Feeding Chamber Research Articles

Ingestion and Nutrient Budget of Attwater's Pocket Gopher (Geomys attwateri)

We measured ingestion by Attwater's pocket gopher (Geomys attwateri) in the coastal prairie of Texas by placing feeding chambers in their tunnels. We constructed a nutrient budget from ingestion, species of plants eaten, and nutrient content of these plants, and we compared it to that for the hispid cotton rat (Sigmodon hispidus), also common in this habitat, and the laboratory rat. Concentration of minerals ingested by G. attwateri appeared sufficient for growth and reproduction. Concentration of protein was lower and concentration of fiber was higher in diets of G. attwateri than in diets of S. hispidus or that was required for laboratory rats. High concentration of fiber reduces digestibility and impedes assimilation of protein. We concluded that protein was likely a limiting nutrient and that a low protein:fiber ratio in the diet during summer could be responsible for the observed decline in reproduction in that season.

Feeding behaviour after injection of α-adrenergic receptor agonists into the median raphe nucleus of food-deprived rats

This study investigated the participation of median raphe nucleus (MnR) α1-adrenergic receptors in the control of feeding behaviour. The α1-adrenergic agonist phenylephrine (PHE) and α2-adrenergic agonist clonidine (CLON) (at equimolar doses of 0, 6 and 20nmol) were injected into the MnR of: a) rats submitted to overnight fasting (18h); or b) rats maintained with 15g of lab chow/day for 7days. Immediately after the drug injections, the animals were placed in the feeding chamber and feeding and non-ingestive behaviours such as grooming, rearing, resting, sniffing and locomotion were recorded for 30min. The results showed that both doses of PHE injected into the MnR of overnight fasted animals decreased food intake accompanied by an increase in the latency to start feeding. A reduction in feeding duration was observed only after treatment of the MnR with the 20nmol dose of PHE. Both locomotion duration and sniffing frequency increased after injection with the highest dose PHE into the MnR. Feeding frequency and the other non-ingestive behaviours remained unchanged after PHE treatment in the MnR. Both doses of PHE injected into the MnR of food-restricted rats decreased food intake. This hypophagic response was accompanied by a decrease in feeding duration only after treatment of the MnR with the highest dose of PHE. The latency to start feeding and feeding frequency were not affected by injection of either dose of PHE into the MnR. While both doses of PHE increased sniffing duration, the highest dose of PHE increased resting duration and resting frequency. Treatment with CLON into the MnR did not affect feeding behaviour in either of the food deprivation conditions. The present results indicate the inhibitory functional role of α1-adrenergic receptors within the MnR on feeding behaviour.

Alpha 1 receptor antagonist in the median raphe nucleus evoked hyperphagia in free-feeding rats

Serotonergic neurons in the median raphe nucleus (MnR) are stimulated by α 1-adrenergic agonists and inhibited by α 2-agonists. This study investigated the effect of the blockade of the MnR α 1-adrenergic receptors of free feeding rats as an attempt to elucidate the functional role of these receptors in the control of feeding behavior. In addition, an α 2-receptor antagonist was also administered in the MnR in order to strengthen the previous suggestion that α 2-adrenergic receptors participate in the control of feeding behavior, probably decreasing the facilitatory influence on MnR serotonergic neurons. The α 1-adrenergic antagonist prazosin (PRA, 40 nmol) or vehicle was injected into the MnR 15 min before treatment with phenylephrine (PHE, 0.2 nmol). The α 2-adrenergic antagonist yohimbine (YOH, 40 nmol) was administered 15 min before clonidine (CLO, 20 nmol) or vehicle in free-feeding rats. After the injections, the animals were placed in the feeding chamber for 30 min to evaluate the ingestive and non-ingestive behaviors. At the end of the experiment the quantity of food and water consumed were measured. While treatment with PRA in the MnR followed by PHE did not change the feeding behavior, PRA injection alone into the MnR caused hyperphagia accompanied by a reduction in the latency to start eating, an increase in feeding frequency and an increase in the feeding duration. Pretreatment with YOH in the MnR blocked the hyperphagic effect induced by CLO. The present data reinforce our previous suggestion that the MnR α 2-adrenergic receptors participate in the control of feeding behavior, probably decreasing the facilitatory influence on MnR serotonergic neurons of free-feeding animals. Furthermore, these results indicate that this influence is tonically mediated by α 1-adrenergic receptors upon MnR neurons, which inhibit food intake.

