[Influence of mulberry cultivars Morus spp. on the production and quality of silkworm Bombyx mori L. (Lepidoptera: Bombycidae) cocoons].

The success of sericiculture greatly depends on the availability of mulberry cultivars with agronomic characteristics that maximize the production and quality of silkworm, Bombyx mori L., cocoons. The effect of the cultivars Miura (standard) and Korin, and the hybrids SM 14, SM 63, SK 1, SK 4 and FM 86 was evaluated on silkworm development, and on cocoon production and quality, at the Instituto Agronômico do Paraná, IAPAR, in Londrina, PR, Brazil (23 +/- 3 degrees C; 61 +/- 8% RH). The experiment was arranged in a randomized block design with four replicates. Larvae feeding either on 'SK 4' or on 'Korin' showed a higher weight compared to that of larvae feeding on 'Miura'. Cocoon weight (both sexes) and pupae weight (male) obtained with larvae fed on SK 4 were higher compared with that of insects that fed on Miura; there was no difference among the remaining treatments. Silk net weight was independent of the cultivar used. Cocoon shell weight was similar amongst insects raised on 'Miura' and on the other mulberry materials. The percentage of cocoon spinning was higher than 90% in all treatments, with the spinning concentrating in the first two days. The proportion of first grade cocoons varied from 80% (SK4) to 90%. The results obtained with the studied cultivars were either similar or superior to that of the standard cultivar Miura with emphasis to 'SK 4', thus showing the potential use of these cultivars in sericulture in the state of Paraná.