Publication Type

Journal Article

Journal Name

Phytoparasitica

Publication Date

1-1-2001

Abstract

Eight new Bacillus thuringiensis Berliner (Bt) isolates originally recovered from different source materials and geographic locations in Kenya were tested against Chilo partellus (Swinhoe) on sorghum grown in a greenhouse. All isolates had been demonstrated previously to be toxic to this pest. Bt strains were cultured in a liquid growth medium and preserved as powders for experimental application. Three-week-old sorghum plants (4-6 leaves) were artificially infested with 20 neonate C. partellus and sprayed 24 h later with Bt suspensions. Non-infested sorghum and infested non-treated sorghum served as the comparative checks within each experimental trial. Plant development and dead-heart formation were monitored up to harvest; at harvest, grain yield was recorded. In each replicate trial, all of the Bt strains tested reduced plant damage consistently, compared with the infested, non-treated checks. Dead-heart formation was significantly reduced and grain yields were significantly higher. Three novel isolates, A-3, A-C-2 and M44-2, provided superior levels of protection throughout. Statistically, there was no difference among these three Bt treatments and the non-infested check in terms of the number of dead-hearts (i.e., non-yielding plants) that formed during the course of the experiment. In the infested, non-treated check plots, dead-hearts developed in 74.5±10.0% of the plants, compared with only 3.1±1.2% of the non-infested plants, and 3.1±1.5%, 6.2±2.0% and 6.2±2.0% of the plants treated with M44-2, A-3 and A-C-2, respectively. At harvest, the weight of grain obtained from the non-infested control plots was considered to be 100% of the potential yield for each experimental replicate. In the infested, non-treated controls, only 14±5.6% of the potential yield was realized. When isolates M44-2, A-3 and A-C-2 were applied, proportionate yields of 83±5.4%, 93±2.3% and 98±1.2%, respectively, were obtained. Results showed that the Bt strains selected may have a strategic role to play in the management of C. partellus, providing applications are timed to target young larvae feeding in the leaf whorl.

Keywords

Bacillus thuringiensis, Biological control, Bt, Chilo partellus, Control on sorghum, New isolates

Download

Share

COinS