Development of captive bongos (Tragelaphus eurycerus): Activity budgets and developmental milestones

The development of changes in visual orientation, posture, activity budgets, and behavioral milestones was examined in five bongo calves which were observed from birth to 4 or 6 months of age. The only significant change in the calves' visual orientation was an increase in orientation to food. Reclining declined significantly over weeks, while standing increased and moving did not change. Overall, stationary behaviors dominated the activity budget, but decreased significantly over the study. The category that included locomotion, object exploration, and auto-play did not change, while forage and rumination increased significantly. Contrary to expectation, the decline in suckling was not significant. Affiliative interactions with the dam decreased significantly during the study, but increases in affiliation with other bongos were not significant. Levels of agonistic behavior between the calves and their dams and other herd members were low throughout the study, and did not change significantly. One female calf achieved several developmental milestones later than the others. It is suggested that these differences may have been influenced by the dominance status of her dam. The results conform to the general developmental pattern of “hider” bovids. Bongos, however, show somewhat different patterns of social development than eland, which are reported to be more precocial in expression of aggressive and sexual behaviors. © 1992 Wiley-Liss, Inc.     

Factors influencing the landing of maleEpiphyas postvittana (Walker) exhibiting pheromone-mediated flight (Lepidoptera: Tortricidae)

The effects of changes in various visual and olfactory properties of a white card surface on the landing position of male Epiphyas postvittanaexhibiting pheromone-mediated flight were studied in a wind tunnel. Males landed predominantly at the most downwind position of a surface in line with the pheromone source, regardless of the strength of the source. The position on the surface that males landed was strongly influenced by visual factors. The landing position of males appeared to be influenced by visual cues along all three axes of the surface. Decreases in either the dimension horizontally perpendicular to the wind direction or the vertical dimension resulted in greater numbers of males landing farther upwind on the surface than the downwind edge. Visual changes in the axis along the wind direction also affected the position at which males landed. For example, when presented with two white card surfaces with a 4- cm gap between them, males tended to land on the downwind edge of the upwind surface (on which the source was located). When the gap was bridged with clear Mylar, the landing pattern was significantly different, with the greater proportion of males landing on the downwind surface. However, when Mylar was placed on the plexiglass floor of the tunnel (in addition to bridging the gap), the landing pattern on the surface was not significantly different from that on the two surfaces without the Mylar bridge. It is suggested that during the prelanding and landing phases of pheromone-mediated flight, male moths orient to visual features of the surface containing the pheromone source rather than to visual features of the source (conspecific female moth) itself.     

Behavioral response ofGraminella nigrifrons (Homoptera: Cicadellidae) to experimentally manipulated vibrational signals

Mate recognition for the leafhopper Graminella nigrifrons(Forbes) occurs when a male spontaneously emits a multisectional vibrational calling song to which females respond by emitting simple pulses. Significant differences were found among males in the duration, number of chirps, and chirp rate within sections of the song and the total song. Repeatability (proportion of total variation due to differences among males) of call features ranged from very low (0.04 for total chirps in song) to high (0.67 for section 3 chirp rate). However, song modification and playback experiments revealed that the variation in the measured song features was not important in determining whether a female will respond. Rather, female response depended only on the presence of two of the three types of pulses which comprise a chirp. These essential pulses were found within chirps of all call sections that contain chirps. Manipulation of chirp rates from 0.58 to 2.70 times the normal rate did not affect female response, nor did changing the period of silence between the essential pulse types from 0.25 to 1.75 times the normal period. These results suggest that components of the male calling song function in mate recognition but are not used by females to discriminate among conspecific males.     

Predators and avian community organization: an experiment in a semi-desert grassland

Summary We provide experimental evidence that predators are a major factor organizing a community of granivorous grassland birds (mostly emberizid finches). Our focus is not on the lethal effects of predators, but on the simple idea that (i) birds will not settle where they perceive a high risk of predation, and (ii) species differ in their perception of the safety of woody vegetative cover due to differences in antipredator escape behavior. Consistent with this idea is the fact that the composition of this grassland community responds markedly to minor manipulations in the distribution of woody cover. In particular, with the addition of cover to open grasslands, species with cover-dependent escape tactics increase in abundance, while the abundance of cover-independent species decreases greatly; this decrease may reflect aggression from cover-dependent species, but evidence suggests that some cover-independent species may actively avoid cover-rich areas per se. Non-predatory effects of cover, most notably those concerning food resources and microclimate, appear unable to explain these results. Predators may influence many communities of terrestrial vertebrates via species-specific responses to cover.     

