality.

Multimodal Temporal Pattern Discrimination Is Encoded in Visual Cortical Dynamics.

Discriminating between temporal features in sensory stimuli is critical to complex behavior and decision-making. However, how sensory cortical circuit mechanisms contribute to discrimination between subsecond temporal components in sensory events is unclear. To elucidate the mechanistic underpinnings of timing in primary visual cortex (V1), we recorded from V1 using two-photon calcium imaging in awake-behaving mice performing a go/no-go discrimination timing task, which was composed of patterns of subsecond audiovisual stimuli. In both conditions, activity during the early stimulus period was temporally coordinated with the preferred stimulus. However, while network activity increased in the preferred condition, network activity was increasingly suppressed in the nonpreferred condition over the stimulus period. Multiple levels of analyses suggest that discrimination between subsecond intervals that are contained in rhythmic patterns can be accomplished by local neural dynamics in V1.

Affective trajectories: Are hens influenced by positive and negative changes in their living conditions?

Most studies of the effects of housing and husbandry on animals' affective states and welfare investigate the impact of stable living conditions, comparing for example, animals living in enriched environments with those living in non-enriched ones. Changes in living conditions, including from more to less enriched environments, have also been found to have effects on measures of affective state and welfare in some species. But these studies have not investigated whether it is the trajectory of change that has affected the animals (e.g., worsening conditions), or simply the nature of their final environment (e.g., non-enriched). Here, we hypothesised that laying hens living in worsening conditions across a six-week period (gradually moving from preferred to non-preferred living conditions; "Trajectory to Non-Preferred", TNP, n = 30), would show evidence of more negative affective states and poorer welfare than those living continuously in non-preferred conditions for the same duration ("Stable Non-Preferred", SNP, n = 30). We also hypothesised that hens living in improving conditions (gradually moving from non-preferred to preferred living conditions; "Trajectory to Preferred", TP, n = 30), would show evidence of more positive affective states and better welfare than those living continuously in preferred conditions ("Stable Preferred", SP, n = 30). The preferred living condition provided extensive resources and intermittent rewarding events (such as the delivery of food treats) known to be valued and preferred by most hens, while the non-preferred living condition provided just basic resources and intermittent aversive events (e.g., loud noises). The hens' affective states and welfare were measured using home-pen behavioural observations, body condition assessments, physiological stress measures (e.g., blood corticosterone, glucose, etc.), physical challenge tests, and judgement bias tests. A number of differences between hens in the trajectory and stable living conditions were found: TP hens were lighter, showed more foraging behaviour and less standing alert and head-shaking than SP hens, while TNP hens showed more head-shaking, mild feather pecking and aggressive attacking of pen mates than SNP hens. However, some of these differences failed to reach significance following Benjamini adjustments for multiple testing. The groups also did not differ in their judgement biases (measured in a sub-sample of 12 hens per experimental group), response to physical challenges, or measures of physiological stress. We conclude that the hens in the present study showed some evidence of responsiveness to 'affective trajectories' in their living conditions, but no definitive effects on their affective states and welfare.

Sensitivity of a shark nursery habitat to a changing climate

Nursery area habitats such as estuaries are vital for the success of many fish populations. Climate change is altering conditions in these areas, which can thus impact the availability of suitable nursery habitat. The sandbar sharkCarcharhinus plumbeususes Chesapeake Bay (USA) as a nursery habitat during the summer months from birth up to 10 yr of age. To assess the impacts of climate change on juvenile sandbar sharks, we developed a habitat model using longline data collected from a fishery-independent survey within Chesapeake Bay. With this model, we projected contemporary and future distributions of suitable habitat for juvenile sandbar sharks in Chesapeake Bay under varying environmental regimes. Predicted suitable juvenile sandbar shark habitat was negatively impacted by future increases in temperature, but positively influenced by future decreases in dissolved oxygen. The latter trend was likely related to the habitat partitioning that occurs between different life stages. Changes in salinity had relatively small impacts. By end-of-century the projected amount of suitable bottom habitat decreased; however, when incorporating the entire water column, projected suitable habitat increased. This suggests that juvenile sandbar sharks may need to make a behavioral shift to avoid non-preferred conditions, which could alter their foraging ecology or refuge strategies. As nursery habitats change with climate change, it is crucial to understand how a species may be impacted during this vital life stage when trying to predict overall species success in the future.

Sling-based infant carrying affects lumbar and thoracic spine neuromechanics during standing and walking

BackgroundRegular infant carrying might be a contributing factor for the development and progression of low back and pelvic girdle pain in mothers after childbirth. However, the neuromechanical adaptations of the spine due to different sling-based carrying techniques are not sufficiently well understood in order to provide evidence-based carrying recommendations. Research questionWhat are the immediate effects of different sling-based infant carrying techniques on trunk neuromechanics? MethodsUsing a Vicon motion capture and a wireless surface electromyography system, three-dimensional pelvis and spinal kinematics as well as activation patterns of eight trunk muscles were derived from fifteen healthy young women during upright standing and level walking without carrying a load and while carrying a 6 kg-dummy with a sling in front and on either side. Data were analyzed using Statistical Parametric Mapping, allowing group comparisons of discrete parameters (standing) as well as continuous data (walking). To distinguish between clinically relevant and clinically not relevant kinematic findings, statistically significant differences were only considered in case of ≥5°. ResultsCompared to unloaded walking, carrying the dummy in front was mainly associated with increased lumbar lordosis (standing: (Δ8.8°, p = 0.006; walking: (Δ ≥ 8.2°, 1–100% of gait cycle [%GC], p < 0.001). When carrying the dummy on the preferred side, increased thoracic kyphosis (standing: ≥6.4°, p ≤ 0.003; walking: Δ ≥ 5.6°, 1–100%GC, p < 0.001) and axial rotation towards the ipsilateral side (standing: Δ5.3°, p = 0.003; walking: Δ ≥ 5.0°, 46–58%GC, p = 0.002) were observed. All three conditions entailed increased paraspinal muscle activity during walking, although only unilaterally in side carrying (lumbar, preferred condition: Δ ≥ 13.2%maxMVIC, 49–57%GC, p < 0.001; thoracic, non-preferred condition: Δ ≥ 5.3%maxMVIC, 47–58%GC, p < 0.001). SignificanceCarrying an infant alternating on both sides using a sling could be advantageous for preventing musculoskeletal pain resulting from excessive lumbar hyperextension and paraspinal muscle hyperactivation in women after childbirth.

