Dispersal of Bacillus thuringiensis var. kurstaki in an experimental cabbage field

TY - JOUR

T1 - Dispersal of Bacillus thuringiensis var. kurstaki in an experimental cabbage field

AU - Pedersen, J. C.

AU - Damgaard, P. H.

AU - Eilenberg, J.

AU - Hansen, B. M.

PY - 1995/1/1

Y1 - 1995/1/1

N2 - The field population dynamics of Bacillus thuringiensis var. kurstaki DMU67R isolated from cabbage leaves was investigated. Two experimental cabbage plots were spray inoculated with a suspension of sporulated bacteria containing 6.5 x 107 colony-forming units (cfu)/mL DMU67R or with a sterile medium control. To study transport between phyllosphere and soil, plastic covering was used during spraying to ensure that DMU67R was applied only on leaves (8.5 x 106 cfu/g) or on soil (1.2 x 104 cfu/g). Numbers of DMU67R declined five log units during the first 4 weeks after spraying of leaves: the initial half-life (1st week) was 16 h. In topsoil, however, a long-term persistency was demonstrated with a half-life exceeding 100 days. Dispersal by rain splash from topsoil to lower leaves of cabbage was demonstrated. After 1 year, analysis of the top 15 cm of soil showed that 77% of DMU67R remained in the 0- to 2-cm topsoil layer. When DMU67R was applied on leaves, larvae of Pieris brassicae were killed within 7 days after spraying. Germination of DMU67R was demonstrated in dead P. brassicae larvae but not in any leaf or soil sample. Pitfall sampling demonstrated dispersal of DMU67R by means of carabid beetles (up to 135 m) and other surface-active insects carrying 102-103 cfu/g wet mass.

AB - The field population dynamics of Bacillus thuringiensis var. kurstaki DMU67R isolated from cabbage leaves was investigated. Two experimental cabbage plots were spray inoculated with a suspension of sporulated bacteria containing 6.5 x 107 colony-forming units (cfu)/mL DMU67R or with a sterile medium control. To study transport between phyllosphere and soil, plastic covering was used during spraying to ensure that DMU67R was applied only on leaves (8.5 x 106 cfu/g) or on soil (1.2 x 104 cfu/g). Numbers of DMU67R declined five log units during the first 4 weeks after spraying of leaves: the initial half-life (1st week) was 16 h. In topsoil, however, a long-term persistency was demonstrated with a half-life exceeding 100 days. Dispersal by rain splash from topsoil to lower leaves of cabbage was demonstrated. After 1 year, analysis of the top 15 cm of soil showed that 77% of DMU67R remained in the 0- to 2-cm topsoil layer. When DMU67R was applied on leaves, larvae of Pieris brassicae were killed within 7 days after spraying. Germination of DMU67R was demonstrated in dead P. brassicae larvae but not in any leaf or soil sample. Pitfall sampling demonstrated dispersal of DMU67R by means of carabid beetles (up to 135 m) and other surface-active insects carrying 102-103 cfu/g wet mass.

KW - Bacillus thuringiensis

KW - cabbage

KW - dispersal

KW - Pieris brassicae

KW - population dynamics

KW - soil

UR - http://www.scopus.com/inward/record.url?scp=0028939769&partnerID=8YFLogxK

U2 - 10.1139/m95-016

DO - 10.1139/m95-016

M3 - Journal article

AN - SCOPUS:0028939769

SN - 0008-4166

VL - 41

SP - 118

EP - 125

JO - Canadian Journal of Microbiology

JF - Canadian Journal of Microbiology

IS - 2

ER -