Autoria: OLIVEIRA, L. J.; HOFFMANN-CAMPO, C. B.

Resumo: The gall-maker and stem borer, S. subsignatus, rose from a minor to an important pest as soybean fields expanded to new areas and cultivation systems changed. The chemical control of this pest is difficult due to its concealed habit in the pre- and post-embryonic stage. Therefore, other control alternatives are necessary, specially in large fields. Hence, sources of soybean resistance to S. subsignatus have been searched for at Embrapa Soybean, Londrina, Paraná State. Thirty genotypes were tested under greenhouse and field conditions in completely randomized no-choice and randomized block multiple-choice design experiments. Tests were performed during four seasons with different genotypes each year, as genotypes not showing resistance were replaced by others of interest. The susceptible control genotypes used in the 1999/00 and 2000/01 seasons were 'Embrapa 4' and 'BR-16'in 2001/02 and 2002/03. In 2002/03, besides greenhouse tests (no-choice and multiple-choice), a field-cage test was performed with artificial infestations of S. subsignatus adults. Genotypes were not significantly different from the control genotype at any season in no-choice test. In general, multiple-choice tests promoted a better discrimination between genotypes than no-choice tests. In the 1999/00 season, greenhouse multiple-choice test, BRQ 96-3065 and PI 227687 were less damaged by S. subsignatus than other tested genotypes. In the 2000/01 greenhouse multiple-choice test, PI 227687, BRQ-96-3065 and BR-95-1159 were less damaged than others, but only PI 227687 was significantly different (F=4,42; P<0,001) compared to the control ('Embrapa 4'). In 2001/02, the total damage (feeding marks + leaf cut + oviposition + dead plant) was lower in 'IAC-100', PI 171451, PI 227687 and 'IAC-24' than in 'BR-16'. In the 2002/03 season, greenhouse multiple-choice test, the most resistant genotypes were PI227687, BRQ 96-3065, KI-S 601 and Ocepar 17. In the field, during this season, PI227687, BRQ 96-3065 and CS 201 performed better in the presence of S. subsignatus. The results suggest that non-preference is one of the resistance mechanisms of soybean to S. subsignatus. Futhermore PI 227687 appears to be a source of potential resistance to be used by breeders in insect resistance programs. Other genotypes such as BRQ 95-3065 and PI 171451 also showed some potential, but to confirm this more studies are necessary.

Ano de publicação: 2004

Tipo de publicação: Resumo em anais e proceedings

Unidade: Embrapa Soja

Palavras-chave: Soja