Trophic Ecology of Hyalella sp. (Crustacea: Amphipoda) in a High Andes Headwater River with Travertine Deposits

AbstractWe studied the diet of 50 individuals of Hyalella sp. collected in the karstic headwaters of a high‐altitude Andean river (3817 m a.s.l. Peru) in four different habitats: macrophytes, bryophytes, leaf litter, and layers of travertine. The gut content analysis showed a dominance of fine particulate organic matter (FPOM) in most habitats – layers of travertine (69.5%), Myriophylum (58.5%) and bryophytes (56.8%) – except for individuals collected in leaf litter where coarse particulate organic matter (CPOM) represented 68% of gut content, which indicates a high trophic flexibility of Hyalella sp. Likewise, in an experiment with feeding chambers in situ during three days, twenty individuals of Hyalella sp. presented a higher consumption of leaf litter of native species (Polylepis sp.) (0.025 mg/day) than those of an introduced species (Eucalyptus globulus) (0.008 mg/day). (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Phenylephrine into the median raphe nucleus evokes an anxiolytic-like effect in free-feeding rats but does not alter food intake in free feeding rats

This study investigated the role of MnR α 1-adrenergic receptors in the control of anxiety-like and feeding behaviors and attempted to reveal a possible functional association between both behaviors. The α 1-adrenergic agonist phenylephrine (PHE) (at doses of 0.2, 2, 6, 20 nmol) or saline was injected into the MnR or into the pontine nucleus (Pn) of free-feeding rats. The animals were exposed to the elevated plus maze to analyse spatial–temporal and ethological variables. Subsequently, the ingestive and non-ingestive behaviors were recorded during 30 min and feeding and drinking behaviors were measured. Both in the elevated plus-maze and in the feeding chamber, all PHE doses injected into the MnR decreased the risk assessment frequency, an ethological parameter of anxiolytic-like effect. The spatial–temporal variables remained unchanged after PHE treatment. Feeding behavior was not affected by PHE into the MnR. The anxiety-like or ingestive behaviors were not affected by PHE treatment in the Pn, an area adjacent to the MnR. These data indicate that α 1-adrenergic receptors within MnR participate in the control of anxiety-like behaviors. The absence of effects on feeding behavior after MnR α 1-adrenergic activation could be due to an elevated α 1-adrenergic tonus and its possible strong facilitatory influence on 5-HT neurons within MnR. Furthermore, the present results suggest that anxiety-like and feeding behaviors controled by MnR adrenergic circuits operate by independent neural pathways.

Research Toward an Artificial Diet for Adult Asian Citrus Psyllid

Abstract Research progress is reported on an artificial diet for adult Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae). The primary objective was to develop a system for screening antimicrobial peptides and other potential toxic proteins for activity against adults. The base diet was a sterilized solution of sucrose (30%) and yellow-green food coloring (0.5%) in tap water. All of the studies presented were conducted at 25°C, 75% RH, and a photoperiod of 14:10 (L:D) h. Adult psyllids were <7 d old when they were transferred to diet. Addition of the food coloring was necessary to prompt adults to feed. Among the feeding trials discussed, a mean of 69.1 ± 3.2% adults survived for 14 d on the base sucrose diet. Survival rates of males and females were similar. Adults feeding on the sucrose diet may have ingested less food than adults feeding on citrus leaf disks based on differences in quantities of adult excrements deposited in feeding chambers. However, survival of adults feeding on leaf disks over a 2-wk period was only marginally better than survival of adults feeding on the base sucrose diet, and final rates of survival of adults fed these two food sources were not significantly different.