Predator-induced behavioral defense and its ecological consequences for two calanoid copepods

Summary We used an automated technique for the observation and quantification of zooplankton swimming behavior to study the behavioral responses of two congeneric, herbivorous, freshwater copepod prey to a copepod predator (Limnocalanus macrurus). One prey, Diaptomus sicilis, often co-occurs with Limnocalanus, while previous studies indicated that the zoogeographic distribution of the second prey, Diaptomus oregonensis, was independent of the predator. We found that in the presence of Limnocalanus, D. sicilis swims more slowly and with less hopping and jumping than D. oregonensis. Diaptomus sicilis is also attacked and consumed by the predator Limnocalanus macrurus less frequently than D. oregonensis. We suggest that the faster, noisier swimming of D. oregonensis increases its vulnerability to Limnocalanus. The behavioral defenses to both prey are induced by the presence of the predator, and may represent two different anti-predator strategies, crypsis and avoidance for D. sicilis and D. oregonensis respectively. In a zoogeographical analysis D. oregonensis occurs at densities below D. sicilis in lakes where Limnocalanus is at elevated abundances, while in low-predator lakes the opposite is true. This distribution pattern supports our experimental results, and suggests that D. sicilis is adapted to survive with Limnocalanus, while D. oregonensis is not.     

Effects of selective cholecystokinin antagonists L364,718 and L365,260 on food intake in rats

The selective type A and B cholecystokinin (CCK) receptor antagonists L364,718 and L365,260 were used to identify the receptor subtype that mediates the satiety effect of endogenous CCK. Male rats (n = 12–13/group), fed ground rat chow ad lib, received L364,718 (0, 1, 10, 100, or 1000 μg/kg IP) or L365,260 (0, 0.1, 1, 10, 100, 1000, or 10,000 μg/kg IP) 2 h after lights off, and food intake was measured 1.5, 3.5, and 5.5 h later. L364,718 significantly stimulated 1.5-h food intake by more than 40% at 10 μg/kg and higher doses; cumulative intake at 3.5 and 5.5 h remained elevated by about 20% at 1000 and 100 μg/kg of L364,718, respectively. In contrast, L365,260 had no significant stimulatory effect on feeding at any dose. The potency of L365,260 for antagonizing gastrin-stimulated gastric acid secretion was examined in unanesthetized rats. Male rats (n = 14), prepared with gastric and jugular vein cannulas, received doubling doses of gastrin (G-17I) (0.16–5 nmol/kg/h IV), each dose for 30 min, and gastric juice was collected for each 30-min period. G-17I stimulated gastric acid output dose dependently; the minimal effective dose was 0.16 nmol/kg/h, while maximal output (5-fold above basal) occurred at 5 nmol/kg/h. L365,260 (0, 1, 10, 100, 1000, or 10,000 μg/kg IV), administered 30 min before continuous infusion of G-17I (1.25 or 5 nmol/kg/h), significantly inhibited acid output only at 10,000 μg/kg; cumulative 60-min output was decreased by 60%. These results suggest that CCK acts at CCK-A receptors to produce satiety during the dark period in ad lib-feeding rats.     

Basic carboxyl groups of hemoglobin S: Influence of oxy-deoxy conformation on the chemical reactivity of Glu-43(β)

The -carboxyl groups of Glu-43() and Glu-22() of hemoglobin-S (HbS), two intermolecular contact residues of deoxy protein, are activated by carbodiimide atp H 6.0. The selectivity of the modification by the two nucleophiles, glycine ethyl ester (GEE) and glucosamine, is distinct. Influence ofN-hydroxysulfosuccinimide, a reagent that rescues carbodiimide-activated carboxyl (O-acyl isourea) as sulfo-NHS ester, on the overall selectivity and efficiency of the coupling of Glu-22() and Glu-43() with nucleophiles has been investigated. Sulfo-NHS increases the extent of coupling of nucleophiles to HbS. The rescuing efficiency of sulfo-NHS(increase in modification) with GEE and galactosamine as nucleophiles is 2.0 and 2.8, respectively. In the presence of sulfo-NHS, the extent of modification of a carboxyl group is a direct reflection of the extent to which it is activated (i.e., the protonation state of the carboxyl group). The modification reaction exhibits very high selectivity for Glu-43() with GEE and galactosamine (GA) in the presence of sulfo-NHS. From the studies of the kinetics of amidation of oxy-HbS at its Glu-43() (i.e., chemical reactivity) as a function of thepH in the region of 5.5–7.5, the apparentpKa of its -carboxyl group has been calculated to be 6.35. Deoxygenation of HbS, nearly doubles the chemical reactivity of Glu-43() of HbS atpH 7.0. It is suggested that the increased hydrophobicity of the microenvironment of Glu-43(), which occurs on deoxygenation of the protein, is reflected as the increased chemical reactivity of the -carboxyl group and could be one of the crucial preludes to the polymerization process.     

