Traumatic myiasis in dogs caused by Wohlfahrtia magnifica and its importance in the epidemiology of wohlfahrtiosis of livestock

Abstract.  In the province of Al Hoceima, northern Morocco, and on two farms in Hungary, dogs were inspected for the presence of traumatic myiasis. Nine and four infested dogs were found in Morocco and Hungary, respectively. All the larvae and adults reared from them in the laboratory were identified as Wohlfahrtia magnifica (Schiner) (Diptera: Sarcophagidae). To our knowledge, these are the first cases of wohlfahrtiosis in dogs to be reported in these countries. All infested animals lived close to livestock, where wohlfahrtiosis was endemic. Infested body sites included limbs (six cases), external genitalia (two), ears (three), nose (one) and neck (one). Developing larvae caused severe welfare problems and tissue destruction in most cases. Although the number of cases reported here is small, wohlfahrtiosis in dogs may be very important from an epidemiological perspective because farm and stray dogs can act as both reservoirs and carriers of this parasitic fly species. Therefore, education of dog owners concerning the risk factors in endemic regions is recommended in order to reduce the prevalence of wohlfahrtiosis in dogs and thereby in livestock. Both owners and veterinarians should pay regular attention to any wounds and to the natural orifices of dogs, especially during the fly seasons.     

A retrospective and geographical epidemiological survey of traumatic myiasis in southern Italy

A survey on the prevalence and geographical distribution of traumatic myiasis in sheep, and the risk factors for the disease, was carried out in a region of southern Italy. A total of 138 sheep flocks were selected and visited to acquire data on the presence or absence of traumatic myiasis using both a questionnaire for retrospective analysis and animal inspection. Prevalences registered at the farm and animal levels, respectively, were 8.7% and 6.3% in 2010, and 5.8% and 5.0% in 2011. Records of the occurrence of the parasitic disease in this region are recent: a statistically significant (P < 0.01) progressive increase in the number of farms affected (from 0.7% to 8.7%) has been registered since 2007. Wohlfahrtiosis was found in 11 of 95 (11.6%) geographical units sampled and three significant (P < 0.05) clusters of spatial farm aggregation were identified in the southern part of the study area. A total of 158 presently uninfested farms were considered to be at high risk for transmission as a result of their proximity to infested farms. The spreading of Wohlfahrtia magnifica (Diptera: Sarcophagidae) in southern regions of Italy represents a warning that the risk for infestation may become more significant in other Italian regions, as well as other European countries.     

Orientation of flying male Anobium punctatum (Coleoptera: Anobiidae) to sex pheromone: separating effects of visual stimuli and physical barriers to wind

Abstract. Flying male woodworm, Anobium punctatum , are able to locate a source of female pheromone offered as a point source but land more quickly if the same odour source is presented on a model 'tree' (cylinder). We tested the response to a two-dimensional black 'tree' marked as a silhouette on the upwind screen of the wind tunnel, with or without a hidden upwind barrier to the wind. The beetles responded equally to pheromone presented on a visual silhouette with wind barrier and to the hidden upwind wind-barrier alone, suggesting that the wind-barrier itself has a significant effect on insect orientation and landing: visual stimuli do not add to the landing response if the barrier is present. However, without the barrier upwind, landing was faster when the visual stimulus was present than without. This is the third forest-living species to be shown to respond in this way, which suggests this phenomenon may be more widespread. The possibility that this phenomenon is present in other, non-forest, phytophagous insects, their predators and parasitoids is discussed.     

Fly abundance and climate as determinants of sheep blowfly strike incidence in southwest England

