Pruning enhances field releases of Pseudophilothrips ichini (Hood) (Thysanoptera: Phlaeothripidae), a biological control agent of Brazilian peppertree in Florida

Brazilian peppertree (Schinus terebinthifolia) is one of the most widespread upland invasive plants in Florida. Chemical and mechanical controls are time consuming, expensive, and require frequent reapplications. Previous research indicated that thrips feeding under greenhouse conditions reduced Brazilian pepper seedling growth by 80%.  This biological control agent will provide land managers with a cost-effective means of controlling Brazilian pepper by reducing the current and expensive reliance on herbicidal control. Releases of the biological control agent Pseudophilothrips ichini began in 2019. This biological control agent feeds and reproduces on the young, tender leaf flushes that are more prevalent during the rainy season. This can be problematic for maintaining productive field nurseries and releasing agents during portions of the year when there are fewer flushing tips. Techniques were developed to promote populations of biological control agents by pruning existing Brazilian pepper plants and monitoring the incidence of flushing tips prior to biocontrol agent releases made at four sites in Florida. Pruned Brazilian pepper plants had increased incidence and duration of flush tips. In two of the four sites, pruned plants produced more flush tips during the dry season, ameliorating the seasonal absence of flushing tips. Both leaf nitrogen and moisture content increased in flush tips. Thrips choice tests showed significantly more thrips on the flush tips and these had a 4-fold increase in F₁ production. This method should assist in developing field nurseries for local production and redistribution of thrips.