Feeding Biology Research Articles

Feeding biology of Diplogasteritus nudicapitatus and Rhabditis curvicaudata (Nematoda) related to food concentration and temperature, in sewage treatment plants.

The feeding biology of two bacterivorous nematodes found in percolating filter-bed sewage treatment plants were investigated in relation to food supply and temperature at all developmental stages. Temperature profoundly affected feeding activity and ingestion rates. As temperature increased ingestion rates increased. The larger species, Rhabditis curvicaudata possessed lower rates of pharyngeal pulsation than the small species Diplogasteritus nudicapitatus. R. curvicaudata reduced feeding activity as bacterial density fell from 8x109 cells ml-1 to 5x107 cells ml-1, below which it ceased feeding. D. nudicapitatus pumped continuously at a more or less constant rate irrespective of food density. The evolutionary and ecological aspects of these two patterns of feeding behaviour are discussed.

The ecological interaction between arctic charr, Salvelinus alpinus (L.), and the plerocercoid stage of Diphyllobothrium ditremum

Six hundred and two arctic charr, Salvelinus alpinus, from a small lake (30 ha) were examined for infection with plerocercoids of Diphyllobothrium ditremum the only species of this genus present; 466 (77.4%) harboured the parasite in an overdispersed infection. The prevalence of infection increased with age and reached 100% at 7+ years for males and 8+ years for females. The rate of infection appeared to be related to the feeding biology of the charr which did not change within the age span studied. The rate of increase in density of infection (plerocercoids per fish) decreased with age as did the degree of overdispersion. It is concluded that the infection probably induces mortality in the fish population, and that such mortality is dependent on parasite density.

Feeding potential and biology of lesser meal worm, Alphitobius diaperinus (Panz.) (Col., Tenebrionidae), preying on Corcyra cephalonica St. (Lep., Pyralidae)

AbstractThe grubs and adults of the lesser meal worm, Alphitobius diaperinus (Panz.) were found gregariously feeding on the eggs and larvae of Corcyra cephalonica St. for the first time in India. The developmental period from egg to adult was completed in 70 to 89 days at 27 ± 1 °C and 65 ± 5% R. H. The mean egg, larval and pupal periods were 6.6, 68.8 and 8.4 days, respectively. The longevity of most of the beetles was between 14 and 16 months and they laid fertile eggs ranging between 1059 to 1874 per female. Some of the beetles are found to survive beyond 16 months and lay very few eggs. The beetles remained active in the laboratory throughout the year with a peak during summer season.ZusammenfassungErnährungspotential und Biologie des Kleinen Mehlkäfers, Alphitobius diaperinus (Panz.) (Col., Tenebrionidae), eines Prädators bei Corcyra cephalonica St. (Lep., Pyralidae)Die Larven und Adulten von A. diaperinus wurden erstmals in Indien als Prädatoren von Eiern und Larven der Pyralide C. cephalonica festgestellt. Die Entwicklungszeit vom Ei bis zum Käfer betrug bei 27° C und 65% rel. F. 70 bis 89 Tage. Die mittlere Entwicklungsdauer der Eier, Larven und Puppen betrug 6,6–68,8 und 8,4 Tage. Die Lebensdauer der meisten Käfer lag zwischen 14 und 16 Monaten. Während dieser Zeit legten die Weibchen maximal 1874 Eier ab. Einige der Käfer lebten länger als 16 Monate und legten nur wenige Eier. Die Käfer blieben im Labor während des ganzen Jahres aktiv bei einem Aktivitätsmaximum im Sommer.

On the biology of Ameroseius dendrovagans (Acari, Mesostigmata, Ameroseiidae)

Results of observations on the feeding habit and biology of Ameroseius dendrovagans Flechtmann & Flechtmann are given.

Detritivory in neotropical fish communities

Fish communities of major river systems in South America contain a high proportion of detritivorous fishes in the families Prochilodontidae and Curimatidae. These families include important fish stocks that in some regions comprise over 50 percent of the community ichthyomass. As a group, detritivores have anatomical-physiological adaptations for collection and digestion of detritus, but the actual mechanisms of these presumed adaptations have to-date only been inferred. Dietary requirements have not been identified. Behavioral adaptation is implied by feeding habitat selection but its nutritional significance is unknown. Because many of these species have commercial importance, and because ongoing construction of impoundments threatens to disrupt seasonal migrations between spawning and feeding areas, an understanding of the feeding biology of detritivores is important.