The relationships between abundance of the blowfly Lucilia sericata (Meigen) (Diptera: Calliphoridae), climate, animal management procedures and the incidence of cutaneous myiasis (blowfly strike) in sheep were examined in three sheep pasture systems in southwest England during the summers of 2002 and 2003. In each year, flies were collected using liver-baited sticky targets, daily weather and routine husbandry practices were noted and the age-class of each animal infested and body position of each strike were recorded. On sites where no strike control was used, 5.8-12.1% of ewes and 5.7-15.8% of lambs were struck. Ewe strikes predominated at the beginning of the season. The incidence of ewe strikes was significantly associated with higher mean temperature, rainfall and shearing; shearing was associated with a 95% reduction in the risk of ewe strike. In lambs, the incidence of strike was significantly related to higher fly abundance, ewe shearing, treatment and mean ambient temperature. Lambs were 4.6 times more likely to be struck after the ewes had been shorn than before; however, the strongest relationship was with mean L. sericata abundance. Average minimum threshold temperatures of 9.5 degrees C for lamb strikes and 8.5 degrees C for all strikes were extrapolated, below which oviposition did not occur. Over 80% of ewe strikes occurred in the breech region in 2002, as did 100% in 2003. However, in lambs both body and breech strikes occurred in both years. The distribution of lamb strikes appeared to change over time, with breech strikes predominating in May, June and July and body strikes occurring increasingly later in the season. The incidence of lamb breech strikes was significantly associated with higher L. sericata abundance and ewe shearing but there was no relationship with weather conditions. By contrast, the risk of body strike in lambs was significantly associated with higher blowfly abundance, higher rainfall and higher maximum temperatures. The relationship between strike incidence and L. sericata abundance is important because it enhances our understanding of strike incidence patterns and management of this disease. Clearly, any factors that facilitate larger L. sericata populations, such as inappropriate carcass burial or increased average ambient temperatures, are likely to increase the incidence of strike.     

Climate change and livestock parasites: integrated management of sheep blowfly strike in a warmer environment

The incidence of parasite‐mediated livestock disease is the result of a complex interaction of factors such as parasite and host abundance, host susceptibility, climate and, critically, farmer husbandry and intervention strategies, all of which change seasonally in space and time. Given the complexity of the interacting factors, the effects of environment changes on disease incidence are hard to predict, as accordingly are the optimal husbandry responses required to ameliorate any effects. Here a model system is used to explore these issues. Cutaneous myiasis (blowfly strike) is common disease of livestock and would be expected to be highly sensitive to even small changes in climate; it provides a good model for highlighting the problems inherent in attempting to predict the effect of climate change on livestock disease incidence. For this, a stochastic simulation model is used to examine the changes in the seasonal incidence of ovine cutaneous myiasis on farms in the United Kingdom and the likely effects of changes in husbandry and control strategies. The simulations show that the range of elevated temperatures predicted by current climate change scenarios result in an elongated blowfly season with earlier spring emergence and a higher cumulative incidence of strike. Overall, higher temperatures increased strike incidence disproportionately in ewes in early summer, but had relatively less direct effect on the pattern of lamb strike incidence; a +3 °C increase in average temperature approximately doubles the cumulative incidence of strike in lambs but results in four times more strikes in ewes. A range of strike management options is examined and the models show that changes in husbandry practices are also likely to have an important effect in reducing early season ewe strike incidences. The simulations suggest that integrated changes in husbandry practices are likely to be able to manage expected increases in strike, given the range of climate changes currently predicted.     

Visual and olfactory cues for mate orientation behaviour in male white-spotted longicorn beetle, Anoplophora malasiaca

Olfactory and visual cues were shown to mediate short‐distance orientation in Anoplophora malasiaca (Thomson) (Coleoptera: Cerambycidae). In a laboratory test, more than 80% (n = 42) of males walked straight upward when presented with an untreated surface with a 75° slope. When a freshly killed female was fixed at a short distance (10 cm ahead and 5 cm to left/right) from the starting point, 50% of males (n = 30) were oriented toward the female before direct contact. Similar behavioural responses were observed when female extract was directly applied to the slope or to a glass rod model fixed on the slope. When black, white, and transparent coloured rods with the extract were presented, the orientation response was significantly greater for black than to white and transparent rods, to which only a negligible response was observed.     

Effects of ovarian development and protein deprivation on the activity and locomotor responses of the blowfly, Lucilia sericata, to liver odour

Abstract. The spontaneous activity and locomotor responses to liver odour of females of the blowfly Lucilia sericata Meigen (Diptera: Calliphoridae) were examined in the laboratory using a rocking-box olfactometer. Spontaneous activity levels depended on fly age, previous exposure to protein and recent oviposition history; 1-day-old females, 3-day-old protein-fed females, and females that had recently oviposited exhibited lower levels of spontaneous activity than protein-deprived or fully gravid individuals. Changes in locomotor activity in response to liver odour also depended on previous exposure to protein. In protein-fed flies, activity decreased in response to liver odour and then increased on termination of an odour pulse. This response became more pronounced with age, broadly in line with the expected state of oocyte maturation. This pattern of change was not evident in protein-deprived females. The results are discussed in relation to the relative importance of protein and oviposition-site resources to L. sericata and the resultant age and ovarian development-stage biases evident in field catches.     

