Equine parascarosis under the tropical weather conditions of Ethiopia: a coprological and postmortem study

A cross-sectional coprological survey in the regions of Ada, Akaki, Bereh and Boset, and a retrospective postmortem investigation were conducted to study the epidemiology of Parascaris equorum in donkeys and horses in Ethiopia. Faecal samples from 803 working donkeys and 402 horses were collected, and the numbers of worms recovered from 112 donkeys examined postmortem between 1995 and 2004 were analysed. There was a high prevalence of infection and faecal egg output of P equorum in both donkeys and horses, and the severity of the infection in donkeys was increased irrespective of their age. The prevalence of the infection in the donkeys was 51.1 per cent and in the horses 16.2 per cent, and the prevalence in the donkeys examined postmortem was 55 per cent. There was no significant difference between different age groups of donkeys in either the prevalence or the intensity of the infection. The prevalence of the infection was significantly higher in the Ada and Akaki regions than in the Bereh and Boset regions.     

Species richness and composition differ in response to landscape and biogeography

Context

Understanding how landscape patterns affect species diversity is of great importance in the fields of biogeography, landscape ecology and conservation planning, but despite the rapid advance in biodiversity analysis, investigations of spatial effects on biodiversity are still largely focused on species richness.

Objectives

We wanted to know if and how species richness and species composition are differentially driven by the spatial measures dominating studies in landscape ecology and biogeography. As both measures require the same limited presence/absence information, it is important to choose an appropriate diversity measure, as differing results could have important consequences for interpreting ecological processes.

Methods

We recorded plant occurrences on 112 islands in the Baltic archipelago. Species richness and composition were calculated for each island, and the explanatory power of island area and habitat heterogeneity, distance to mainland and structural connectivity at three different landscape sizes were examined.

Results

A total of 354 different plant species were recorded. The influence of landscape variables differed depending on which diversity measure was used. Island area and structural connectivity determined plant species richness, while species composition revealed a more complex pattern, being influenced by island area, habitat heterogeneity and structural connectivity.

Conclusions

Although both measures require the same basic input data, species composition can reveal more about the ecological processes affecting plant communities in fragmented landscapes than species richness alone. Therefore, we recommend that species community composition should be used as an additional standard measure of diversity for biogeography, landscape ecology and conservation planning.

     

Hill Shape Effect on Yield,Quality, Stolon Length and Tuber Orientation of Two Potato Cultivars

Potato (Solanum tuberosum L.) cultivars are mostly planted using similar seed piece planting depths and hill shapes even though cultivars have unique tuber and stolon characteristics. A hill-shape study was conducted at Aberdeen, Idaho to determine the effects of hill shape on yield and field-green tuber yields and quality along with stolon length and tuber spatial orientation for two potato cultivars, 'Defender' and 'Summit Russet.' Plots were planted in late April to early May. Prior to emergence four hill shapes were formed: 1) plant-and-drag, 2) broad, 3) normal, and 4) peaked. Defender had higher total yield with the broad hill, but there were no differences among the remaining three hill shapes. For Defender, U.S. No. 1 yield was lower with the plant-and-drag hill shape, and the normal and peaked hills produced lower field-green tuber yield. Hill shape had no effect on total, U.S. No. 1, or field-green tuber yields of Summit Russet. The peaked hill resulted in a deeper uppermost tuber for Defender, while the uppermost tuber was deeper in the normal and peaked hills for Summit Russet. The broad hill resulted in a larger average tuber size for Defender, but hill shape had no effect on tuber size for Summit Russet. Total number of tubers per plant, stolon length and tuber spatial orientation were not affected by hill shape for either cultivar. Hill shape and height are important considerations in maximizing yield of saleable tubers, so needs to be customized according to cultivar-dependent stolon length and tuber orientation characteristics.     

Defender: A high-yielding, processing potato cultivar with foliar and tuber resistance to late blight

The potato cultivar Defender is high-yielding, white-skinned, and notable for having foliar and tuber resistance to late blight infection caused byPhytophthora infestans (Mont.) de Bary. It was released in 2004 by the USDA-ARS and the agricultural experiment stations of Idaho, Oregon, and Washington. Defender is suitable for processing into french fries and other frozen potato products directly from the field or from storage. Defender also may be used for fresh markets in regions such as California, where cultivars with long tubers and white skin are traditionally grown. Resistances to late blight and other potato diseases make Defender an ideal candidate for organic potato production. Defender consistently produced greater total and U.S. No. 1 yields than ‘Russet Burbank’ in Idaho trials. In early harvest trials conducted in the western U.S., average total yields of Defender were 17% and 23% greater than yields for ‘Ranger Russet’ and ‘Shepody’, respectively. In full-season trials conducted in the western U.S., Defender averaged 10% and 15% higher yields than Ranger Russet and Russet Burbank, respectively. Specific gravity of Defender is consistently high, with values comparable to those of Ranger Russet; tuber ascorbic acid (Vitamin C) levels are also high. In addition to late blight, Defender also is resistant to tuber early blight (Alternaria solani, (Ellis & G. Martin), L.R. Jones & Grout), potato virus X, and net necrosis; it has moderate levels of resistance to Verticillium wilt (Verticillium dahliae, Kleb), pink rot, foliar early blight, corky ringspot, and Erwinia soft rot. Defender is susceptible to scab (common and powdery) and potato leafroll virus; it has moderate susceptibility to dry rot (Fusarium spp.) and potato virus Y. Susceptibilities to internal necrosis, tuber greening, and blackspot bruise also have been noted, but may be minimized through cultural and harvest practices.     

Ranger Russet: A long Russet potato variety for processing and fresh market with improved quality,disease resistance,and yield

Ranger Russet, a new full-season potato variety, was jointly released to growers by the U.S. Department of Agriculture and the Agricultural Experiment Stations of Idaho, Oregon, Washington, and Colorado on May 14, 1991. Ranger Russet was tested in irrigated performance trials in the Western U.S. since 1979. It produces a large yield of high quality, long, russet-skinned tubers that are well suited for baking and processing into french fries. Ranger Russet is more resistant than Russet Burbank to Verticillium wilt, viruses X and Y, leafroll net necrosis, and Fusarium dry rot. It is highly resistant to hollow heart.