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1.
With few exceptions insects whose larvae develop in freshwater possess positive polarotaxis, i.e., are attracted to sources of horizontally polarized light, because they detect water by means of the horizontal polarization of light reflected from the water surface. These insects can be deceived by artificial surfaces (e.g. oil lakes, asphalt roads, black plastic sheets, dark-coloured cars, black gravestones, dark glass surfaces, solar panels) reflecting highly and horizontally polarized light. Apart from the surface characteristics, the extent of such a ‘polarized light pollution’ depends on the illumination conditions, direction of view, and the threshold p* of polarization sensitivity of a given aquatic insect species. p* means the minimum degree of linear polarization p of reflected light that can elicit positive polarotaxis from a given insect species. Earlier there were no quantitative data on p* in aquatic insects. The aim of this work is to provide such data. Using imaging polarimetry in the red, green and blue parts of the spectrum, in multiple-choice field experiments we measured the threshold p* of ventral polarization sensitivity in mayflies, dragonflies and tabanid flies, the positive polarotaxis of which has been shown earlier. In the blue (450 nm) spectral range, for example, we obtained the following thresholds: dragonflies: Enallagma cyathigerum (0% < p* ≤ 17%), Ischnura elegans (17% ≤ p* ≤ 24%). Mayflies: Baetis rhodani (32% ≤ p* ≤ 55%), Ephemera danica, Epeorus silvicola, Rhithrogena semicolorata (55% ≤ p* ≤ 92%). Tabanids: Tabanus bovinus, Tabanus tergestinus (32% ≤ p* ≤ 55%), Tabanus maculicornis (55% ≤ p* ≤ 92%).  相似文献   

2.
The horizontally polarizing surface parts of shiny black cars (the reflection-polarization characteristics of which are similar to those of water surfaces) attract water-leaving polarotactic insects. Thus, shiny black cars are typical sources of polarized light pollution endangering water-leaving insects. A new fashion fad is to make car-bodies matt black or grey. Since rough (matt) surfaces depolarize the reflected light, one of the ways of reducing polarized light pollution is to make matt the concerned surface. Consequently, matt black/grey cars may not induce polarized light pollution, which would be an advantageous feature for environmental protection. To test this idea, we performed field experiments with horizontal shiny and matt black car-body surfaces laid on the ground. Using imaging polarimetry, in multiple-choice field experiments we investigated the attractiveness of these test surfaces to various water-leaving polarotactic insects and obtained the following results: (i) The attractiveness of black car-bodies to polarotactic insects depends in complex manner on the surface roughness (shiny, matt) and species (mayflies, dolichopodids, tabanids). (ii) Non-expectedly, the matt dark grey car finish is much more attractive to mayflies (being endangered and protected in many countries) than matt black finish. (iii) The polarized light pollution of shiny black cars usually cannot be reduced with the use of matt painting. On the basis of these, our two novel findings are that (a) matt car-paints are highly polarization reflecting, and (b) these matt paints are not suitable to repel polarotactic insects. Hence, the recent technology used to make matt the car-bodies cannot eliminate or even can enhance the attractiveness of black/grey cars to water-leaving insects. Thus, changing shiny black car painting to matt one is a disadvantageous fashion fad concerning the reduction of polarized light pollution of black vehicles.  相似文献   

3.
In these experiments, oviposition by laboratory-reared Anopheles gambiae s.s. was as likely to occur from a vertical perch, as from a horizontal sitting position on a substrate of moist mud or open water. Tall cylinders with moist, dark walls provided an enclosed vertical resting surface from which An. gambiae deposited eggs. Similar numbers of eggs were deposited in these cylinders as on dark and moist horizontally-positioned ovipositional substrates. Likewise, An. gambiae oviposited equally from a vertical perch among emergent surrogate reeds vs. sitting horizontally on mud. Open ovipositional resources with exposed resting surfaces presenting 45°, 90°, and 135° angles relative to the cage floor received fewer eggs than a horizontally positioned, moist and dark ovipositional dish, even though more An. gambiae females settled on these angled resting surfaces post-oviposition. We conclude that vertical resting sites are adequate perches from which oviposition can occur if they provide high humidity and the paramount dark and wet ovipositional cues for An. gambiae oviposition.  相似文献   