The biology of Carangidae (Teleostei) in Natal estuaries

The occurrence and abundance of 17 species of Carangidae in Natal estuaries are described. The following six species are of significance in the estuarine community: Caranx ignobilis, C. melampygus, C. papuensis, C. sexfasciatus, Lichia amia and Scomberoides lysan. Only juveniles and subadults utilize estuaries. The time of recruitment, growth rates and feeding biology of the six species were investigated. Among the juveniles, C. ignobilis and C. sexfasciatus are mainly piscivorous on a variety of small estuarine fishes and estuarine dependent juveniles of marine species, while C. melampygus, C. papuensis and S. lysan filter feed on mysids and juvenile penaeids. Subadults of all species are piscivorous, although C. papuensis and S. lysan retain a suitable gill raker structure for filter feeding and a proportion of their diet consists of mysids and penaeids. The salinity and turbidity preferences of each species were investigated. All are euryhaline but C. melampygus, C. papuensis and 5. lysan are only found in clear water. It is suggested that the more widespread estuarine distribution of juvenile C. sexfasciatus and C. ignobilis may be related to their turbidity tolerances. The role of carangids in Natal estuaries is discussed in relation to their ecological significance in estuaries as predators and their degree of estuarine dependence.

THE FEEDING HABITS OF MINNOWS OF THE GENUSBARBUS(PISCES, CYPRINIDAE) IN AFRICA, WITH SPECIAL REFERENCE TOBARBUS AIVOPLUSWEBER

SUMMARY A twelve month study of the feeding biology of the chubbyhead barb, Barbus anoplus, Weber, 1897, from Lake Le Roux on the Orange River is described. B. anoplus taken from the open-water habitat fed mainly on copepods and cladocerans whereas those living in a small stream fed mainly on aquatic insect larvae and had a more varied diet. Seasonal shifts in the diet for both juvenile and adult minnows were observed. The smaller length groups changed from benthic feeding in spring to mainly mid-water feeding in summer. The larger fish prey on corixids in sumer but switch to mainly chiro-nomid larvae and zooplankton in winter. The minnows fed actively during the day with peak feeding in mid-morning and at dusk. It is suggested that the euryphagous feeding behaviour of B. anoplus is partially responsible for the widespread distribution of this species in southern Africa and for the successful colonization of the new shoreline habitat of Lake Le Roux. A review of the feeding biology of small Barbus species...

Stephens' Woodrat, a Dietary Specialist

The feeding biology of Stephens' woodrat ( Neotoma stephensi ) was studied in juniper woodlands in Arizona. Microscopic examinations were made of fecal samples from live-trapped animals, observations were made on foraging behavior, and data on plant communities occupied by this woodrat were gathered. Stephens' woodrat is a dietary specialist, unique in its ability to utilize juniper throughout the year. Some 90% of the diet is juniper: foliage is most important, but male and female cones are also eaten. This woodrat is a highly selective central-place forager, feeding repeatedly on certain individual junipers and avoiding others. Such finely tuned foraging probably facilitates the exploitation of junipers with unusually low levels of defensive, digestibility-reducing chemicals, and may be the key to this animal's success as a juniper specialist. Stephens' woodrat may be considered a relict species, largely restricted to areas supporting vestiges of a xeric juniper woodland that in the early Holocene was widespread in the southwestern United States.

The ecology ofSphyraena barracuda(Osteichthyes: Perciformes) in the Kosi system with notes on the Sphyraenidae of other Natal estuaries

The ecology of Sphyraena barracuda was studied in the Kosi estuary system of Natal. Fry enter from the sea at a length of 20 mm and live in shallow marginal weed-beds until a length of 80 mm when they move to fringing Phragmites reed-beds. After reaching 300 mm they move to open water areas. No specimens longer than 500 mm were recorded and none were mature. Growth is rapid, they attain 180 mm in the first six months and after two years measure 400-500 mm. They leave the estuary after about two years. Their significance in the estuarine fish community is due to their predation, at all sizes, on a variety of estuarine-dependent juvenile fishes (e.g. Rhabdosargus spp., Mugilidae) and adults of estuarine species (e.g. Ambassis spp.). S. barracuda was recorded at salinities between 4°/oo and 35°/oo, only in very clear water and at temperatures from 14,4 °C to 37 °C. Sphyraena bleekeri and S. qenie, which are also clear-water species, were found at Kosi in salinities from 0,5 to 35%o. They are also piscivorous on a range of small teleosts. Sphyraena iello is the most widespread barracuda in Natal estuaries, but only juveniles were recorded. This species is tolerant of a wide range of turbidities and salinities which enables it to live under most estuarine conditions. The distribution, ecology and interspecific interactions among Sphyraenidae in Natal estuaries are discussed in relation to their feeding biology, habitat preferenda and physical tolerances.