Filtration rates of mosquito larvae in suspensions of latex microspheres and yeast cells

Filtration rates of fourth instars of Aedes aegypti L., Anopheles albimanus Wiedemann, Anopheles quadrimaculatus Say and Culex quinquefasciatus Say (Diptera: Culicidae) were determined by quantifying removal rates of suspended latex microspheres or yeast cells. Average filtration rates were 33–34 l/larva/h (An. quadrimaculatus), 49–55 (An. albimanus), 490–590 (C. quinquefasciatus) or 590–690 l/larva/h (Ae. aegypti) for larvae exposed to latex beads suspended in phagostimulant yeast extract solutions. In suspensions of yeast cells, filtration rates of Ae. aegypti and C. quinquefasciatus were not significantly different from filtration rates in latex bead suspensions. Larval density, ranging from 0.3 to 2.4 individuals/ml in tests with Ae. aegypti and C. quinquefasciatus and up to 4.8 larvae/ml in tests with Anopheles, did not influence filtration rates.

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Zusammenfassung Die Filtrierraten von Viertlarven der Stechmückenarten Aedes aegypti, Anopheles albimanus, Anopheles quadrimaculatus und Culex quinquefasciatus wurden in Laborversuchen bestimmt. Dabei wurde die Filtrierrate definiert als ein Wasservolumen, welches pro Stunde von einer Larve von den Testpartikeln (Hefezellen oder Latexkugeln mit einem Durchmesser von 2 m) befreit wurde. Nach Exposition der Larven in Dichten zwischen 0.15 und 2.4 Larven/ml (Ae. aegypti und C. quinquefasciatus), oder zwischen 0.6 und 4.8 Larven/ml (Anopheles) wurde der Partikelgehalt der Suspensionen in einem elektronischen Partikelzähler bestimmt. Die Filtrierraten wurden über die Verringerung der Partikeldichte mit zunehmender Larvendichte entsprechend einer in der Literatur angegebenen Formel berechnet.Suspensionen von Hefezellen wurden von Ae. aegypti Larven mit einer Leistung von 680±220 l/Larve/h gefiltert. Bei Larven von C. quinquefasciatus wurden Filtrierraten von 600±120 l/Larve/h gemessen. Die Filtrierraten beider Arten waren unabhängig von der Larvendichte. In Suspensionen von Latexpartikeln (zur Phagostimulation der Larven wurden diese Partikel in Lösungen von Hefeextrakt angeboten) wurden die folgenden Filtrierraten festgestellt: An quadrimaculatus: 33–34, An. albimanus: 49–55, C. quinquefasciatus: 490–590, und Ae. aegypti: 560–690 l/Larve/h. Die Larvendichte hatte auch hier keinen Einfluss auf die Filtrierrate. Hefezellen und Latexpartikel wurden von Ae. aegypti und C. quinquefasciatus mit statistisch nicht signifikant verschiedenen Filtrierraten aufgenommen. Die Filtrierraten der Anopheles Larven waren um mehr als eine Zehnerpotenz kleiner als die Filtrierraten von Culex und Aedes, und auch untereinander signifikant verschieden. Der Einfluss der Filtrierraktivität von Stechmückenlarven auf das Seston der Brutgewässer wird diskutiert.

     

60-Hz electric fields: detection by female rats

Female rats were trained to detect a vertical, 60-Hz electric field using the same apparatus and procedure we used previously to study behavioral detection of the field by male rats. Each rat was trained individually to press a lever in the presence of the field and not to press in its absence. Correct detections occasionally produced a food pellet. The probability of detecting the field increased as field strength increased. The threshold of detection--ie, the field strength required for detections at a probability of 0.5 after correction for errors--varied among rats between 3 and 10 kV/m. Behavioral detection by female rats was indistinguishable from that by male rats.     

Effects of steroid hormones on the neuropil of the hypothalamic paraventricular nucleus of male chickens

Summary Testosterone and corticosterone, administered in doses of 0.5 mg/day for two weeks to three-day-old male chickens, induced alterations in the distributional pattern and in the number of synapses in the rostral neuropil of the hypothalamic paraventricular nucleus. This avian nucleus is a target area for both above-mentioned hormones and also one of the most important centers involved in the regulation of behavioral patterns related to reproduction. Testosterone increased the number of synapses in the rostral paraventricular nucleus, while corticosterone altered their distributional pattern causing an increase in type-B terminals; according to morphological criteria the latter are regarded to represent aminergic endings. Similar results were induced by simultaneous administration of both testosterone and corticosterone. Precocious sexual behavior was also provoked by double treatment.Preliminary results have been presented on the occasion of the 5th ENA meeting (Liège, Belgique, Sept. 1981) and the 1st Italian Meeting of Cell Biology (Rimini, Italy, April 1982)This study was supported by CNR bilateral grants (82.00215.04 & 83.00492.04), MPI 40% and European Training Program in Brain and Behaviour Researchs (twinning grant)