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1.
Compared to non-flying nest-dwelling ectoparasites, the biology of most species of flying ectoparasites and its potential impact on avian hosts is poorly known and rarely, if ever, reported. In this study we explore for the first time the factors that may affect biting midge (Diptera: Ceratopogonidae) and black fly (Diptera: Simuliidae) abundances in the nest cavity of a bird, the hole-nesting blue tit Cyanistes caeruleus, and report their effects on adults and nestlings during reproduction. The abundance of biting midges was positively associated with nest mass, parental provisioning effort and abundance of blowflies and black flies, while negatively associated with nestling condition. Furthermore, a medication treatment to reduce blood parasitaemias in adult birds revealed that biting midges were more abundant in nests of females whose blood parasitaemias were experimentally reduced. This finding would be in accordance with these insect vectors attacking preferentially uninfected or less infected hosts to increase their own survival. The abundance of black flies in the population was lower than that of biting midges and increased in nests with later hatching dates. No significant effect of black fly abundance on adult or nestling condition was detected. Blood-sucking flying insects may impose specific, particular selection pressures on their hosts and more research is needed to better understand these host–parasite associations.  相似文献   

2.
Synopsis Ontogenetic increases in mouth size and changes in dentition of percoid fishes may affect the size and species of prey selected, thus influencing the fundamental trophic niche. To examine the influence of oral anatomy on prey selectivity by pinfish, Lagodon rhomboides, and snook, Centropomus undecimalis, two co-occurring percoid fishes with contrasting mouth morphologies, the mouth size, dentition, stomach contents, and available prey during ontogeny were quantified. Based on the presence of prey fragments in stomach contents and direct behavioral observation, prey were categorized by the feeding mode used during capture (suction/ramfeeding or biting). Centropomus has a larger size-specific gape than Lagodon during all ontogenetic stages. Although both feeding modes were used by Lagodon during ontogeny, the amount of prey captured using suction/ram-feeding declined and the amount of prey captured by biting increased with standard length. This change in feeding mode was associated with a change in incisor shape and width: Lagodon < 39 mm SL possessed narrow, pointed incisors and strongly selected amphipods, which are captured using suction/ram-feeding; Lagodon> 40 mm SL possessed wide, flat-topped incisors and significantly increased their selectivity for polychaetes, which are captured by biting. Centropomus used ram-feeding to capture prey at all ontogenetic stages. Size-selective feeding by Centropomus was apparent but could not be due to gape-limitation alone, because average prey body depth was only 45% of gape and was not proportional to absolute mouth size increase during ontogeny. Dietary diversity was greatest during the transition from suction/ram-feeding to biting in Lagodon. Lagodon had a higher dietary diversity at all ontogenetic stages than Centropomus, due in part to Lagodon's use of multiple feeding modes.  相似文献   

3.
The Marine Corps Recruit Depot on Parris Island, SC, is surrounded by tidal salt marshes, which are breeding habitats for many pestiferous biting flies. Knowledge of biting fly behavior patterns is needed to develop effective pest management strategies in urban areas adjacent to salt marshes. We measured biting midge (Ceratopogonidae) and mosquito (Culicidae) seasonal abundance and diel activity patterns on Parris Island using CO2‐baited suction traps from November 2001 – November 2004. Of the three biting midge species collected, Culicoides furens was most abundant (86.2% of total) and was present in high numbers from late March to November. Culicoides hollensis (12.0% of total) was present during spring and fall but absent in summer and winter; and Culicoides melleus (1.7% of total) was present in spring through fall but absent in winter. Abundance of C. furens had a positive linear correlation with air temperature and rainfall. There were nonlinear correlations between air temperature and C. hollensis and C. melleus numbers, which were most abundant at moderate temperatures. Of 18 mosquito species collected, the most abundant were Aedes taeniorhynchus (42.7% of total), Aedes sollicitans (26.3% of total), Culex salinarius (15.6% of total), Culex quinquefasciatus (7.3% of total), and Aedes vexans (5.7% of total); other species comprised <5% of collections. Aedes taeniorhynchus numbers were positively correlated with temperature and rainfall, and Cx. salinarius was correlated with soil moisture. Activity of most biting midges and mosquitoes were highest the first two hours following sunset. Species of biting flies were present in all months, suggesting that year‐round control measures are necessary to reduce exposure to potential disease vectors and nuisance biting.  相似文献   