Further studies on the anatomy and ecology of opisthobranch molluscs feeding on the scleractinian coral Porites

Three further species of opisthobranch molluscs are reported to feed on the scleractinian coral Pontes in Tanzania. Further information on Cuthona poritophages Rudman, 1979, is also included. The anatomy of the aeolid Phestilla lugubris{Bergh, 1870, =P. sibogae Bergh, 1905) and a new species of Phestilla is described, as is the anatomy of the arminacean Pinufius rebus. The new species of Phestilla, and Pinufius, are, for the first time, reported to feed on Porites. Notes on the anatomy of the type-species of Phestilla, P. melanobrachia Bergh, 1874, are included to make possible a definition of the genus Phestilla. Aspects of the feeding biology, life history, defence mechanisms and habitat specificity of the four Porites-feeding opisthobranchs are described and discussed. The four species are shown to have evolved radular teeth of remarkably similar shape. Each species utilizes a different part of the coral tissue as food. The three aeolids have replaced functional cnidosacs at the tip of their cerata with batteries of large secretory cells. Phestilla lugubris and Pinufius rebus are also reported for the first time from the Great Barrier Reef, Queensland and the new species of Phestilla is reported from Queensland and Hawaii.

Feeding and reproductive biology of eleotrid fishes in a tropical estuary

Five species of eleotrid fishes (Gobiomorus dormitor, Dormitator maculatus, Eleotris amblyopsis, Eleotris pisonis and Leptophilypnus fluviatilis) are known from the Tortuguero estuary of Costa Rica. One, E. amblyopsis, appears tightly linked to the presence of mats of macrophytes and two others, E. pisonis and D. maculatus, are largely limited to this habitat in the lower estuary. All three of these species feed on hyacinth roots. Despite certain food and habitat specializations among the forms, there is evidence of competition and predation among four species. Individuals of breeding size have never been found in the system for D. maculatus and L. fluviatilis. Alternative means of establishing and maintaining eleotrid populations are suggested.

Insect Behavior, Resource Exploitation, and Fitness

Optimal foraging theory has stimulated many ecologists to take up studies of insect feeding behavior. It is asserted that study of food choice in animals, generally called the theory of optimal diets, is still in its infancy; however, since its inception more than a decade ago, interest in optimal diets has grown at an impressive rate (124). This statement, reflecting a common view among ecologists, deserves careful consideration. The study of food choice did not start with Emlen's (37) note on time, energy, and food resources. The voluminous literature on food selection by insects is the subject of numerous reviews (11 , 25, 78). What Waddington & Holden (124) probably meant is that the earlier studies of food choice mean very little because they lack a central theory that will explain and predict the foraging of animals (94). If the economics of feeding is the major selective factor governing the evolution of feeding behavior, then the theory of optimal diets would be the central concept around which all studies of food choice must be organized. Perhaps the great hopes for optimal foraging theory as a general explana­ tion for feeding biology are now being tempered ( 1 14), but the debates about the theory still make little or no reference to the physiological basis for food recognition, feeding responses, and nutritional value of foods (4, 5, 29, 49,

Biology and Physiology of Feeding in Adult Lampreys

Although landlocked sea lampreys (Petromyzon marinus) attack all but a few of the smallest teleosts in the Great Lakes, the large cold-water species have received the most predation. Information on the feeding habits of anadromous lampreys is limited, but they probably are not specific in their choice of hosts. Species differences exist in the relative proportions of blood and muscle tissue which are consumed. The landlocked sea lamprey primarily feeds on the blood of host fishes at rates of 3–30% of its wet body weight∙d−1 (10 °C). The estimated gross conversion efficiency for this species feeding ad libitum at 10 °C is 39%. This relatively high efficiency is partly attributable to the nature of their blood diet which results in small fecal energy losses of about 3.4% of intake energy. Maximum growth rates occur at 20 °C for sea lampreys of 10–30 g initial weight and at 15 °C for lampreys of 30–90 g. At all experimental temperatures (5–20 °C), growth rates decline with increases in lamprey weight. Increases in sea lamprey weight and in water temperature up to 20 °C cause the rate of host mortality to rise suggesting that, under natural conditions, mortality is seasonal. Landlocked sea lampreys show a preference for specific areas on their hosts, select larger hosts more frequently, and are not attracted to hosts that have lampreys feeding on them. Such strategies serve to maximize food intake and prolong host survival while ensuring food material of constant energy content.Key words: adult lampreys, feeding, hosts, growth rate, temperature, host mortality, behavior