4.
We reveal here the visual ecological reasons for the phenomenon that aquatic insects often land on red, black and dark-coloured cars. Monitoring the numbers of aquatic beetles and bugs attracted to shiny black, white, red and yellow horizontal plastic sheets, we found that red and black reflectors are equally highly attractive to water insects, while yellow and white reflectors are unattractive. The reflection-polarization patterns of black, white, red and yellow cars were measured in the red, green and blue parts of the spectrum. In the blue and green, the degree of linear polarization p of light reflected from red and black cars is high and the direction of polarization of light reflected from red and black car roofs, bonnets and boots is nearly horizontal. Thus, the horizontal surfaces of red and black cars are highly attractive to red-blind polarotactic water insects. The p of light reflected from the horizontal surfaces of yellow and white cars is low and its direction of polarization is usually not horizontal. Consequently, yellow and white cars are unattractive to polarotactic water insects. The visual deception of aquatic insects by cars can be explained solely by the reflection-polarizational characteristics of the car paintwork.  相似文献   

5.
Summary Light polarized by reflection was tested in the field for its attractiveness to flying insects. Attracted insects include bugs: some living in water (Corixidae, Notonectidae, Pleidae), others living on its surface (Gerridae) or near it (Saldidae). Beetles were also attracted: some are aquatic (Hydrophilinae, Dytiscidae, Haliplidae, Hydraenidae), others inhabit moist substrates (Sphaeridiinae). Also included are Chironomidae among other nematocerans. Non-polarized reflected light failed to attract any of these insects even at intensities far higher.Three response groups emerge. One is attracted whenever the degree of polarization is high in the UV-range, irrespectively of the degree of polarization in other wavelength ranges, and irrespectively of colour or brightness of the background beneath the polarizing, reflecting surface. The polarization vision of these insects operates in the UV-range. Another group was attracted only by the reflecting surface over a dark background, where the reflected light was highly polarized at all wave-lengths visible to insects. The third group ranges in between.Some Helophorus species behave in spring like members of the first group; in fall, like members of the second group.The distribution of the above response groups within various taxa is provided. Sensory mechanisms and eco-physiological implications are discussed.Abbreviations B matt black surface - b; y; w; a black, yellow white material and aluminum foil, reflection characteristics as described in the text; - G glass - G/b; G/y; G/w; G/a glass panes on different materials - Gb, y, w; Gb, y, Gb types of animals differing in behavior  相似文献   

6.
ABSTRACT

Stomatopod crustaceans have highly mobile, independently moving compound eyes that are sensitive to both linearly and circularly polarized light. They rotate their eyes to predictable angles when viewing a linearly polarized target, and they scan their eyes frequently to sample the visual field. Angles of scans are roughly perpendicular to the plane of the midband (a set of specialized parallel rows of equatorial ommatidia). We investigated scanning eye movements in one Caribbean stomatopod species (Neogonodactylus oerstedii) in uniform visual fields that were vertically polarized, horizontally polarized, or depolarized. We found that mean eye rotation and scan angles differed significantly among these different treatments. Average scan angles differed by 12°, being more horizontal in a vertically polarized field than in a horizontally polarized one, and also more horizontal in a vertically polarized field than in a depolarized field. Thus, these stomatopods adjusted visual scanning to the polarization of the visual environment.  相似文献   