4.
The abundance and host-seeking activity of the biting midge, Forcipomyia taiwana (Shiraki), were measured in Central Taiwan at 418 locations with low, medium, and high densities using a human-bait method. Abundance estimates at 10 min after sampling commenced were comparable to longer sampling periods of 20 min, allowing a shorter 10 min sampling period to be used throughout. Host-seeking F. taiwana females were only active during daylight and biting activity did not occur after sunset. The diurnal activity of host-seeking females changed seasonally, beginning at around 07:00–08:00 during the spring equinox, summer solstice, and autumnal equinox, whereas activity began an hour later in winter. Most females were collected during 10:00–16:00, with a peak abundance during 13:00–15:00. Blood-sucking activity of female F. taiwana were positively correlated with ambient temperature with a minimum threshold of 18 °C. When different years, seasons, trapping times, environmental factors, and female adults trapped were analyzed using multiple regression model, the results showed that all these factors contributed to the regression model and the determination coefficient (R2) of this multiple regression model was 0.81.  相似文献   

5.
The kinetics of the head and function of select jaw muscles were studied during biting behavior in the lemon shark, Negaprion brevirostris. High speed cinematography and electromyography of seven cranial muscles were recorded during bites elicited by a probe to the oral cavity. In weak bites mandible depression was followed by mandible elevation and jaw closure without cranial elevation. In strong bites cranial elevation always preceded lower jaw depression, lower jaw elevation, and cranial depression. The average duration of the strong bites was rapid (176 msec), considering the size of the animal relative to other fishes. Different electromyographic patterns distinguished the two forms of bite, primarily in activity of the epaxial muscles, which effect cranial elevation. A composite reconstruction of the activity of seven cranial muscles during biting revealed that epaxial muscle activity and consequently cranial elevation preceded all other muscle activity. Mandible depression was primarily effected by contraction of the common coracoarcual and coracomandibularis, with assistance by the coracohyoideus. Simultaneous activity of the levator hyomandibulae is believed to increase the width of the orobranchial chamber. The adductor mandibulae dorsal was the primary jaw adductor assisted by the adductor mandibulae ventral. This biomechanically conservative mechanism for jaw opening in aquatic vertebrates is conserved, with the exception of the coracomandibularis, which is homologous to prehyoid muscles of salamanders.  相似文献   

6.
To better understand how safety factors of biological structures evolve, we examined the frequency of claw failure, and the intra‐ and interspecific patterns of variation in maximum biting force and breaking strength in the claws of six species of Cancer (Linnaeus) crabs that live in sympatrv along the coast of the northeastern Pacific: C. antennarius, C. branneri, C. gracilis, C. maguter, C. oregonensis and C. productus. Although the breakage frequencies in natural populations were similar among species (6%), they were higher than predicted based on failure probabilities calculated from laboratory measurements of biting force and breaking strength for healthy pristine claws. The incidence of claw damage was correlated with the degree of wear, suggesting that claws later in the intermolt interval were more likely to fail. Within species, safety factors increased from 3.1 to 4.6 with increasing instar number due primarily to a decline in muscle stress (force per unit area of apodeme). Surprisingly, the lower maximum muscle stress generated by later instars appeared to be due to behavioral restraint, since it was not accompanied by relatively lower muscle mass. In addition, among individuals of the same claw size, lower breaking forces were correlated with lower maximum biting force, and both were correlated with lighter cuticle and closer muscle mass, suggesting a coupling that maintains a more stable safety factor over the moult cycle. In some species, size‐adjusted maximum biting forces were higher for males than females, but this paralleled differences in breaking strength, so safety factors did not differ between the sexes. Among the six Cancer species, one exhibited an unusually high safety factor (C. oregonensis, 7.4) and another an unusually low one (C. maguter, 2.6). The remaining four species were similar to each other and exhibited an intermediate safety factor (3.6). From a phylogenetic perspective, the species with more extreme safety factors appeared to be derived from a common ancestor with an intermediate safety factor. From an ecological perspective, species more closely associated with rocky substrata, and presumably a higher incidence of hard‐shelled prey, exhibited higher safety factors. But safety factors were also correlated with relative claw size, and sexual dimorphism in claw size. Although we cannot say whether habitat, diet or sexual selection are primarily responsible for the differences in safety factors observed among species, the cost of producing a relatively larger claw seems an unlikely explanation because safety‐factors did not differ between males and females in any of the sexually dimorphic species.  相似文献   

