The Influence of Previous Experience and Starvation on Aphid Feeding Behavior

It was hypothesized that (1) previous experience of aphids on a host plant leads to differences in their feeding behavior relative to aphids without previous experience on it and that (2) a change in the physiological state of the aphid modifies their experience-induced behavior. Using electronic recording, the feeding behavior of the aphid Sitobion fragariae (Walker) on wheat Triticum aestivum L. and oat Avena sativa L. was examined, comparing aphids with or without previous experience on a given host and with or without a period of starvation before assessing probing behavior. All comparisons were performed within a single aphid clone to minimize the effect of genetic variation. Feeding behavior on wheat was significantly affected by previous experience and starvation. The effect of previous experience interacted with the host plant where feeding behavior was tested. Aphids feeding on wheat following previous experience on wheat showed a longer time and a higher number of pathway activities and less time in waveform F (i.e., mechanical stylet work and penetration difficulties) than did aphids feeding on wheat after a previous experience on oat. No differences in the time from the beginning of the recording until the first salivation into the sieve elements were found. When aphids were subjected to a period of starvation, the time devoted to xylem ingestion increased compared with that of nonconstrained aphids. These results are discussed in terms of factors affecting foraging decisions.     

Studying <Emphasis Type="Italic">Daphnia</Emphasis> feeding behavior as a black box: a novel electrochemical approach

We present a novel approach for examining the complex feeding behavior of a filter feeder at a previously unexploited scale. A Daphnia lives in a viscous environment and thus creates a feeding current with a distinct laminar inflow and a repetitive pulsed outflow. We propose that by treating the feeding apparatus as a black box, and using the pulsed outflow current as a surrogate to the inside working of the apparatus, we can calculate feeding rate in near real time. The structure of the outflow is interpreted as a direct representation of the organism’s response to its environment. Therefore, we examine how the work performed by an organism’s feeding apparatus is altered according to environmental factors and metabolic demands. Our approach is an integration of optical (Schlieren system) and electrochemical (chronoamperometry) techniques that allow for real time visualization and temporal analysis of flow systems, respectively. As electrochemistry requires a tracer chemical, we employed low dopamine concentrations (≤ 1mM), and tested the effect of dopamine on the heart rate and swimming of Daphnia. It appears that dopamine free in solution at concentrations below 10 mM has no adverse effects on the organism, and all observed differences in Daphnia feeding behavior were due to environmental or metabolic factors. The feeding nature of daphnids in the presence or absence of food, and differences between the sexes is reported. Our results indicate that in the absence of food a Daphnia has a strict and repetitive feeding behavior with short delays between pumping actions. However, in the presence of food this behavior becomes complex, with increased delays between pumps, perhaps designed to maximize feeding efficiency. Our observations demonstrate that males have a higher appendage beat frequency than females under identical conditions. We hypothesize that the difference may be dictated by metabolic demand, as a male spends more time actively seeking a mate. The application of electrochemistry to the study of Daphnia feeding behavior is an improvement over current methods for its near real time quantification of behavioral response, its versatile application under varying environmental conditions and its extreme sensitivity to changes in the organism’s feeding behavior. This technique is a valuable addition to the current tools available for studying Daphnia feeding behavior and will allow us to learn more about the interactions of an organism with its environment. Guest editor: Piet Spaak Cladocera: Proceedings of the 7th International Symposium on Cladocera     

Zooplankton capture by a coral reef fish: an adaptive response to evasive prey

Synopsis High-speed cinematography and video using modified Schlieren optics and laser illumination helped elicit details of prey capture mechanisms used by Chromis viridis while feeding on calanoid copepods and Artemia. Chromis viridis is capable of a ram-jaw, low-suction feeding, as well as a typical suction feeding behavior described for other species of planktivores. By adjusting the degree of jaw protrusion and amount of suction used during a feeding strike, this fish can modulate its feeding strikes according to the prey type being encountered. The ram-jaw feeding mode enables C. viridis to capture highly evasive calanoid copepods within 6 to 10 msec. The use of specialized feeding behavior for evasive prey and the ability to vary feeding behavior are adaptations for feeding on evasive prey.     