Olfactory and visual stimuli used in orientation to conifer seedlings by the pine weevil, Hylobius abietis

Abstract. The influence of noncontact plant cues is investigated on the likelihood that individual conifer seedlings will be found by walking adults of the pine weevil, Hylobius abietis, in the field. Traps with solely odour or solely visual stimuli catch significantly more weevils than stimulus-free traps, and traps with the combination of odour and visual stimuli catch more weevils than traps with odour or visual stimuli alone. There is essentially an additive effect between odour and visual stimuli. The reactions to odour and visual stimuli are similar for three phases of the pine weevil's life cycle associated with three ages of clear-cuttings (i.e. sites where all trees have been harvested). Visual stimuli appear to be at least as important as odour for the pine weevil in finding an undamaged conifer seedling.     

Role of host-plant stimuli in sexual behaviour of small ermine moths (Yponomeuta)

ABSTRACT. 1. Studies involving experiments with olfactometers and field experiments have shown that the release of sex-pheromone by females of Yponomeuta spp. is stimulated by the presence of host plants.
2. While in Y.evonymellus L. less females emitted pheromone in the absence of host plants, in Y.padellus L. the initiation of pheromone release was delayed.
3. Females of Y.evonymellus, Y.cagnagellus Hüb., Y.padellus and Y.plumbellus D. & S. all preferred a place with host-plant odour to one with non-host odours for sex-pheromone release.
4. Male preference for host-plant odour was demonstrated in the laboratory only for Y.cagnagellus.
5. Trap catches in the field indicated a reinforcement of female attractiveness by host-plant stimuli.     

Integration of visual and olfactory cues of hosts and non-hosts by three bark beetles (Coleoptera: Scolytidae)

Abstract.  1. There has been a long-standing pre-occupation with how phytophagous insects use olfactory cues to discriminate hosts from non-hosts. Foragers, however, should use whatever cues are accurate and easily assessed, including visual cues.
2. It was hypothesised that three bark beetles, the mountain pine beetle (MPB), Dendroctonus ponderosae Hopkins, the Douglas-fir beetle (DFB), D. pseudotsugae Hopkins, and the western balsam bark beetle (WBBB), Dryocoetes confusus Swaine, integrate visual and olfactory information to avoid non-host angiosperms (e.g. paper birch, trembling aspen), that differ in visual and semiochemical profile from their respective host conifers (lodgepole pine, Douglas-fir, interior fir), and tested this hypothesis in a series of field trapping experiments.
3. All three species avoided attractant-baited, white (non-host simulating) multiple-funnel traps, and preferred attractant-baited black (host-simulating) traps. In experiments combining white, non-host traps with non-host angiosperm volatiles, bark beetles were repelled by these stimuli in an additive or redundant manner, confirming that these species could integrate visual and olfactory information to avoid non-host angiosperms while flying.
4. When antiaggregation pheromones were released from white traps, the DFB and MPB were repelled in an additive-redundant manner, suggesting that beetles can integrate diverse and potentially anomalous stimuli.
5. The MPB demonstrated the most consistent visual preferences, suggesting that it may be more of a 'visual specialist' than the DFB or WBBB, for which visual responses may be more contingent on olfactory inputs.     

The Visual Orientation Strategies of Mantis religiosa and Empusa fasciata Reflect Differences in the Structure of Their Visual Surroundings

In the present study, peering behaviour, which is used to measure distance by the image motion caused by head movement, is examined in two types of mantid. Mantis religiosa inhabits a region of dense grass consisting of uniform, generally uniformly aligned, and closely spaced elements and executes slow, simple peering movements. In contrast, Empusa fasciata climbs about in open regions of shrubs and bushes which consist of irregular, variably aligned and variably spaced elements and it executes comparatively quick, complex peering movements. Hence, it seems that in these two species of mantid, the same orientation mechanism has been adapted to the unique structures of their visual surroundings. Apparently M. religiosa uses motion parallax and E. fasciata uses a combination of motion parallax and forward and backward movements (image expansion/contraction over time) to detect object distances.     

