Predispersal seed predation in native leguminous shrubs and trees in savannas of southern Botswana

Seed predation by insects in the seed-crop of nine Acacia species, Dichrostachys cinerea , and Peltophorum africanum was examined in various tree savannas in Botswana. The degree of infestation varied strongly between and within species from 0% ( P. africanum ) to more than 80% ( A. hebeclada, D. cinerea ). Whereas in all Acacia species only one phytophagous hymenopteran ( Oedaule sp.) was present, the number of bruchid species varied between one ( Bruchidius sahlbergi on A. hebecluda, B. uberatus on A. nilotica ) and eight species ( Bruchidius div. spec., Caryedon sp., Spermophagus rufonotutus on A. tortilis ).
The life history of B. sahlbergi was studied in detail and lasted at least 100 days from egg to adult beetle. The life-span of adult beetles may extend to a further 57 days.

Résumé

Des observations ont été réalisées sur les dégâts d'insects dans les graines de neuf espèces d' Acacia , de Dichrostachys cinerea et de Peltophorum africanum dans les savanes arborées du Botswana. Le taux d'infestation varie fortement aussi bien entre les espèces que parmi les espèces de 0% ( P. africanum) à plus de 80% ( A. hebeclada, C. cinerea ). Alors que toutes les especes d' Acacia n'héberge qu'un seul Hyménoptère phytophage ( Oedaule sp.), le nombre d'espèces de Bruchidae observées varie de une ( Bruchidius sahlbergi sur A. hebeclada, B. uberatus sur A. nilotica) à huit ( Bruchidius div. spec., Caryedon sp., Spermophagus rufonotatus sur A. tortilis ).
Le cycle de développement de B. sahlbergi a étéétudié et dure au moins une certaine de jours. La longévité des adultes de cette espèce peut atteindre 57 jours.     

Development of the Swine Coccidium Eimeria debliecki Douwes, 1921 in Mammalian Cell Cultures1

Sporozoites of Eimeria debliecki entered human fetal lung and porcine kidney cells grown in cultures and underwent one merogenous cycle, terminating in the production of second-generation trophozoites. Sporozoites were intracellular 1 h post-inoculation (PI) and developed into sporozoite-shaped meronts at 40 h PI. These meronts, one of which was motile, had from two to ten nuclei. Sporozoite-shaped meronts then developed into elongate or spheroidal meronts with 10 to 24 nuclei by two days PI. Ten to 26 first-generation merozoites were formed by budding from the meront surface. Mature first-generation merozoites were most numerous three days PI. Most meronts had ruptured and released nonmotile merozoites into the culture medium by four days PI. Merozoites that were not released became rounded and developed into second-generation trophozoites. Refractile bodies were present in all developmental stages. No further development was observed five through eight days PI.     

Behavioral Adaptations of Intertidal Hermit Grabs

SYNOPSIS. AS an ecotone, the littoral environment is often complexand is generally rich in numbers and species of organisms. Thedisadvantages of the biotope in terms of exposure to physicalfactors of both the marine and terrestrial environments arepatent, but the advantages are not so evident. The continualreplenishment of food brought from the sea, particularly fordetritus-feeding animals such as hermit crabs, coupled withthe possibility and ability to establish microhabitatswith microclimaticconditions may constitute the principal advantage. Escape fromspecialized predators may also be important. Hermit crabs havesuccessfully exploited most intertidal environments. As membersof the "benthic detritus-feeding guild" food is abundant, andby utilizing their shells in conjunction with movements withinthe littoral zone they have met successfully most of the rigorsof the environment. The shell also provides some protectionfrom predation, particularly from non-specialized predators.Indeed,the behavioral patterns associated with living in shells whichpermit the shell to serve as a microhabitat constitute the majoradaptation enabling the hermit crabs to exploit the intertidalenvironment so successfully.     

