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Feeding Behaviour (feeding + behaviour)
Selected AbstractsOntogeny of Acoustic and Feeding Behaviour in the Grey Gurnard, Eutrigla gurnardusETHOLOGY, Issue 3 2005M. Clara P. Amorim Although sound production in teleost fish is often associated with territorial behaviour, little is known of fish acoustic behaviour in other agonistic contexts such as competitive feeding and how it changes during ontogeny. The grey gurnard, Eutrigla gurnardus, frequently emits knock and grunt sounds during competitive feeding and seems to adopt both contest and scramble tactics under defensible resource conditions. Here we examine, for the first time, the effect of fish size on sound production and agonistic behaviour during competitive feeding. We have made sound (alone) and video (synchronized image and sound) recordings of grey gurnards during competitive feeding interactions. Experimental fish ranged from small juveniles to large adults and were grouped in four size classes: 10,15, 15,20, 25,30 and 30,40 cm in total length. We show that, in this species, both sound production and feeding behaviour change with fish size. Sound production rate decreased in larger fish. Sound duration, pulse duration and the number of pulses increased whereas the peak frequency decreased with fish size, in both sound types (knocks and grunts). Interaction rate and the frequency of agonistic behaviour decreased with increasing fish size during competitive feeding sessions. The proportion of feeding interactions accompanied by sound production was similar in all size classes. However, the proportion of interactions accompanied by knocks (less aggressive sounds) and by grunts (more aggressive) increased and decreased with fish size, respectively. Taken together, these results suggest that smaller grey gurnards compete for food by contest tactics whereas larger specimens predominantly scramble for food, probably because body size gives an advantage in locating, capturing and handling prey. We further suggest that sounds emitted during feeding may potentially give information on the motivation and ability of the individual to compete for food resources. [source] Nociceptin/Orphanin FQ Peptide in Hypothalamic Neurones Associated with the Control of Feeding BehaviourJOURNAL OF NEUROENDOCRINOLOGY, Issue 2 2010N. Maolood Nociceptin/orphanin FQ (N/OFQ), an endogenous peptide agonist of the opioid N/OFQ receptor, has been implicated in the regulation of energy balance. In the present study, we have used immunohistochemistry to investigate the cellular localisation and colocalisation of N/OFQ-immunoreactive cell bodies in hypothalamic regions containing neurones producing orexigenic or anorexigenic transmitters. In colchicine-treated rats, N/OFQ immunoreactivity was demonstrated in many cell bodies of the arcuate nucleus (Arc), paraventricular nucleus (PVN) and lateral hypothalamic area (LHA). Double-labelling revealed that N/OFQ was present in some neurones located in the ventrolateral part of the Arc producing pro-opiomelanocortin, as shown by the presence of the anorexigenic peptides ,-melanocyte-stimulating hormone (,-MSH) and cocaine- and amphetamine-regulated transcript and, occasionally, in single neurones of the ventrolateral Arc producing orexigenic agouti-related peptide, but not neuropeptide Y. N/OFQ immunoreactivity was also demonstrated in a few tyrosine hydroxylase- or dynorphin (DYN)-containing neurones in the dorsomedial part of the Arc. In the parvocellular PVN, N/OFQ was demonstrated in some thyrotrophin-releasing hormone- or DYN-, but not corticotrophin-releasing hormone-containing neurones. Most N/OFQ-immunoreactive neurones in the LHA contained orexin- and DYN, but not melanin-concentrating hormone. The results obtained, demonstrating the presence of N/OFQ in some ,-MSH- and in many orexin-containing neurones, suggest a functional relationship between these neuropeptides and N/OFQ in the control of feeding behaviour and body weight. [source] Role of prey,host plant associations on Harmonia axyridis and Episyrphus balteatus reproduction and predatory efficiencyENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 1 2008Ammar Alhmedi Abstract In order to predict possible locations of Harmonia axyridis Pallas (Coleoptera: Coccinellidae) and Episyrphus balteatus DeGeer (Diptera: Syrphidae) in the field, we studied their oviposition and prey preferences in relation to several host plant,prey associations under laboratory conditions. Oviposition preference of H. axyridis and E. balteatus females was determined for three aphid (Homoptera: Aphididae),host plant associations: Microlophium carnosum Buckton on stinging nettle [Urtica dioica L. (Urticaceae)], Acyrthosiphon pisum Harris on green pea [Pisum sativum L. (Fabaceae)], and Sitobion avenae F. on wheat [Triticum aestivum L. (Poaceae)]. Prey preference of H. axyridis and E. balteatus larvae was determined with the aphids M. carnosum, A. pisum, and S. avenae. Harmonia axyridis females showed a strong oviposition preference for the stinging nettle,M. carnosum association. The preferred association for ovipostion by E. balteatus was pea-hosting A. pisum, on which fecundity was also highest. Feeding behaviour was less restricted in H. axyridis, in which the preferred preys were M. carnosum and S. avenae. A lower specificity of predation was observed in E. balteatus larvae with respect to A. pisum. These laboratory experiments may help us to understand the spatial distribution of H. axyridis and E. balteatus in the field. [source] Feeding studies on gynoparae, males and apterous virginoparae of Myzus persicae on potato by electrical penetration graphJOURNAL OF APPLIED ENTOMOLOGY, Issue 8 2004J. T. Margaritopoulos Abstract:, Feeding behaviour of parthenogenetic apterae, post-teneral gynoparae and males of a holocyclic parthenogenetic lineage of Myzus persicae (Sulzer) (Hem., Aphididae) was studied on potato plants, Solanum tuberosum L. (Solanaceae) by DC-electrical penetration graph recording. Differences were observed between morphs during the 7-h recordings, specifically in the first phase of subcuticular probing and in xylem and phloem-related activities. The time required for the first penetration and first cell puncture of the non-vascular tissues was shorter in apterae than in gynoparae and males. Apterae more often showed phloem activities and sustained sap ingestion (100%) than winged morphs (ca. 25%). In addition, phloem ingestion was much longer in