Escape trajectories of the rockpool prawn (Palaemon elegans) in response to visual and mechanosensory stimuli

Small crustaceans, such as the rockpool prawn Palaemon elegans Rathke, respond to the approach of predators by executing a version of the crustacean tail-flip response, known as the ‘jack-knife’. We used two types of stimulus to investigate the escape behaviour of P. elegans, specifically the escape trajectories taken by individual prawns. The first stimulus consisted of mechanosensory cues, while the second stimulus included visual and mechanosensory cues. Responses to the two stimulus types differed, with the combined cues from the second stimulus type resulting in escapes over longer distances, and with greater directionality, compared to those following purely mechanosensory stimulation. Altering the direction of approach of the ‘predator’ affected the proportion of escapes that were to the side opposite from the eliciting stimulus and strongly influenced escape trajectories. Such unpredictability in the escape direction of P. elegans may be an example of so-called ‘Protean’ behaviour.     

初级视皮层神经元响应反应与撤反应的朝向选择性

朝向选择性是初级视皮层(17区或V1)神经元的基本性质,在图形感知中起着关键作用.同时这些神经元对于持续时间大于100 ms的视觉刺激具有清晰的响应反应(Onset responses)和撤反应(Offset responses).以往的研究只关注响应反应的朝向选择性,而忽视了对撤反应的朝向选择性研究.我们比较了响应与撤反应的朝向调谐性质,大多数细胞的撤反应与响应反应基本上具有相似的最优朝向,而撤反应的朝向调谐宽度有窄于响应反应的趋势,撤反应的最优延迟普遍滞后于响应反应的最优延迟.撤反应的朝向选择性略强于响应反应和具有显著长的反应延迟提示,皮层内的反馈输入可能在形成撤反应的朝向选择性中起着作用.本研究揭示了撤反应的朝向选择性在刺激朝向的连续表征和主体在形状知觉的后期对朝向的精细区分中起着作用.     

A Population Density Approach That Facilitates Large-Scale Modeling of Neural Networks: Analysis and an Application to Orientation Tuning

We explore a computationally efficient method of simulating realistic networks of neurons introduced by Knight, Manin, and Sirovich (1996) in which integrate-and-fire neurons are grouped into large populations of similar neurons. For each population, we form a probability density that represents the distribution of neurons over all possible states. The populations are coupled via stochastic synapses in which the conductance of a neuron is modulated according to the firing rates of its presynaptic populations. The evolution equation for each of these probability densities is a partial differential-integral equation, which we solve numerically. Results obtained for several example networks are tested against conventional computations for groups of individual neurons.We apply this approach to modeling orientation tuning in the visual cortex. Our population density model is based on the recurrent feedback model of a hypercolumn in cat visual cortex of Somers et al. (1995). We simulate the response to oriented flashed bars. As in the Somers model, a weak orientation bias provided by feed-forward lateral geniculate input is transformed by intracortical circuitry into sharper orientation tuning that is independent of stimulus contrast.The population density approach appears to be a viable method for simulating large neural networks. Its computational efficiency overcomes some of the restrictions imposed by computation time in individual neuron simulations, allowing one to build more complex networks and to explore parameter space more easily. The method produces smooth rate functions with one pass of the stimulus and does not require signal averaging. At the same time, this model captures the dynamics of single-neuron activity that are missed in simple firing-rate models.     

The role of volatile semiochemicals in mediating host location and selection by nuisance and disease-transmitting cattle flies