7.
Ecological photopollution created by artificial night lighting can alter animal behavior and lead to population declines and biodiversity loss. Polarized light pollution is a second type of photopollution that triggers water-seeking insects to ovisposit on smooth and dark man-made objects, because they simulate the polarization signatures of natural water bodies. We document a case study of the interaction of these two forms of photopollution by conducting observations and experiments near a lamp-lit bridge over the river Danube that attracts mass swarms of the mayfly Ephoron virgo away from the river to oviposit on the asphalt road of the bridge. Millions of mayflies swarmed near bridge-lights for two weeks. We found these swarms to be composed of 99% adult females performing their upstream compensatory flight and were attracted upward toward unpolarized bridge-lamp light, and away from the horizontally polarized light trail of the river. Imaging polarimetry confirmed that the asphalt surface of the bridge was strongly and horizontally polarized, providing a supernormal ovipositional cue to Ephoron virgo, while other parts of the bridge were poor polarizers of lamplight. Collectively, we confirm that Ephoron virgo is independently attracted to both unpolarized and polarized light sources, that both types of photopollution are being produced at the bridge, and that spatial patterns of swarming and oviposition are consistent with evolved behaviors being triggered maladaptively by these two types of light pollution. We suggest solutions to bridge and lighting design that should prevent or mitigate the impacts of such scenarios in the future. The detrimental impacts of such scenarios may extend beyond Ephoron virgo.  相似文献   

8.
Photovoltaic solar panels represent one of the most promising renewable energy sources, but are strong reflectors of horizontally polarized light. Polarized light pollution (PLP) associated with solar panels causes aquatic insects to prefer to oviposit on panels over natural water bodies, with potential to negatively impact their global populations as solar energy expands. We evaluate the hypothesis that anti-reflective coatings (ARCs) used to increase the energy efficiency of solar panels will reduce the amount of PLP they reflect, and their attractiveness to aquatic insects. We created artificial test surfaces that mimicked the optical properties of coated and uncoated solar panels and exposed them to wild populations of polarotactic mayflies (Ephemeroptera), horseflies (Tabanidae) and non-biting midges (Chironomidae) used as indicators of PLP. We evaluated the reflection-polarization properties of test surfaces from four different angles of view and under sunny and overcast skies in the visible and ultraviolet parts of the spectrum. Matte (i.e. ARC-coated) sunlit solar panels were strong sources of horizontally polarized light only when the sun was afront and behind, in contrast to uncoated panels which exceeded common polarization-sensitivity thresholds for aquatic insects from all four viewing directions. As predicted by these polarization patterns, horsefly numbers and water-seeking behaviors were significantly reduced by ARCs. Under overcast skies, both matte and shiny (i.e. uncoated) panels were insect-detectible sources of PLP. Matteness modestly reduced the degree of polarization of reflected light, but not sufficiently such that fewer chironomids were attracted to them. Mayflies actually preferred matte panels under overcast skies. ARCs are most likely to reduce PLP and benefit aquatic insects under sunny skies and when used in conjunction with white non-polarizing gridding, but may actually exacerbate the severity of their negative effects under overcast conditions. Consequently, even current ARC technology has a role to play in aquatic insect conservation, but strategic deployment of solar panels away from water bodies and temperate regions may trump these benefits.  相似文献   

9.
A quantitative and qualitative survey was carried out for airborne fungus spores coming into contact with horizontally and vertically gravitation sampling oriented surfaces in the atmosphere of Giza city. Czapek Dox agar, malt extract agar, potato dextrose agar and Sabouraud dextrose agar Petri dishes were exposed monthly to the five oriented surfaces of a polystyrene cube, throughout a one-year period. Significant differences (P < 0.01) were observed between the total counts of caught airborne fungi contacting with the horizontal compared to other vertically oriented surfaces. Conversely, there were no significant differences observed between the total catch of airborne fungi using the various sampling media. The results revealed that vertical sampling provides valuable information that may be lost from horizontal sampling alone. A total of 5,053 colonies belonging to 40 fungal organisms were identified. Alternaria (24.26%), Aspergillus (19.2%), Cladosporium (14.5%) and Penicillium (11.43%) were the most predominant fungal genera. Collected fungi were grouped into high, medium, low and rare components depending upon their frequency in the studied atmosphere. Aspergillus niger, Aspergillus parasiticus, Alternaria, Cladosporium and Penicillium were regularly found on all oriented surfaces. However, Arthrobotrys, Biospora, Chaetomium, Pleospora, Trichothecium and Verticillium were rarely found in the air. Positive and/or negative correlations were observed between the total fungal counts and the predominant fungal types with meteorological parameters during sampling days.  相似文献   

