饥饿和食物单宁酸对东方田鼠(Microtus fortis)食物摄入量和觅食行为的影响

实验室条件下,测定饥饿和食物单宁酸对东方田鼠食物摄入量和觅食行为的影响。结果表明,饥饿使实验个体的食物总摄入量增加,食物摄入率及口量大小随饥饿强度的增大而增加,而觅食频次则无显著改变,实验个体每取食回合的觅食时间呈缓慢增加的趋势,与对照组比较,觅食时间差异不显著。东方田鼠优先选择0%单宁酸食物,次为3%单宁酸食物,而对6%单宁酸食物的摄入量最少。在饥饿条件下,东方田鼠食物摄入率的增加主要源于其口量大小,觅食频次和觅摄食时间对食物摄入量增加的贡献不显著。在饥饿条件下,植食性小哺乳动物并未通过延长觅食时间,降低用于防卫、繁殖活动时间来增加食物摄入量,而是通过增加口量大小,提高其食物摄入率来满足其营养需要。验证了饥饿与植物次生化合物共同作用引起田鼠类动物生理的改变,能影响其食物摄入量及觅食行为的假设。     

Effects of temporal variation in the risk of predation by least weasel (Mustela nivalis) on feeding behavior of field vole (Microtus agrestis)

Predation risk tends to vary in time. Thus prey animals face a problem of allocating feeding and antipredator effort across different risk situations. A recent model of Lima and Bednekoff (1999) predicts that a prey should allocate more feeding effort to low risk situations and more antipredator effort to high risk situations with increasing relative degree of risk in high risk situations (attack ratio). Furthermore when the proportion of time the prey spends in the high risk situation (p) increases, the prey have to eventually feed also in the high risk situations. However the increase in feeding effort in low risk situations should clearly exceed that in high risk situations as p increases. To test these predictions we measured feeding effort of field voles (Microtus agrestis) exposed to varying presence of least weasel (Mustela nivalis) and its feces in laboratory conditions. We generated quantitative predictions by estimating attack ratios from results of a pilot experiment. The model explained 15% of the observed variation in feeding effort of voles. Further analyses indicated that feeding effort was lower in high risk situations than in low risk situations at high attack ratio, but not at a lower one. Voles exposed to a presence of a weasel for extended periods showed signs of nutritional stress. Still we did not find any increase in feeding effort with increasing p. This was obviously due to the relatively low maximal p we used as we included only conditions likely to occur in nature.     

Surviving winter: Food,but not habitat structure,prevents crashes in cyclic vole populations

Vole population cycles are a major force driving boreal ecosystem dynamics in northwestern Eurasia. However, our understanding of the impact of winter on these cycles is increasingly uncertain, especially because climate change is affecting snow predictability, quality, and abundance. We examined the role of winter weather and snow conditions, the lack of suitable habitat structure during freeze‐thaw periods, and the lack of sufficient food as potential causes for winter population crashes. We live‐trapped bank voles Myodes glareolus on 26 plots (0.36 ha each) at two different elevations (representing different winter conditions) in southeast Norway in the winters 2013/2014 and 2014/2015. We carried out two manipulations: supplementing six plots with food to eliminate food limitation and six plots with straw to improve habitat structure and limit the effect of icing in the subnivean space. In the first winter, all bank voles survived well on all plots, whereas in the second winter voles on almost all plots went extinct except for those receiving supplemental food. Survival was highest on the feeding treatment in both winters, whereas improving habitat structure had no effect. We conclude that food limitation was a key factor in causing winter population crashes.     

Antifungal activity of helenin and isohelenin

Two sesquiterpene lactones, helenin and isohelenin, were examined for their activity against 16 species of fungi. These compounds varied greatly in their antifungal activities. At concentrations of 10 μg/ml, the lactones strongly inhibited the growth of Microsporum cookei, Trichophyton mentagrophytes and Trichothecium roseum, while other fungi were only inhibited by considerably higher levels (100–1000 μg/ml). It is suggested that these secondary plant metabolites might be of potential use as antifungal agents, especially if their activity and specificity could further be enhanced through modifications in their chemical structure.     

