Effects of ultraviolet LED versus incandescent bulb and carbon dioxide for sampling abundance and diversity of Culicoides in Florida.

Biting midges (Ceratopogonidae: Culicoides) are vectors of bluetongue virus and epizootic hemorrhagic disease virus which cause significant morbidity and mortality in ruminants. Recently, ultraviolet light emitting diodes (UV/LEDs) in conjunction with suction traps have been widely utilized for Culicoides spp. collections. Despite the use of these traps, limited work has been done comparing sampling variability associated with these light types with and without CO2. For this objective, mini-CDC light traps with four different attractant combinations were operated at eight sites across Florida between April and October 2017. Trap attractants included white-incandescent lights and UV/LEDs with and without CO2 to determine optimum combinations of light type and attractant for species richness, diversity, and abundance of Culicoides spp. in Florida. The results of the study demonstrate that traps with UV/LED light collect greater richness, diversity, and abundance of Culicoides species than traps with white-incandescent light. Addition of CO2 resulted in greater diversity in traps with UV/LED lights, but lower diversity in traps with white-incandescent light. Therefore, CO2 may be used to increase the abundance of Culicoides spp. collected by traps, regardless of light type, but the ability for CO2 to attract a higher number and diversity of species to traps varies by the light type used. Therefore, we suggest using CO2 primarily in conjunction with UV/LED light. When CO2 is not available, UV/LED light used alone can be substituted without a significant loss in species richness or diversity, although abundance of most Culicoides species will be significantly lower in the absence of CO2.

Appetitive Symptoms Differentially Predict Treatment Response to Fluoxetine, Light, and Placebo in Nonseasonal Major Depression.

OBJECTIVE: We previously reported that morning bright light therapy is efficacious in adults with nonseasonal major depressive disorder (MDD), both on its own and in combination with fluoxetine. Given that appetitive symptoms predict response to bright light therapy in seasonal depression, we examined, in this secondary analysis, whether the same held true in these nonseasonal MDD patients. METHODS: Data were collected from October 7, 2009, to March 11, 2014. One hundred twenty-two patients who met DSM-IV-TR criteria for MDD without a seasonal pattern were randomly assigned to light monotherapy, fluoxetine, combination light and fluoxetine, or double-placebo (inactivated negative ion generator plus placebo pill). Multiple regression assessed the percentage change in Montgomery-Asberg Depression Rating Scale (MADRS) scores based on treatment condition, appetitive symptom score at baseline (sum of 4 items on the Structured Interview Guide for the Hamilton Depression Rating Scale, Seasonal Affective Disorders version), and the condition-by-appetitive score interaction. Sex was considered as a possible moderator of these effects. RESULTS: The overall regression model predicting treatment response was highly significant (P < .001), and the treatment condition-by-appetitive score interaction was a strong predictor of MADRS change scores (t = 2.65, P = .009). For individuals in the placebo group, more appetitive symptoms at baseline predicted less decrease in MADRS scores at 8 weeks (r = -0.37; large effect size). In contrast, for individuals in the active treatment groups, more appetitive symptoms at baseline predicted more of a decrease in depression scores at 8 weeks (fluoxetine group r = +0.23, medium effect size; light therapy group r = +0.11, small effect size; combination group r = +0.32, medium to large effect size). No moderation effect of sex was found. CONCLUSIONS: More severe appetitive symptoms at baseline predicted treatment response differentially across the 4 treatment groups. Contrary to prior findings in seasonal depression, this association was not robust for MDD patients receiving light therapy alone, although it was stronger in patients receiving fluoxetine with or without light. As the group sample sizes were modest, the current findings should be considered as preliminary only. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00958204.

Foraging strategy of wasps - optimisation of intake rate or energetic efficiency?

