Transmission of Salmonid Whirling Disease by Birds Fed Trout Infected with Myxosoma cerebralis

SYNOPSIS. Mallard ducks, Anas platyrhynchos and a black crested night heron, Nycticorax nycticorax were fed trout infected with Myxosoma cerebralis (Hofer) in 2 separate experiments. Feces from the birds were deposited in troughs containing M. cerebralis -free mud as well as in 1 trough without mud. Spore suspensions were also added directly to mud in 1 trough and to another trough without mud. Susceptible rainbow trout, Salmo gairdneri , developed whirling disease in all troughs containing mud contaminated with M. cerebralis but remained free of infection when exposed to M. cerebralis in troughs without mud. This demonstrates the possibility of bird transmission of the organism causing whirling disease to previously non-contaminated waters.     

Biochemical tests for identification of mycelial cultures of basidiomycetes

Twenty-four biochemical tests have been developed to identify basidiomycetes from mycelial cultures. Eleven are designated ‘instant tests’ because results are obtained within 24 h; ten of these test for specific enzymes, the other is based on a reaction between vanillin and unknown fungal metabolites. The remaining thirteen tests require incubation periods ranging from 1 to 4 days and are thus designated ‘incubated tests’. Sixteen of these tests were applied first to identified isolates of Peniophora sacrata, Sclerotium rolfsii, Stereum purpureum and Trametes versicolor. They distinguished these species satisfactorily, so these sixteen tests, and eight others devised subsequently, were applied to unidentified basidiomycetes isolated from diseased roots of fruit crops. The results of these tests enabled the isolates to be placed in seven groups. All isolates in a particular group were morphologically similar which further suggested that each group might correspond to a species and that isolates could be defined on the basis of biochemical tests.     

Development and characterization of six new microsatellite markers for the silver‐ or gold‐lipped pearl oyster,Pinctada maxima (Pteriidae)

Six di‐, tri‐ and tetranucleotide microsatellite loci were developed for the silver‐ or gold‐lipped pearl oyster Pinctada maxima using a linker‐ligated, magnetic bead enrichment protocol. Based on a minimum of 134 Indonesian pearl oyster samples, number of alleles and observed heterozygosity at each locus ranged from six to 17 alleles and from 0.172 to 0.813 (mean = 0.448), respectively. Mean polymorphic information content for the six loci was 0.562. These loci should be very useful in DNA parentage analyses and population differentiation of P. maxima in Australia and Indonesia.     

Sampling for aphids by traps and by crop inspection

The catches of thirty aphid genera and species during 3 years in a suction trap at 40 ft and on a yellow cylindrical sticky trap at 5 ft at Rothamsted and Broom's Barn are tabulated. Suction-trap catches were the more consistent but both were more effective at recording the first seasonal immigration of Myzuspersicae (Sulz.) and Aphis fabae Scop, than the British Sugar Corporation crop-inspection scheme. The catches show the differential attraction to yellow by different species, the effects of local vegetation, and the seasonal distribution of aphids that are crop pests or potential vectors of viruses.     

The use of egg counts and suction trap samples to forecast the infestation of spring-sown field beans, Vicia faba, by the black bean aphid, Aphis fabae

Daily suction trap samples at a height of 12·2 m collected throughout the year, winter egg and ‘spring’ population counts on the spindle tree, Euonymus europaeus, and initial infestations of the black bean aphid, Aphis fabae, on field bean, Vicia faba, crops are available from Southern England since 1970. In different areas, estimates of the sizes of the autumn migrations, the over-wintering egg populations, the spring fundatrigeniae and the spring migrations, have been used to forecast field bean crop infestation levels which, in turn, project subsequent trap catches of alatae. The forecasts of crop infestation become progressively more accurate from the autumn migration to the following spring migration, accounting for 28%, 54%, 54% and 64% of the variance respectively. In areas where traps are sited, the spring migration trap samples give the most accurate estimate of the size and timing of crop infestation. Autumn trap catches are particularly useful as very early forecasts of likely very large or very small populations on field beans about 8 months later, but otherwise they lack precision. Egg sampling in winter provides a considerably more accurate forecast approximately 5 months before crop infestations. In spring (May), fundatrigeniae sampled on spindle are most useful for predicting time of migration, and provide approximately 2 weeks' warning for insecticide application, if needed. Finally, trap sampling of the spring migration provides the latest estimate of both the sizes of crop infestations and the timing of insecticide treatment. The E. europaeus and aerial sampling systems are complementary, the traps providing systematic, continuous information and the E. europaeus samples greater detail. Combined, they can provide excellent long-term fore-warning of the need for chemical control and short-term warning of control timing. Forecasts have been 90% correct in eight years out of nine. The error in the ninth year may be due to immigration from the European mainland.