Entodiniomorph Ciliates from the Stomach of Hippopotamus amphibius, with Descriptions of Two New Genera and Three New Species

Entodiniomorph ciliates, belonging to the family Cycloposthiidae, are described from the stomach contents of Hippopotamus amphibius. Monoposthium acanthum gen. n., sp. n., with typical cycloposthiid structure, differs from other genera in having only 1 caudalium. Parentodinium gen. n., represented by P. africanum sp. n. and P. ostrea sp. n., although superficially resembling Entodinium, is considered to be a relatively unspecialized cycloposthiid.     

Vector specificity of barley yellow dwarf virus serotypes and variants in southwestern Idaho

Plants with symptoms of barley yellow dwarf virus (BYDV) obtained in infection feeding assays of aphids collected in the field in Idaho between 1986 and 1988 were tested for virus transmissibility by possible aphid vectors. Isolates obtained during 1987–1988 were also tested with a range of polyclonal antisera which distinguished PAV, MAV, SGV, RPV and RMV serotypes. In 1989 some Idaho (ID) BYDV isolates, maintained as standards for comparison, were serotyped and tested for aphid transmissibility, using 11 species of aphids. There was not always the expected correspondence between serotype and vector specificity for ID isolates. For isolates obtained from field-collected Rhopalosiphum padi, vector transmissibility and serotype corresponded with previous reports; however, 44% of isolates which were serotyped as RMV were also transmissible by species other than Rhopalosiphum maidis. Similarly, the transmissibility of the ID laboratory standards did not always conform to the reported vector specificity of serotypes. The laboratory ID-MAV culture was transmitted by Metopolophium dirhodum and Myzus persicae as well as by Sitobion avenae. The laboratory ID-SGV culture was transmitted by R. padi and 5. avenae as well as by Schizaphis graminum. The ID-RPV culture was transmitted by S. graminum and Rhopalosiphum insertum as well as R. padi. Both of two laboratory ID-RMV cultures were transmissible by R. insertum and R. padi transmitted one of them. The results indicate that, for isolates collected in Idaho, vector specificity cannot be assumed from their serotypes.     

Seed survival and periodicity of seedling emergence in ten species of annual weeds

Seeds or fruits of 10 species of annual weeds were collected in each of 3 years and mixed with the top 7 · 5 cm of sterilised soil (confined in cylinders sunk in the ground outdoors and cultivated three times yearly. The numbers of seedlings emerging were recorded for 5 yr and the numbers of viable seeds remaining then determined. Emergence of Anagallis arvensis, Anchusa arvensis, Chaenorrhinum minus and Euphorbia peplus was mainly in spring; Lamium amplexicaule and Myosotis arvensis also had a spring peak but emergence continued in summer and autumn. Seedlings of Aphanes arvensis appeared almost entirely in autumn and those of Lamium purpureum between May and October. Veronica arvensis had spring and autumn peaks, while Fumaria densiflora showed no definite pattern. Except for Anagallis arvensis and F. densiflora, in which there was apparent innate dormancy due to the seed coat, most seedlings appeared in the first year with a decrease, usually exponential, from year to year. This was most rapid in C. minus and E. peplus, of which few viable seeds remained after 5 yr. Seed survival for the other species ranged from 2·6% of those sown for Anchusa arvensis to 14·8% for F. densiflora.     

Buried Secrets: Truth and Human Rights in Guatemala

Buried Secrets: Truth and Human Rights in Guatemala. Victoria Sanford. New York: Palgrave, 2003. 313 pp.     

Study on the factors affecting storage of edible aroids

The effects of temperature (15 °C, 25 °C, 30°C and 24–29°C), relative humidity (45%, 85% and 86–98%) and harvest maturity on the storage behaviour of cormels of the edible aroid species Colocasia esculenta and Xanthosoma sagittifolium were studied. The changes monitored were respiration rates, weight losses, incidence of decay and sprouting. Post-harvest losses that occurred during storage were influenced by the storage conditions, the state of maturity at harvest and the morphological characteristics of the cormels. When stored under high temperature and humidity more sprouting and decay occurred with C. esculenta cormels than with X. sagittifolium cormels. Less sprouting and decay occurred with Colocasia cormels at high temperature and low humidity than at high temperature and high humidity but higher weight losses were recorded. Wound pathogens were the major cause of post-harvest deterioration in Colocasia cormels and the causal pathogen of cormel decay was Sclerotium rolfsii. Under conditions of low temperature (15 °C) and high humidity (85%), cormels of both C. esculenta and X. sagittifolium were successfully stored for periods of 5–6 weeks. Similar storage periods were also possible under tropical ambient conditions with the Xanthosoma cultivars used in these experiments. Under the same storage conditions up to 60% decay occurred in the Colocasia cormels indicating the need for post-harvest fungicide treatment.     

The Biology of Neobursaridium gigas Balech, 1941 (Ciliata: Heterotrichida)

SYNOPSIS. N. gigas Balech, 1941, has been found again in Uganda and cultured in the laboratory. Some features of its morphology and behavior were studied. The buccal cavity has a small pit. Trichocysts are found in the endoplasm as well as the cortex. The ciliate appears to be highly sensitive to light. Cyclops was an important predator. The size of N. gigas is very variable.