In endothermic wasps, foraging is an expensive activity. To maximise the benefit for the colony, wasps can optimise either the intake rate or energetic efficiency of a foraging trip. We investigated the foraging behaviour of vespine wasps under variable environmental and reward conditions. We trained them to forage for 0.5 mol l-1 sucrose solution from an artificial flower in a flow-through respiratory measurement chamber, and simultaneously measured their body temperature using infrared thermography to investigate interactions between thermoregulation and energetics. Measurement of carbon dioxide release (for energetic calculations) and load mass enabled the direct determination of foraging efficiency. An unlimited reward increased the wasps' energetic effort to increase the suction speed through high body temperatures. With reduced reward (limited flow), when an increased body temperature could not increase suction speed, the wasps decreased their body temperature to reduce the metabolic effort. Solar heat gain was used differently, either to increase body temperature without additional metabolic effort or to save energy. The foraging efficiency was mainly determined by the flow rate, ambient temperature and solar heat gain. In shade, an unlimited sucrose flow and a high ambient temperature yielded the highest energetic benefit. A limited flow reduced foraging efficiency in the shade, but only partly in sunshine. Solar radiation boosted the efficiency at all reward rates. Wasps responded flexibly to varying reward conditions by maximising intake rate at unlimited flow and switching to the optimisation of foraging efficiency when the intake rate could not be enhanced due to a limited flow rate.

Adult Tea Green Leafhoppers, Empoasca onukii (Matsuda), Change Behaviors under Varying Light Conditions.

Insect behaviors are often influenced by light conditions including photoperiod, light intensity, and wavelength. Understanding pest insect responses to changing light conditions may help with developing alternative strategies for pest control. Little is known about the behavioral responses of leafhoppers (Hemiptera: Cicadellidae) to light conditions. The behavior of the tea green leafhopper, Empoasca onukii Matsuda, was examined when exposed to different light photoperiods or wavelengths. Observations included the frequency of locomotion and cleaning activities, and the duration of time spent searching. The results suggested that under normal photoperiod both female and male adults were generally more active in darkness (i.e., at night) than in light. In continuous darkness (DD), the locomotion and cleaning events in Period 1 (7:00-19:00) were significantly increased, when compared to the leafhoppers under normal photoperiod (LD). Leafhoppers, especially females, changed their behavioral patterns to a two day cycle under DD. Under continuous illumination (continuous quartz lamp light, yellow light at night, and green light at night), the activities of locomotion, cleaning, and searching were significantly suppressed during the night (19:00-7:00) and locomotion activities of both females and males were significantly increased during the day (7:00-19:00), suggesting a shift in circadian rhythm. Our work suggests that changes in light conditions, including photoperiod and wavelength, can influence behavioral activities of leafhoppers, potentially affecting other life history traits such as reproduction and development, and may serve as a method for leafhopper behavioral control.

Experience-related reorganization of giant synapses in the lateral complex: Potential role in plasticity of the sky-compass pathway in the desert ant Cataglyphis fortis.

Cataglyphis desert ants undergo an age-related polyethism from interior workers to relatively short-lived foragers with remarkable visual navigation capabilities, predominantly achieved by path integration using a polarized skylight-based sun compass and a stride-integrating odometer. Behavioral and physiological experiments revealed that the polarization (POL) pattern is processed via specialized UV-photoreceptors in the dorsal rim area of the compound eye and POL sensitive optic lobe neurons. Further information about the neuronal substrate for processing of POL information in the ant brain has remained elusive. This work focuses on the lateral complex (LX), known as an important relay station in the insect sky-compass pathway. Neuroanatomical results in Cataglyphis fortis show that LX giant synapses (GS) connect large presynaptic terminals from anterior optic tubercle neurons with postsynaptic GABAergic profiles of tangential neurons innervating the ellipsoid body of the central complex. At the ultrastructural level, the cup-shaped presynaptic structures comprise many active zones contacting numerous small postsynaptic profiles. Three-dimensional quantification demonstrated a significantly higher number of GS (∼ 13%) in foragers compared with interior workers. Light exposure, as opposed to age, was necessary and sufficient to trigger a similar increase in GS numbers. Furthermore, the increase in GS numbers was sensitive to the exclusion of UV light. As previous experiments have demonstrated the importance of the UV spectrum for sky-compass navigation in Cataglyphis, we conclude that plasticity in LX GS may reflect processes involved in the initial calibration of sky-compass neuronal circuits during orientation walks preceding active foraging.

Sweet and bitter taste in the brain of awake behaving animals.