apterae than in winged morphs, 3458 s and 25,70 s respectively. In contrast, winged morphs spent 14,21% of the available time ingesting sap from xylem while in apterae xylem sap uptake was only for 2% of the time. Furthermore, the data showed that males perform in general all the feeding behaviours that other conspecific morphs exhibit. The differences in feeding behaviour among morphs of M. persicae are discussed in relation to host specialization and to their possible involvement in non-persistent transmission of viruses. [source] Observations on feed size and capture success in the larval butterfly splitfin (Ameca splendens Miller & Fitzsimons, 1971, Pisces: Goodeidae) reared on zooplanktonJOURNAL OF APPLIED ICHTHYOLOGY, Issue 3 2007F. Peña-Aguado Summary In this study, we quantified the feeding behaviour (encounter, attack, capture. and ingestion) of larval A. splendens on micro-crustacean prey [cladocerans: Alona rectangula, Simocephalus vetulus (separately neonates and adults), Ceriodaphnia dubia, Daphnia pulex (juveniles), Moina macrocopa and ostracods: Heterocypris incongruens]. Although we initially (first 4 weeks) offered rotifers (Brachionus calyciflorus and B. patulus), they were not consumed by the larvae and hence observations with these prey were discontinued. Feeding behaviour was observed during the first 10 weeks. Fifteen observations were made with each prey species (seven diets × four replicates). Experiments were conducted in 50 ml transparent containers with 20 ml fish-conditioned water into which one fry was introduced. Before introducing the fish, 20 individuals of a given cladoceran prey species or 50 individuals of a rotifer prey species were introduced. Until the fourth week, we used 20 ml of medium and thereafter 30 ml, but the prey density used remained constant (1 ind. ml,1). Observations (10 min per fry per cladoceran replicate) were taken under a stereomicroscope (20×) for the first 2 weeks and later with a lamp and a magnifying lens. The number of encounters (E), attacks (A), captures (C) and ingestions (I) were recorded. During the study period, there was a 60% increase in gape size but only a 30% increase in body length. The number of encounters of larval A. splendens was highest (192) on M. macrocopa and lowest (29) on ostracods and adult S. vetulus (59). The inverse relationship between capture success and prey size was more pronounced during the latter half of the study period. Compared with all the other prey types offered, A. splendens fed maximally on M. macrocopa, which therefore could be a suitable diet for the larval rearing of this fish species. [source] Effects of environmental variables on fish feeding ecology: implications for the performance of baited fishing gear and stock assessmentJOURNAL OF FISH BIOLOGY, Issue 6 2004A. W. Stoner The effectiveness of baited fishing gear ultimately depends upon behaviour of the target species , activity rhythms, feeding motivation, and sensory and locomotory abilities. While any environmental parameter that mediates feeding or locomotion can have an important influence on the active space presented by the bait and fish catchability, few biologists have considered how such variation in behaviour might affect catch per unit effort (CPUE) and the resultant stock abundance estimates or population parameters. This review reveals that environment-related variation in feeding behaviour can act through four different mechanisms: metabolic processes, sensory limitations, social interactions and direct impacts. Water temperature, light level, current velocity and ambient prey density are likely to have largest effects on fish catchability, potentially affecting variation in CPUE by a factor of ten. Feeding behaviour is also density-dependent, with both positive and negative effects. Over time and geographic space a target species can occupy wide ranges of environmental conditions, and in certain cases, spatial and temporal variation in feeding biology could have a larger impact on CPUE than patterns of abundance. Temperature, light and current can be measured with relative facility and corrections to stock assessment models are feasible. Making corrections for biological variables such as prey density and bait competitors will be more difficult because the measurements are often not practical and relationships to feeding catchability are more complex and poorly understood. There is a critical need for greater understanding of how environmental variables affect feeding-related performance of baited fishing gear. A combination of field observations and laboratory experiments will be necessary to parameterize stock assessment models that are improved to accommodate variation in fish behaviour. Otherwise, survey data could reveal more about variation in behaviour than abundance trends. [source] Safety of meloxicam to critically endangered Gyps vultures and other scavenging birds in IndiaANIMAL CONSERVATION, Issue 2 2007D. Swarup Abstract Widespread veterinary use of the non-steroidal anti-inflammatory drug diclofenac is responsible for the population collapse of three species of Gyps vulture in south Asia; these species are now critically endangered. Vultures die when they consume carcasses of livestock that contain lethal residues of diclofenac. National and international conservation organizations have urgently recommended that diclofenac be banned and replaced with alternative drugs that are relatively safe to Gyps vultures and other scavenging birds. We tested the safety of the NSAID meloxicam on the oriental white-backed vulture, long-billed vulture and a range of other scavenging birds in India (Egyptian vulture Neophron percnopterus, cattle egret Bubulcus ibis, house crow Corvus splendens, large-billed crow Corvus machrorhynchos and common mynah Acridotheres tristis). Meloxicam was administered by oral intubation [at 0.5 and 2.0 mg kg,1 vulture body weight (bw)], or through feeding with muscle or liver tissue (at 0.3 to 2.1 mg kg,1 vulture bw) from meloxicam-treated buffalo Bubalus bubalis. We estimate that 2.0 mg kg,1 bw is the maximum likely exposure in the wild. All 31 Gyps vultures and the 20 other scavenging birds given meloxicam survived. Feeding behaviour remained normal and there were no significant differences between the treated and control groups in body mass, or the blood haematology and biochemistry parameters monitored, including those known to be affected by diclofenac (uric acid levels and alanine transferase activity). Meloxicam is used