Eimeria procyonis sp. n., an Isospora sp., and a Redescription of E. nuttalli Yakimoff and Matikaschwili, 1932 (Protozoa: Eimeriidae) from the American Raccoon (Procyon lotor)

SYNOPSIS. Thirty-two of 48 raccoons examined were infected with a previously undescribed species of Eimeria which is herein named E. procyonis. Of the 32 infected animals, 10 also harbored E. nuttalli and 1 had Isospora sp. oocysts.
The ellipsoid to ovoid oocysts of E. procyonis measured 23.4 × 18.0 (16–29 × 13–24) μm; its sporocysts measured 12.1 × 9.3 (11.5–15 × 7–10) μm, each containing a slightly flattened substiedal body. The sporocyst residuum consisted of numerous scattered granules each ∼1 μm in diameter. The oocyst wall was double-layered. The outer layer appeared rough and pitted, measuring 1.5 μm, except at the micropyle where it was 1 μm thick.
The oocysts of the Isospora sp. measured 16.8 × 13.7 (16–18.5 × 12.5–15.5) μm. The wall consisted of a single layer ∼0.5 μm thick. The sporocysts measured 11.2 × 9.1 (9.5–11.5 × 8–10) μm, and each contained 4 elongate sporozoites. The oocysts of E. nuttalli measured 17.5 × 13.6 (12-21 × 11-15) μm, with a smooth single-layered wall approximately 0.7 μm thick. The sporocysts measured 12.2 × 7.1 (9-13 × 5.5–11) μm. Each sporocyst had a thin, dark, Stieda body and the sporocyst residuum consisted of many fine granules.     

The Convergent Development of Orb-webs in Cribellate and Ecribellate Spiders

Orb-webs are highly developed and can be understood as the besttechnical solution of the problem how to place capture-threadsin the most efficient and economical way. They are built bycribellate and ecribellate spiders. Phylogenetical relationsbetween some families of Cribellate and Ecribellate cannot beignored, but for some important reasons it is difficult to imaginethat on the level of orb-weaving cribellate spiders became ecribellateby reducing the cribellum. Thus, these specialised webs musthave developed on both sides independently and are the resultof a convergent evolution. Steps leading from primitive useof threads for capturing insects to the typical and latter modifiedorb-webs of Cribellate and Ecribellate can be discerned.     

Relationships among turtles of the genus Clemmys (Reptilia, Testudines, Emydidae) as suggested by plastron scute morphology

The Conservative morphology of hardshelled turtles has fostered the use of size relationships between epidermal scutes (scales) on the shell to differentiate between species and subspecies of many taxa. The size relationship of the six major pairs of plastral scutes were used to compare the four currently recognized species of the genus Clemmys with each other. as well as with the distantly related Graptemys barbouri using Jaccard Coefficients. Shannon-Weiner diversity indices, and multivariate analysis. Results were concordant among the three techniques used and confirm our prediction that plastral morphology varies little among closely related species and widely among distantly related taxa. Clemmys muhlenbergii appears to he more different from Clemmys guttata than previously suggested. Analysis of plastral morphology shows promise as a taxonomic tool for turtle systematists.     

Role of Ethylene in Senescence of Petals--Morphological and Taxonomical Relationships

Petal senescence in mature flowers was studied in 93 speciesfrom 22 families. The initial symptom of senescence was eitherwilting or abscission, but in some species the time span betweenwilting and abscission was very short. There was no apparent relationship between corolla form (choripetalousor sympetalous), ovary position (inferior or superior with respectto the corolla) and type of senescence (initial wilting or initialabscission). In monocots no initial abscission was found, whilein dicots the difference between the wilting type and the abscissiontype was generally at the family level. With respect to petalsenescence, sensitivity to exogenous ethylene (C₂H₄) was alsorelated to the family level. Except for a few families (all tested Campanulaceae, Caryophyllaceaeand Malvaceae, and most Orchidaceae), most of the flowers investigatedthat showed initial wilting were not sensitive to exogenousethylene, e.g. all tested Compositae, Iridaceae, and Liliaceae.Most of the flowers showing initial abscission were sensitiveto exogenous ethylene (Geraniaceae, Labiatae, Ranunculaceae,Rosaceae, Scrophulariaceae). Experiments with silver thiosulphate (STS) confirmed the effectsof exogenous ethylene, both in flowers showing initial wiltingand in flowers showing initial abscission. The data indicate,therefore, that ethylene is involved in the natural senescenceof only a minority of the wilting type of flowers and in a majority(if not all) of the abscising type of flowers. Key words: Abscission, ethylene, senescence, silver thiosulphate