THE OCCURRENCE AND ADAPTIVE SIGNIFICANCE OF NOCTURNAL HABITS IN WATERFOWL

This paper reviews the occurrence of nocturnal activity, particularly foraging, in wildfowl (Anseriformes) and shorebirds (Charadrii), and discusses its significance. Many duck species are mainly active at night while others regularly feed during both the day and night. Some ducks and geese are normally day feeders and occasionally forage during darkness. In a few duck species, courtship also has been observed at night. Most shorebirds forage both by day and night, in temperate and in tropical latitudes. Some are mainly crepuscular and nocturnal feeders and also display at dusk and at night. Some species may use their daytime territory at night. A few shorebird species, including some visual peckers and long-billed tactile probers, use the same foraging method to detect and capture food by night as by day. However, some long-billed species that forage visually during daytime modify their feeding techniques and rely completely or partly on tactile means for detecting prey at night. Large eyes seem an advantage to plovers and other sight feeders for night feeding. Numerous touch-sensitive corpuscles in the bill of ducks and many scolopacid species favour tactile feeding. Some ducks, geese and shorebirds may especially use moonlit nights for feeding though, in a few species, moonlight seems to have no effect. The possible role of bioluminescence is also discussed. Nocturnal activity may occur for two reasons. The night may be preferred because foraging is more profitable or safest from predators. Alternatively, birds may be forced to forage at night because they fail to collect all their food requirements during the day. The evidence for both hypotheses is reviewed. Nocturnal activity does appear to allow wildfowl, and perhaps shorebirds, to avoid diurnal predators (including man). Shorebirds, and some ducks also seem to take advantage of prey that are more abundant and/or accessible at night. The main evidence for the supplementary feeding hypothesis comes from studies of seasonal variations in the occurrence of nocturnal feeding, about which rather little is known at present. The increasing availability of modern night-viewing equipment may help to fill this gap. There are two important implications arising from the widespread occurrence of nocturnal activity in wildfowl. Most knowledge on time and energy budgets is based on daytime studies, and so may need to be revised. Wintering dabbling ducks and shorebirds, at least in some regions, may use different habitats by day and by night. If confirmed, there would be a need to preserve some wintering habitats which, although little used by ducks and shorebirds during the day, may be intensively used at night.     

Biochemical Identification and Phylogenetic Relationships in Free-Living Amoebas of the Genus Naegleria1

Using isoelectric focusing, the zymograms of 23 pathogenic and nonpathogenic Naegleria strains were studied for the activity of 16 enzymes. Certain enzymes (lactate dehydrogenase, L-threonine dehydrogenase, superoxide dismutase, acid phosphatase, malic enzyme, and leucine aminopeptidase) proved particularly useful from a practical point of view as they allow easy and reliable identification of pathogenic N. fowleri and N. australiensis as well as nonpathogenic N. lovaniensis strains. Genetic interpretation of these zymograms gave estimates of genetic distances that largely confirmed the taxonomic position of the Naegleria species. In addition, the genetic data suggest that there are two main phylogenetic groups in the genus Naegleria.     

Bryozoaires des milieux récifaux miocèes du sillon sud-rifain au Maroc

Moissette, P. & Saint Martin, J_:P. 1995 11 30 Bryozoaires des milieux récifaux miocenes du sillon sud-rifain au Maroc. [Bryozoans from Miocene reef environments in the South-Rifian corridor of Morocco. In late Miocene coral reefs from the Fes area (Northern Morocco), bryozoans are the best-represented group. An inventory of the bryozoan fauna (59 species) was taken on two reefs with different organization and palaeogeographical situation in a late Miocene seaway between the Atlantic and the Mediterranean. A study of the bryozoans and their zoarial forms allows an improved reconstruction of reefal environments and available habitats. Membraniporiforrn (encrusting) colonies largely predominate, whereas celleporiforms (nodular colonies) are more rare. Rigid erect (vinculariiform, adeoniform, and reteporiform) and rigid articulated zoarial types (cellariiform and catenicelliform) are fairly well represented. At depths of about 10 m and on the reef front encrusting bryozoans were well developed in cryptic habitats on living coral substrates. Erect species lived in cavities provided by the coral framework, and plants offered flexible substrates for the attachment of epiphytal forms. □Bryozoa, coral reefs, Morocco, Messininn, pulueoecology. Dans les récifs coralliens du Miocène supérieur de la région de Fes (Maroc septentrional), les bryozoaires constituent, parrni les organismes conservés, le groupe le mieux représenté. Un recensement de la fame de bryozoaires (59 espèces) a été effectué dans deux récifs d'organisation et de situation paléogéographique différentes, dans un secteur de communication entre Atlantique et Méditerranée au MiocéFne supérieur. L'étude des bryozoaires et de leurs formes zoariales permet de proposer une meilleure reconstitution de I'environnement récifal et des habitats disponibles. Les colonies membraniporiformes (encrobtantes) predominent largement, alors que les cellepori-formes (colonies noduleuses) sont beaucoup plus rares. Les types zoariaux érigés rigides (vincula-riiforme, adéoniforme et rétéporiforme) et érigés articulés (cellariiforme et catenicelliforme) sont assez bien représentés. A des profondeurs denviron 10 m et dans la partie antérieure des constructions récifales, les bryozoaires encroûtants étaient bien développés dans des habitats cryptiques sur substrats coralliens vivants. Des formes dressées vivaient dans les cavités ménagées par le bâti corallien et des supports végétaux permettaient également la fixation de formes épiphytes. □Bryozouires, récifs coralliens, Muroc, Messinien, puléoécologie.     