10.
The present study aimed to evaluate the behaviour of larvae of Rhipicephalus microplus exposed to different stimuli. A Y-olfactometer was positioned vertically and R. microplus larvae were exposed to environmental air, CO2 alone, N,N-diethyl-3-methylbenzamide (DEET) alone, and CO2 combined with the repellents DEET and (E)-2-octenal. Tests were also conducted with the olfactometer positioned horizontally; in this case, however, only CO2 was tested. In all tests conducted with the Y-olfactometer positioned vertically, CO2 activated R. microplus larvae even in the presence of DEET and (E)-2-octenal, although activation was lower when these repellents were used. In the absence of CO2, larval behaviour against DEET was similar to that of the larvae in the control group. In the tests performed with the olfactometer positioned horizontally, the larvae had no significant response to the presence of CO2. The larvae were not attracted to or repelled by any compound tested in either the vertical or horizontal position of the olfactometer. The lack of horizontal displacement, attraction or repellence may have been a result of the ambush behaviour of this tick species. However, when larvae were exposed to stimuli and the olfactometer was positioned vertically, the interference of attractant and repellent stimuli in larval behaviour was assessed.  相似文献   

11.
The mechanisms of aposematism (unprofitability of prey combined with a conspicuous signal) have mainly been studied with reference to vertebrate predators, especially birds. We investigated whether dragonflies, Aeshna grandis, avoid attacking wasps, Vespula norwegica, which are an unprofitable group of prey for most predators. As a control we used flies that were painted either black or with yellow and black stripes. The dragonflies showed greater aversion to wasps than to flies. Black-and-yellow-striped flies were avoided more than black ones, suggesting that aposematic coloration on a harmless fly provides a selective advantage against invertebrate predators. There was no significant difference in reactions to black-painted and black-and-yellow wasps, indicating that, in addition to coloration, some other feature in wasps might deter predators. In further experiments we offered dragonflies artificial prey items in which the candidate warning signals (coloration, odour and shape) were tested separately while other confounding factors were kept constant. The dragonflies avoided more black-and-yellow prey items than solid black or solid yellow ones. However, we found no influence of wasp odour on dragonfly hunting. Dragonflies were slightly, but not significantly, more reluctant to attack wasp-shaped prey items than fly-shaped ones. Our results suggest that the typical black-and-yellow stripes of wasps, possibly combined with their unique shape, make dragonflies avoid wasps. Since black-and-yellow stripes alone significantly decreased attack rate, we conclude that even profitable prey species (i.e. Batesian mimics) are able to exploit the dragonflies' avoidance of wasps. Copyright 2003 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour.   相似文献   

12.
Suaeda salsa, a leaf succulent shrub in the family Chenopodiaceae, is one of the most important halophytes in China. Suaeda salsa produces dimorphic seeds (soft brown seeds and hard black seeds). Seeds of S. salsa were collected from the coastal salt flats near Huanghua City, China. Experiments were conducted to determine the salinity-alleviating effect of plant growth regulators, nitric oxide, nitrate, nitrite and light on the germination of dimorphic seeds of S. salsa. Brown seeds had a higher germination rate than black seeds in all experiments. Black seeds were more sensitive to salt in the absence of light in comparison to brown seeds. Brown seeds absorbed water more quickly in comparison to black seeds and were found to be more tolerant of salt stress. Our results showed that 1-aminocyclopropane-1-carboxylate (ACC, the immediate precursor of ethylene), nitrite, GA4 and BA improved seed germination in the presence of salt. However, nitrate, GA1, GA3 failed to alleviate salt stress. ABA inhibited seed germination and seedling growth. Possible mechanisms involved in the alleviation of salt stress in S. salsa seeds and the ecological adaptation of the seeds to the environment are discussed.  相似文献   