Sequential foraging of dusky dolphins with an inspection of their prey distribution

The aim of this work was to analyze the sequential foraging behavior of dusky dolphins (Lagenorhynchus obscurus). Foraging sequences were defined when more than two feeding bouts occur with a traveling bout between them. We hypothesized that traveling costs of searching for prey patches were related to the time spent feeding on a patch. In addition, the distribution and seasonal variation of anchovy schools were studied in the area to better understand dolphins' behavior. We observed dolphins from a research vessel from 2001 to 2007, and recorded their location and behavior. Anchovy data were collected during two hydro‐acoustic surveys. Dusky dolphin behaviors varied seasonally; they spent a greater proportion of time traveling and feeding in the warm season (Kruskal‐Wallis: H = 172.07, P < 0.01). During the cold season dolphin groups were more likely to exhibit diving behavior and less surface feeding. We found a positive correlation between searching and foraging time (r = 0.88, P = 0.019), suggesting that the costs associated with searching were compensated by an increase in the energy intake during the foraging bout. There was an association between dusky dolphin and anchovy distribution, in that they co‐varied spatially and seasonally.     

The nutritional contribution of males affects the feeding behavior and spatial distribution of females in a bruchid beetle,<Emphasis Type="Italic"> Bruchidius dorsalis</Emphasis>

The relationship between the quality/quantity of male investment and the feeding behavior of females was investigated in a bruchid weevil, Bruchidius dorsalis (Fahraeus), whose males donate nutrition via seminal fluid to females. Experiments on the effect of feeding regimes of both sexes on the mating frequency of females showed that females mated at a higher frequency if given low-quality food or poor male investment. On the other hand, the experiment that examined the effect of male investment quality on female feeding behavior showed that females receiving the high-quality investment exhibited feeding behavior less often. These results suggest that male investment and feeding behavior play the same role for B. dorsalis females. These experiments also showed that there are sex-related asymmetries in mating and feeding behaviors: females mated more often but males fed more often. Moreover, a field census suggested that only males visited non-host flowers to feed on the pollen and nectar during the non-flowering period of the host plants; females always stayed on the host plants irrespective of the flowering phenology. These results suggest that in B. dorsalis courtship role reversal and sex-specific feeding modes are fairly fixed and obligatory, and that male investment, derived from sexual selection, could affect the feeding behavior and spatial distribution of both sexes, which may have far-reaching impact in various ecological contexts.     

Advances in the Study of Feeding Behaviors, Mechanisms, and Mechanics of Sharks

Sharks as a group have a long history as highly successful predatory fishes. Although, the number of recent studies on their diet, feeding behavior, feeding mechanism, and mechanics have increased, many areas still require additional investigation. Dietary studies of sharks are generally more abundant than those on feeding activity patterns, and most of the studies are confined to relatively few species, many being carcharhiniform sharks. These studies reveal that sharks are generally asynchronous opportunistic feeders on the most abundant prey item, which are primarily other fishes. Studies of natural feeding behavior are few and many observations of feeding behavior are based on anecdotal reports. To capture their prey sharks either ram, suction, bite, filter, or use a combination of these behaviors. Foraging may be solitary or aggregate, and while cooperative foraging has been hypothesized it has not been conclusively demonstrated. Studies on the anatomy of the feeding mechanism are abundant and thorough, and far exceed the number of functional studies. Many of these studies have investigated the functional role of morphological features such as the protrusible upper jaw, but only recently have we begun to interpret the mechanics of the feeding apparatus and how it affects feeding behavior. Teeth are represented in the fossil record and are readily available in extant sharks. Therefore much is known about their morphology but again functional studies are primarily theoretical and await experimental analysis. Recent mechanistic approaches to the study of prey capture have revealed that kinematic and motor patterns are conserved in many species and that the ability to modulate feeding behavior varies greatly among taxa. In addition, the relationship of jaw suspension to feeding behavior is not as clear as was once believed, and contrary to previous interpretations upper jaw protrusibility appears to be related to the morphology of the upper jaw-chondrocranial articulation rather than the type of jaw suspension. Finally, we propose a set of specific hypotheses including: (1) The functional specialization for suction feeding hypothesis that morphological and functional specialization for suction feeding has repeatedly arisen in numerous elasmobranch lineages, (2) The aquatic suction feeding functional convergence hypothesis that similar hydrodynamic constraints in bony fishes and sharks result in convergent morphological and functional specializations for suction feeding in both groups, (3) The feeding modulation hypothesis that suction capture events in sharks are more stereotyped and therefore less modulated compared to ram and bite capture events, and (4) The independence of jaw suspension and feeding behavior hypothesis whereby the traditional categorization of jaw suspension types in sharks is not a good predictor of jaw mobility and prey capture behavior. Together with a set of questions these hypotheses help to guide future research on the feeding biology of sharks.     

