Regulation of nectar collection in relation to honey storage levels by honey bees, Apis mellifera

Honey bees collect distinct nutrient sources in the form ofnectar (energy) and pollen (nitrogen). We investigated the effectof varying energy stores on nectar and pollen foraging. We foundno significant changes in nectar foraging in response to changesin honey storage levels within colonies. Individual foragersdid not vary activity rates or nectar load sizes in responseto changes in honey stores, and colonies did not increase nectarintake rates when honey stores within the hive were decreased.This result contrasts with pollen foraging behavior, which isextremely sensitive to colony state. Our data show that individualforaging decisions during nectar collection and colony regulationof nectar intake are distincdy different from pollen foraging.The behavior of honey bees illustrates that foraging strategy(and therefore foraging models) can incorporate multiple currencies,including both energy and protein intake.[Behav Ecol 7: 286–291(1996)]     

The energetic consequences of behavioral variation in a marine carnivore

Intraspecific variability in foraging behavior has been documented across a range of taxonomic groups, yet the energetic consequences of this variation are not well understood for many species. Understanding the effect of behavioral variation on energy expenditure and acquisition is particularly crucial for mammalian carnivores because they have high energy requirements that place considerable pressure on prey populations. To determine the influence of behavior on energy expenditure and balance, we combined simultaneous measurements of at‐sea field metabolic rate (FMR) and foraging behavior in a marine carnivore that exhibits intraspecific behavioral variation, the California sea lion (Zalophus californianus). Sea lions exhibited variability in at‐sea FMR, with some individuals expending energy at a maximum of twice the rate of others. This variation was in part attributable to differences in diving behavior that may have been reflective of diet; however, this was only true for sea lions using a foraging strategy consisting of epipelagic (<200 m within the water column) and benthic dives. In contrast, sea lions that used a deep‐diving foraging strategy all had similar values of at‐sea FMR that were unrelated to diving behavior. Energy intake did not differ between foraging strategies and was unrelated to energy expenditure. Our findings suggest that energy expenditure in California sea lions may be influenced by interactions between diet and oxygen conservation strategies. There were no apparent energetic trade‐offs between foraging strategies, although there was preliminary evidence that foraging strategies may differ in their variability in energy balance. The energetic consequences of behavioral variation may influence the reproductive success of female sea lions and result in differential impacts of individuals on prey populations. These findings highlight the importance of quantifying the relationships between energy expenditure and foraging behavior in other carnivores for studies addressing fundamental and applied physiological and ecological questions.     

Foraging in nature: Contrasting responses to resource heterogeneity at small‐ and large‐spatial scales

A key problem faced by foragers is how to forage when resources are distributed heterogeneously in space. This heterogeneity and associated trade‐offs may change with spatial scale. Furthermore, foragers may also have to optimize acquiring multiple resources. Such complexity of decision‐making while foraging is poorly understood. We studied the butterfly Ypthima huebneri to examine how foraging decisions of adults are influenced by spatial scale and multiple resources. We predicted that, at a small‐spatial scale, the time spent foraging in a patch should be proportional to resources in the patch, but at large‐spatial scales, due to limitations arising from large travel costs, this relationship should turn negative. We also predicted that both adult and larval resources should jointly affect foraging butterflies. To test these predictions, we laid eleven plots and sub‐divided them into patches. We mapped nectar and larval resources and measured butterfly behavior in these patches and plots. We found that adult foraging behavior showed contrasting relationships with adult resource density at small versus large‐spatial scales. At the smaller‐spatial scale, butterflies spent more time feeding in resource‐rich patches, whereas at the large‐scale, butterflies spent more time feeding in resource‐poor plots. Furthermore, both adult and larval resources appeared to affect foraging decisions, suggesting that individuals may optimize search costs for different resources. Overall, our findings suggest that the variation in foraging behavior seen in foragers might result from animals responding to complex ecological conditions, such as resource heterogeneity at multiple spatial scales and the challenges of tracking multiple resources.     

