The effects of drone age, semen storage and contamination on semen quality in the honey bee (Apis mellifera)

Abstract. The effect of semen storage time, drone age and semen contamination on honey bee semen quality was investigated using assays for motility and viability of semen in vitro. Four age groups (1, 2, 4 and 6 weeks) and five storage times (0, 1, 2, 4 and 6 weeks) were examined. As storage time increased, sperm viability and motility significantly decreased. However, motility patterns of unstored semen samples were significantly lower than those samples that were stored up to 2 weeks. Sperm viability decreased significantly with increasing drone age, but motility patterns did not change. Those semen samples that were found to be contaminated with foreign particles or microorganisms had a significantly lower mean viability than uncontaminated samples.     

Macroinvertebrate functional feeding groups in the middle and lower reaches of the Buffalo River, eastern Cape, South Africa. I. Dietary variability

• 1 The question of whether the diets of twelve abundant macroinvertebrate taxa from the middle and lower reaches of the Buffalo River (eastern Cape, South Africa) were too variable to allow them to be assigned to functional feeding groups (FFGs) was addressed.
• 2 Spatial, temporal and developmental variations in diet were assessed. Foregut content analysis was used as an index to compare diets.
• 3 Foregut contents were compared from early (small) and late (large) instar larvae collected from riffles at thirteen sites in summer, and from riffles, stony backwaters and sediments at four of these sites in spring, summer, autumn and winter, in 1987.
• 4 For all individuals of all taxa, fine amorphous detritus (0.5–250 μm), was the most common dietary item. Differences in diet followed a similar pattern for all taxa. The most frequent differences in dietary content were between large and small larvae. The foreguts of large larvae contained more material, and a wider variety of rare items than small larvae. Neither species nor FFGs could be distinguished on the basis of foregut contents.
• 5 Two dietary types were recognized. The eight mayfly larvae were fine detritivores, having ingested fine detritus almost exclusively. In contrast, the two hydropsychid caddisfly larvae had ingested a mixed diet; their gut contents included chirinous invertebrate remains and other items as well as fine detritus.
• 6 Intra-specific dietary variability was not so great as to prevent these taxa from being assigned to FFGs. On the contrary, inter-specific dietary content was so similar that gut content analysis could not provide a positive basis upon which to identify FFGs.

     

Ultrastructure of the loop of terebratulide brachiopods

The folded and twisted calcareous ribbon, forming both the ascending and descending lamellae of the loop of Waltonia inconspicua (Sowerby), is a two-layered structure consisting of a wedge of regularly stacked secondary layer fibres that overlie a thin layer of non-fibrous calcite (herein termed brachiotest). On one surface, that facing into the mantle cavity, secondary fibrous mosaic predominates, but smooth, finely banded brachiotest occurs as a narrow marginal lip upon which secondary layer fibres proliferate and progressively overlap. This growing edge of the ribbon is secreted by long, folded epithelial cells with digitate extensions to their apical plasmalemmas, which are distinguishable from the cuboidal epithelium-secreting fibres and their membranous sheaths. The other surface, facing the body cavity and the brachial coelom, consists entirely of roughened brachiotest exhibiting prominent banding that is aligned parallel to the growing loop edge. This surface is overlain by microfilamentar epithelium acting as a holdfast for the connective tissue frame of the lophophore. The other edge of the ribbon consists of truncated sections of both secondary-layer fibres and brachiotest which bear signs of resorption consistent with the degenerated state of the associated epithelium. Growth of the Waltonia loop is controlled by these localized processes of secretion and resorption of the fibrous and brachiotest layers and is typical of all terebratulides so far studied. The brachiotest is not homologous with the non-fibrous primary shell secreted at the valve margin. □ Brachiopoda, Articulata, Terebratulida, ultrastructure, lophophore, loop.     

