ICRAF's first ten years

This article is about the institutional development of the International Council for Research in Agroforestry. It follows the Council's history from the initial ideas in the IDRC-sponsored study Trees, Food and People, its formalization in 1977, the early years up to 1980, when the Council was searching for an identity, the expansive years 1981–85, when in-house capability was built up and the foundation laid of the agroforestry discipline, to the present phase, from 1986, when major field research programmes are being initiated. The main emphasis is on the strategies and priorities behind the programmes in the different phases. A summary is given of the Council's development and growth in terms of funding and staffing. In the final section, some thoughts are expressed about ICRAF in the 1990s.Director, ICRAF; Forester     

Stilbenes and resin acids in relation to the penetration of Heterobasidion annosum through the bark of Picea abies

Concentrations of the stilbene glucosides astringin and isorhapontin, which ranged from 5 to 50 mg/g fresh weight in Picea abies bark, decreased in response to in vivo infection with the root-rot fungus Heterobasidion annosum. The initial concentration of the stilbene astringin was negatively correlated with the depth of hyphal penetration. Resin acid contents increased following infec-tion, but were not correlated with the depth of hyphal penetration. The spatial distribution of stilbene glucosides in spruce stem, root collar and root bark, and the seasonal variations in con-centration, were estimated.     

Predicting moisture content and density distribution of Scots pine by microwave scanning of sawn timber II: evaluation of models generated on a pixel level

The purpose of this study was to use images from a microwave sensor on a pixel level for simultaneous prediction of moisture content and density of wood. The microwave sensor functions as a line-scan camera with a pixel size of 8mm. Boards of Scots pine (Pinus sylvestris), 25 and 50mm thick, were scanned at three different moisture contents. Dry density and moisture content for each pixel were calculated from measurements with a computed tomography scanner. It was possible to create models for prediction of density on a pixel level. Models for prediction of moisture content had to be based on average values over homogeneous regions. Accuracy will be improved if it is possible to make a classification of knots, heartwood, sapwood, etc., and calibrate different models for different types of wood. The limitations of the sensor used are high noise in amplitude measurements and the restriction to one period for phase measurements.     

Breed Differences in Natriuretic Peptides in Healthy Dogs

Background

Measurement of plasma concentration of natriuretic peptides (NPs) is suggested to be of value in diagnosis of cardiac disease in dogs, but many factors other than cardiac status may influence their concentrations. Dog breed potentially is 1 such factor.

Objective

To investigate breed variation in plasma concentrations of pro‐atrial natriuretic peptide 31‐67 (proANP 31‐67) and N‐terminal B‐type natriuretic peptide (NT‐proBNP) in healthy dogs.

Animals

535 healthy, privately owned dogs of 9 breeds were examined at 5 centers as part of the European Union (EU) LUPA project.

Methods

Absence of cardiovascular disease or other clinically relevant organ‐related or systemic disease was ensured by thorough clinical investigation. Plasma concentrations of proANP 31‐67 and NT‐proBNP were measured by commercially available ELISA assays.

Results

Overall significant breed differences were found in proANP 31‐67 (P < .0001) and NT‐proBNP (P < .0001) concentrations. Pair‐wise comparisons between breeds differed in approximately 50% of comparisons for proANP 31‐67 as well as NT‐proBNP concentrations, both when including all centers and within each center. Interquartile range was large for many breeds, especially for NT‐proBNP. Among included breeds, Labrador Retrievers and Newfoundlands had highest median NT‐proBNP concentrations with concentrations 3 times as high as those of Dachshunds. German Shepherds and Cavalier King Charles Spaniels had the highest median proANP 31‐67 concentrations, twice the median concentration in Doberman Pinschers.

Conclusions and Clinical Importance

Considerable interbreed variation in plasma NP concentrations was found in healthy dogs. Intrabreed variation was large in several breeds, especially for NT‐proBNP. Additional studies are needed to establish breed‐specific reference ranges.     