Disentangling olfactory and visual information used by field foraging birds

Foraging strategies of birds can influence trophic plant–insect networks with impacts on primary plant production. Recent experiments show that some forest insectivorous birds can use herbivore‐induced plant volatiles (HIPVs) to locate herbivore‐infested trees, but it is unclear how birds combine or prioritize visual and olfactory information when making foraging decisions. Here, we investigated attraction of ground‐foraging birds to HIPVs and visible prey in short vegetation on farmland in a series of foraging choice experiments. Birds showed an initial preference for HIPVs when visual information was the same for all choice options (i.e., one experimental setup had all options with visible prey, another setup with hidden prey). However, if the alternatives within an experimental setup included visible prey (without HIPV) in competition with HIPV‐only, then birds preferred the visual option over HIPVs. Our results show that olfactory cues can play an important role in birds’ foraging choices when visual information contains little variation; however, visual cues are preferred when variation is present. This suggests certain aspects of bird foraging decisions in agricultural habitats are mediated by olfactory interaction mechanisms between birds and plants. We also found that birds from variety of dietary food guilds were attracted to HIPVs; hence, the ability of birds to use plant cues is probably more general than previously thought, and may influence the biological pest control potential of birds on farmland.     

Into the deep: the functionality of mesopelagic excursions by an oceanic apex predator

Comprehension of ecological processes in marine animals requires information regarding dynamic vertical habitat use. While many pelagic predators primarily associate with epipelagic waters, some species routinely dive beyond the deep scattering layer. Actuation for exploiting these aphotic habitats remains largely unknown. Recent telemetry data from oceanic whitetip sharks (Carcharhinus longimanus) in the Atlantic show a strong association with warm waters (>20°C) less than 200 m. Yet, individuals regularly exhibit excursions into the meso‐ and bathypelagic zone. In order to examine deep‐diving behavior in oceanic whitetip sharks, we physically recovered 16 pop‐up satellite archival tags and analyzed the high‐resolution depth and temperature data. Diving behavior was evaluated in the context of plausible functional behavior hypotheses including interactive behaviors, energy conservation, thermoregulation, navigation, and foraging. Mesopelagic excursions (n = 610) occurred throughout the entire migratory circuit in all individuals, with no indication of site specificity. Six depth‐versus‐time descent and ascent profiles were identified. Descent profile shapes showed little association with examined environmental variables. Contrastingly, ascent profile shapes were related to environmental factors and appear to represent unique behavioral responses to abiotic conditions present at the dive apex. However, environmental conditions may not be the sole factors influencing ascents, as ascent mode may be linked to intentional behaviors. While dive functionality remains unconfirmed, our study suggests that mesopelagic excursions relate to active foraging behavior or navigation. Dive timing, prey constituents, and dive shape support foraging as the most viable hypothesis for mesopelagic excursions, indicating that the oceanic whitetip shark may regularly survey extreme environments (deep depths, low temperatures) as a foraging strategy. At the apex of these deep‐water excursions, sharks exhibit a variable behavioral response, perhaps, indicating the presence or absence of prey.     

Antipredator Behavior in Desmognathus ochrophaeus: Threat‐Specific Responses to Chemical Stimuli in a Foraging Context

Prey species may reduce the likelihood of injury or death by engaging in defensive behavior but often incur costs related to decreased foraging success or efficiency. To lessen these costs, prey may adjust the intensity or type of antipredator behavior according to the nature of the perceived threat. We evaluated the potential for threat‐sensitive responses by Allegheny Mountain dusky salamanders (Desmognathus ochrophaeus) exposed to chemical stimuli associated with predation by asking three questions: (1) Do individual D. ochrophaeus respond to chemical cues in a threat‐sensitive manner? (2) Do salamanders exhibit the same pattern of behavioral response while foraging? and (3) Is foraging efficiency reduced when focal individuals are exposed to stimuli from predators or predation events? In our first experiment, we evaluated salamander chemosensory movements (nose‐taps), locomotor activity (steps), and edge behavior in response to chemical stimuli from disturbed and injured conspecifics as well as predatory Gyrinophilus porphyriticus and found that individual D. ochrophaeus show a significant graded increase in nose‐taps when exposed to cues from conspecifics and a reduction in activity when exposed to the predator. In our second experiment, we again observed salamander responses to the same chemical stimuli but in this instance added five Drosophila prey to the test dishes. We found that salamanders exhibited a similar pattern of response to the chemical stimuli in the presence of prey, showing a graded increase in nose‐taps to cues from conspecifics and a reduction in activity when exposed to the predator. However, foraging efficiency (i.e. the proportion of successful strikes) did not vary significantly among treatments. Our data show that individual D. ochrophaeus detect and differentially respond to chemical stimuli associated with predation, but do not significantly reduce foraging efficiency. Overall, the type and relative intensity of these responses is largely unaffected by the presence of potential prey.     