Tasselia ordamensis: A biogenic structure of probable deposit-feeding and gardening maldanid polychaetes

The internal structure and growth direction of well-preserved Tasselia ordamensis specimens from the Upper Cretaceous–Cenozoic of Antarctica and Tierra del Fuego are not compatible with its current interpretation as a domichnion/equilibrichnium trace fossil. Accordingly, its functional morphology and the likely ethology of the producer are revised. Tasselia is a protrusive structure composed of a lined inner tube surrounded by vertically stacked sediment disks and ending in a basal chamber. Each disk has two domains of active burrow fills. The micritic, outer burrow fill domain consists of radial petaloid elements containing abundant radiolaria, calcispherules, diatoms and plant debris. This domain was formed by excavation due to deposit feeding; thereby non-ingested particles remained in the chamber and ingested particles passed through the gut to the sediment surface. Microfossil-rich material was collected at the sediment surface, placed in the feeding chamber, and rearranged within the petaloid elements probably after pulsed delivery of organic matter. The wineglass-shaped inner burrow fill domain is enriched in coarser particles and its petaloid elements crosscut the outer burrow fill domain. This domain probably functioned as “culturing compartment” for bacteria and its secondary reworking implies some form of ‘gardening’ and feeding on these bacterial populations at depth. The concentric striae on the organic-lined inner tube and the vertically stacked series of sediment-disks suggest maldanid polychaetes as the producers of T. ordamensis.

Rhizolith balls from the Lower Cretaceous of Patagonia: Just roots or the oldest evidence of insect agriculture?

A new type of trace fossil from the Lower Cretaceous of Patagonia that may record the oldest evidence of insect agriculture is represented by biconvex, sub-spherical, carbonate balls composed of a dense mass of rhizoliths. The best preserved balls show an external wall, a tunnel entrance, and vertical, large rhizoliths crossing from top to base, from which a mass of smaller rhizoliths arise. In some cases there is a pelletal surface texture in internal layers of the wall. Some specimens show meniscate tubes attributed to organisms different than the constructors of the chambers, probably attracted by the original organic matter. Micromorphology, analyzed by thin sections and SEM, shows strong evidence of high fungal activity associated to the original roots. Four different hypotheses are analyzed to explain the origin of the balls. The less probable ones are either that the balls were produced only by a self induced and localised overgrowth of secondary and tertiary rootlets from a group of neighbouring primary roots, or that they were crayfishes' feeding chambers. Rhizolith arrangement, as well as other characters, essentially rule out both hypotheses. The hypotheses involving social insects, termites and ants, are more risky, considering the lack of support from the body fossil record, the biogeography of these extant insects, and particularly the lack of definitive evidence of discrete fungus or bacterial gardens in the balls. However, the trace fossils described herein partially resemble the nests and behaviour of the African termite Sphaerothermes sphaerothorax, particularly because of the presence of roots inside a thick lined chamber excavated around them to cultivate bacterial combs. The ant origin of these balls is at least a hypothesis to explore considering the size, shape, wall, entrance tunnel, presence of traces of associated organisms, and particularly roots. The roots and wall relate these balls to hypothesised scenarios for the origin of fungus agriculture in ants. One hypothesis suggests that primitive Attini developed fungus agriculture from the habit of feeding on fungi associated with roots (mycorrhizae) and still other proposes that adventitious fungi on nest walls were responsible for the arise of fungiculture. The balls would supply physical evidence that by the lower Cretaceous some social insects excavated chambers around uncut roots, which in turn provided optimal conditions for fungi development. These rhizolith balls possibly constitute the oldest physical evidence for the origin of fungiculture in social insects, and represent a critical contribution of ichnology to this hot topic intensively discussed on the basis of a scattered body fossil record and molecular phylogeny.