Molecular determination of the predator community of a cassava whitefly in Colombia: pest-specific primer development and field validation

In South America, the whitefly Aleurotrachelus socialis is one of the principal pests of cassava (Manihot esculenta Crantz), reaching high population levels throughout the Andean region. Management of this species is primarily based upon the use of insecticides, while biological control has received limited attention. Till present, knowledge of A. socialis natural enemies is restricted to occasional records of predators and parasitoids. In this study, we developed PCR primer sets specific for the cassava whitefly, A. socialis, to identify their predator community in Colombian cassava. Eleven percent of 586 predator specimens (representing 131 taxa from 29 families) tested positive for cassava whitefly DNA. Of the 21 predator taxa that consumed cassava whiteflies, an unidentified netwing beetle (Lycidae), an unidentified spider species (Araneae), Harmonia axyridis (Coleoptera: Coccinellidae), a Cereaochrysa sp. (Neuroptera: Chrysopidae), and a Leucochrysa sp. (Chrysopidae) were the taxa that consumed cassava whiteflies most frequently under field conditions. Two abundant predators in the system, Delphastus sp. (Coccinellidae) and the long-legged fly, Condylostylus sp. (Diptera: Dolichopodidae), were both positive for whitefly DNA, but did not have the strongest trophic linkage to the pest relative to other predators. This study shows that a diverse predator community affects cassava whitefly in southern Colombia, and provides the groundwork for the design of cassava production systems with minimal pesticide inputs.     

Bacterial numbers in a pine forest soil in relation to environmental factors

Numbers of soil bacteria stained with acridine orange (AO) or fluorescein diacetate (FDA) were studied for 3 and 2 yr respectively. Three pine forest sites were used and both organic and mineral soil layers were included. Different patterns of fluctuation in bacterial numbers were found each year. Significant correlations were demonstrated between AO-stained bacterial numbers and soil moisture content and between FDA-stained bacteria and the accumulated precipitation during a week before the sampling date. In multiple regression analyses 60–80% of the variation in numbers of AO-stained bacteria could be accounted for by soil moisture and numbers of bacterial-feeding nematodes at the sampling dates, and 30–45% of the variation in numbers of FDA-stained bacteria was accounted for by precipitation.     

Clinically Diseased Cats with Non-suppurative Meningoencephalomyelitis have Borna Disease Virus-specific Antibodies

A spontaneous neurological disease in cats characterized by behavioural and motor disturbances was reported in Sweden by Kronevi et al (1974). Generally, the animals showed no gross pathological lesions. Detailed neuro-pathological investigation revealed mononuclear perivascular cuffing and gliosis throughout the brain and spinal cord consistent with a non-suppurative meningoencephalomyelitis. After this first report, the disease has become recognized in different parts of Sweden, preferably Uppland and the area around Lake Mälaren, and is referred to as “staggering disease” of cats. The clinical manifestation of the disease includes hindleg ataxia and paresis (Fig. 1), inability to retract the claws (Fig. 2), mental changes, anorexia, increased salivation, hypersensitivity to sound and light, hyperesthesia, impaired vision and seizures (Kronevi et al 1974, Ström et al 1992). Despite treatment with antimicrobial drugs and corticosteroids most cats deteriorate and die or have to be euthanised after 1-4 weeks of illness.     

Effect of sample volume size and sampling method on feline longitudinal myocardial velocity profiles from color tissue Doppler imaging

ObjectivesThe aims of this study were to compare the effect of sample volume (SV) size settings and sampling method on measurement variability and peak systolic (s′), and early (e′) and late (a′) diastolic longitudinal myocardial velocities using color tissue Doppler imaging (cTDI) in cats.AnimalsTwenty cats with normal echocardiograms and 20 cats with hypertrophic cardiomyopathy.MethodsWe quantified and compared empirical variance and average absolute values of s′, e′ and a′ for three cardiac cycles using eight different SV settings (length 1,2,3 and 5 mm; width 1 and 2 mm) and three methods of sampling (end-diastolic sampling with manual tracking of the SV, end-systolic sampling without tracking, and random-frame sampling without tracking).ResultsNo significant difference in empirical variance could be demonstrated between most of the tested SVs. However, the two settings with a length of 1 mm resulted in a significantly higher variance compared with all settings where the SV length exceeded 2 mm (p < 0.001). There was an overall significant effect of sampling method on the variability of measurements (p = 0.003) and manual tracking obtained the lowest variance. No difference in average values of s′, e′ or a′ could be found between any of the SV settings or sampling methods.ConclusionWithin the tested range of SV settings, an SV length of 1 mm resulted in higher measurement variability compared with an SV length of 3 and 5 mm, and should therefore be avoided. Manual tracking of the sample volume is recommended.