Taste is responsible for evaluating the nutritious content of food, guiding essential appetitive behaviours, preventing the ingestion of toxic substances, and helping to ensure the maintenance of a healthy diet. Sweet and bitter are two of the most salient sensory percepts for humans and other animals; sweet taste allows the identification of energy-rich nutrients whereas bitter warns against the intake of potentially noxious chemicals. In mammals, information from taste receptor cells in the tongue is transmitted through multiple neural stations to the primary gustatory cortex in the brain. Recent imaging studies have shown that sweet and bitter are represented in the primary gustatory cortex by neurons organized in a spatial map, with each taste quality encoded by distinct cortical fields. Here we demonstrate that by manipulating the brain fields representing sweet and bitter taste we directly control an animal's internal representation, sensory perception, and behavioural actions. These results substantiate the segregation of taste qualities in the cortex, expose the innate nature of appetitive and aversive taste responses, and illustrate the ability of gustatory cortex to recapitulate complex behaviours in the absence of sensory input.

What do foraging wasps optimize in a variable environment, energy investment or body temperature?

Vespine wasps (Vespula sp.) are endowed with a pronounced ability of endothermic heat production. To show how they balance energetics and thermoregulation under variable environmental conditions, we measured the body temperature and respiration of sucrose foragers (1.5 M, unlimited flow) under variable ambient temperature (T a = 20-35 °C) and solar radiation (20-570 W m(-2)). Results revealed a graduated balancing of metabolic efforts with thermoregulatory needs. The thoracic temperature in the shade depended on ambient temperature, increasing from ~37 to 39 °C. However, wasps used solar heat gain to regulate their thorax temperature at a rather high level at low T a (mean T thorax ~ 39 °C). Only at high T a they used solar heat to reduce their metabolic rate remarkably. A high body temperature accelerated the suction speed and shortened foraging time. As the costs of foraging strongly depended on duration, the efficiency could be significantly increased with a high body temperature. Heat gain from solar radiation enabled the wasps to enhance foraging efficiency at high ambient temperature (T a = 30 °C) by up to 63 %. The well-balanced change of economic strategies in response to environmental conditions minimized costs of foraging and optimized energetic efficiency.

Foraging activity of commensal Mus musculus in semi-captivity conditions. Effect of predator odours, previous experience and moonlight.

BACKGROUND: Mus musculus is a pest in urban and rural habitats where it consumes and contaminates food and may transmit diseases to human and domestic animals. Its control by anticoagulants is partially effective because of aversive behaviours and resistance. In this context, we wanted to assess the potential of the use of predator odours as repellents in experimental feeding trials using urine and faeces of domestic cats and faeces of geoffroyi cat, a wild small felid that is one of the main rodent predators in the study area. We also assessed the effect of previous experience and moonlight on foraging activity. RESULTS: We did not find an aversive response to cat odours in Mus musculus individuals. There was a trend to consume food in the same feeding stations over time, and the visit rate was lower in periods with high moonlight than in periods with low moonlight. CONCLUSIONS: Predator odours did not seem to be useful as rodent repellents, but maintaining illumination may lower rodent foraging activity. As rodents maintain their feeding sites over time, toxic baits may be more efficiently placed at sites previously known to be used by rodents.

Mushroom body output neurons encode valence and guide memory-based action selection in Drosophila.

Animals discriminate stimuli, learn their predictive value and use this knowledge to modify their behavior. In Drosophila, the mushroom body (MB) plays a key role in these processes. Sensory stimuli are sparsely represented by ∼2000 Kenyon cells, which converge onto 34 output neurons (MBONs) of 21 types. We studied the role of MBONs in several associative learning tasks and in sleep regulation, revealing the extent to which information flow is segregated into distinct channels and suggesting possible roles for the multi-layered MBON network. We also show that optogenetic activation of MBONs can, depending on cell type, induce repulsion or attraction in flies. The behavioral effects of MBON perturbation are combinatorial, suggesting that the MBON ensemble collectively represents valence. We propose that local, stimulus-specific dopaminergic modulation selectively alters the balance within the MBON network for those stimuli. Our results suggest that valence encoded by the MBON ensemble biases memory-based action selection.

Using differential responses to light spectra as a monitoring and control tool for Arhopalus ferus (Coleoptera: Cerambycidae) and other exotic wood-boring pests.