Aspects of the feeding behavior and trophic ecology of suspension-feeding rotifers

While the evidence is not yet adequate to provide a general assessment of rotifer feeding in the dynamics of planktonic communities, there can be no question but that the feeding biology of this group is a rich and exciting field for freshwater ecologists and natural historians. Two recent reviews, those of Dumont (1977) and Pourriot (1977), provide ample evidence for this assertion, together summarizing some 70 years of research on rotifer feeding behavior. This paper is a further discussion of certain aspects of the feeding behavior and feeding ecology of free-swimming, suspension-feeding rotifers. I will deliberately omit consideration of sessile or predacious genera since the feeding biology of these forms has been reviewed very recently; sessile rotifers are examined by Wallace (1980) and the predacious genus Asplanchna by Gilbert (1979).

The Feeding Biology of Ant-Lion Larvae: Growth and Survival in Morter obscurus

Growth and survival of ant-lion larvae were investigated at four sites in Sierra Leone. Pitfall trapping showed prey density and biomass to decline as the dry season progressed. Very few large prey were available and most were too large for ant-lions to capture. At three sites ant-lion density declined and mean weight increased through the dry season, larvae disappearing from the sites at the same date despite differences in initial densities. Rain caused the death of many small larvae at one site and the survivors subsequently grew more rapidly. Despite intra-site differences in growth rates three sites showed no evidence of competition. At the fourth site, with a much greater size range of larvae, large individuals had a competitive advantage over small ones; larger pits were either more widely separated from their nearest neighbours, or their neighbours were smaller than average. It is argued that food and not time is the factor limiting growth rates. Very small and large larvae are the vulnerable stages in larval development, the latter because of the scarcity of large prey.

The Feeding Biology of Ant-Lion Larvae: Prey Capture, Handling and Utilization

SUMMARY (1) The general feeding biology of Morter obscurus is described. (2) First instar larvae, because they use a different pit construction technique, have steeper-walled pits than later instars. Pit diameter and larval length are linearly related. (3) Capture success is determined mainly by the relative sizes of predator and prey. For a given relative size instar 1 larvae are more successful because of the steep-walled pits. Capture success drops to zero when ants can place some of their legs outside the pit. Third instar larvae were more successful than second instar larvae in pits of the same size. Capture success, particularly for large larvae, is 100% over much of the prey size range. (4) Successful attacks on ants with thick exoskeletons occurred almost exclusively via the gaster whereas mandible insertion for ants with thin exoskeletons frequently occurred elsewhere. (5) Differences in pit morphology and prey capture behaviour in Macroleon lynceus are documented and related to habitat differences. In Morter, pit morphology is crucial for prey capture, while strength is more important for the larger Macroleon. (6) Handling time was divided into time to capture (Ta), time to death (Td), and time to extract body contents (Te). T, was constant for small prey but increased rapidly for larger prey. Td was constant for all sizes of predator and prey. Te increased with prey size and decreased with increasing predator size and temperature. Te seems to depend not only on the amount of extractable food but also on the shape of the victim. (7) Hunger has no effect on prey handling time or food extraction efficiency. However hungry larvae are more likely to move their pits. Ant-lions can capture prey falling into the pit when already feeding and so increase their food supply. (8) Growth rates of larvae feeding on different sized prey were measured. Large larvae grew more slowly than small ones when fed on the same sized prey because of higher maintenance costs. For a given sized predator, growth per unit weight of prey received declined with increasing prey size because of increased feeding costs. Each size of ant-lion had a prey size for which the costs per unit return were a minimum, this size changing abruptly from very small prey for the first two instars to large prey for the final instar. (9) The feeding biology of the three instars is compared and contrasted. First instar larvae are adapted to achieve a high capture success rate on a small prey size range because feeding costs are high and escapes therefore expensive. For large larvae, maintenance costs are more important and selection has favoured a large size range of catchable prey. While the behaviour of ant-lion larvae is consistent with an energy maximizer strategy it is concluded that the approach is of limited value in this instance.