13.
14.
1. Previous studies in a variety of ecosystems have shown that ecologically and economically important benthic and bentho‐pelagic fishes avoid hypoxic (<2 mg O2 L?1) habitats by moving vertically or horizontally to more oxygenated areas. While avoidance of hypoxic conditions generally leads to a complete shift away from preferred benthic prey, some individual fish continue to consume benthic prey items in spite of bottom hypoxia, suggesting complex habitat utilisation and foraging patterns. For example, Lake Erie yellow perch (Perca flavescens) continue to consume benthic prey, despite being displaced vertically and horizontally by hypolimnetic hypoxia. 2. We hypothesised that hypolimnetic hypoxia can negatively affect yellow perch by altering their distribution and inducing energetically expensive foraging behaviour. To test this hypothesis, we used drifting hydroacoustics and trawl sampling to quantify water column distribution, sub‐daily vertical movement and foraging behaviour of yellow perch within hypoxic and normoxic habitats of Lake Erie’s central basin during August‐September 2007. We also investigated the effects of rapid changes in ambient oxygen conditions on yellow perch consumption potential by exposing yellow perch to various static and fluctuating oxygen conditions in a controlled laboratory experiment. 3. Our results indicate that, while yellow perch in general avoid hypoxic conditions, some individuals undertake foraging forays into hypoxic habitats where they experience greater fluctuations in abiotic conditions (pressure, temperature and oxygen concentration) than at normoxic sites. However, laboratory results suggest short‐term exposure to low oxygen conditions did not negatively impact consumption potential of yellow perch. 4. Detailed understanding of sub‐daily individual behaviours may be crucial for determining interactive individual‐ and ecosystem‐level effects of stressors such as hypoxia.  相似文献   

15.
In two laboratory experiments we tested juvenile yellow perch, Perca flavescens, for behavioural responses to alarm cues of injured conspecifics and several prey guild members: adult perch, Iowa darters, Etheostoma exile and spottail shiners, Notropis hudsonius. Spottail shiners are phylogenetically distant to yellow perch whereas Iowa darters and perch are both members of the Family Percidae. Groups of juvenile yellow perch increased shoal cohesion and movement towards the substrate after detecting conspecific alarm cues when compared to cues of injured swordtails, Xiphophorus helleri, a species phylogenetically distant from perch. Individual juvenile perch increased shelter use and froze more when exposed to chemical alarm cues from both juvenile and adult perch, shiners and darters compared to exposure to injured swordtail cues or distilled water. The response to cues of darters may indicate that alarm cues are evolutionarily conserved within percid fishes or that perch had learned to recognize darter cues. The response to spot tail shiners likely represents learned recognition of the cues of a prey guild member.  相似文献   

16.
The parasitic relationship between a black fly, Simulium annulus, and the common loon (Gavia immer) has been considered one of the most exclusive relationships between any host species and a black fly species. To test the host specificity of this blood‐feeding insect, we made a series of bird decoy presentations to black flies on loon‐inhabited lakes in northern Wisconsin, U.S.A. To examine the importance of chemical and visual cues for black fly detection of and attraction to hosts, we made decoy presentations with and without chemical cues. Flies attracted to the decoys were collected, identified to species, and quantified. Results showed that S. annulus had a strong preference for common loon visual and chemical cues, although visual cues from Canada geese (Branta canadensis) and mallards (Anas platyrynchos) did attract some flies in significantly smaller numbers.  相似文献   