Florally rich habitats reduce insect pollination and the reproductive success of isolated plants

Landscape heterogeneity in floral communities has the potential to modify pollinator behavior. Pollinator foraging varies with the diversity, abundance, and spatial configuration of floral resources. However, the implications of this variation for pollen transfer and ultimately the reproductive success of insect pollinated plants remains unclear, especially for species which are rare or isolated in the landscape. We used a landscape‐scale experiment, coupled with microsatellite genotyping, to explore how the floral richness of habitats affected pollinator behavior and pollination effectiveness. Small arrays of the partially self‐compatible plant Californian poppy (Eschscholzia californica) were introduced across a landscape gradient to simulate rare, spatially isolated populations. The effects on pollinator activity, outcrossing, and plant reproduction were measured. In florally rich habitats, we found reduced pollen movement between plants, leading to fewer long‐distance pollination events, lower plant outcrossing, and a higher incidence of pollen limitation. This pattern indicates a potential reduction in per capita pollinator visitation, as suggested by the lower activity densities and richness of pollinators observed within florally rich habitats. In addition, seed production reduced by a factor of 1.8 in plants within florally rich habitats and progeny germination reduced by a factor of 1.2. We show this to be a consequence of self‐fertilization within the partially self‐compatible plant, E. californica. These findings indicate that locally rare plants are at a competitive disadvantage within florally rich habitats because neighboring plant species disrupt conspecific mating by co‐opting pollinators. Ultimately, this Allee effect may play an important role in determining the long‐term persistence of rarer plants in the landscape, both in terms of seed production and viability. Community context therefore requires consideration when designing and implementing conservation management for plants which are comparatively rare in the landscape.     

Socially biased learning among adult cottontop tamarins (Saguinus oedipus)

We presented adult cottontop tamarins (Saguinus oedipus) with a novel foraging task that had been used previously to examine socially biased learning of juvenile observers [Humle & Snowdon, Animal Behaviour 75:267–277, 2008]. The task could be solved in one of two ways, and thus allowed for an analysis of behavioral matching between an observer and a skilled demonstrator (trained to use one of the two methods exclusively). Because the demonstrator was an adult in both this study and the juvenile study, the influence of the observer's age could be isolated and examined, as well as the behavior of demonstrators toward observers of different ages. Our main goals were to (1) compare adults and juveniles acquiring the same task to identify how the age of the observer affects socially biased learning and (2) examine the relationship between socially biased learning and behavioral matching in adults. Although adults spent less time observing the trained demonstrators than did juveniles, the adults were more proficient at solving the task. Furthermore, even though observers did not overtly match the behavior of the demonstrator, observation remained an important factor in the success of these individuals. The findings suggested that adult observers could extract information needed to solve a novel foraging task without explicitly matching the behavior of the demonstrator. Adult observers begged much less than juveniles and demonstrators did not respond to begging from adult. Skill acquisition and the process of socially biased learning are, therefore, age‐dependent and are influenced by the behavioral interactions between observer and demonstrator. To what extent this holds true for other primates or animal species still needs to be more fully investigated and considered when designing experiments and interpreting results. Am. J. Primatol. 72:287–295, 2010. © 2009 Wiley‐Liss, Inc.     