ASPECTS OF THE FEEDING AND BREEDING BIOLOGY OF THE GIANT KINGFISHER

Summary Arkell, G. B. F. 1979. Aspects of the feeding and breeding biology of the Giant Kingfisher. Ostrich 50:176-181. Giant Kingfishers Megaceryle maxima were studied during 1972–1975 on the Eerste and Blaauwklip Rivers near Stellenbosch (33 53s; 18 50E), South Africa. Nest record cards of the Southern African Ornithological Society were examined for dimensions of the nest, nest lining, clutch-size and brood-size. The feeding rate of nestlings was determined from observations at the nest. Two adults, comprising a pair of breeding birds, and a fledgling wert equipped with breast-mounted miniature radio transmitter packages to monitor the birds activity and home range. Cape River Crabs Potamon perlatus apparently were the main prey of the kingfishers. A correlation was found between the activity patterns of kingfishers and of crabs, which peaked in the mornings and evenings.

Feeding, assimilation, and growth of mud snail larvae, Nassarius obsoleyus (Say), on three different algal diets

Nassarius obsoletus (Say) veliger larvae were fed three different phytoplankton diets in the laboratory: Isochrysis galbana Parke, Thalassiosira pseudonana (Hust.) Hasle & Heimdal, and Dunaliella tertiolecta Butcher. The relationship between growth rate and ability of the larvae to ingest and assimilate the different algae was investigated. To properly design the assimilation experiments, certain basic aspects of the feeding biology of the gastropod larvae were studied: the relationship between container size and feeding rate, light level and feeding rate, rate of gut evacuation in the presence and absence of food, and filtration and ingestion rates as a function of food concentration. Growth rates, ingestion rates, and efficiencies of carbon retention varied with the algal species provided, although relative growth could not be predicted from measurements of relative rates of carbon uptake from the different phytoplankton species. Larval growth rates are probably determined primarily by the abilities of the different algal species used in our experiments to provide necessary micro-nutrients. Retention efficiencies (carbon retained/carbon ingested) were low, ranging between ≈9 and 17%. Estimates of maximum assimilation efficiencies for young Nassarius obsoletus veligers are also much lower than most values reported for other Zooplankton.

Relations trophiques entre la microfaune et la microflore du sol; aspects qualitatifs et quantitatifs

Abstract Trophic relationships between the microfauna and the microflora of the soil: qualitative and quantitative aspects. Decomposition of all the organic matter produced by a terrestrial ecosystem is a complex process in which both micro-organism and soil animals take part. Microbial attacks on plant matter start early and increase with the seasons so that the leaves become coated more and more with yeasts. Then in autumn, the dead leaves on the ground are rapidly infested with fungi; most small invertebrates feeding on litter are more interested probably in fungal hyphae or spores than in ordinary plant material. A field study has been made on the recolonization by microfauna and microflora in forest soil samples first heat-dried and then incubated. Oxygen consumption measurements showed greater metabolic activity in the treated soil samples than in the controls. Natural rehydration following desiccation promoted the development of a great number of microbial germs (74430- 103/g in controlled soil samples), but of restricted number of fungal species. Meanwhile surfacedwelling and edaphic Collembolan species soon invaded the treated plots in excessive numbers: these events indicate that the desiccated soil samples were acting as bait with which the soil animals were more concerned with the quantity than the quality. Electron microscopy of the faeces from four coexisting Collembolan species revealed that animals do not compete for food resources of the same biotope (spores, fungal hyphae, algae, bacteria), thus corroborating the general ecological theory that holds that groups of related species sharing habitats develop different choices in food. The ingested organisms are not completely digested and an important part, when evacuated, are still viable. Thus we may assume that the role of Collembola is important in disseminating propagules of soil microflora. The use of fine microgravimetric techniques has enabled us to estimate the weight of droppings in two coexisting Collembola species. The amount of ingested food kept inside the gut is very important; it is about 20% of the dry body weight. Ecological implications of the various aspects of the feeding biology of soil fauna are discussed. The evidence suggests that electron microscopy is very helpful in determining the feeding habits of soil animals and their role as regulators in the decomposition of soil forest litter systems.

Biology of Labdia Sp. (Lepidoptera: Cosmopterygidae), a Miner in Phyllodes of Acacia.

Labdia sp. mines phyllodes of several species of Acacia possessing large phyllodes. Its development in, and association with, A. saligna are outlined; the four larval instars all feed mainly on epidermis and palisade tissue, and pupation occurs within the mine. Faeces are extruded from the mine but retained in a mass on the outside and may protect the pupa. The life history and feeding biology of Labdia are compared with those of Acrocercops plebeia (Turner).