Usefulness of multiple chalk‐based food colorings for inducing better gene silencing by feeding RNA interference in planarians

Planarians have become widely recognized as one of the major animal models for regeneration studies in invertebrates. To induce RNA interference (RNAi) by feeding in planarians, the widely accepted protocol is one in which animals undergo two or three feedings of food containing double‐stranded RNA (dsRNA) plus visible food coloring (e.g., blood) for confirmation of feeding by individual animals. However, one possible problem is that incorporated food coloring is often retained within the gut for several days, which makes it difficult to confirm the success of each round of dsRNA feeding based on the difference of the color density within the gut before and after feeding. As a consequence, the difference of appetite levels among individuals undergoing dsRNA feeding leads to phenotypic variability among them due to insufficient knockdown. In our attempts to overcome this problem, we have developed a novel method for achieving robust confirmation of the success of dsRNA feeding in individuals fed multiple times by means of including a combination of three different colored chalks (pink, yellow and blue) as food coloring. Notably, we found that this method is superior to the conventional method for positively marking individuals that actively consumed the dsRNA‐containing food during four times of once‐daily feeding. Using these selected animals, we obtained stable and sufficiently strong RNAi‐induced phenotypes. We termed this improved multi‐colored chalk‐spiked method of feeding RNAi “Candi” and propose its benefits for gene function analysis in planarians.     

An endophytic fungus reduces herbivory in its recently colonised grass host: a food-choice experiment on common voles, weeping alkaligrass and Epichlo? typhina

The interactions of endophytes with plants are believed to evolve over time from parasitic to mutualistic, and in the seed-transmitted fungal endophytes, these interactions are conventionally treated as mutualistic. The weeping alkaligrass Puccinellia distans has recently dispersed to new habitats in Europe, where it was colonised by the seed-transmitted fungus Epichlo? typhina. The E. typhina-infected weeping alkaligrass has a fertility advantage over -uninfected plants, but this advantage is held only over shorter time scales. We assess the antiherbivore value of E. typhina in mature weeping alkaligrass against common voles Microtus arvalis, a herbivore naturally co-occurring with weeping alkaligrass. In two consecutive food-choice tests conducted in a lab, we examined feeding by na?ve voles on E. typhina-infected (E+) and -uninfected grass (E?) originating from Central Europe. In the first test, all voles consumed comparable amounts of E+ biomass and E? biomass. In the subsequent test, the voles reduced their feeding rates by 57?%, but E+ food was avoided twice as frequently as E? food (75 vs. 33?% reduction). This result suggests that toxins produced by E. typhina repel herbivores soon after the first contact. We show that in addition to its direct fitness consequences, endophyte-mediated resistance to herbivory increases the fertility advantage of E. typhina-infected weeping alkaligrass. This effect can increase the ability of weeping alkaligrass to invade habitats with intense herbivory.     

Pollen feeding proteomics: Salivary proteins of the passion flower butterfly,Heliconius melpomene

While most adult Lepidoptera use flower nectar as their primary food source, butterflies in the genus Heliconius have evolved the novel ability to acquire amino acids from consuming pollen. Heliconius butterflies collect pollen on their proboscis, moisten the pollen with saliva, and use a combination of mechanical disruption and chemical degradation to release free amino acids that are subsequently re-ingested in the saliva. Little is known about the molecular mechanisms of this complex pollen feeding adaptation. Here we report an initial shotgun proteomic analysis of saliva from Heliconius melpomene. Results from liquid-chromatography tandem mass-spectrometry confidently identified 31 salivary proteins, most of which contained predicted signal peptides, consistent with extracellular secretion. Further bioinformatic annotation of these salivary proteins indicated the presence of four distinct functional classes: proteolysis (10 proteins), carbohydrate hydrolysis (5), immunity (6), and “housekeeping” (4). Additionally, six proteins could not be functionally annotated beyond containing a predicted signal sequence. The presence of several salivary proteases is consistent with previous demonstrations that Heliconius saliva has proteolytic capacity. It is likely that these proteins play a key role in generating free amino acids during pollen digestion. The identification of proteins functioning in carbohydrate hydrolysis is consistent with Heliconius butterflies consuming nectar, like other lepidopterans, as well as pollen. Immune-related proteins in saliva are also expected, given that ingestion of pathogens is a likely route to infection. The few “housekeeping” proteins are likely not true salivary proteins and reflect a modest level of contamination that occurred during saliva collection. Among the unannotated proteins were two sets of paralogs, each seemingly the result of a relatively recent tandem duplication. These results offer a first glimpse into the molecular foundation of Heliconius pollen feeding and provide a substantial advance towards comprehensively understanding this striking evolutionary novelty.     

