Evaluation of the developmental phases of two mulberry cultivars in the biological and productive performance of. the silkworm (Bombyx mori L.)

Abstract

Objective: To evaluate the performance of the silkworm when fed mulberry cultivars in different developmental phases. Material and Method: Developed at the Research and Development Unit of the Agência Paulista de Tecnologia dos Agronegócios da Secretaria de Abastecimento e Agricultura do Estado de São Paulo (APTAlSAA), Gália, Sp, Brazil, between 12/31/1997 and 05/06/1999. The experiment was started when Bombyx mori L. caterpillars in the 3'" instar, were fed two mulberry cultivars (1256/4 and Korin) in four vegetative phases of development (7, 10, 13 and 16 weeks); in the 5th instar, biological features and cocoon production were analyzed. Results: The analysis of each mulberry cultivar in the different developmental phases showed variations of the biological features caterpillar live weight (PV) and weight gain (GP) only. Among the productive features studied, only the cocoon shell weight (PCS) did vmy, when proceeding from caterpillars fed the Korin cultivar. When the two cultivars were compared in each developmental phase, variations were noted only for the biological features PV and chrysalis weight (PCr) and for the productive features cocoon weight (PC), PCS and number of cocoons formed (NC). Conclusions: When leaves of both mulberry cultivars in a developmental phase around 10 weeks were fed to the caterpillars in the 3'" and 4th instars, they presented good PV in the 5th instar. However, better GP was observed when they were fed leaves in a more advanced developmental phase (above 10 weeks). There was little influence of treatments on the net silk percentage (PSL) and of the developmental phase of the plant on the NC. In general, the Korin cultivar enabled better biological and productive performance of the silkworm.