Electronically monitored cowpea aphid feeding behavior on resistant and susceptible lupins

The feeding behavior of cowpea aphid, Aphis craccivora Koch (Homoptera: Aphididae) was examined on seedlings of narrow leafed lupin, Lupinus angustifolius L., and yellow lupin, L. luteus L., using electronic monitoring of insect feeding behavior (EMIF). Aphid feeding behavior was first compared between resistant (cv. Kalya) and susceptible (cv. Tallerack) varieties of narrow-leafed lupin. Aphids spent significantly more time in non- penetration and stylet pathway activities, and significantly less time in the sieve element phase on Kalya than on Tallerack, suggesting that feeding deterrence is an important component of aphid resistance in Kalya. Aphid feeding on a susceptible yellow lupin variety (cv. Wodjil) was then compared with that on two resistant lines, one (Teo) with high and the other (94D024-1) with low seed alkaloid content. There were no consistent differences in aphid feeding behavior between Wodjil and Teo. Total, mean and percentage sieve element phase times were significantly lower, and total and percentage times in non-phloem phase were greater on 94D024-1 than on Wodjil, suggesting the possibility of phloem-based deterrence in 94D024-1.     

The rostral micro-tooth morphology of blue marlin,Makaira nigricans

Billfish rostra potentially have several functions; however, their role in feeding is unequivocal in some species. Recent work linked morphological variation in rostral micro-teeth to differences in feeding behavior in two billfish species, the striped marlin (Kajikia audax) and the sailfish (Istiophorus platypterus). Here, we present the rostral micro-tooth morphology for a third billfish species, the blue marlin (Makaira nigricans), for which the use of the rostrum in feeding behavior is still undocumented from systematic observations in the wild. We measured the micro-teeth on rostrum tips of blue marlin, striped marlin, and sailfish using a micro–computed tomography approach and compared the tooth morphology among the three species. This was done after an analysis of video-recorded hunting behavior of striped marlin and sailfish revealed that both species strike prey predominantly with the first third of the rostrum, which provided the justification to focus our analysis on the rostrum tips. In blue marlin, intact micro-teeth were longer compared to striped marlin but not to sailfish. Blue marlin had a higher fraction of broken teeth than both striped marlin and sailfish, and broken teeth were distributed more evenly on the rostrum. Micro-tooth regrowth was equally low in both marlin species but higher in sailfish. Based on the differences and similarities in the micro-tooth morphology between the billfish species, we discuss potential feeding-related rostrum use in blue marlin. We put forward the hypothesis that blue marlin might use their rostra in high-speed dashes as observed in striped marlin, rather than in the high-precision rostral strikes described for sailfish, possibly focusing on larger prey organisms.     

Future social rank: forecasting status in the green anole (Anolis carolinensis)

Predicting the future social standing of an individual without aggressive social interaction may seem contradictory, as formation of social rank depends on agonistic interactions. In the lizard Anolis carolinensis, predicting social rank is possible using latency to eyespot formation (sympathetic darkening of postorbital skin from green to black during stressful agonistic interactions), because they form more rapidly in male lizards that become dominant. Darkened eyespots also inhibit aggressive behavior. As the timing of eyespot formation appears to be an important component of stress responsiveness and future social status, we hypothesized that a proactive disposition toward non-aggressive behavior, such as feeding and courtship, would be associated with aggressiveness. We assessed the relationship between rank and the temporal dynamics of eyespot formation, latencies to aggressive display, feeding, and reproductive behavior. Male lizards that became dominant were faster to respond to all types of stimuli tested (aggression, feeding, and courtship). The temporal dynamics of the neuroendocrine stress response appear to influence the motivation for behavioral response. Animals that recover from stress more quickly also eat, court, and fight more readily. In summary, this work suggests that latencies to aggressive, reproductive, and feeding behavior, as well as eyespot signals, are reliable predictors of future social status of individual male A. carolinensis.     