Taking a trip to the shelf: Behavioral decisions are mediated by the proximity to foraging habitats in the black‐legged kittiwake

For marine top predators like seabirds, the oceans represent a multitude of habitats regarding oceanographic conditions and food availability. Worldwide, these marine habitats are being altered by changes in climate and increased anthropogenic impact. This is causing a growing concern on how seabird populations might adapt to these changes. Understanding how seabird populations respond to fluctuating environmental conditions and to what extent behavioral flexibility can buffer variations in food availability can help predict how seabirds may cope with changes in the marine environment. Such knowledge is important to implement proper long‐term conservation measures intended to protect marine predators. We explored behavioral flexibility in choice of foraging habitat of chick‐rearing black‐legged kittiwakes Rissa tridactyla during multiple years. By comparing foraging behavior of individuals from two colonies with large differences in oceanographic conditions and distances to predictable feeding areas at the Norwegian shelf break, we investigated how foraging decisions are related to intrinsic and extrinsic factors. We found that proximity to the shelf break determined which factors drove the decision to forage there. At the colony near the shelf break, time of departure from the colony and wind speed were most important in driving the choice of habitat. At the colony farther from the shelf break, the decision to forage there was driven by adult body condition. Birds furthermore adjusted foraging behavior metrics according to time of the day, weather conditions, body condition, and the age of the chicks. The study shows that kittiwakes have high degree of flexibility in their behavioral response to a variable marine environment, which might help them buffer changes in prey distribution around the colonies. The flexibility is, however, dependent on the availability of foraging habitats near the colony.     

Foraging behavior of a Dipteran leaf miner on exploited and unexploited hosts

Summary The foraging behavior of females of the leaf miner, Agromyza frontella (Rondani), (Diptera: Agromyzidae) when encountering unexploited or exploited alfalfa plants was studied in large field cages and in laboratory bioassays. Females did not recognize any exploited leaflets before contacting them and did not distinguish between leaflets with an egg or first instar larva and unexploited leaflets, even after contact. Only one fly oviposited in leaflets which contained 80–120 nutrition holes, one late second or third instar larva or which were marked with an epideictic pheromone in field cages. In laboratory bioassays females oviposited less in leaflets containing a second or third instar larva or an empty larval mine than in unexploited ones. Females foraging on unexploited leaflets engaged in area-restricted search and 10 of 11 females remained on the test plant for the full 60 min of observation. However, females foraging on exploited plants were much more active, spent a greater proportion of their time searching for suitable hosts, had the highest rates of visitation to all above ground plant parts and emigrated to the cage walls before 60 min had elapsed. These quantitative measures of foraging behavior indicated that females ranked plants after landing on them in the following order: unexploited plants >plants marked with pheromone or with many nutrition holes >plants with late instar larvae. The order of host ranking by foragers was in general agreement with the suitability of the host plants for larval survival, development and reproduction, as estimated from previous laboratory studies.Females of A. frontella foraging on unexploited alfalfa plants fed and oviposited significantly more often in the upper apical leaflets than in the lower, older leaflets. However, the choice of feeding site by flies on exploited plants did not vary with leaflet position (age), indicating that females fed in order to sample leaflet quality and that females investigated lower (older) leaves after they discovered that the preferred upper leaves were occupied. These data suggest that high quality oviposition sites may be limiting for A. frontella females, which could explain why superparasitism of leaflets sometimes occurs in nature, even when unexploited sites are available.     

Density‐mediated indirect interactions alter host foraging behaviour of parasitoids without altering foraging efficiency

1. Foraging decisions of parasitoids are influenced by host density via density‐mediated indirect interactions. However, in the parasitoid's environment, non‐suitable herbivores are also present. These non‐hosts also occur in different densities, which can affect a parasitoid's foraging behaviour. 2. The influence of non‐host densities can be expressed during the first phase of the foraging process, when parasitoids use plant volatiles to locate plants infested by their host. They may also play a role during the second phase, when parasitoids use infochemicals from the host and plant to locate, recognise and accept the host. 3. By using laboratory and field setups, it was studied whether the density of non‐host herbivores influences these two phases of the foraging behaviour of the parasitoid Cotesia glomerata as well as the parasitoid's efficiency to find its host, Pieris brassicae caterpillars. 4. The findings show that a high non‐host density, regardless of the species used, negatively affected parasitoid preference for host‐infested plants, but that the behaviour on the plant and the total host‐finding efficiency of the parasitoids were not influenced by non‐host density. 5. These results are discussed in the context of density‐mediated indirect interactions.     