to treat a wide range of livestock ailments and is licensed and manufactured in India. We recommend that meloxicam be introduced as rapidly as possible across the Indian sub-continent as an alternative to diclofenac. [source] Daily activity budget of captive and released Scarlet macaw Ara macao at Playa San Josecito Release Site, Costa RicaINTERNATIONAL ZOO YEARBOOK, Issue 1 2005J. CORNEJO Baseline data for 17 behaviours grouped into six categories were collected for ten captive and nine soft-released Scarlet macaws Ara macao, in order to analyse daily activity budgets. Most of the birds were captive-bred and hand-reared. The captive birds spent less time on Socializing and Feeding behaviours than the released birds but spent more time on Maintenance behaviour and No Activity. The observation protocol developed here is a useful tool for monitoring the birds during pre-release training and, once released, to determine quantitatively whether a bird was properly prepared for survival in the wild. [source] Hypocretin/orexin in fish physiology with emphasis on zebrafishACTA PHYSIOLOGICA, Issue 3 2010P. Panula Abstract One hypocretin/orexin (hcrt) gene has been identified in several fish species. The first pufferfish gene was identified in 2002 and the zebrafish gene was cloned in 2004. Its structure is very similar to that of mammals, and it encodes for two active peptides with C-termini similar to those of mammals. The gene is expressed in the brain in only one hypothalamic nucleus, which sends projections to the telencephalon, diencephalon, mesencephalon and rhombencephalon. The terminal fibres are found in close contact with many aminergic cell groups, including those of raphe serotonergic, locus coeruleus noradrenergic, several dopaminergic cell groups and the sole histaminergic hypothalamic cluster. One receptor corresponding to mammalian hcrt 2 receptor has been identified in fish. Overexpression of hcrt in zebrafish has been reported to consolidate wakefulness and inhibit rest. On the other hand, fish lacking the hcrt receptor show short and fragmented sleep instead of sleepiness and cataplexy. Food deprivation increases hcrt mRNA expression in zebrafish brain, and intracerebroventricular hcrt peptides stimulate food consumption and feeding behaviour in goldfish. Hcrt peptides thus have important roles in fish physiology. Many genetic and functional methods available render fish, especially zebrafish, a suitable organism to study new aspects of hcrt physiology in vertebrates. [source] Possible common central pathway for resistin and insulin in regulating food intakeACTA PHYSIOLOGICA, Issue 4 2009C. Cifani Abstract Aim:, Adipose tissue has been the object of intense research in the field of obesity and diabetes diseases in the last decade. Examination of adipocyte-secreted peptides led to the identification of a unique polypeptide, resistin (RSTN), which has been suggested as a link between obesity and diabetes. RSTN plays a clearly documented role in blocking insulin (INS)-induced hypoglycaemia. As brain injection of INS affects feeding behaviour, we studied the possible interaction between INS and RSTN in food-deprived rats, measuring effects on food intake. In addition, we examined how RSTN might affect neuropeptide Y (NPY)-induced feeding, as studies have shown that rat RSTN can interfere with the NPY system. Methods:, Overnight food-deprived rats were injected into the third brain ventricle (3V) with either INS (10 or 20 mUI), RSTN (0.1,0.4 nmol/rat), or saline before access to food. Another group of rats was injected into the 3V with RSTN alone, NPY alone or RSTN plus NPY. Their food intake and body weight were measured. Results:, Our results confirm the hypophagic effect of RSTN on food deprivation-induced food intake, and more importantly, show that RSTN neither potentiates nor blocks the effects of INS on food intake, but does reduce the hyperphagic effect of NPY. Conclusion:, The observation that RSTN does not modify feeding INS-induced hypophagia, but does influence NPY-induced feeding, points to the possibility that RSTN may be involved in control of food intake through an NPY-ergic mechanism as INS. [source] Fragmentation, habitat composition and the dispersal/predation balance in interactions between the Mediterranean myrtle and avian frugivoresECOGRAPHY, Issue 1 2010Juan P. González-Varo Human-induced fragmentation and disturbance of natural habitats can shift abundance and composition of frugivore assemblages, which may alter patterns of frugivory and seed dispersal. However, despite their relevance to the functioning of ecosystems, plant-frugivore interactions in fragmented areas have been to date poorly studied. I investigated spatial variation of avian frugivore assemblages and fruit removal by dispersers and predators from Mediterranean myrtle shrubs (Myrtus communis) in relation to the degree of fragmentation and habitat features of nine woodland patches (72 plants). The study was conducted within the chronically fragmented landscape of the Guadalquivir Valley (SW Spain), characterized by ~1% of woodland cover. Results showed that the abundance and composition of the disperser guild was not affected by fragmentation, habitat features or geographical location. However, individual species and groups of resident/migrant birds responded differently: whereas resident dispersers were more abundant in large patches, wintering dispersers were more abundant in fruit-rich patches. Predator abundances were similar between patches, although the guild composition shifted with fragmentation. The proportion of myrtle fruits consumed by dispersers and predators varied greatly between patches, but did not depend on bird abundances. The geographical location of patches determined the presence or absence of interactions between myrtles and seed predators (six predated and three non-predated patches), a fact that greatly influenced fruit dispersal success. Moreover, predation rates were lower (and dispersal rates higher) in large patches with fruit-poor heterospecific environments (i.e. dominated by myrtle). Predator satiation and a higher preference for heterospecific fruits by dispersers may explain these patterns. These results show that 1) the frugivore assemblage in warm Mediterranean lowlands is mostly composed of fragmentation-tolerant species that respond differently to landscape changes; and 2) that the feeding behaviour of both dispersers and predators influenced by local fruit availability may be of great importance for interpreting patterns of frugivory throughout the study area. [source] Vector within-host feeding preference mediates transmission of a heterogeneously distributed pathogenECOLOGICAL ENTOMOLOGY, Issue 3 2010MATTHEW P. DAUGHERTY 1. Ecological theory predicts that vector preference for certain host species or discrimination between infected versus uninfected hosts impacts disease incidence. However, little information exists on the extent to which vector within-host feeding preference mediates transmission. This may be particularly important for plant pathogens, such as sharpshooter transmission of the bacterium Xylella fastidiosa, which are distributed irregularly throughout hosts. 