Feeding response of a benthic copepod to ciliate prey type,prey concentration and habitat complexity

1. Protozoans are important consumers within microbial food webs and, in turn, they represent potential prey for small metazoans. However, feeding interactions within these food webs are rarely characterised and this is especially true for freshwater sediments. 2. We aimed to quantify the feeding links between a freshwater meiofaunal copepod and ciliates in two laboratory experiments. The first experiment addressed the response of Eucyclops serrulatus towards ciliate density and type (two ciliate species of the same genus differing in terms of body size). A second experiment assessed the effect of habitat structure on feeding rates by introducing different structural complexity into the feeding arena. In contrast to the first experiment, which was run only for one time period, this experiment also tested three different total feeding times (4, 7 and 9 h). 3. Eucyclops serrulatus exhibited high ingestion rates, with 3–69 ciliates copepod^?1 h^?1 consumed depending on food concentration, food type and habitat complexity. Copepods exhibited a preference for the smaller ciliate when total ciliate concentration was low, but selected both ciliates equally when food concentrations were medium or high. However, at very high food concentration, Eucyclops preferred the larger ciliate (which was 1/3 of its own body size), suggesting that the longer handling times of the larger prey are rewarding when the large prey is present in high numbers. In terms of total numbers consumed, copepods fed on more small ciliates, but in terms of carbon units both ciliates were selected equally when total prey concentration was low or medium. However, copepods derived more carbon from the larger prey at high and very high prey concentrations (up to 0.7 μgC out of a maximum of 1.1 μgC copepod^?1 h^?1). Habitat complexity influenced the feeding of copepods when it was observed over time. 4. The copepod–ciliate link is well known from the pelagic zone of both marine and freshwater habitats. We have shown its potential importance within the benthos, where it can be influenced by food identity, food quantity and possibly by habitat complexity.     

Jaw and hyolingual movements during prey transport in varanid lizards: effects of prey type

The ability to modulate feeding kinematics in response to prey items with different functional properties is likely a prerequisite for most organisms that feed on a variety of food items. Variation in prey properties is expected to reveal variation in feeding function and the functional role of the different phases in a transport cycle. Here we describe the kinematics of prey transport of two varanid species, Varanus niloticus and Varanus ornatus. These species were selected for analysis because of their highly specialised hyolingual system and food transport mechanism (inertial food transport). In these animals, tongue and hyoid movements are expected to make no, or only a minor, contribution to prey transport. We observed statistically significant prey type effects that could be associated with prey properties such as mass, size and mobility. These data show that both species are capable of modulating the kinematics of food transport in response to different prey types. Moreover, not only the kinematics of the jaws were modulated in response to prey characteristics but also the anterior/posterior movements of the tongue and hyoid. This suggests a more important role of the tongue and hyolingual movements in these animals than previously suspected. In contrast, head movements were rather stereotyped and were not modulated in response to changes in prey type.     

Do laying hens eat and forage in excreta from other hens?

Worldwide, farm animals are kept on litter or foraging substrate that becomes increasingly soiled throughout the production cycle. For animals like laying hens, this means that it is likely they would scratch, forage and consume portions of excreta found in the litter or foraging substrate. However, no study has investigated the relative preference of laying hens for foraging and consumption of feed mixed with different percentages of excreta. A total of 48 White Leghorn laying hens of two strains, a commercial strain (Lohmann LSL-Lite (LSL), n=24) and UCD-003 strain (susceptible to liver damage, n=24), were individually housed and given access to feed mixed with increasing percentages of hen excreta (0%, 33%, 66% and 100% excreta diets) and corn as a luxury food reward (four corn kernels per diet daily). The amount of substrate and number of corn kernels consumed from each diet was recorded for a period of 3 weeks. Both LSL and UCD-003 hens preferred to consume and forage in diets with 0% excreta, followed by 33% and finally diets containing 66% and 100% excreta. Despite the presence of excreta-free diets, birds consumed on average 61.3 g per day of the diets containing excreta. Neither physical health, measured by plasma enzyme activity levels, nor cognitive differences, assessed by recalling a visual discrimination task, was associated with relative feeding or foraging preference. In conclusion, this study demonstrated a clear preference for feeding and foraging on substrate without excreta in laying hens. However, considering the amount of excreta diets consumed, further studies are needed to understand the causes and consequences of excreta consumption on physiological and psychological functioning, and how this information can be used to allow adjustments in the management of foraging substrates in farmed birds.     

