Elm leaf beetle control using the biological insecticide, Novodor (Bacillus thuringiensis subsp. tenebrionis) [Pyrrhalta luteola]. [Symposium paper]
1994
Wells, A.J. (Nufarm Ltd, Laverton North (Australia)) | Kwong, R.M. (Victorian Dept. of Conservation and Natural Resources, Frankston (Australia). Biological Control Unit) | Field, R. (Museum of Victoria, Melbourne (Australia))
The efficacy of Bacillus thuringiensis subsp. tenebrionis (Novodor, Btt) against first and third instars of elm leaf beetle, Pyrrhalta luteola (Muller) was studied in the laboratory on elm leaves, on potted elm trees in the field, and a mixed population on established elm trees in the field. Dose response curves from laboratory bioassays indicated first and third instar mortality increased with increasing rate. A minimum 10-fold increase in the rate was required to give equivalent control of elm leaf beetle third instar to that of elm beetle first instar-0.03 percent Btt to 0.3 percent Btt for 95-100 percent control. Potted elm tree trials confirmed these rates for first and third instar larvae. The mean percent reduction of a mixed elm beetle population in the field was 56.5 percent for 0.3 percent Btt and 67.2 percent for 0.6 percent Btt. These lower levels of control reflected a 14 day delay in application and possibly less than adequate spray coverage.
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