Viability of a Freshwater Mussel (Elliptio complanata) as a Biomechanical Filter for Aquaculture Ponds I: Clearance Rate of Chlorophyll-α

The production and livelihood of aquaculture facilities depend on increased growth of species being harvested. Only 15%-25% of nitrogen and phosphorus are retained in farmed fish even when all feed is consumed. In both marine and freshwater aquaculture systems, bivalves have proven to be an inexpensive method for controlling algal growth through suspension feeding. With 25% of the native U.S. freshwater mussel species under federal protection, their use in aquaculture ponds could lead to further propagation and restoration of natural populations. Elliptio complanata is an important species in Delaware rivers and connected estuaries; a recent two-year study by the United States Geological Survey found that 98% of mussels found in the Delaware River were Elliptio complanata. The objective of this study was to calculate the clearance rate of E. complanata in a laboratory study. This would help us determine if mussels can serve as an addition to chemical and mechanical filtration regiments and thrive in an aquaculture setting. Using feeding chambers we investigated the effect of E. complanata on algae grown from an aquaculture pond and on a cultured alga over a four-hour period. Temperature, dissolved oxygen, and pH were monitored, and samples were than analyzed for total chlorophyll-α. The average of both the single cell using Chlorella vulgaris and mixed assemblage treatments chlorophyll-α clearance rate was 0.187 liters per hour per mussel. Prior to this experiment, these mussels were held for a period for two months in the holding system in the laboratory. The resulting low clearance rate as compared to the previous studies in the field is possibly due to the stress from holding these mussels. However, our study demonstrated that mussels have the potential to be used in an aquaculture setting and/or recreational ponds to help reduce algae populations that can occur as a result of eutrophication.

Efficacy of the Bm86 antigen against immature instars and adults of the dog tick Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae)

The Bm86 antigen has been used to control ticks of the Boophilus genera in integrated programs that also include the use of acaricides. Because of recent phylogenetic studies have lead to the inclusion of all Boophilus species within the Rhipicephalus genera, we aimed to investigate the efficacy of the Bm86 antigen on the biotic potential of Rhipicephalus sanguineus. Domestic dogs were vaccinated with Bm86 and challenged with the three instars of R. sanguineus. Male and female mongrel dogs were divided into two groups of four animals each, comprising non-vaccinated and vaccinated animals. Immunized dogs were given two doses of an experimental formulation containing 50μg of recombinant Bm86, at 21 days interval while the other group was given placebo, consisting of the same preparation without Bm86. Each dog was challenged 21 days after the last dose with 250 larvae, 100 nymphs and 55 adults (25 females and 30 males) released inside feeding chambers (one per instar) glued to their shaved flank. The effect of the vaccination was evaluated by determining biological parameters of ticks including the yield rates of larvae, nymphs and adult females. Adult females engorged weight, egg mass weight, efficiency rate of conversion to eggs (ERCE) and hatchability. In addition, sera were collected from dogs at 0, 21, 36, 45 and 75 days after the vaccination and used for the detection of specific antibodies by ELISA. Collection rates of larvae, nymphs and adult females fed on vaccinated dogs were significantly (p<0.05) reduced by 38%, 29% and 31%, respectively, as compared with non-vaccinated controls. Significant reductions were also observed in weight of engorged females and egg mass, in ERCE, but not in the hatch rate of ticks fed on immunized dogs. ELISA data revealed a marked and significant increase in optical densities of sera from vaccinated animals after the second dose of Bm86. We concluded that the Bm86 antigen used as a vaccine for dogs reduced the viability and biotic potential of the R. sanguineus.

Desert detritivory: Nutritional ecology of a dung beetle ( Pachysoma glentoni) subsisting on plant litter in arid South African sand dunes