Lateralization in feeding is food type specific and impacts feeding success in wild birds

Current research suggests that hemispheric lateralization has significant fitness consequences. Foraging, as a basic survival function, is a perfect research model to test the fitness impact of lateralization. However, our understanding of lateralized feeding behavior is based predominantly on laboratory studies, while the evidence from wild animals in natural settings is limited. Here we studied visual lateralization in yellow‐footed green pigeons (Treron phoenicoptera) feeding in the wild. We aimed to test whether different types of food objects requiring different searching strategies elicit different eye/hemisphere biases. When feeding on relatively large, uniformly colored food objects (mahua flowers) which can be present or absent in the viewed patch, the majority of pigeons relied mostly on the left eye–right hemisphere. In contrast, when feeding on smaller and more abundant food objects, with color cues signaling its ripeness (sacred figs), right‐eye (left‐hemisphere) preference prevailed. Our results demonstrate that oppositely directed visual biases previously found in different experimental tasks occur in natural feeding situations in the form of lateralized viewing strategies specific for different types of food. The results suggest that pigeons rely on the hemisphere providing more advantages for the consumption of the particular type of food objects, implying the relevance of brain lateralization as a plastic adaptation to ecological demands. We assessed the success of food discrimination and consumption to examine the link between lateralization and cognitive performance. The use of the preferred eye resulted in better discrimination of food items. Discrimination accuracy and feeding efficiency were significantly higher in lateralized individuals. The results showed that visual lateralization impacted pigeons’ feeding success, implicating important fitness benefits associated with lateralization.     

Self-grooming and sibling recognition in meadow voles,Microtus pennsylvanicus,and prairie voles,M. ochrogaster

Self-grooming in response to the odours of an opposite-sex conspecific may reflect sexual motivation on the part of the actor. We tested the hypothesis that meadow voles, Microtus pennsylvanicus, and prairie voles,M. ochrogaster , both self-groom at different rates when exposed to the odours of their siblings as compared to those of nonsiblings. This prediction was studied under the context of social memory for siblings and the effects of isolation on memory for siblings. The hypothesis explains the self-grooming responses of meadow voles isolated from their siblings for 10 days and of prairie voles isolated from their siblings for 20 days. However, 20 days of isolation for male and female meadow voles, and 30 days of isolation for male prairie voles were sufficient to induce these animals to self-groom at a similar rate to both sibling and nonsibling odours, suggesting that after isolation these animals no longer recognized their opposite-sex siblings. Female prairie voles isolated for 30 days self-groomed more in response to the odours of male nonsiblings than to those of male siblings, suggesting that female prairie voles still recognize their male siblings after isolation. This study is the first to provide empirical evidence that, in the context of sibling recognition, self-grooming behaviour is directed at unfamiliar opposite-sex conspecifics, and that the communicative function of self-grooming (sexual motivation) is associated with social memory for siblings. Differences in the self-grooming behaviour of meadow voles and prairie voles may be associated with several aspects of their life history characteristics.     

Influence of the abundance of food resources on the feeding habits of the red fox, Vulpes vulpes, in western Switzerland

J.-M. WEBER
The influence of food abundance on red fox feeding habits was studied in the Swiss Jura Mountains between November 1990 and February 1992, during a low density period in the water vole population cycle. Six food categories–water voles, small mammals, domestic stock, earthworms, wild fruits and exploitable scraps–were censused during the present research and their seasonal abundances were estimated in fixed plots. Fox scats were collected and analysed at regular monthly intervals.
The diet of foxes was found to be correlated with seasonal food supply. A positive significant correlation between seasonal abundances and relative proportions in the diet was found for food categories showing a clear seasonality (earthworms, wild fruits and exploitable scraps), whereas no correlation was recorded for the other food resources. Diet composition observed in the present study was compared with that recorded in the same study area between 1988 and 1990 by Weber & Aubry (1993), when water voles were very common and accounted for more than 50% of the diet. A significant change was recorded in red fox feeding habits: the most important aspects of this modification of the diet was the decrease in water vole importance accompanied by the increase in the frequency of occurrence of other food categories, such as wild fruits and scavengeable items.     