2. We documented the within-host distribution of two vector species that differ in transmission efficiency, the leafhoppers Draeculacephala minerva and Graphocephala atropunctata, and which are free to move throughout entirely caged alfalfa plants. The more efficient vector D. minerva fed preferentially at the base of the plant near the soil surface, whereas the less efficient G. atropunctata preferred overwhelming the top of the plant. 3. Next we documented X. fastidiosa heterogeneity in mechanically inoculated plants. Infection rates were up to 50% higher and mean bacterial population densities were 100-fold higher near the plant base than at the top or in the taproot. 4. Finally, we estimated transmission efficiency of the two leafhoppers when they were confined at either the base or top of inoculated alfalfa plants. Both vectors were inefficient when confined at the top of infected plants and were 20,60% more efficient when confined at the plant base. 5. These results show that vector transmission efficiency is determined by the interaction between leafhopper within-plant feeding behaviour and pathogen within-plant distribution. Fine-scale vector and pathogen overlap is likely to be a requirement generally for efficient transmission of vector-borne pathogens. [source] Being a generalist herbivore in a diverse world: how do diets from different grasslands influence food plant selection and fitness of the grasshopper Chorthippus parallelus?ECOLOGICAL ENTOMOLOGY, Issue 2 2010ALEXANDRA FRANZKE 1. Generalist insect herbivores occupy a variety of habitats that differ in food plant composition. Dietary mixing has been proposed as a possibility for generalists to overcome nutritional deficiencies of single plant species, but only a few studies have investigated herbivore feeding and fitness for diets that resemble natural scenarios. We studied feeding behaviour, survival, and reproduction of the generalist grasshopper Chorthippus parallelus raised on food plants of four typical habitats. 2. Grasshopper diet consisted of grasses (92.5%), legumes (6.7%) and, in small quantities, other forbs (0.8%). Diet selection differed between the four food plant mixtures, and depended on grasshopper sex and developmental stage. There was no correlation between the relative abundance of plant species in the field and the fraction of these species in the grasshopper diet. 3. Grasshoppers survived on average for 40.4 ± 1.0 days before maturity, grew 106.8 mg until maturity moult, and females laid 4.1 ± 0.4 egg pods, each of which contained 8.5 ± 0.4 eggs. However, despite the differences in feeding behaviour, grasshopper fitness was the same in all of the four food plant mixtures. While the digestibility of ingested food was similar in the four different treatments, indices indicated differences in the conversion efficiency to body mass. 4. Our results show that C. parallelus is a plastic feeder with no fixed preferences in diet composition. The results emphasise that generalist herbivores can counteract putative quality deficiencies of single food plants by selective dietary mixing. [source] Herbivore control of annual grassland composition in current and future environmentsECOLOGY LETTERS, Issue 1 2006Halton A. Peters Abstract Selective consumption by herbivores influences the composition and structure of a range of plant communities. Anthropogenically driven global environmental changes, including increased atmospheric carbon dioxide (CO2), warming, increased precipitation, and increased N deposition, directly alter plant physiological properties, which may in turn modify herbivore consumption patterns. In this study, we tested the hypothesis that responses of annual grassland composition to global changes can be predicted exclusively from environmentally induced changes in the consumption patterns of a group of widespread herbivores, the terrestrial gastropods. This was done by: (1) assessing gastropod impacts on grassland composition under ambient conditions; (2) quantifying environmentally induced changes in gastropod feeding behaviour; (3) predicting how grassland composition would respond to global-change manipulations if influenced only by herbivore consumption preferences; and (4) comparing these predictions to observed responses of grassland community composition to simulated global changes. Gastropod herbivores consume nearly half of aboveground production in this system. Global changes induced species-specific changes in plant leaf characteristics, leading gastropods to alter the relative amounts of different plant types consumed. These changes in gastropod feeding preferences consistently explained global-change-induced responses of functional group abundance in an intact annual grassland exposed to simulated future environments. For four of the five global change scenarios, gastropod impacts explained > 50% of the quantitative changes, indicating that herbivore preferences can be a major driver of plant community responses to global changes. [source] Alternative use of food resources causes intra-cohort variation in the size distribution of young-of-the-year perch (Perca fluviatilis)ECOLOGY OF FRESHWATER FISH, Issue 3 2008R. Urbatzka Abstract,,, Body sizes of young-of-the-year (YOY) perch (Perca fluviatilis) at the end of their first summer are extremely variable and range in different studies between 4 and 15 cm. To analyse whether size divergences in YOY perch may be attributed to alternative use of food resources, adult perch were stocked into two previously fishless ponds and growth, size distribution and food intake of the YOY perch were recorded. In addition to perch, adult bream (Abramis brama) were introduced to produce juvenile bream that could serve as a food resource for YOY perch. The body sizes of YOY perch at the end of the experiment