Dry conditions limit microbial decomposition of plant litter in deserts, which leaves a primary role to detritivorous macroarthropods. In the sandy arid strip along the west coast of South Africa, such detritivores include the large scarabaeid dung beetle Pachysoma glentoni. Highly unusual among dung beetles, this species collects surface litter and drags it into an underground storage and feeding chamber which is abandoned after 6–7 days. Fresh stores for single beetles and for breeding pairs (mean depths: 30 and 39 cm) contained about 1.1 and 2.9 g organic matter, respectively. Using ergosterol as a biomarker for fungal biomass, we tested the hypotheses that (1) the dry detritus takes up water underground; (2) this promotes fungal growth on the detritus, and (3) fungi are the main food of the beetles. These hypotheses were disproved, but the stored litter, including floral remains, was shown to have relatively high quality (mean atomic C:N ratio: 35) and the beetles assimilated about 60% of it. Estimated weekly water gain per beetle, supplied entirely by the food, was about 0.6 g. Our results highlight unique nutritional adaptations to survival in deserts without the usual dung beetle food: wet dung of large herbivores.

The Effect of Prey Density on Predators: Conspicuousness and Attack Success Are Sensitive to Spatial Scale

In contrast to the numerous studies that have examined the response of predators to prey group size, little is known about how prey density affects prey detection and the accuracy of attacks. We demonstrate that increasing the density of Daphnia magna swarms increases conspicuousness to a natural predator, the three-spined stickleback. Denser areas of groups were more conspicuous, as the fish attacked prey in denser parts of the group than would be expected if they attacked the nearest prey upon entering the feeding chamber. The spatial error of attacks also increased with the density around the target; hence, different stages of predation (searching for vs. successfully attacking prey) seem to select for opposing responses to prey density. However, whereas the effect of density on target selection only occurred using a global measure of density (average interindividual distance), the effect on attack error was only significant using a local measure of density (Voronoi polygon area). We believe this effect of spatial scale reflects the reduction in the number of prey in the visual field of the predator as an attack progresses, providing a perceptual basis for the importance of spatial scale in density-dependent processes.

Woody Stem Galls Interact With Foliage to Affect Community Associations

Gall wasps (Hymenoptera: Cynipidae) hijack the physiology of their host plant to produce galls that house wasps throughout their immature stages. The gall-maker-host plant interaction is highly evolved, and galls represent an extended phenotype of the gall wasp. We evaluated two-way interactions between stem galls produced by Dryocosmus kuriphilus Yasumatsu on Castanea spp. (Fagales: Fagaceae) and foliage directly attached to galls (gall leaves) using gall leaf excision experiments and herbivore bioassays. Early season gall leaf excision decreased the dry weight per chamber (nutritive index) and thickness of the protective schlerenchyma layer and increased the number of empty chambers and the occurrence and size of exterior fungal lesions. Leaf excision also caused a modestly significant (alpha = 0.1) increase in the incidence of feeding chamber fungi and herbivory by Curculio sayi Gyllenhal (Coleoptera: Curculionidae), and a modest decrease in parasitoids. This study shows that gall leaves are important for stem gall development, quality, and defenses, adding support for the nutrient and enemy hypotheses. We also evaluated the effects of stem galls on the suitability of gall leaves to Lymantria dispar L. (Lepidoptera: Lymantriidae) herbivory to assess the extent of gall defenses in important source leaves. Relative growth rate of L. dispar larvae was greater on gall leaves compared with normal leaves, indicating that, despite their importance, gall leaves may be more suitable to generalist insect herbivores, suggesting limitations to the extended phenotype of the gall wasp. Our results improve our knowledge of host-cynipid interactions, gall source-sink relations, and D. kuriphilus community interactions.

Morphology of immature stages in the neotropical nonfrugivorous Tephritinae Fruit Fly Species Rachiptera limbata Bigot (Diptera: Tephritidae) on Baccharis linearis (R. et Pav.) (Asteraceae)