The role of frugivory in plant diversity maintenance – a simulation approach

Frugivores may play a key role in plant species coexistence by equalizing the species’ representation in the seed rain. Rare species may benefit from enhanced dispersal if frugivores prefer locally scarce fruits, or if rare plants are found in neighborhoods of high fruit density. Using a simulation model of frugivorous birds foraging on landscapes we tested if increased diversity in the seed rain could emerge from rare‐biased fruit selection, from the spatial configuration of plants, or both. In the absence of rare‐biased fruit selection, frugivores were not able to increase the diversity of the seed rain in any of our simulated landscapes. In contrast, when frugivores were attracted to locally scarce fruits, we found increased diversity in the seed rain whenever frugivore mobility across the landscape was high and plant species were well‐mixed in the fruiting neighborhoods. Irrespectively of the behavioral mechanism involved, landscape fragmentation lead to losses in diversity and species richness of simulated communities. In all simulations, density‐dependent mortality of dispersed seeds increased diversity in the community of seedlings. However, landscape homogenization at the scale of frugivores movements decreased the magnitude of this diversification effect. In summary, our study shows that frugivory has the potential to increase diversity in the seed rain when frugivores display rare‐biased fruit choices, provided that rare and common plants form heterogeneous neighborhoods. They also show that fragmentation is a major threat for diversity maintenance in the early‐regenerating community. Finally, they show that rarity confers advantages during regeneration only if it occurs at the scale of frugivores’ foraging decisions.     

Human behavioral ecology and niche construction

We examine the relationship between niche construction theory (NCT) and human behavioral ecology (HBE), two branches of evolutionary science that are important sources of theory in archeology. We distinguish between formal models of niche construction as an evolutionary process, and uses of niche construction to refer to a kind of human behavior. Formal models from NCT examine how environmental modification can change the selection pressures that organisms face. In contrast, formal models from HBE predict behavior assuming people behave adaptively in their local setting, and can be used to predict when and why people engage in niche construction. We emphasize that HBE as a field is much broader than foraging theory and can incorporate social and cultural influences on decision‐making. We demonstrate how these approaches can be formally incorporated in a multi‐inheritance framework for evolutionary research, and argue that archeologists can best contribute to evolutionary theory by building and testing models that flexibly incorporate HBE and NCT elements.     

Does morphology predict behavior? Correspondence between behavioral and morphometric data in a Tyrant‐flycatcher (Tyrannidae) assemblage in the Santa Marta Mountains,Colombia

ABSTRACT Morphology is commonly used as a predictor of ecological relationships among species when studying local assemblages of Neotropical birds. Nevertheless, most evidence supporting ecomorphological correspondence in birds comes from studies of communities and not from local assemblages and, moreover, from temperate latitudes. To increase our understanding of ecomorphological correspondence in Neotropical assemblages, we used three multivariate approaches to evaluate correspondence between morphological and foraging behavior data in a tyrant‐flycatcher assemblage (N= 12 species) in the Santa Marta Mountains in Colombia. Principal components analyses revealed similar species ordinations when using morphological measurements (beak size and shape, tarsus length, wing length, and tail length) or behavioral data (behavioral types of searching for prey and prey capture) separately. Discriminant function analyses tested the ability of morphological traits to predict foraging behavior, showing that more than 90% of all measured individuals (N= 267) were correctly classified in previously defined categories of search and attack behavior. Finally, Canonical correlation analyses revealed a significant correlation between morphological data and two independent datasets of search and attack behavior. Our results demonstrate that morphology can accurately predict ecology in an assemblage of Neotropical tyrannids, and similar results have been reported in previous studies of temperate Tyrant‐flycatchers. Our results also show that bill size and shape, wing length, and tarsus length are the best predictors of foraging behavior in this assemblage. Testing for ecomorphological correspondence in other Neotropical taxa would help identify subsets of phenotypic traits that could be used for a practical, but reliable, determination of ecological relationships within different assemblages.     