The role of volatile semiochemicals in mediating the location and selection within herds of Holstein-Friesian heifers by nuisance and disease-transmitting cattle flies was investigated using coupled gas chromatography-electrophysiology (GC-EAG), coupled gas chromatography-mass spectrometry (GC-MS), electrophysiology (EAG), laboratory behaviour and field studies. Using volatile extracts collected by air entrainment from heifers in the Netherlands, a number of active peaks were located by coupled GC-EAG for Musca autumnalis (de Geer) (Diptera: Muscidae) and Haematobia irritans (L.) (Diptera: Muscidae). Volatile samples were also collected from two heifers in Denmark shown in previous counting experiments to differ significantly in their fly loads. Coupled GC-EAG using Ha. irritans antennae revealed differences in the EAG response to the samples, with additional EAG activity in the sample collected from the heifer with the lower fly load. To identify more EAG active compounds, volatiles were also collected from 48-h-old urine by air entrainment. In total, 23 compounds were located and identified by coupled GC-EAG and GC-MS. Further electrophysiological testing of these compounds with five fly species [M. autumnalis, Ha. irritans, Hydrotaea irritans (L.) (Diptera: Muscidae), Stomoxys calcitrans (L.) (Diptera: Musicidae) and Wohlfahrtia magnifica (Schiner) (Diptera: Sarcophagidae)] showed that only some of the compounds were physiologically active across the range of flies tested. These included 1-octen-3-ol, 6-methyl-5-hepten-2-one, (Z)-3-hexen-1-ol, naphthalene, and all EAG active compounds identified from urine. Compounds showing significant EAG activity were tested for behavioural activity using a wind-tunnel designed for measuring upwind flight behaviour. At certain concentrations, 1-octen-3-ol, 6-methyl-5-hepten-2-one and 3-octanol increased upwind flight, whereas naphthalene, propyl butanoate and linalool reduced upwind flight. In field studies using small herds of heifers ranked according to their fly load, individual slow-release formulations of 1-octen-3-ol and 6-methyl-5-hepten-2-one, when applied to low and high fly loading heifers, reduced fly loads on these individuals. This study provides evidence for the hypothesis that the natural differential attractiveness within herds of Holstein-Freisian heifers, i.e. a single host species, for cattle flies is partly due to differences in volatile semiochemicals emitted from the host. It is suggested that this phenomenon applies to other vertebrate host species and their associated insect pests.     

Orientation responses of individual larder beetles,Dermestes ater (Coleoptera,Dermestidae), to directional shifts in wind stimuli

Anemotaxis in adult larder beetles, Dermestes ater,was investigated using a locomotion compensator, to uncover the mechanism(s) by which beetles maintain a course direction relative to a wind stimulus. Compared to walking in still air, anemotactically orienting beetles walk with the following characteristics over 60-s periods: (1) reduced locomotor and turning rates, (2) sustained, relatively straight paths with course directions at various angles to the wind, and (3) an increased tendency to stop for brief periods. Differences in wind speed affect mainly path straightness, which increases positively with stimulus intensity. Beetles track the wind direction equally well moving up or downwind, and they are able to orient at angles either close to the wind or at more oblique angles. When the wind direction was shifted 90°, the beetles turned, usually over the short angle, to their previous course heading relative to the stimulus. Indvidual beetles exhibited preferred course directions over several trials within a period of 20 min. Each beetle regained its particular anemotactic angle after the 90° shift in the stimulus direction. Although the beetles paused in some trials, stopping was not required to reorient to the altered stimulus direction.     

Orientation of male gypsy moths,Lymantria Dispar (L.), to pheromone sources: The role of olfactory and visual cues

The role of olfaction and vision in the close-ranging flying and walking orientation of male gypsy moths, Lymantria dispar(L.), to females was studied in the forest and in the laboratory. In the forest, feral males found an isolated pheromone source as readily as one supplemented with female visual cues; dead, acetonerinsed females deployed without pheromone received virtually no visitations. In flight tunnel choice experiments using cylinders as surrogate trees and pheromone in different spatial configurations, visual attributes of the female did not influence either the males' choice of landing site or the efficiency with which they located the female. Rather, the presence of pheromone on the cylinder was necessary to elicit orientation as well as landing and walking on the cylinder. When a female visual model was placed in various positions around a pheromone source, walking males oriented primarily to the chemical stimulus. There were, however, indications that males would alter their walking paths in response to female visual cues over short distances (<5 cm), but only if they continued to receive pheromone stimulation. When visual and chemical cues were abruptly uncoupled by altering the trajectory of the pheromone plume, most males responded to the loss of the odor cue rather than to visual cues from the female. Temporal pheromone stimulation patterns affected male walking orientation. When stimulated by pheromone, males oriented toward the source; loss of the odor cue prompted an arearestricted local search characterized by primarily vertical and oblique movements with frequent reversals in direction. Presumably these maneuvers enhance the likelihood of recontacting the plume or serendipitously encountering the female. The apparent lack of visual response to the female is discussed in light of morphological and behavioral evidence suggesting that gypsy moths were formerly nocturnal.