Rachiptera limbata Bigot develops on Baccharis linearis (R. et Pav.) in the areas around Santiago, Chile. The larvae feed on stem tissues and secrete a liquid that hardens to form a protective feeding and pupation chamber. The immature stages of Neotropical species of Tephritinae are poorly known. In this paper, the morphology of the immature stages of R. limbata are described and compared, in a phylogenetic context, with other Tephritinae species. Antennomaxillary complex, pads, oral ridge, cephalopharyngeal skeleton, anterior and posterior spiracles and anal lobes of first-, second-, third-instar larvae and pupae were studied with optical and scanning electron microscopy. The cephalopharyngeal skeleton is darkly sclerotized and shows an opening or window in the ventral cornua. This trait seems to be plesiomorphic in R. limbata and in other Neotropical species. First-instar larvae anterior spiracles are absent; whereas in second and third instars spiracles are developed as a row of five short tubules. In first- and second-instar larvae, the posterior spiracular slit has only a single hair per bundle; whereas third-instar larvae lack hairs. This last trait seems to be consequence of a larval development delay and an apomorphic trait in R. limbata, compared to other Neotropical and Neartical species.

Breathing spiral waves in the chlorine dioxide–iodine–malonic acid reaction-diffusion system

Breathing spiral waves are observed in the oscillatory chlorine dioxide-iodine-malonic acid reaction-diffusion system. The breathing develops within established patterns of multiple spiral waves after the concentration of polyvinyl alcohol in the feeding chamber of a continuously fed, unstirred reactor is increased. The breathing period is determined by the period of bulk oscillations in the feeding chamber. Similar behavior is obtained in the Lengyel-Epstein model of this system, where small amplitude parametric forcing of spiral waves near the spiral wave frequency leads to the formation of breathing spiral waves in which the period of breathing is equal to the period of forcing.

Identification of Proteins, Enzymes and Potential Vaccine Candidates from the Aust Paralysis Tick, Ixodes Holocyclus Using 2D-PAGE and Equalizer Technology

Ticks are blood-feeding arthropods that are vectors for many diseases of humans and animals caused by viral, rickettsial, bacterial, fungal, protozoal and nematode pathogens. Extensive studies of the antihaemostatic molecules (anticoagulants, vasodilators, platelet aggregation inhibitors) in the saliva of blood-feeding arthropods (Rhodnius prolixus, bed bugs, sandflies, mosquito) have been reported (Champagne,2005) but very little is known about the proteins involved in the attachment and feeding processes of ticks and this is particularly so for Ixodes holocyclus. To date, no complete genome has been published for any tick species and EST libraries are available for only four species (Boophilus microplus, Amblyomma variegatum, Ripecephalus appendiculatus and Ixodes scapularis). Thus a targeted proteomic approach to the investigation of I.holocyclus was initiated seeking to identify the enzymes secreted into the feeding chamber and enzymes involved into the digestion of haemoglobin. Enzymes were detected in whole, unengorged female tick extracts and whole, engorged female tick extracts whose proteins had been equalized using Proteominer beads, a combinatorial hexapeptide ligand library bound to chromatographic beads that aims to embrace all proteins present in a sample (Boschetti et al, 2007). The proteins in the extracts were then separated by 2D-PAGE and visualised by the fluorescent peptide substrate assay method developed by Zhao and Russell (2003). The method uses commercially available, enzyme specific, peptide substrates containing 4-methyl-coumaryl -7-amide that

Influence of Temperature on Rate of Uptake and Subsequent Horizontal Transfer of [&lt;SUP&gt;14&lt;/SUP&gt;C]Fipronil by Eastern Subterranean Termites (Isoptera: Rhinotermitidae)

The effect of temperature on [14C]fipronil uptake and transfer from donor (D) to recipient (R) Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae) workers was evaluated. Test chambers used in the fipronil uptake study were constructed from petri dishes containing autoclaved soil treated with 1 ppm [14C]fipronil (1.14 microCi of total radioactivity per petri dish), distilled water, and R. flavipes workers. Test chambers were held in environmental growth chambers preset at 12, 17, 22, 27, and 32 degrees C. For the fipronil transfer study, donor termites stained with Nile blue-A were exposed to soil treated with 1 ppm [14C]fipronil for 2 h. Donors were then combined with unexposed recipient termite workers at either 1D:5R, 1D:10R, or 1D:20R ratios. Test chambers consisted of a nest and feeding chamber connected by a piece of polyethylene tube and held in growth chambers at 12, 17, 22, 27, and 32 degrees C. Worker termites were sampled over time and the amount of [14C]fipronil present was measured by scintillation counting. Some degree of uptake and transfer occurred at all temperatures and ratios in this study. The highest level of uptake occurred by termites held at 22-32 degrees C, followed decreasingly by 17 and 12 degrees C. Maximum transfer of [14C]fipronil occurred at the higher ratios (1:5 > 1:10 > 1:20) of donors to recipients. Data presented in this study suggest that temperature is one of the key factors affecting the rate of uptake and subsequent horizontal transfer of [14C]fipronil in subterranean termites.