Monoterpenes emitted by the large pine weevil, Hylobius abietis (L.) feeding on Scots pine, Pinus sylvestris L.

Abstract. Attraction of the large pine weevil, Hylobius abietis (L.) (Coleoptera: Curculionidae) to pine logs was enhanced by the presence of weevils already on the logs. We investigated the volatiles emitted by insects feeding on host trees to determine the mechanism of the attraction. Chemical analyses of the collected volatiles showed large amounts of monoterpenes. There were no qualitative differences in the collections, between Scots pine alone and pine plus feeding weevils, nor between males and females, mated or virgin. Strong quantitative differences in monoterpenes existed that were correlated to the surface of cut bark. Electroantennograms (EAGs) were recorded on male and female antennae stimulated by increasing doses of collected volatiles. EAGs for pine alone and pine plus weevils at the same stimulus loading in (a + P)-pinene gave superimposable curves. EAGs of male and female volatiles were also identical. These results suggest an attraction mediated by host plant allelochemicals rather than by an aggregation pheromone.     

Large Genetic Heterogeneity Within Amoebas of the Species Naegleria gruberi and Evolutionary Affinities to the Other Species of the Genus

The allozyme survey was extended to 7 strains of Naegleria gruberi and N. jadini in order to further characterize the genetic structure of these free-living amoebas. As formerly known for several characters the electrophoretic evidence reveals considerable heterogeneity at the genetic level among N. gruberi strains. Moreover, 2 distinct gene pools, that might likely represent natural taxa, are clearly identified. The single strain of N. jadini appears evolutionarily related to 1 group of N. gruberi which is also related to N. a. australiensis.     

Ecophysiological aspects of bruchid reproduction. I. The influence of pod maturity and seeds of Phaseolus vulgaris and the influence of insemination on the reproductive activity ofZabrotes subfasciatus

ABSTRACT.

• 1 Economically important bruchid beetles like Zabrotes sub-fasciatus (Boh.) are able to reproduce both in the field before the legume crop harvest – whilst the seeds are still enclosed within pods – and on seeds in storage sites.
• 2 To take into account this reproductive feature, the influence of pods at different stages of maturity and seeds of Phaseolus vulgaris (Lin.) together with the influence of insemination on the reproductive activity of Zabrotes subfasciatus were examined.
• 3 Female fecundity, insemination and ovarian production were studied under laboratory conditions approximating as closely as possible to the thermal and photoperiodic regimes of the Costa Rican region from which the experimental strain originated.
• 4 The three stages of pod maturity used in experiments (fresh green, fresh yellow and dry yellow pods, all non-dehiscent) induced copulations and significantly stimulated oogenesis. Fecundities of females in the presence of pods were low and did not differ from controls.
• 5 The influence of bean seeds on female reproductive activity was more pronounced than that of pods. Contact with seeds led to a marked increase in the number of sexual meetings, ovarian production and egg-laying activity. Under these conditions, eggs are laid directly on the larvae's food.
• 6 Insemination alone stimulated oogenesis but did not induce egg-laying.
• 7 Possible additive or synergistic interactions between host plant information perceived by females, the effects of egg-laying and insemination are suggested to explain the observed results.
• 8 The adaptive value of this form of reproductive regulation by host plant seeds and pods is discussed in terms of the natural history and oviposition behaviour of Zabrotes subfasciatus.

     

Trifluoperazine-Sensitive Step during Sea Urchin, Echiuroid and Pelecypod Egg Activation

Trifluoperazine, a calmodulin-antagonist, is shown to inhibit egg activation by ionophore A 23187 in sea urchin (I₅₀: 43 μM), by trypsin in echiufoids (I₅₀: 22 μM) and by KCl in bivalves (I₅₀: 34 μM). In each case the inhibition could be reversed by washing the eggs and the trifluoperazine-sensitive period was clearly limited. In Barnea and Urechis , trifluoperazine inhibits calcium uptake. A common trifluoperazine-sensitive step, possibly involving calmodulin, may thus be shared by a variety of animal groups during egg activation.     

Equine Culicoides hypersensitivity in Florida: biting midges collected in light traps near horses

Twenty-three species of Culicoides were trapped near pruritic horses during a 2-year survey in Florida. Nearly 99% of the biting midges collected were represented by Culicoides insignis Lutz, C. edeni Wirth and Blandon, C. stellifer (Coquillett), C. niger Root and Hoffman, C. haematopotus Malloch and C. venustus Hoffman. The relative contribution to the total catch by each of these species varied among collection sites. Seasonally, different species attain their largest population sizes at different times. Association of species collected in light traps with the seasonality of lesion development on the horses suggests that more than one species must be involved in causing Culicoides hypersensitivity in horses from Florida. Nulliparous females were present in most months that females of the same species were active; in some cases, species were trapped in each month of the year, particularly at the more southerly sites. The species of biting midge most likely to be involved in Culicoides hypersensitivity in horses in Florida are C. insignis, C. stellifer and C. venustus based upon their mammalophilic behaviour and seasonality.