ranged from 32 to 168 mm with a bimodal size distribution. The combination of stomach content analyses and stable isotope signatures revealed that the small size cohort were planctivorous/benthivorous while the large size cohort was piscivorous/cannibalistic. Results implicated that different feeding behaviour contributed to the size divergences in YOY perch and that the extreme growth of the large size cohort was induced by piscivory. [source] Effects of predator-induced visual and olfactory cues on 0+ perch (Perca fluviatilis L.) foraging behaviourECOLOGY OF FRESHWATER FISH, Issue 2 2006V. N. Mikheev Abstract,,, Foraging juvenile fish with relatively high food demands are usually vulnerable to various aquatic and avian predators. To compromise between foraging and antipredator activity, they need exact and reliable information about current predation risk. Among direct predator-induced cues, visual and olfactory signals are considered to be most important. Food intake rates and prey-size selectivity of laboratory-reared, naive young-of-the-year (YOY) perch, Perca fluviatilis, were studied in experiments with Daphnia magna of two size classes: 2.8 and 1.3 mm as prey and northern pike, Esox lucius, as predator. Neither total intake rate nor prey-size selectivity was modified by predator kairomones alone (water from an aquarium with a pike was pumped into the test aquaria) under daylight conditions. Visual presentation of pike reduced total food intake by perch. This effect was significantly more pronounced (synergistic) when visual and olfactory cues were presented simultaneously to foraging perch. Moreover, the combination of cues caused a significant shift in prey-size selection, expressed as a reduced proportion of large prey in the diet. Our observations demonstrate that predator-induced olfactory cues alone are less important modifiers of the feeding behaviour of naive YOY perch than visual cues under daylight conditions. However, pike odour acts as a modulatory stimulus enhancing the effects of visual cues, which trigger an innate response in perch. [source] Lost zooplanktivorous cichlid from Lake Victoria reappears with a new tradeECOLOGY OF FRESHWATER FISH, Issue 4 2003E. F. B. Katunzi Abstract,,, The zooplanktivorous cichlid Haplochromis pyrrhocephalus, which was one of the most common haplochromine species in the Mwanza Gulf of Lake Victoria, had almost completely disappeared after the Nile perch upsurge in the 1980s. In the second half of the 1990s, this species suddenly reappeared in the strongly changed ecosystem. Gut content investigation revealed a change in diet. Currently, H. pyrrhocephalus eats large prey more frequently than in the past. These large prey comprise fish, shrimps and molluscs. The latter two were never encountered in specimens from the past. Particularly feeding on molluscs was unexpected, as it had been suggested that, because of anatomical constraints, molluscivory and zooplanktivory are incompatible in cichlid fish. Our observations provide a new example of the extreme versatility in feeding behaviour in haplochromine cichlids. [source] Host plant changes produced by the aphid Sipha flava: consequences for aphid feeding behaviour and growthENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2002W.L. Gonzáles Abstract Induced plant responses may affect the behaviour and growth of the attacking herbivore insect. The aphid Sipha flava (Forbes) produces reddish spots on the infested leaf of its host plant Sorghum halepense (L.). In order to assess the consequences on the aphid of this presumptive induced plant response, we studied the feeding behaviour and growth of S. flava on previously infested and non-infested leaves of S. halepense. Considering that the reddish pigment could play a defensive role, its effect on aphid survival was determined in artificial diets. In addition, changes in the histology of the leaf and the chemical nature of the induced pigment were also studied. Aphids devoted a significantly shorter total time to non-penetration activities in infested than in non-infested leaves. Time before the first phloem ingestion tended to be shorter in infested leaves. The mean relative growth rate of S. flava nymphs was significantly higher on infested than on non-infested leaves. Survival of aphids on diet containing the reddish extract was not significantly different from that on the control diet. Infestation of S. halepense by S. flava produced a reddish coloration in the leaf, which was identified as an anthocyanin by UV-visible spectrometry. Light microscopy showed that only mesophyll cells of previously infested plants presented swelled, dispersed, and heterogeneously stained chloroplasts with a higher accumulation of starch granules, no grana arranged in stacks, and reduction in the amount of inner membranes (thylakoids), relatively to chloroplasts of non-infested leaves. Scanning electron micrographs of leaf surface revealed reduced presence of crystalline epicuticular waxes of epidermal cells in infested leaves as compared to non-infested ones. The main conclusion is that the attack of S. flava to S. halepense leaves induced plant susceptibility where aphid feeding behaviour and growth were both enhanced on previously infested leaves. [source] The influence of ant-attendance on aphid behaviour investigated with the electrical penetration graph techniqueENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 1 2002Gisep Rauch Abstract For the mutualistic interaction between the aphid Metopeurum fuscoviride Stroyan (Homoptera: Aphididae) and the ant Lasius niger L. (Hymenoptera: Formicidae) it has been shown that ant-tended aphids develop faster, reproduce at a higher rate, and live longer than aphids not tended by ants. We used electrical penetration graphs (EPG) to investigate if behavioural patterns differ between ant-tended and untended M. fuscoviride during 8 h experiments. Measurements were made on adult aphids from four different ant-tended colonies that continued to be tended by L. niger during the experiments, and from four different colonies where ant workers were excluded several days before the start of the experiment and that were also not tended by ants during the experiments. Ants readily tended wired aphids and ant tending did not interfere with the EPG measurements. There were no significant differences in the duration of sieve element penetration or in any other analysed feeding-related EPG parameters between ant-tended and untended individuals. However, the