Control of Tomato Hornworms on Tobacco with Microbial Insecticides and An Insect Growth Regulator, 1986

Abstract

Abstract Two microbial insecticides and an insect growth regular were evaluated in the laboratory and field for control of tomato hornworms on tobacco at the Research Station, Agriculture Canada, Delhi, On. Tobacco seedlings were transplanted on 26 May. Plots, 20.0 × 3.5 ft, were arranged in a randomized block design with 2 replications. Each plot was a single row of 10 plants. Materials were applied to the upper and lower surfaces of tobacco leaves using a Knapsack sprayer with an adjustable nozzle at a rate of 40 gal/acre on 14 Aug. Test insects were 3rd- and 4th-instar larvae of the tomato hornworm collected from tobacco plants in an unsprayed field. In the laboratory tests, the larvae, 10 for each replicate, were placed individually in 24-oz wide-mouth jars. Two hours after application of the insecticides, random samples of tobacco leaves were collected from each plant, taken to the laboratory, and placed in the jars with the larvae. In field tests, the larvae were placed on the treated tobacco plants in the test plots at the rate of 1 larva/plant about 3 h after treatment. In evaluating the effectiveness of the treatments, larval mortalities were assessed daily for 12 days for the laboratory tests and 4 days for the field tests. Larvae that remained on the leaves and showed any reaction when gently touched were considered alive. Abbotts formula was used to correct for the mortality occurring in the check. Before analysis of variance, data were transformed into angular units, and Duncan’s multiple range test was used to separate treatment means. Means were converted to original units for tabulation.