Variables Controlling Entry into and Exit from the Steady-State,One of Two Modes of Feeding in Aplysia

Background

Aplysia feeding is a model system for examining the neural mechanisms by which changes in motivational state control behavior. When food is intermittently present, Aplysia eat large meals controlled by a balance between food stimuli exciting feeding and gut stimuli inhibiting feeding. However, when food is continuously present animals are in a state in which feeding is relatively inhibited and animals eat little. We examined which stimuli provided by food and feeding initiate steady-state inhibition of feeding, and which stimuli maintain the inhibition.

Results

Multiple stimuli were found to control entry into the steady-state inhibition, and its maintenance. The major variable governing entry into the steady-state is fill of the gut with bulk provided by food, but this stimulus cannot alone cause entry into the steady-state. Food odor and nutritional stimuli such as increased hemolymph glucose and L-arginine concentrations also contribute to inhibition of feeding leading to entry into the steady-state. Although food odor can alone cause some inhibition of feeding, it does not amplify the effect of gut fill. By contrast, neither increased hemolymph glucose nor L-arginine alone inhibits feeding in hungry animals, but both amplify the inhibitory effects of food odor, and increased glucose also amplifies the effect of gut fill. The major variable maintaining the steady-state is the continued presence of food odor, which can alone maintain the steady-state for 48–72 hrs. Neither increased glucose nor L-arginine can alone preserve the steady-state, although they partially preserve it. Glucose and arginine partially extend the effect of food odor after 72 hrs.

Conclusions

These findings show that control of Aplysia feeding is more complex than was previously thought, in that multiple inhibitory factors interact in its control.     

Food Sorting by Collared Lemmings (Dicrostonyx groenlandicus) and Prairie Voles (Microtus ochrogaster): A Cautionary Note for Digestibility Studies

Small herbivores are often confronted with poor quality diets; in response to this situation, they may sort their food to increase diet quality. Neutral detergent fiber (NDF) levels were measured in three pelleted diets fed to collared lemmings (Dicrostonyx groenlandicus) and prairie voles (Microtus ochrogaster) and compared to levels in orts collected from the same diets and animals. Lemmings sorted and discarded the fibrous parts of food pellets on all three diets (17.3% to 25.9% higher NDF in orts), whereas voles sorted out fibrous particles on only one diet. Calculations of NDF digestibility were significantly reduced by particle sorting (up to 16.9% decrease in digestibility). In reviewing the literature, we found that in more than half of studies examined, orts may not have been analyzed for these differences. Researchers must carefully consider such effects, especially when conducting digestibility studies with herbivores on pelleted diets.     

Countercurrent flows,water movements and nutrient absorption in the locust midgut

Using amaranth dye as a marker solute, the movements of fluids in the gut of Schistocerca gregaria was studied, either by feeding a meal containing the dye or by injecting the dye into the haemolymph, and by comparing the distribution of amaranth with those of naturally-occurring solutes in the alimentary tract.In animals deprived of food for more than 2–4 hr, some of the fluid from the Malpighian tubules moves forward through the solid food matrix in the midgut carrying solutes into the anterior midgut and gastric caeca, where water is absorbed. After a meal the crop empties at a rate which saturates the absorptive capacity of the anterior caeca, producing a net movement of fluid down the midgut and so such a countercurrent system is not observed in animals fed ad lib., where dye introduced into the gut always moves posteriorly.A countercurrent fluid movement confers several advantages on the alimentary system which act to maximise the efficiency of nutrient absorption: the principal disadvantage of the countercurrent system is that noxious solutes, as well as nutrients, will accumulate at high concentrations near the permeable site of nutrient uptake. Thus a countercurrent flow of solutes is observed only when the insect is deprived of food and the need to conserve nutrient resources exceeds that of excretion of noxious substances. Ways in which the site of nutrient absorption may be protected from noxious solutes are discussed.The anterior caeca gradually become bloated with dark fluid as digestion proceeds; this is expelled into the midgut when a fresh meal is ingested.     

Does the newly weaned piglet select a zinc oxide supplemented feed,when given the choice?