quality of the EPG recordings did not allow the distinction between the EPG-waveform E1 (salivation only) and E2 (salivation and ingestion). These results suggest that the changes in life-history traits of ant-tended aphids do not result from changes in time of sieve element penetration waveforms. Alternative mechanisms may involve an increase in the rate of sap uptake or a higher effectiveness in nutrient uptake in the presence of ants. Our study demonstrates that the EPG technique is a useful tool to investigate the feeding behaviour of aphids during interactions with ants. [source] Analysis by DC,EPG of the resistance to Bemisia tabaci on an Mi -tomato lineENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2001Y.X. Jiang Abstract The tomato Mi gene confers resistance to nematodes, Meloidogyne spp., and to the potato aphid, Macrosiphum euphorbiae (Thomas). Previous greenhouse choice assays with Bemisia tabaci (Gennadius) showed that tomato commercial varieties carrying this gene had significantly lower values of host suitability and whitefly reproduction than varieties lacking Mi. This indicated that Mi, or another gene in its region, could regulate partial resistance. In order to characterise this resistance, probing and feeding behaviour of Bemisia tabaci B-biotype was studied with DC Electrical Penetration Graph (EPG) technique on the near-isogenic tomato lines Moneymaker (without Mi) and Motelle (carrying Mi). Significant differences (P < 0.05) between tomato lines were found in EPG parameters related to epidermis and/or mesophyll tissues. On Motelle, a lower percentage of whiteflies achieved phloem phase and they made more probes before attaining first phloem phase, had a higher ratio (number of probes before first phloem phase)/(total number of probes), had a longer total duration of non-probing time, and a longer time before making the first intracellular puncture and before making the first phloem phase. In contrast, most of the parameters related to phloem phase were found not to differ significantly between these near-isogenic lines. The behavioural data strongly suggest that the partial resistance in the variety Motelle is due to factors in the epidermis and/or mesophyll that inhibit the whiteflies from reaching phloem sieve elements. However, once the stylets reach a sieve element, whitefly behaviour did not differ between the two varieties. Thus, phloem sap of the two varieties appears to be equally acceptable to the whiteflies. Further studies are necessary to provide a better understanding of these mechanisms of resistance to whiteflies in tomatoes. [source] Influence of parasitism by encyrtid parasitoids on the feeding behaviour of the cassava mealybug Phenacoccus herreniENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2001P.-A. Calatayud Abstract Three encyrtid parasitoids Apoanagyrus (Epidinocarsis) diversicornis, Aenasius vexans, and Acerophagus coccois (Hymenoptera: Encyrtidae) are used to control the cassava mealybug Phenacoccus herreni Cox & Williams (Sternorrhyncha: Pseudococcidae), an important pest of cassava in South America. The influence of parasitism on the feeding behaviour of mealybugs was studied by observing honeydew secretion and by the electrical penetration graph technique (EPG, DC-system). Honeydew secretions were observed after parasitism until mummy transformation. No strong EPG parameter differences were found between parasitised and control insects. All results indicated that parasitised mealybugs keep feeding on the phloem sap after parasitism until mummy transformation. The main influence of parasitism on EPG parameters is the appearance of a new pattern resembling the E2 pattern at the extracellular level and labelled H. This pattern was also produced with control insects located on an unfavourable feeding site and could be associated with a stress response. It might be related to the still unclear E(c) pattern of aphids. The relationship of H to stylet activities is discussed. [source] Behavioural observations of Pieris brassicae larvae indicate multiple mechanisms of action of analogous drimane antifeedantsENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2000L. Messchendorp Abstract We tested 11 analogous synthetic drimane antifeedant compounds for their feeding inhibiting effects on larvae of the large white butterfly Pieris brassicae L. (Lepidoptera: Pieridae) in no-choice tests on the host plant Brassica oleracea L. Furthermore, we observed larval feeding behaviour in no-choice tests to analyze temporal effects of five drimanes. The results show that the five analogous antifeedants differentially influence feeding behaviour and locomotion activity. Warburganal and polygodial are most likely sensory mediated antifeedants. Habituation to these compounds occurs soon after the onset of the tests (i.e., within 0.5,1.5 h). Compound 5 and confertifolin are probably not direct, sensory mediated antifeedants. After 0.5,1.5 h of exposure, these compounds inhibit not only feeding, but also locomotion behaviour, indicating postingestive, toxic effects. Isodrimenin inhibits feeding from the onset of the test and is probably a sensory mediated antifeedant. No habituation occurs to this compound, indicating that isodrimenin is either a very strong antifeedant or that it additionally has postingestive, toxic effects. Topical application of the drimanes on the larval cuticle revealed feeding inhibiting effects, but these could not be related to the occurrence of postingestive feeding inhibiting effects, indicating that this method is inappropriate to show possible postingestive effects of drimanes in P. brassicae. In conclusion, the behavioural observations performed in this research indicate that analogous drimanes inhibit feeding by P. brassicae larvae through multiple mechanisms of action. The results show that, when developing a structure activity relationship (SAR) for a series of antifeedants, it is important to distinguish the mode of action which underlies inhibition of feeding. [source] Egg Colour Covaries with Female Expression of a Male Ornament in the Spotless Starling (Sturnus unicolor)ETHOLOGY, Issue 10 2007Isabel López-Rull The sexually selected egg colour hypothesis (SSECH) proposes that egg colouration is as a post-mating sexually selected signal of female phenotypic quality, maintained by a higher allocation of paternal care. Similarly, some female traits can reflect genetic quality or condition and males could use this information in mate choice or in modulating