计算机视觉在线虫进食行为自动分析中的应用

秀丽隐杆线虫被广泛地用作研究基因与行为关系的绝佳模式生物.线虫的咽部神经元回路控制着复杂的进食行为.为了研究进食行为的分子机制,有必要对线虫进食行为表型分析鉴定.然而,目前为止,几乎所有的线虫进食行为表型鉴定都是通过人眼来判断.因为其泵入食物的肌肉运动频率高,该行为的分析是很困难而且效率低下的.为解决这个问题,我们设计了基于计算机视觉技术的自动化成像系统来高通量分析线虫进食行为表型.此成像系统对进食表型的检测准确率达到98%以上,并使得连续可靠地分析其表型细微变化成为可能.同时,在保证高准确率的前提下单位时间内分析数据的效率比人工分析提高了3倍.     

High levels of arbuscular mycorrhizal fungus colonization on Medicago truncatula reduces plant suitability as a host for pea aphids (Acyrthosiphon pisum)

This study sheds light on a poorly understood area in insect-plant-microbe interactions,focusing on aphid probing and feeding behavior on plants with varying levels of arbuscular mycorrhizal(AM)fungus root colonization.It investigates a commonly occurring interaction of three species:pea aphid Acyrthosiphon pisum,barrel medic Medicago truncatula,and the AM fungus Rhizophagus irregularis,examining whether aphid-feeding behavior changes when insects feed on plants at different levels of AM fungus colonization(42% and 84% root length colonized).Aphid probing and feeding behavior was monitored throughout 8 h of recording using the electrical penetration graph(EPG)technique,also,foliar nutrient content and plant growth were measured.Summarizing,aphids took longer to reach their 1st sustained phloem ingestion on the 84% AM plants than on the 42% AM plants or on controls.Less aphids showed phloem ingestion on the 84% AM plants relative to the 42% AM plants.Shoots of the 84% AM plants had higher percent carbon(43.7%)relative to controls(40.5%),and the 84% AM plants had reduced percent nitrogen(5.3%)relative to the 42% AM plants(6%).In conclusion,EPG and foliar nutrient data support the hypothesis that modifications in plant anatomy(e.g.,thicker leaves),and poor food quality(reduced nitrogen)in the 84% AM plants contribute to reduced aphid success in locating phloem and ultimately to differences in phloem sap ingestion.This work suggests that M.truncatula plants benefit from AM symbiosis not only because of increased nutrient uptake but also because of reduced susceptibility to aphids.     

Examining the relatedness of behaviors through experimentation: switching on and off chewing and feeding behaviors in a parasitic wasp

Melittobia digitata (Hymenoptera: Eulophidae) are parasitoids known for their cooperative escape behavior. The initial sequences of this escape chewing behavior have been compared to the initial sequences of their feeding behavior. We sought to experimentally test whether these sequences were interchangeable. We were successful in turning off chewing and turning on feeding in a chewing situation, and turning on chewing and turning off feeding in a feeding context. We discuss the implications of this finding for the origin and evolution of these behaviors, and how experimental tests of key cues can be helpful for understanding the evolution of behavioral patterns.     

Behavioral response of manatees to variations in environmental sound levels

Florida manatees (Trichechus manatus latirostris) inhabit coastal regions because they feed on the aquatic vegetation that grows in shallow waters, which are the same areas where human activities are greatest. Noise produced from anthropogenic and natural sources has the potential to affect these animals by eliciting responses ranging from mild behavioral changes to extreme aversion. Sound levels were calculated from recordings made throughout behavioral observation periods. An information theoretic approach was used to investigate the relationship between behavior patterns and sound level. Results indicated that elevated sound levels affect manatee activity and are a function of behavioral state. The proportion of time manatees spent feeding and milling changed in response to sound level. When ambient sound levels were highest, more time was spent in the directed, goal‐oriented behavior of feeding, whereas less time was spent engaged in undirected behavior such as milling. This work illustrates how shifts in activity of individual manatees may be useful parameters for identifying impacts of noise on manatees and might inform population level effects.     