An experiment was conducted to examine whether weaned piglets would display preference for a food containing a pharmacological level of zinc oxide (ZnO). A total of 60 piglets were weaned at 7.8 kg ± 0.14 (s.e.m.) and 27.8 ± 0.11 days of age into eight mixed sex groups of seven or eight piglets per pen. Groups were balanced for litter origin, weaning weight and sex. Piglet feeding behaviour was constantly recorded by a multi-spaced feeding behaviour recording system (Leeds University Feeding Behaviour System) in each pen. Each pen of pigs was offered ad libitum access to two different foods (16.2 MJ digestible energy, 16 g lysine/kg), which differed only in the level of ZnO supplementation: unsupplemented (U) or supplemented (Z; ZnO 3100 mg/kg). Both foods contained a basal level of zinc (100 mg/kg). Feeding time was recorded for each individual at each trough. Piglets were weighed at weaning and at 7 and 13 days thereafter. The experiment ran for 13 days. Any piglet observed with post-weaning scour (Y) was recorded and treated appropriately whereas healthy piglets were categorised as N (no scour). Preference for a food was defined as being significantly different from 50% of total feed intake or time spent feeding. There was no difference between piglet numbers selecting each food as their first meal. However, within the first 24 h, piglets preferred (P < 0.001) food U, spending only 36.3% (32.2 to 40.5; 95% confidence interval) of feeding time at food Z. Throughout the experiment, piglets showed aversion (P < 0.001) to food Z, consumption being 8.9% (5.1 to 13.6) and 15.7% (8.9 to 23.9) of total intake in weeks 1 and 2, respectively. Individual piglets showed their preference for food U with only 16.6% (14.6 to 18.5) and 21.8% (19.6 to 24.0) of feeding time spent on food Z in weeks 1 and 2, respectively. Scouring piglets did not show any difference in feeding behaviour from healthy piglets in either week. Average piglet gain (of all piglets) was low, at 0.039 ± 0.03 and 0.272 ± 0.04 kg/day in weeks 1 and 2, respectively. Given a choice, weaned piglets showed a clear preference for the food U even when exhibiting post-weaning scour. It can be concluded that the newly weaned, naïve, piglet is not able to recognise a food with clear health and performance benefits but selected the food U due to the reduced palatability of the food Z.     

Variation in predation risk and vole feeding behaviour: a field test of the risk allocation hypothesis

Many prey animals experience temporal variation in the risk of predation and therefore face the problem of allocating their time between antipredator efforts and other activities like feeding and breeding. We investigated time allocation of prey animals that balanced predation risk and feeding opportunities. The predation risk allocation hypothesis predicts that animals should forage more in low- than in high-risk situations and that this difference should increase with an increasing attack ratio (i.e. difference between low- and high-risk situations) and proportion of time spent at high risk. To test these predictions we conducted a field test using bank voles (Clethrionomys glareolus) as a prey and the least weasel (Mustela nivalis nivalis) as a predator. The temporal pattern and intensity of predation risk were manipulated in large outdoor enclosures and the foraging effort and patch use of voles were measured by recording giving-up densities. We did not observe any variation in feeding effort due to changes in the level of risk or the proportion of time spent under high-risk conditions. The only significant effect was found when the attack ratio was altered: the foraging effort of voles was higher in the treatment with a low attack ratio than in the treatment with a high attack ratio. Thus the results did not support the predation risk allocation hypothesis and we question the applicability of the hypothesis to our study system. We argue that the deviation between the observed pattern of feeding behaviour of bank voles and that predicted by the predation risk allocation hypothesis was mostly due to the inability of voles to accurately assess the changes in the level of risk. However, we also emphasise the difficulties of testing hypotheses under outdoor conditions and with mammals capable of flexible behavioural patterns.     

Interrelationships between yeast fungi and collembolans in soil

The possibility of feeding on green and newly fallen leaves of the small-leaved lime Tilia cordata was studied for the collembolans Protaphorura armata and Vertagopus pseudocinereus. Young leaves grown under sterile conditions and almost free of yeast fungi were found to be toxic to the collembolan V. pseudocinereus: feeding on them led to the death of the animals. Leaves grown under natural conditions were nontoxic: when used by the collembolans as feed, they provided for collembolan growth and fecundity. Feeding preferences of the collembolans in relation to the yeasts attributed to different ecomorphs—epiphytes, litter saprophytes, pedobionts, and saccharobionts—were studied. Of the 24 yeast strains isolated from plant green parts, litter, and soil and assigned to eight species, no strain was revealed that was not used by the collembolans. However, certain yeast strains were preferable for the collembolans. The population of the V. pseudocinereus collembolans feeding on the yeast Rhodotorula glutinis (nss 31–4) exceeded that grown on Cryptococcus terricola (2044) 1.5-fold. Thus, the collembolans have feeding preferences in relation to yeast fungi, as was shown earlier with mycelial micromycetes. The possible mechanisms of the feeding preferences of the collembolans in relation to yeasts are discussed.