7.
Tetraodontiform fishes are characterized by jaws specialized for powerful biting and a diet dominated by hard-shelled prey. Strong biting by the oral jaws is an unusual feature among teleosts. We present a functional morphological analysis of the feeding mechanism of a representative tetraodontiform, Balistes vetula. As is typical for the order, long, sharp, strong teeth are mounted on the short, robust jaw bones of B. vetula. The neurocranium and suspensorium are enlarged and strengthened to serve as sites of attachment for the greatly hypertrophied adductor mandibulae muscles. Electromyographic recordings made from 11 cranial muscles during feeding revealed four distinct behaviors in the feeding repertoire of B. vetula. Suction is used effectively to capture soft prey and is associated with a motor pattern similar to that reported for many other teleosts. However, when feeding on hard prey, B. vetula directly bit the prey, exhibiting a motor pattern very different from that of suction feeding. During buccal manipulation, repeated cycles of jaw opening and closing (biting) were coupled with rapid movement of the prey in and out of the mouth. Muscle activity during buccal manipulation was similar to that seen during bite-captures. A blowing behavior was periodically employed during prey handling, as prey were forcefully “spit out” from the mouth, either to reposition them or to separate unwanted material from flesh. The motor pattern used during blowing was distinct from similar behaviors described for other fishes, indicating that this behaviors may be unique to tetraodontiforms. Thus B. vetula combines primitive behaviors and motor patterns (suction feeding and buccal manipulation) with specialized morphology (strong teeth, robust jaws, and hypertrophied adductor muscles) and a novel behavior (blowing) to exploit armored prey such as sea urchins molluscs, and crabs. © 1993 Wiley-Liss, Inc.  相似文献   

8.
Tail damage within the production of finisher pigs is an animal welfare problem. Recent research suggests that removal of known risk factors may not be enough to eliminate tail biting, especially in undocked pigs, thus a different strategy is worth investigating. This could be early detection of tail biting, using behavioural changes observed before tail damage. If these early stages of tail biting can be detected before tail damage occurs, then tail damage could be prevented by early interventions. The first step in developing such a strategy is to identify the types of behaviour changes that emerge during early stages of tail biting. Thus, the aim of the current study was to investigate whether pen level activity and object manipulation evolved differently during the last 7 days before the scoring of tail damage (day 0) for pens scored with tail damage (tail damage pens) and pens not scored with tail damage (matched control pens). The study included video recordings for twenty-four tail damage pens and thirty-two matched control pens. Activity level and object manipulation were observed the last 7 days before day 0 during the morning (0600 to 0800 h), afternoon (1600 to 1800 h) and evening (2200 to 2400 h, only activity level). Both activity level and object manipulation were analysed using generalised linear mixed effects models with a binomial distribution for activity level and a negative binomial distribution for object manipulation. The probability of being active was higher in tail damage pens compared to control pens during the afternoon the last 5 days before day 0 (P<0.001). This was seen due to a decrease in activity level in the control pens, which makes it difficult to identify future tail damage pens from this difference. Object manipulation was lower in tail damage pens compared to the control pens on all 7 days before day 0, but only in pens with undocked pigs (P<0.01). Thus, it is still unknown when this difference in object manipulation initiated. It was concluded that both activity level and object manipulation seemed related to ongoing tail biting and should be investigated through more detailed observations and for a longer time to establish the normal behaviour pattern for a particular pen. Thus, it is suggested that future research focusses on developing automatic monitoring methods for pen level activity and object manipulation and applies algorithms that establish and detect deviations from the normal behaviour pattern of the pen before tail damage.  相似文献   