Using EEG for Predicting User Preferences of Physical Compliance in Human-Robot Cooperation

Using EEG for Predicting User Preferences of Physical Compliance in Human-Robot Cooperation

Facultative nocturnal behaviour in snakes: experimental examination of why and how with Ratsnakes (Elaphe obsoleta) and Racers (Coluber constrictor)

Diel activity patterns are often fixed within species such that most animals can be classified as diurnal, crepuscular, or nocturnal, and have sensory abilities that reflect when they are active. However, many snake species appear capable of switching between diurnal and nocturnal activity. Here, we evaluate the hypothesis that some species are constrained in their activity by the sensory cues used for foraging. We experimentally assessed differences between two sympatric snake species in their ability to alter diel activity patterns, to address why those snakes that switch do so (do thermal constraints force them to be active in otherwise nonpreferred conditions?), and to explore how sensory abilities to locate prey facilitate or constrain this shift. Ratsnakes (Elaphe obsoleta (Say in James, 1823)) were active when temperature was optimal, regardless of light level, suggesting their activity pattern is genuinely plastic. Consistent with our predictions, Ratsnakes successfully detected prey in low and high light using visual or chemical cues, and were most successful when cues were coupled. Racers (Coluber constrictor L., 1758) were almost exclusively diurnal, regardless of temperature, and became less active when daytime temperatures were suboptimal. The ability of Ratsnakes to shift activity may confer a foraging advantage and should buffer Ratsnakes and similarly flexible species from climate change, whereas climate change may pose a more serious threat to inflexible species such as Racers.

Behaviour and use of space in fattening rabbits as influenced by cage size and enrichment

In the few previous studies on the effects of space allowance on fattening rabbit behaviour, space allowance was confounded with group size. This is the first study of fattening rabbit behaviour in which space allowance was varied whilst group size was stable (8 animals per pen), although this meant that stocking density and total cage size were altered simultaneously. Behaviour was studied at 6 and 9 weeks of age during artificially created dawn, daytime and dusk phases, and compared between cages with and without a wooden enrichment structure. Although a wide range of space allowances was studied (seven different cage sizes between 0.40 and 1.60 m 2) the observed effect on behaviour was limited: only sternal lying increased consistently with decreasing space allowance. In the larger cages, grooming was performed when animals had more free space around them. However, grooming did not decrease in smaller cages, suggesting that this behaviour was important enough to be performed under non-preferred conditions. The wooden enrichment structure decreased lateral lying and cage manipulation. Effects on lying behaviour and cage manipulation have previously been reported for gnawing sticks. However, in contrast to findings on gnawing sticks, the enrichment structure also decreased social contact. Although social contact is generally seen as positive, the rabbits may have used the structure as a visual or physical barrier to protect themselves from unwanted interactions with conspecifics. As expected, rabbits were generally more active during dawn and dusk than during daytime. Specific behaviour patterns varied between dawn and dusk, and future studies may use this information to pinpoint the most favourable observation time. In summary, providing fattening rabbits housed in groups of eight with more space had a limited effect on their behavioural time budget. Thus, only minimal support was found for the suggestion that decreased cage size impedes welfare in this species, although rabbits did seem to prefer more space during grooming. In contrast, provision of a wooden structure improved welfare, as shown by a decrease in cage manipulation and interactions with conspecifics.

Performance, Workload, and Stress in Vigilance: The Power of Choice

Observers were provided the illusion of choice by permitting them to ‘choose’ an easy or a hard version of a vigilance task. Participants were then assigned at random to either the condition they expressed preference for or their non-preferred condition. Participants in the comparison control condition were not offered the opportunity to choose. Task demand was manipulated using event rate variation, divided into high and low event rates. Results indicated that permitting participants a choice regarding ‘difficulty level’ and subsequently assigning them to that level enhanced signal detections but did not reduce their perceived workload and stress. In contrast, offering a choice and then assigning observers to their non-preferred condition impaired performance relative to a condition in which no choice was provided. This pattern of effects was more pronounced at the low compared to the high event rate. These results confirm the importance of motivational effects in vigilance and the impact choice has on performance in tasks requiring sustained attention.

The effect of dimensional preference on optional shift behavior and concept attainment of retarded adolescents

Sixty-three moderately retarded adolescents of similar chronological and mental ages participated in an experiment designed to assess the influence of dimensional dominance and preference on two concept learning tasks. After dominance assessment, subjects were randomly assigned to either a preferred or nonpreferred condition and received both an optional shift and concept assessment test. The results indicated a significant difference between color- and form-dominant learners and between subjects assigned to preferred and nonpreferred dimensions. No difference was observed on the concept assessment measure. A significantly greater number of subjects solved the optional shift task intradimensionally. Intradimensional shifts were also learned faster than extradimensional shifts. The data were interpreted in terms of developmental and mediation hypotheses and viewed as consistent with Zeaman and House’s chaining prediction.