Selection of Bemisia nymphal stages for oviposition or feeding,and host-handling times of arrhenotokous and thelytokous <Emphasis Type="Italic">Eretmocerus mundus</Emphasis> and arrhenotokous <Emphasis Type="Italic">E. eremicus</Emphasis>

Host-handling behavior is an important aspect of parasitoid foraging behavior. When a parasitoid encounters a potential host, the handling behavior starts with the evaluation of the host and continues if the host has been judged acceptable. Host handling is usually terminated after egg laying or host feeding and host marking. Host-handling behavior of an arrhenotokous population of two Eretmocerus species, E. mundus Mercet and E. eremicus Rose and Zolnerowich, along with a thelytokous population of E. mundus were compared under laboratory conditions. Several elements of host-handling behavior, including encountering, ascending, turning on host, descending, preening, egg laying, and host feeding were recorded. There were no correlations among the durations of these phases across parasitoid populations/species or host nymphal instars. Duration of different phases of host-handling behavior showed only slight and sometimes significant differences between different Eretmoceruspopulations/species. The actual laying of the egg had the longest duration of all host-handling behaviors, and was longer on third nymphal instars than on younger ones. Females of the three populations/species accepted the first three nymphal stages either for egg laying or for host feeding. Females spent a lot of time to make wounds in the host when preparing for host feeding, and eventually killed the host. The implications of these findings for the use of the different Eretmoceruspopulations/species in biological control are discussed.     

Flexibility in the Foraging Behavior of Blue Tits in Response to Short‐Term Manipulations of Brood Size

Previous work suggests that short‐term changes in feeding rate are usually produced by the parent‐offspring interaction. However, few studies have properly tested this assumption. In this study, we attempt to explore the short‐term consequences of daily (within‐pair) brood size manipulations (reduced, original, and enlarged) on feeding behavior (provisioning rates, prey size, and prey type) of Mediterranean blue tits Cyanistes caeruleus. Total provisioning rates were lowest when broods were reduced in size and greatest when broods were enlarged. Mean prey size was also affected by the brood size changes: parents tended to bring larger prey when confronted with low brood demand reinforcing the view that a trade‐off exists between minimizing foraging time and maximizing food quantity. Such differences in feeding frequencies and the load sizes delivered may be explained by changes in the parents’ foraging tactic. Increase of brood size compelled parents to work harder and be less selective in prey choice; we found that stressed birds with a high level of feeding responsibility (hungry nestlings) opted to concentrate on more readily available food items (Tortricids). On the other hand, their immediate reaction when faced with a low level of feeding responsibility was to decrease this prey type in the diet, so that the percentage of other preys (Noctuids) in the diet increased. There was no intersexual difference in the way in which parents responded to the manipulation. In sum, our results revealed a flexibility in foraging strategies of blue tits to cope with changing scenarios, which supports the idea that provisioning behavior is largely governed by nestling demand.     

Feeding behavior of the cichlid,Sarotherodon galilaeum: selective predation on Lake Kinneret zooplankton

In laboratory feeding trials, we analyzed the feeding behavior and selectivity of the cichlid, Sarotherodon galilaeum, for zooplankton prey from Lake Kinneret, Israel. The feeding behavior was dependent on fish size. Fish less than 20 mm SL fed on zooplankton as obligate particulate feeders. Fish from 20 to 42 mm SL fed either as particulate feeders or as filter feeders. Fish larger than 62 mm SL fed as obligate filter feeders. Particulate-feeding fish were size selective and had highest feeding electivities for large-sized zooplankton species. Filter-feeding fish had highest feeding electivities for zooplankton species with poor escape ability. In general, S. galilaeum predation pressure would be greatest on Ceriodaphnia reticulata, a large-bodied and easily captured species which is selected by both particulate-feeding and filter-feeding fish.     

Searching efficiency of the lady beetleCoccinella septempunctata larvae in uniform and patchy environments

Experiments were conducted on the searching behavior and searching efficiency of the lady beetleCoccinella septempunctata bruckii Mulsant under conditions of various prey distributions and prey densities. The larvae changed their searching behavior before and after feeding. Before feeding the larvae moved quickly and the searching paths were nearly linear. But after feeding the speed decreased and turning angle increased. The speed and turning angle reverted gradually and recovered the initial pattern 95 s after feeding. The searching efficiency differed depending on the prey distribution. At low prey density, searching was most efficient when prey were distributed uniformly. But at middle and high prey densities, searching was most efficient when prey items were highly aggregated. The observed searching behavior of 4th instarC. septempunctata larvae was likely to be optimal considering the natural distribution of colonies of their prey, aphids.     