9.
This study describes the sequence of behaviour during aggressive encounters between male ‘tizón’ lizards (G. galloti galloti) and assesses the effect of morphological and behavioural traits on the outcome and intensity of staged aggressive encounters between males. Aggressive encounters ranged from only throat extension to escalated fights with biting and rolling over. Winners were heavier, had longer heads, and performed tongue-flicking, throat extension and biting at a higher rate than losers. The rate of aggressive behaviour increased with decreasing difference in snout-to-vent length, head length and head width of the contestants. The results are in agreement with some predictions of the sequential assessment game model in that probability of victory increased with the difference in fighting ability and that the rate of aggressive behaviour was higher in contests between animals of similar size.  相似文献   

10.
Electromyographical (EMG) activity was recorded bilaterally from the masseter and temporalis muscles of alert ferrets (Mustela putorius furo) during mastication and crushing. Electromyographic activity was also recorded during biting while a bite-force transducer placed between the carnassial teeth registered forces ranging from 1.5 to 48.8 N. Linear regression analysis demonstrates that temporalis and masseter EMG activity are linearly related to bite force. Electromyographic activity from the balancing-side muscles is nearly equal to EMG activity of the working-side muscles during bone crushing with the carnassial teeth. It is hypothesized that a high percentage of balancing-side muscle activity in ferrets can be recruited during carnassial biting because the postglenoid process prevents ventral displacement of the working-side mandibular condyle.  相似文献   

11.
The physico-biological ecological complex in Plateau State has by definition increased the potential of most rivers to support the breeding and dispersal of vector species as well as human acquisition and dissemination of the disease for several months in a year. Though villagers in endemic areas are of the know of the nuisance of blackfly bites, but the majority of them lacked the aetiological knowledge of onchocercal lesion. Hence disease management is misdirected towards consulting the oracle and appeasing the gods. The vectors of onchocerciasis in Plateau State, S. damnosum, and S. sirbanum are wet season breeders with their peak biting density occurring at the height of rainy season. However, biting flies carry more infective parasites at the beginning and end of rain. These vectors exhibit bimodal biting activity: a small one in the morning hours and a pronounced evening peak. Biting activity is at least influenced by two major climatic factors; illumination and temperature. However, the fastest changing climatic factor relative to an increase in the biting activity of flies was illumination. Microfilarial load in the skin of patients does not significantly change throughout the year or when biopsies are taken under shade throughout the day. Extreme temperatures, however, have significant reducing effect on the skin microfilarial. The epidemiological relevance of these in the ongoing MECTIZAN delivery in the State are discussed.  相似文献   

12.
Environmental factors may strongly affect avian‐biting fly interactions in different ways because insects are heterothermic organisms that depend greatly on environmental variables to activate their metabolism and behaviour. We studied the effects of weather on both blackfly (Simuliidae) and biting midge Culicoides (Ceratopogonidae) abundance in nests of three passerine species: blue tits Cyanistes caeruleus, great tits Parus major and pied flycatchers Ficedula hypoleuca, breeding in the same area. We controlled for different host‐related factors (hatching date, brood size and host species). Blackfly abundance was negatively related to minimum temperature. In addition, blackfly and biting midge abundances were negatively affected by wind speed measured at 07.00 h, but blackfly abundance was positively associated to wind speed at 18.00 h. We found higher blackfly and biting midge abundances in nests with larger broods breeding later in the season, and significantly higher biting midge abundance in pied flycatcher nests as compared to tit nests. These results represent, to our knowledge, the first report of both environmental and host‐related effects on haematophagous fly abundance in the nests of wild hole‐nesting birds.  相似文献   