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.     

Sexual niche partitioning in two species of New Guinean Pachycephala whistlers

Sex differences in foraging behavior have been widely reported in the ornithological literature, but few examples are available from tropical avifaunas. Differences between males and females in foraging behavior have been hypothesized to be a byproduct of sexual size dimorphism or a result of niche partitioning to reduce intersexual competition for food or different reproductive roles. From 2010 to 2013, I used foraging data and mist‐net capture rates from multiple study sites to examine possible sex differences in the foraging behavior of two New Guinean Pachycephala whistlers. I found that male Regent (Pachycephala schlegelii) and Sclater's (Pachycephala soror) whistlers consistently foraged in higher strata than females. It is unlikely that these differences are due to sexual dimorphism because these species exhibit little sexual dimorphism. Sex differences in foraging behavior were consistent across years and study sites and did not appear linked to breeding behavior, supporting the food‐competition hypothesis, but not the reproductive‐roles hypothesis. Male territorial defense often occurs in relatively high strata in Pachycephala whistlers, possibly influencing male foraging strata. However, male territorial behavior cannot explain why females predominately forage in lower strata. Instead, intersexual competition for food resources is likely the primary driver of differences in the foraging behavior of male and female Regent and Sclater's whistlers.     

The foraging behavior of Japanese macaques Macaca fuscata in a forested enclosure:Effects of nutrient composition,energy and its seasonal variation on the consumption of natural plant foods

In the wild, primate foraging behaviors are related to the diversity and nutritional properties of food, which are affected by seasonal variation. The goal of environmental enrichment is to stimulate captive animals to exhibit similar foraging behavior of their wild counterparts, e.g. To extend foraging time. We conducted a 12-month study on the foraging behavior of Japanese macaques in a semi-naturally forested enclosure to understand how they use both provisioned foods and naturally available plant foods and what are the nutritional criteria of their consumption of natural plants. We recorded time spent feeding on provisioned and natural plant foods and collected the plant parts ingested of their major plant food species monthly, when available.We conducted nutritional analysis (crude protein, crude lipid, neutral detergent fiber-'NDF', ash) and calculated total non-slructural carbohydrate - 'TNC' and total energy of those food items. Monkeys spent 47% of their feeding time foraging on natural plant species. The consumption of plant parts varied significantly across seasons. We found that leaf items were consumed in months when crude protein, crude protein-to-NDF ratio, TNC and total energy were significantly higher and NDF was significantly lower, fruit/nut items in months when crude protein and TNC were significantly higher and crude lipid content was significantly lower, and bark items in months when TNC and total energy were higher and crude lipid content was lower. This preliminary investigation showed that the forested enclosure allowed troop members to more fully express their species typical flexible behavior by challenging them to adjust their foraging behavior to seasonal changes of plant item diversity and nutritional content, also providing the possibility for individuals to nutritionally enhance their diet.     