Systemic mazindol reduces food intake in rats via suppression of meal size and meal number

The aim of the present study was to determine the impact of the appetite suppressant mazindol on meal pattern in rats. Meal patterns were monitored in adult male rats after mazindol dosing during the first three hours of the dark cycle using automated feeding chambers (BioDAQ). Mazindol (0, 0.25, 1.25 and 2.5 mg/kg, IP) produced a dose-dependent hypophagia and hypodipsia. Meal size and meal number were significantly suppressed by mazindol. The meal pattern findings indicate that mazindol inhibits eating in the rat via a suppression of both meal size and meal number.

Biological aspects of Amblyomma brasiliense (Acari: Ixodidae) under laboratory conditions

Although Amblyomma brasiliense Aragão 1908 has been reported as one of the most aggressive ticks to humans in Brazil, information about the biology of this tick species is virtually inexistent. This work reports data on the life cycle of A. brasiliense fed on rabbits and pigs and maintained in an incubator at 20 degrees C, 90% RH and 12 h of light for off-host development. Tick yield of adult females fed on pigs and rabbits was 81.2% and 58.3%, respectively. Females fed on pigs had mean engorgement weight of 862.3 mg and egg mass of 208 mg, while females fed on rabbits had mean engorgement weight of 606.1 mg and egg mass of 160 mg; these values did not differ statistically between host species. Feeding period of female ticks fed on pigs (10 days) was significantly shorter than that on rabbits (17 days). Mean preoviposition period was slightly longer (35.9 days) for ticks fed on pigs than on rabbits (30 days). The minimum incubation period of eggs of ticks from both host species was similar and over 100 days. Egg production efficiency was low for females fed on both hosts (less than 30% and 20% for ticks from pigs and rabbits, respectively). More than 55% of larvae and 79% of nymphs fed on rabbits, set free inside the feeding chambers, engorged successfully. These ticks attained an engorgement weight of 1.3 and 18.2 mg, respectively, and fed for approximately 5 days. The minimum pre-molt period was 30 days for engorged larvae and over 44 days for nymphs. Molting success was low, less than 50% in the case of larvae and less than 20% for nymphs. Further studies are required to better determine the off-host requirements of this tick species.

Feeding in a Calcareous Sponge: Particle Uptake by Pseudopodia

Sponges are considered to be filter feeders like their nearest protistan relatives, the choanoflagellates. Specialized "sieve" cells (choanocytes) have an apical collar of tightly spaced, rodlike microvilli that surround a long flagellum. The beat of the flagellum is believed to draw water through this collar, but how particles caught on the collar are brought to the cell surface is unknown. We have studied the interactions that occur between choanocytes and introduced particles in the large feeding chambers of a syconoid calcareous sponge. Of all particles, only 0.1-microm latex microspheres adhered to the collar microvilli in large numbers, but these were even more numerous on the choanocyte surface. Few large particles (0.5- and 1.0-microm beads and bacteria) contacted the collar microvilli; most were phagocytosed by lamellipodia at the lateral or apical cell surface, and clumps of particles were engulfed by pseudopodial extensions several micrometers from the cell surface. Although extensions of the choanocyte apical surface up to 16 microm long were found, most were 4 microm long, twice the height of the collar microvilli. These observations offer a different view of particle uptake in sponges, and suggest that, at least in syconoid sponges, uptake of particles is less dependent on the strictly sieving function of the collar microvilli.