13.
Ixodes acutitarsus is said to be the largest Ixodes tick in the world. Human biting activity of I. acutitarsus was reported for the first time in Taiwan. Ticks were observed from April to December and collected from infested humans during trips to the mountainous areas of northern, central, southern and eastern Taiwan. Host range, seasonal prevalence, and the vectorial capacity of I. acutitarsus ticks for various human pathogens need to be further identified.  相似文献   

14.
Studies have demonstrated that electronic mosquito repellers are useless and that some of them could even increase the attraction of mosquitoes. While testing some electronic repellers, we noted that they also promoted an increase in biting rates. The present work has evaluated three commercial devices and a computer program working on five different sound frequencies. In a test chamber, the number of Aedes aegypti L. bite attempts was computed during four cycles of 3 min each by alternately turning the devices off and on. The mosquito biting rates for five sound frequencies (ranging from 9.6 kHz to 18.2 kHz) initially demonstrated a significant increase (ranging from around 20% to 50%), which decreased from 8.3% to 25.1% when the repellers were turned off. The biting rate significantly increased at 11.8 kHz (33.7%) when the device was turned on again. The danger of using electronic repellers and the role of sound frequencies stimulating mosquito biting are discussed.  相似文献   

15.
Monthly collections were made of man‐biting female blackflies: Simulium auripellitum Enderlein, S. guianense Wise, S. minusculum Lutz and S. nigrimanum Macquart (Diptera: Simuliidae) from four catching stations in the newly discovered focus of human onchocerciasis at Minaçu (13°35′ S 48°18′ W), 300 km north of Brasília in Goiás State. These provided baseline data on biting habits, population density and seasonal prevalence during the year before completion of the Serra da Mesa hydroelectric dam on the Rio Tocantins near Minaçu, in a project investigating the effect of dam construction on onchocerciasis transmission in the area. All four simuliid species were most abundant during the dry season, and only bit in low numbers (S. auripellitum S.minusculum, S. nigrimanum) or were absent (S. guianense) in the wet season. Simulium minusculum was the predominant species at all catching stations, being particularly abundant by the large River Tocantins. The other three species were mainly associated with smaller rivers. In the dry season, biting rhythms of S. minusculum varied with catching site, while S. nigrimanum showed peaks of activity in early morning and during the afternoon. Experimental infection with Onchocerca volvulus (Leuckart) (Nematoda: Onchocercidae), from a human volunteer, showed that this parasite could develop fully in the four simuliid species, which are all considered to be potential vectors in the area.  相似文献   

16.
17.
Analysis of synchronously recorded cine-radiographs and electromyograms in two rodents (Aplodontia rufa and Marmota monax) demonstrates that jaw movements and muscle activiteis during incisal functions are distinctly different from those found during mastication. Movements during incisal biting are primarily along the midline, accompanied by symmetrical activity of the jaw adductor muscles. Most biting cycles do not end in contact between upper and lower incisors. When contact does occur, the lower incisors are dragged along the lingual surfaces of the upper incisors. Cropping, or tip-to-tip occlusion of upper and lower incisors, was not observed. Sharpening of the lower incisors, a behavior which may be unique to the Rodentia, was recorded in both A. rufa and M. monax. During sharpening, the lingual surface of the lower incisor is dragged across the tip of the upper incisor producing a lingual wear facet. Like incisal biting, sharpening movements are primarily confined to the midline, although there may be lateral movements in some sharpening cycles. Sharpening cycles are among the most rapid cyclic movements recorded in mammals, as the mean frequencies of sharpening are 11 cycles/s in A. rufa and 8 cycles/s in M. monax. © 1995 Wiley-Liss, Inc.  相似文献   