Control of foraging behavior of individuals within an ecosystem context: the clam Macoma balthica,flow environment,and siphon-cropping fishes

Macoma balthica (L.), an abundant clam, ubiquitous in temperate estuaries across the North Atlantic, is known to practice both alternative basic modes of feeding available to seafloor invertebrates. It either holds its feeding organ, the siphon, at a fixed position just above the sediment surface to filter out food particles suspended in the overlying water or else extends and moves its siphon around to vacuum up deposited food particles on the sediment surface. Previous laboratory experiments have established an understanding of the role of current flow in dictating the choice of whether suspension or deposit feeding will be used by marine invertebrates with the facultative flexibility to choose. Faster flows imply greater fluxes of suspended particles so that the energetic rewards of suspension feeding are enhanced. Slower flows imply reduced renewal rates of suspended foods in the bottom boundary layers and enhanced deposition of food particles on the seafloor so that a switch to deposit feeding is favored. Like early optimal foraging theory, this understanding is based on energetic considerations alone without incorporation of broader implications of how population interactions such as predation and competition influence individual foraging behavior. Feeding behavior of Macoma balthica is influenced in the Neuse River estuary by both hydrodynamics and siphon-cropping by juvenile demersal fishes. Under conditions of identical concentrations of suspended particulates in the water column and organic contents of surface sediments, Macoma exhibited much higher levels of deposit feeding where currents were slower. In addition, exclosure and fish inclosure experiments demonstrated that juvenile demersal fishes influence feeding behavior of Macoma by cropping exposed siphons and inducing reduction in deposit-feeding activity. Effects of croppers were substantial in early to midsummer, when juvenile fish abundances were greatest in trawl samples from this estuarine nursery and before the growing fish exhibited ontogenetic changes in diet away from early concentration on bivalve siphons. Field experiments in which siphon-cropping fish were caged at varying distances off the bottom failed to detect any effective behavioral avoidance by Macoma of cropping in response to proximity of fish. One might have hypothesized that under high risk of cropping, Macoma would switch to suspension feeding and away from deposit feeding, the feeding method entailing more risk of losses to croppers because of greater siphon activity and greater extension of siphons on the sediment surface. Consequently, partial predation by siphon-cropping fishes greatly reduces deposit-feeding activity by Macoma balthica during summer as an apparent direct effect of disfigurement and reduction of siphons, the organ required for efficient deposit feeding. Information on current flows alone would not suffice to predict feeding behavior of this marine invertebrate: the influence of partial predation must also be included.     

Four simple stimuli that induce host‐seeking and blood‐feeding behaviors in two mosquito species,with a clue to DEET's mode of action

Bioassays in a wind tunnel showed that a combination of four stimuli releases intense host‐seeking and blood‐feeding behavioral responses from females of the Asian tiger mosquito, Aedes albopictus, and the yellow fever mosquito, Aedes aegypti. The stimuli are carbon dioxide, water vapor, warmth, and adenosine triphosphate (ATP). Mosquitoes responded to this combination with a repertoire of blood‐feeding behaviors that included upwind flight, landing, probing, and engorgement. Absence of carbon dioxide, water vapor, or ATP from the combination of stimuli or exposure to temperatures 12° C below or above human‐host temperature (38° C) significantly attenuated blood‐feeding behavior in both species. Although there is literature documenting the individual importance of each of these stimuli, our work represents the first instance where this combination of stimuli was found sufficient to elicit a complete repertoire of blood‐feeding behaviors in these mosquitoes without involvement of any host specific odor. When mosquitoes were exposed to the four stimuli along with N,N‐diethyl‐3‐methylbenzamide (DEET), feeding behavior was greatly suppressed. We hypothesize that a possible mode of action for DEET against these mosquitoes involves interference of warmth and/or water vapor receptors. An electrophysiological study designed to determine if DEET adversely affects the function of these receptors would be illuminating.