parental investment. In our study, we examined the correlation of individual variation in egg colouration with female expression of a male ornament and how male feeding covaried with these two female traits in the spotless starling, in which egg colour varies widely between clutches and where both sexes possess showy throat feathers that are age dependent and that may signal individual quality. According to the SSECH, high-quality females (females with longer throat feathers) are expected to lay more colourful eggs than low-quality females and males should modify their feeding behaviour accordingly. By means of a principal component analysis, we found that most of the variation in egg colouration was due to brightness differences, and in a lower proportion to chromatic variation. Chromatic variation reflected a ultraviolet (UV) vs. greenness trade-off and was positively associated with throat feather length: females with larger throat feathers laid eggs with higher UV and lower green reflectance. However, egg brightness was not related to female feather length, as the SSECH would predict. Male feedings were positively related to female throat feather length and negatively related to chromatic variation, meaning that males contributed more to nests of females with long throat feathers who laid eggs with higher UV and lower green reflectance. In conclusion, our data provide mixed support for the SSECH: although egg chromatic variation was related to female expression of a male ornament and male parental care, we found no evidence that egg brightness was involved in these processes. [source] Tonic regulation of satiety by 5-HT1B receptors in the mouse: converging evidence from behavioural and c- fos immunoreactivity studies?EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2004Michelle D. Lee Abstract Activation of 5-HT1B receptors is thought to play an important role in the inhibitory influence of serotonin on feeding behaviour and body weight in mammals. Earlier studies have shown that 5-HT1B -knockout (KO) mice eat more and are heavier than wild-type (WT) controls and that the selective 5-HT1B receptor agonist CP-94,253 reduces food intake in food-deprived mice. Here we characterize the behavioural effects of both CP-94,253 and the selective 5-HT1B receptor antagonist SB224289 on feeding and other behaviours within the behavioural satiety sequence, and also report a c- fos mapping study using CP-94,253. CP-94,253 produced a dose-dependent suppression of food intake with a profile consistent with a selective effect on feeding behaviour. These effects were absent or reduced in 5-HT1B -KO mice and in WT mice pretreated with SB224289. SB224289 administered alone enhanced food intake consistent with impaired satiation; a similar effect was apparent in 5-HT1B -KO mice compared to WT. CP-94,253 induced c- fos in a range of structures previously implicated in the expression of feeding behaviour. These results suggest that the activation of 5-HT1B receptors is an important component of endogenous satiation mechanisms in the mouse. [source] The expanding family of -RFamide peptides and their effects on feeding behaviourEXPERIMENTAL PHYSIOLOGY, Issue 3 2004Graham J. Dockray Neuropeptides terminating in -Arg-Phe-NH2 (-RFamide) were first discovered in molluscan nervous systems, but were soon recognized to occur widely throughout the invertebrates. Progress in characterizing members of the family in vertebrates has been slower. In mammals, however, it is now clear that there are at least five genes encoding members of the family, and at least five G-protein-coupled receptors at which they act. The tissue distribution of the peptides and their receptors is wide and there are likely to be many different functions. One of the emerging themes from recent research is that these peptides are involved in control of feeding behaviour both in invertebrates and in vertebrates. This would seem to be a remarkable example of conservation of chemical structure and biological function throughout nervous system evolution. [source] Fish utilisation of managed realignmentsFISHERIES MANAGEMENT & ECOLOGY, Issue 6 2005S. COLCLOUGH Abstract, One area of ecological benefit not yet fully evaluated in European waters is the utilisation of restored saltmarsh habitats by fish species. This study examines the utilisation of managed realignments and relic saltmarsh by fish species. Factors affecting habitat heterogeneity and fish populations are discussed, and recommendations are made with respect to scheme design and management that will maximise the biological and socio-economic values. Fish populations in the high intertidal areas were assessed using a suite of techniques, including observations on feeding behaviour. Each microhabitat was discussed as a function of the extent of fish colonisation. A positive relationship between the degree of fish utilisation and habitat heterogeneity was ascertained using species richness, abundance and behavioural observations. This study will aid habitat valuation for economic justification of managed realignments, over and above existing drivers, such as compensatory habitat for encroachment, flood defence and the European Union Habitats Directive. The work now forms part of a wider European Interreg IIIb project, COMCOAST. [source] Contribution of fungal biomass to the growth of the shredder, Pycnopsyche gentilis (Trichoptera: Limnephilidae)FRESHWATER BIOLOGY, Issue 11 2009NAMIL CHUNG Summary 1.,1. It has been accepted that aquatic hyphomycetes colonising submerged leaves increase the nutritional value of leaf detritus and suggested that fungal biomass plays a greater role in the growth of shredders than leaf tissue itself. However, it is not clear what proportion of the nutritional needs of shredders is met by fungal biomass. 2.,We fed Pycnopsyche gentilis larvae with tulip poplar (Liriodendron tulipifera) leaf discs colonised by the aquatic hyphomycete, Anguillospora filiformis, which had been radiolabelled to quantify the contribution of fungal carbon to the growth of the shredder at different larval developmental stages. Instantaneous growth rates of larvae on this diet were also estimated. 3.,When provided with fungal-colonised leaves (14,16% fungal biomass), the third and the fifth instar larvae of P. gentilis grew at the rates of 0.061 and 0.034 day,1, respectively, but on a diet of sterile leaves, both larval instars lost weight. The incorporation rates of fungal carbon were 31.6 ,g C mg,1 AFDM day,1, accounting for 100% of the daily growth rate of the third instar larvae and 8.6 ,g C mg,1 AFDM day,1, accounting for 50% of the daily growth rate of the fifth instar larvae. 