18.
Abstract A longitudinal entomological and epidemiological study was conducted in five localities of southern Venezuela between January 1999 and April 2000 to determine the abundance, biting behaviour and parity of anopheline mosquitoes (Diptera: Culicidae) in relation to climate variables and malaria incidence. A total of 3685 female anopheline mosquitoes, representing six species, were collected. The most abundant species were Anopheles marajoara Galvão & Damasceno (60.7%) and Anopheles darlingi Root (35.1%), which together represented 95.8% of the total anophelines collected. Abundance and species distribution varied by locality. Malaria prevalence varied from 12.5 to 21.4 cases per 1000 population. Transmission occurred throughout the year; the annual parasite index (API) for the study period was 813.0 cases per 1000 population, with a range of 71.6?2492 per 1000 population, depending on locality. Plasmodium vivax (Grassi & Feletti) (Coccidia: Plasmodiidae) accounted for 78.6% of cases, Plasmodium falciparum (Welch) for 21.4% and mixed infections (Pv+Pf) for < 0.1%. Anopheles marajoara and An. darlingi were more abundant during the rainy season (April–September). There was no significant correlation (P > 0.05) between mosquito abundance and rainfall. Correlations between malaria incidence by parasite species and mosquito abundance were not significant (P > 0.05). Monthly parous rates were similar for An. marajoara and An. darlingi throughout the year, with two peaks that coincided with the dry?rainy transition period and the period of less rain. Peaks in the incidence of malaria cases were observed 1 month after major peaks in biting rates of parous anophelines. Anopheles darlingi engages in biting activity throughout the night, with two minor peaks at 23.00–00.00 hours and 03.00–04.00 hours. Anopheles marajoara has a different pattern, with a biting peak at 19.00?21.00 hours and 76.6% of biting occurring before midnight. Although both vectors bite indoors and outdoors, they showed a highly significant (P < 0.01) degree of exophagic behaviour. The present study constitutes the first effort to characterize the bionomics of anophelines in malaria endemic foci in different ecological situations in relation to malaria transmission in southern Venezuela and to provide relevant information to be considered when planning and implementing vector control programmes.  相似文献   

19.
The stable fly Stomoxys calcitrans (L.) is a cosmopolitan biting fly of both economic and welfare concern, primarily as a result of its painful bite, which can cause blood loss, discomfort and loss of productivity in livestock. Between June and November in 2016 and May and December in 2017, Alsynite sticky‐traps were deployed at four Donkey Sanctuary sites in southwest England, which experience recurrent seasonal biting fly problems. The aim was to evaluate the seasonal dynamics of the stable fly populations and the risk factors associated with abundance. In total, 19 835 S. calcitrans were trapped during the study period. In both years, abundance increased gradually over summer months, peaking in late August/September. There were no relationships between seasonally detrended abundance and any climatic factors. Fly abundance was significantly different between sites and population size was consistent between years at three of the four sites. The median chronological age, as determined by pteridine analysis of flies caught live when blood‐feeding, was 4.67 days (interquartile range 3.8–6.2 days) in males and 6.79 days (interquartile range 4.8–10.4 days) in females; there was no significant, consistent change in age or age structure over time, suggesting that adult flies emerge continuously over the summer, rather than in discrete age‐related cohorts. The data suggest that flies are more abundant in the vicinity of active animal facilities, although the strong behavioural association between flies and their hosts means that they are less likely to be caught on traps where host availability is high. The implications of these results for fly management are discussed.  相似文献   

20.
Summary The biting cycle of Armigeres subalbatus is distinctly crepuscular, exhibiting two peaks of activity, a smaller one at dawn and a larger one at dusk. The biting cycle is entrained to natural light-dark cycles and the time interval from dawn to dawn or dusk to dusk peaks is exactly 24 h and from dawn to dusk or dusk to dawn is about 12 h measured at 50% level. This rhythm manifests itself day after day without any marked qualitative change.The rate of change of light intensity may determine the onset of crepuscular biting. The sudden increase (up to ca. 17 lx) or decrease (down to ca. 4 lx) in the intensity of ambient light at the time of sunrise or sunset coincides with the peak of the biting activity.The density of the population of the host-seeking females fluctuates in relation to the phases of the moon, increasing with the full moon phase and decreasing with the new moon phase.Even though the density of the population is greater outdoors than indoors both at ground levels and in the first floor, the peak of activity occurs at the same time in all the places. A vertical stratification of biting activity was also noticed.  相似文献   

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