Several longhorn beetles (Cerambycidae) and bark beetles (Scolytinae) have been accidentally introduced to New Zealand and are now widespread and abundant. In particular Arhopalus ferus (Mulsant) represents a significant quarantine risk for export timber. Because of this risk timber is fumigated with methyl bromide. Six different light traps baited with different colors (yellow, red, green, white, UV-black light [UV-BL], and UV-black-light-blue [UV-BLB]) were investigated for their population monitoring potential and as a push-pull (incorporating mass trapping) alternative control technique. UV-BLB light traps captured an order of magnitude more A. ferus (122 individuals per night) than yellow light traps (eight individuals per night). The bark beetles Hylurgus ligniperda (F.) and Hylastes ater (Paykull) were most attracted to UV-BL lights that captured 2-4 times more beetles than traps baited with other wavelengths. Results suggest that light traps provide a sensitive method for population monitoring. The responses of these wood borers and bark beetles to different colored light traps provide an opportunity to apply a push-pull control technique. The management of these species could be improved by minimizing the visual attractiveness (push) of wood processing facilities through a conversion to low intensity yellow site lighting, combined with the strategic placement of UV light traps for mass-trapping of residual populations (pull). Light management on its own is unlikely to eliminate the quarantine risk entirely; however, it is likely to reduce populations substantially and contribute toward the aim of reducing methyl bromide use.

Behavioural examination of the infrared sensitivity of rattlesnakes (Crotalus atrox).

Pitvipers (Crotalinae) and boid snakes (Boidae) possess highly sensitive infrared (IR) receptors. The ability of these snakes to image IR radiation allows the assessment of the direction and distance of an IR source (such as warm-blooded prey) in the absence of visual cues. The aim of this study was to determine the behavioural threshold of snakes to an IR stimulus. A moving IR source of constant size and temperature was presented to rattlesnakes (Crotalus atrox) at various distances (10-160 cm) from their snout. The snakes' responses were quantified by measuring distinct behavioural changes during stimulus presentation (head jerks, head fixed, freezing, rattling and tongue-flicking). The results revealed that C. atrox can detect an artificial IR stimulus resembling a mouse in temperature and size up to a distance of 100 cm, which corresponds to a radiation density of 3.35 x 10(-3) mW/cm2. These behavioural results reveal a 3.2 times higher sensitivity to IR radiation than earlier electrophysiological investigations.

Foraging and prey-search behaviour of small juvenile rainbow trout (Oncorhynchus mykiss) under polarized light.

Several fish species appear to be polarization sensitive, i.e. to be able to discriminate a light source's maximum plane of polarization from any other plane. However, the functional significance of this ability remains unclear. We tested the hypothesis that polarized light improves the prey location ability of free-swimming rainbow trout (Oncorhynchus mykiss) in laboratory aquaria. We found that prey location distances increased while the vertical component of prey location angle decreased under polarized compared with unpolarized (diffuse) illumination. The average frequency distribution of the horizontal component of prey location angle was more bimodal under polarized than unpolarized illumination. These results indicate that polarization sensitivity enhances prey location by juvenile rainbow trout.

Magnetic field effects on spatial discrimination and melatonin levels in mice.

Previous research has demonstrated a decrement in spatial discrimination learning following exposure to a .30 Tesla magnetic field. It had been suggested that those findings might be the result of an interaction between the magnetic field and physiological ferromagnetic material (magnetite). In the present study, mice were exposed for 100 min to a 2.0 Tesla field and both their left-right discrimination learning ability and serum melatonin levels were compared with a control group. Results indicated a significant interference with spatial discrimination learning following exposure, but no significant differences in serum melatonin levels. These findings appeared to rule out magnetically induced melatonin fatigue as an explanation of the decrement in spatial learning, as opposed to other possibilities such as magnetic effects on brain magnetite. However, additional controls are suggested for future research.

Memory-based learning in preweanling and adult rats after infantile x-irradiation-induced hippocampal granule cell hypoplasia.

Infantile exposure to x-irradiation induced severe hippocampal granule cell hypoplasia in preweanling and young adult rats. Hippocampally damaged pups, tested at 16 days of age, showed deficits in a memory-based discrimination based on single alternations of reward and nonreward when training was conducted at a 60-s intertrial interval (ITI) but not when conducted at a 30-s ITI. This deficit was still present at the 60-s ITI in animals x-irradiated in infancy and tested at 60-65 days of age. These data provide further support for the role of the hippocampus in intermediate-term memory and demonstrate, in a developmental context, the importance of an intact hippocampus in learning that depends on nonspatial memory.