Colonization of pasture by Kunzea ericoides in the Tidbinbilla Valley,ACT, Australia

Stand morphometry and age structure were analysed for populations of burgan, Kunzea ericoides, which were colonizing pastoral land in the Tidbinbilla Valley, Australian Capital Territory. Three types of stands, (i) closed burgan-dominated; (ii) open burgan-dominated; and (iii) mixed burgan and eucalypts, were compared at each of two locations. Burgan ages were determined from growth ring counts cross-correlated with seasonal rainfall and annual increments in Pinus radiata. Burgan stands have developed from windblown seed coming from nearby forest margins and drainage-lines. The species colonized rural lands in the Tidbinbilla Valley rapidly from the early 1960s, when changes in land use practices occurred which enabled sparse colonists to contribute to rapid population expansion. Colonization was initially slow, but recruitment increased dramatically in the early 1960s in closed and open stands when densities were between 0.01 and 0.03 plants m^-2. These stands did not follow classic secondary succession, as the differences between stands sampled were largely the result of differences in burgan density and floristic composition of the sites at the time of change in land use practices. These differences in turn influenced the phenotypic response of individual plants and the ensuing stand structures. A closed shrub canopy of burgan, together with the species self-replacement strategies, is likely to prevent other species from entering the closed burgan sites and becoming dominant. Where the objective is to limit the spread of burgan, isolated plants, which act as foci for spread, would be the primary target for control.     

Boring Mechanism of Polydora websteri Inhabiting Crassostrea virginica

The boring mechanisms of species of polydorid polychaetes arelittle understood due to lack of experimental evidence and directobservations. In the present studies the boring mechanism ofadults and metamorphosing larvae of Polydora websteri was investigatedby (1) inducing adults and larvae to settle against test substrates,(2) observing behavior in natural burrows and in "artificialblisters" composed of transparent "Pliobond" films surroundingIceland spar substrates, (3) removing the giant setae of wormspriorto tests of boring, (4) applying the giant setae to substrates,and by (5) testing for production of acid. All the layers of oyster shell, including conchiolin, were bored.Calcareous substrates andIceland spar were penetrated rapidlyby adults without the assistance of the giant setae. Nor werethese organs essential to the boring of a larva. A characteristictype of behavior involving close contact with the substrateduring backwards and forwards movements and periods of immobilityalways preceded boring. The worms produced acid, probably somecommon product of metabolism, which can account for these results.     

Phylogenetic relationships of the Papuan Swiftlet Aerodramus papuensis and implications for the evolution of avian echolocation

The swiftlets (genera Aerodramus , Collocalia and Hydrochous ) are unusual among birds in that many species can orientate in complete darkness using echolocation. The position of the Papuan Swiftlet Aerodramus papuensis in this group has been uncertain historically, in part due to morphological differences between it and other swiftlets (it has three toes instead of the usual four) and a lack of data on its behaviour (there is uncertainty about whether it echolocates). Here we investigate the phylogenetic affinities of the Papuan Swiftlet using DNA sequence data from two mitochondrial genes, cytochrome b and ND2. We present evidence that it is able to echolocate but, unlike previously studied species that use echolocation primarily while flying in caves, A. papuensis uses this ability while active outside caves at night. We also provide new evidence for placement of the monotypic Waterfall Swiftlet Hydrochous gigas , a species that does not echolocate. Our data provide strong support for a basal relationship between A. papuensis and other Aerodramus taxa and suggest that this species and H. gigas are sister taxa, a relationship that would indicate paraphyly of the genus Aerodramus . Our phylogeny provides new insights into how echolocation has evolved in the swiftlets, in particular by indicating higher levels of homoplasy in this trait than was previously thought.     

Towards a Non-Terminal Viability Assay for Foraminiferan Protists

ABSTRACT. Epifluorescence microscopy and spectrofluorimetry were investigated as possible non-terminal methods to distinguish live from dead foraminifera. Seven fluorogenic probes (diacetates of fluorescein [FDA], carboxyfluorescein, dichlorofluorescein, and carboxyeosin; AM-esters of biscarboxyethylcarboxyfluorescein [BCECF-AM], calcein, and calcein blue) were tested on Allogromia laticollaris . The probes that consistently produced the brightest fluorescence signals (BCECF-AM and FDA) were judged non-toxic to Allogromia , on the basis of short-term pseudopodial deployment and long-term reproduction assays. Once protocols were established, these two probes were tested on 13 additional benthic foraminiferal species. We found that BCECF-AM is the most suitable probe for direct epifluorescence microscopy of metabolically active foraminifera, especially tectinous and transparent calcareous species. Using spectrofluorimetry, FDA showed promise for opaque species because fluorescence is detected in the incubation media after its release from the cell. However, both approaches could only be used with confidence in light of appropriate controls established for each species examined.