An integrated pest management approach for chilli thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) on roses under field conditions

Chilli thrips, Scirtothrips dorsalis, is an invasive pest, which affect several vegetables, fruits, and ornamentals. The nursery industry that produces Knock Out roses, which is the most widely sold rose in North America, is significant affected by this adventive insect.  We developed an integrated pest management protocol against chilli thrips, which includes monitoring, bio-rational insecticides, and cultural control.  For monitoring, an injury index (visual damage caused by chilli thrips) was highly correlated with the estimated size of chilli thrips populations on roses.  The efficacy of various bio-rational insecticides applied alone was 72%, 55%, 67%, and 58% for the entomopathogenic fungi Metarhizium brunneum and Beauveria bassiana, a botanical insecticide (azadirachtin), and horticultural oil, respectively.   The efficacy of bio-rational insecticides in a rotation program ranged between 52 ± 5.7% and 70 ± 4.2%. A rotation program between spinosad and bio-rational insecticides suppressed the chilli thrips population by 82-95% in comparison to the control. These results suggest that it is possible to reduce by 50% standard insecticide applications yet still maintaining low populations of the chilli thrips. Pruning as a cultural practice significantly reduced but did not eliminate an established chilli thrips infestation without insecticide sprays. An integrated pest management including monitoring, use of eco-friendly insecticides in a rotation program with spinosad, and pruning may regulate populations of chilli thrips below economic thresholds on roses in both nursery industry and landscape.