两种生境下野慈姑繁殖差异及其机制

植物的生长环境不但可直接作用于其可利用资源的多寡及其繁殖分配,而且可通过影响植物所在的群落以及传粉者的组成或行为而间接的导致繁殖差异。然而,直接与间接作用的方向或强度很少被同时关注,从而限制了从机制上理解环境对植物繁殖的影响。选取野慈姑(Sagittaria trifolia L.)为研究材料,将相同基因型组成的植株分别种植在光照差异明显的两个同质园(林荫区与日照区),于盛花期对野慈姑的开花数量、昆虫访花进行了观察,确定其主要访花昆虫、记录访花行为以及野慈姑的繁殖产出水平。研究表明,日照区野慈姑每天开放的花朵和植株数量显著高于林荫区。两个区域内野慈姑的主要访花者有四大类:蚜蝇类、蜂类、蝶类和蝇类;其中林荫区的主要传粉昆虫为蚜蝇类,而日照区为蜂类。日照区昆虫单位时间内的访花频率、昆虫每回合访问的雄花数、总花数和花序数均显著高于林荫区。日照区野慈姑的座果率显著高于林荫区,而单果种子数量与种子面积与林荫区相当。总体而言,日照区野慈姑的繁殖产出达到了林荫区的三倍以上,这是环境的直接作用与环境介导的传粉作用在同一方向上叠加的结果,且前者占主导地位。在关注植物、物理环境和生物因子三者之间互作的前提下,量化每个繁殖阶段的水平,特别是传粉昆虫在不同生境下的表现,阐述了环境异质性导致植物繁殖差异的根本原因。     

Human activity and habitat type affect perceived predation risk in urban white‐footed mice (Peromyscus leucopus)

Predation risk is one of the largest costs associated with foraging in small mammals. Small mammals select microhabitat features such as tree and shrub canopy cover, woody debris and vegetative ground cover that can lower the risk of detection from predators and provide greater protection if discovered. Small mammals also increase foraging activity and decrease selection for cover when cloud cover increases and moon illumination is less. Often researchers assume small mammals in urban areas respond to these cues in the same manner as in natural areas, but these cues themselves are altered in urban zones. In this study, we investigated how Amur honeysuckle (Lonicera maackii) and coarse woody debris (CWD) affected giving‐up density (GUD) in white‐footed mice (Peromyscus leucopus). Each of three habitat treatments (open flood channel, the edge and interior of the honeysuckle patch) contained cover treatments with coarse woody debris present or absent. The six treatment combinations were compared to environmental variables (temperature, humidity and illumination) and habitat variables to test their effect on GUD. Peromyscus leucopus foraged to lower densities in areas with CWD present and also under the honeysuckle canopy, using this invasive shrub to decrease predation risk, potentially increasing survivability within this urban park. Increased human presence negatively affected foraging behavior across treatments. Human presence and light pollution significantly influenced P. leucopus, modifying their foraging behavior and demonstrating that both fine‐ and coarse‐scale urban factors can affect small mammals. Foraging increased as humidity increased, particularly under the honeysuckle canopy. Changes in illumination due to moonlight and cloud cover did not affect foraging behavior, suggesting urban light pollution may have altered behavioral responses to changes in light levels. Lonicera maackii seemed to facilitate foraging in P. leucopus, even though it adversely affects the plant community, suggesting that its impact may not be entirely negative.     

The effect of rearing history and aphid density on volatile‐mediated foraging behaviour of Diaeretiella rapae

1. Parasitoid females foraging for hosts rely on cues derived from the insect host, the host plant and/or their interaction, and all of these can be learned during the immature and adult stages. 2. The present study investigated the importance of rearing history on foraging behaviour of Diaeretiella rapae, an endoparasitoid often associated with aphids feeding on brassicaceous plant species. 3. Parasitoids were reared on one of the four possible combinations, comprising two brassicaceous host plant species, Brassica nigra or Raphanus sativus, and two aphid species Brevicoryne brassicae or Myzus persicae. These parasitoids were tested in a Y‐tube olfactometer and given the choice between volatiles emitted by an aphid‐infested plant (25 or 100 aphids per plant) and an uninfested control plant. The parasitoid's responses were compared when offered: (i) the same plant–aphid combination as the one on which it had been reared; (ii) the same host plant infested with the alternative aphid species; or (iii) an alternative plant with the alternative aphid species. 4. Aphid density did affect the behavioural responses to the various odour sources, but rearing history did not. Diaeretiella rapae only preferred aphid‐induced to non‐induced plant volatiles at low aphid infestation level, whereas they did not discriminate between volatiles at high aphid infestation level. 5. It is concluded that aphid‐induced volatiles of brassicaceous plants play an important role during host habitat location, but seem less important for parasitoids to locate the aphid host itself. The data are discussed in the light of manipulation of host plant defences by aphids.