Genetic analyses of elbow and hip dysplasia in the German shepherd dog

Results from radiographic screening for canine hip dysplasia (CHD) and elbow dysplasia (CED) of 48 367 German shepherd dogs born in 2001–07 were used for the population genetic analyses. Available information included CHD scores for 47 730 dogs, CED scores for 28 011 dogs and detailed veterinary diagnoses of primary ED lesions for a subsample of 18 899 dogs. Quasi‐continuous traits were CHD, CED and cases of CED without radiographically visible primary lesion (CED‐ARTH). Binary coding was used for fragmented medial coronoid process of the ulna (FCP), borderline findings and mild to severe signs of dysplasia in hip and elbow joints. Genetic parameters were estimated in univariate threshold and multivariate linear and mixed linear‐threshold models using Gibbs sampling. Correlations between univariately predicted breeding values (BV) indicated genetic differences between borderline and affected disease status for both CHD (r_BV = 0.5) and CED (r_BV = 0.3). Multivariate genetic analyses with separate consideration of borderline findings revealed moderate heritabilities of 0.2–0.3 for the quasi‐continuous traits with positive additive genetic correlation of 0.3 between CHD and both CED and CED‐ARTH. For FCP, heritability of 0.6 and additive genetic correlations of +0.1 to CHD and ?0.1 to CED‐ARTH were estimated. Results supported the relevant genetic determination of CHD and CED, argued for both diseases against interpretation of borderline findings as healthy and implied genetic heterogeneity of CED. Accordingly, future breeding strategies to reduce the prevalences of CHD and CED in the German shepherd dog should be most efficient when based on BV from multivariate genetic evaluation for CHD, CED‐ARTH and FCP with use of the whole scale of categories for classification of CHD and CED.     

Laboratory transmission of the citrus stubborn disease agent by a leafhopper from theCirculifer tenellus complex from the Jordan Valley

Citrus stubborn disease (=little leaf disease) is known to affect the size of citrus trees, and to reduce the quality and quantity of the fruit. The disease agent,Spiroplasma citri, was isolated and culturedin vitro from Oroblanco, orange and grapefruit orchards throughout the year from different regions in Israel. The agent was transmitted by a leaf-hopper from theCirculifer tenellus complex collected onAtriplex halimus plants in the southern Jordan Valley. The latent period of the agent in this vector was at least 10 days following a 3-day acquisition feeding onMatthiola incana plants. It was similar to that found for a primary isolation in culture medium (LP₅₀=21 days). The limitations of visual inspection for recording disease incidence in citrus groves were determined and this method was compared with other methods for detection of the disease agent (immunoassay and cultivation in a culture medium). Plants from various botanical families were tested for their ability to serve as hosts for the Israeli biotype of the beet leaf-hopper and for the stubborn disease agentS. citri. The possible role of IsraeliC. tenellus in the disease epidemiology is discussed.     

Association of the western flower thrips (Frankliniella occidentalis) with cultivated sunflower (Helianthus annuus) in Israel

In 1992 and 1993, sunflower (Helianthus annuus L.) crops in Israel were heavily damaged by the western flower thrips (WFT),Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). Adult females appear in the heads of sunflower just as the latter begin to blossom; the population decreases towards completion of anthesis. The damage to kernels is greatest at the periphery of the heads, where flowers appear first, and lowest at the center. Fields sown early in the season (in March) are usually the ones infested most by WFT and suffering the greatest damage. Fields sown one month later are less infested, since predatory bugs of the genusOrius are very active at that time.     

Separation of two leafhopper populations of theCirculifer haematoceps complex on different host plants in Israel

TwoCirculifer leafhopper populations of thehaematoceps complex have been collected in large numbers in Israel for several years. One of these leafhoppers inhabited prickly saltwort (Salsola kali) plants on sandy soil on the Mediterranean coast. It has a narrow host range and was found to survive for one generation on turnip. The other leafhopper population was collected in 1986 on common goosefoot (Chenopodium album) plants in the Golan Heights. This population is polyphagous and in the laboratory reproduced well onMatthiola incana, turnip, sugar beet andChrysanthemum coronarium; however, reproduction was nil onPhaseolus vulgaris and very low onBrassica oleracea, Portulaca oleracea andCarthamus tinctorius. Contribution from the Agricultural Research Organization. No. 2502-E, 1988 series.     

Effect of Margosan-O on the development ofEarias insulana

The effect of Margosan-O, a formulation of a natural insecticide obtained from the neem tree (Azadirachta indica A. Juss), on the development of and the penetration rate of larvae of the spiny bollworm,Earias insulana (Boisd.), into cotton bolls was investigated by (i) incorporating Margosan-O into a semisynthetic diet and recording mortality until the adult stage; and (ii) spraying leaves and bolls with, or standing cotton seedlings or twigs of cotton with one boll per twig in aqueous dilutions of Margosan-O in an attempt to protect leaves or cotton bolls from feeding or penetration, respectively, by the larvae. Margosan-O was found to be effective when incorporated into the semisynthetic diet, even at low concentrations, especially when it was offered throughout the larval life span. Survival rate and average weight of the larvae were much lower on leaves treated with 0.5% or 0.2% Margosan-O, or exposed to its systemic effect at 0.5% or 0.25%, than on control leaves. Larval penetration into Margosan-O-sprayed bolls at concentrations of 0.01– 0.5% wasca 30–45% of that into control bolls. Margosan-O was active also as systemic treatment: onlyca 35% of the larvae penetrated the 0.25%-treated bolls compared with the untreated ones.