17.
Turner AM  Chislock MF 《Oecologia》2007,153(2):407-415
Studies in lakes show that fish and crayfish predators play an important role in determining the abundance of freshwater snails. In contrast, there are few studies of snails and their predators in shallow ponds and marshes. Ponds often lack fish and crayfish but have abundant insect populations. Here we present the results of field surveys, laboratory foraging trials, and an outdoor mesocosm experiment, testing the hypothesis that insects are important predators of pulmonate snails. In laboratory foraging trials, conducted with ten species of insects, most insect taxa consumed snails, and larval dragonflies were especially effective predators. The field surveys showed that dragonflies constitute the majority of the insect biomass in fishless ponds. More focused foraging trials evaluated the ability of the dragonflies Anax junius and Pantala hymenaea to prey upon different sizes and species of pulmonate snails (Helisoma trivolvis, Physa acuta, and Stagnicola elodes). Anax junius consumed all three species up to the maximum size tested. Pantala hymenaea consumed snails with a shell height of 3 mm and smaller, but did not kill larger snails. P. acuta were more vulnerable to predators than were H. trivolvis or S. elodes. In the mesocosm experiment, conducted with predator treatments of A. junius, P. hymenaea, and the hemipteran Belostoma flumineum, insect predators had a pronounced negative effect on snail biomass and density. A. junius and B. flumineum reduced biomass and density to a similar degree, and both reduced biomass more than did P. hymenaea. Predators did not have a strong effect on species composition. A model suggested that A. junius and P. hymenaea have the largest effects on snail biomass in the field. Given that both pulmonate snails and dragonfly nymphs are widespread and abundant in marshes and ponds, snail assemblages in these water bodies are likely regulated in large part by odonate predation.  相似文献   

18.
Aggressive behavior of Pachydiplax longipennis during foraging was quantified by observing focal individuals on arrays of artificial perches. Pachydiplax apparently aggressively defend, for up to several hours at a time, one or a few feeding perches. Seventeen percent of all behaviors included agonistic actions, e.g., chasing or physical contact. The frequency of interactions was correlated positively with ambient temperature, solar radiation, prey density and density of other dragonflies. Both sexes initiated and responded to intra- and interspecific aggression; intraspecific interactions were more intense, however. Males had significantly higher interaction rates and fighting success than females, and intraspecific male–male contests were particularly intense. When prey were visibly localized, contest winners commonly gained perches closer to the prey swarm, and aggressive behavior was apparently correlated with feeding opportunity. Despite the frequency of aggression, these dragonflies allocated only about 19 s, on average, to agonistic behavior during 30-min observation periods. This and other costs appear small compared to foraging benefits of occupying a favorable perch, although at a very high interaction intensity high energy costs and lower intake reduce the net energy gain.  相似文献   

19.
The odonate larval communities in three small rivers in Penang Island were studied. More species of dragonflies were found in the Botanical Garden and Titi Teras rivers (13 and 11 respectively) of relatively similar environmental parameters. Fewer (nine) dragonfly species were collected from the Youth Park River which has a lower dissolved oxygen (DO) and a higher biological oxygen demand (BOD), conductivity and turbidity. A mixture of sand, gravel and pebble substrate of Botanical Garden River with dense growth of submerged Hydrilla, grasses and Cladias (Araceae) provided suitable habitats for the dragonflies. The sandy substrate and relatively fast flowing water of Titi Teras River was highly preferred by gomphids. In the Youth Park River, the small community of dragonfly larvae was dominated by tolerant Pseudagrion rubriceps, P. microcephalum, Orthetrum chrysis and Crocothemis servilia. Based on the larval instar distribution of Ictinogomphus decoratus and O. chrysis, very asynchronous populations of these dragonflies occurred in each river. Young larvae were continuously introduced into the populations resulting in undulating growth rate curves. The growth rates of these two species were higher in the Titi Teras River when compared to those in other rivers. Density-dependent mortality, asynchronous cannibalism and fish predation could play important roles in regulating the larval dragonfly population in these rivers.  相似文献   

20.
A new genus of broad‐nosed weevils belonging to the tribe Naupactini (Coleoptera: Curculionidae) is described, based on six species from the Páramo–Puna subregion (Andean region) of South America. Three species are new and three have been transferred from the genus Asymmathetes (Asymmathetes nigrans, Asymmathetes rugicollis, and Asymmathetes vulcanorum). The new genus is recognized by the black, denuded, and shiny tegument, the well‐developed pre‐epistome, the elytral base curved backwards on middle, the reduction of the hindwings, and the widely separated procoxae, closer to the anterior than to the posterior margin of the prosternum. A cladistic analysis of the six species of the new genus plus five out‐groups (Amitrus, Amphideritus, Asymmathetes, Melanocyphus, and Trichocyphus), using 49 morphological characters, resulted in a single cladogram. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166 , 54–71.  相似文献   

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