4.,These results suggest that leaf material colonised by A. filiformis is a high quality food resource for P. gentilis larvae, and that fungal biomass can contribute significantly to the growth of these larvae. Differences in feeding behaviour and digestive physiology may explain the significantly greater assimilation of fungal biomass by the earlier instar than the final instar. To satisfy their nutritional needs the fifth instar larvae would have to assimilate detrital mass that may have been modified by fungal exoenzymes. [source] Predation by the tropical plant Utricularia foliosaFRESHWATER BIOLOGY, Issue 11 2006LIZANDRO SANABRIA-ARANDA Summary 1. We examined the prey captured by individual plants of the tropical carnivorous plant Utricularia foliosa, located in different areas along a creek in the Colombian Amazon and the zooplankton and macroinvertebrate communities associated with the plants. The aims were: (i) to determine whether bladders of different sizes within each plant catch different numbers of prey or exploit different size ranges and types of prey, (ii) if the quantity and composition of prey captured varies temporally and/or spatially and (iii) if the plant has evolved effective mechanisms of attracting prey. 2. Utricularia foliosa captured the most abundant species of macroinvertebrates associated with the plant. Larger bladders captured more, larger and more diverse prey. However, benefits of the extra prey caught by large bladders were not offset by the greater cost of producing bladders larger than approximately 1650 ,m. 3. The number of prey captured was higher in those plants with more carbohydrates per bladder and with a higher ratio of antenna size/bladder length. The antennae enhance capture success by offering the prey a favourable substratum that exploits their natural locomotor and feeding behaviour. However, although carbohydrates may lure prey, carbohydrate production was not a strategy of the plant to enhance the capture of prey, because the amount of carbohydrates in the bladder was related to the abundance of periphyton. [source] Sex-dependent use of information on conspecific feeding activities in an amphibian urodelianFUNCTIONAL ECOLOGY, Issue 2 2009Pedro Aragón Summary 1Animals can make decisions by observing the behaviour of others. Their decisions vary depending on whether the benefits of using such information exceed the costs. Thus, it is worthwhile to explore the potential costs associated with different sources of information to understand the consequences of sociality. Previous studies focused mainly on the costs inherent to information gathering, whereas sex differences with regard to the costs arising from information use have received less attention. 2To explore this further I performed two complementary experiments. The first experiment aimed to examine individual responses to different combinations of information types that are likely to appear in nature, to test whether there is a sex-dependent response in the Bosca's newt, Lissotriton boscai. I tested the time needed for individuals to eat food items by trial-and-error tactics (personal information), and when a conspecific, which was eating or not, was added to the food cue. The second experiment aimed to evoke social interactions that are likely to arise after the choice of using information on conspecific feeding activities is made. I examined the potential costs associated with direct competition between same-sex pairs in food-limited conditions. 3Results of experiment 1 revealed that in both sexes the latency to eat food items was shorter in the presence of non-feeding conspecifics, but only females took advantage when information related to feeding activities where added to the food cue. Results of experiment 2 showed that when faced with a limited resource of food, females were more prone to engage in costly interactions. 4This study suggests that the balance between costs and benefits associated with the short-term use of information on conspecific feeding behaviour in combination with food cues may differ between sexes. Differential information uses by sexes might have profound consequences in intraspecific relationships and in the evolution of vertebrates' social systems. [source] Production and behavioural responses of high- and low-yielding dairy cows to different periods of access to grazing or to a maize silage and soyabean meal diet fed indoorsGRASS & FORAGE SCIENCE, Issue 4 2006O. Hernandez-Mendo Abstract The study examined whether high-yielding cows grazing pasture respond differently from low-yielding cows in milk production and feeding behaviour, to increasing the time made available for eating a maize silage and soyabean meal (TAMS) diet indoors and reducing the time available for grazing (TAG). Two experiments, each lasting 42 d, were carried out in spring (Experiment 1) and autumn (Experiment 2) using Holstein-Friesian cows at two different levels of milk yield (MYL). Milk production and feeding behaviour were examined for TAG + TAMS systems of 19 h, TAG plus 1 h TAMS (19 + 1), and 5 h TAG plus 15 h TAMS (5 + 15). There were two levels of concentrate (0 and 6 kg d,1), and in the spring experiment two sward heights (4,6 and 8,10 cm) were also studied. Milk yield, persistency of milk yield, liveweight change and estimated total DM intake were significantly higher on the 5 + 15 than on the 19 + 1 grazing system in Experiment 1 but not in Experiment 2. There were no significant interactions of TAG + TAMS treatment with MYL for any production or behavioural measurements except for maize silage feeding time, where high MYL cows spent a significantly greater time eating maize silage than low MYL cows on the 5 + 15 treatment but not on the 19 + 1 treatment. It can be concluded that high- and low-yielding cows respond similarly in milk production and feeding behaviour to different combinations of TAG and TAMS. In autumn, estimated daily intakes of herbage were lower on both grazing treatments relative to spring, resulting from lower rates of herbage intake with no compensatory increase in grazing time. In contrast, rates of intake of maize silage were higher in autumn especially on the 19 + 1 system. These results may imply a change of preference from herbage to maize silage between spring and autumn. [source] | |||||||||||||||||||||||||||||||||||||||||||