Biological Control with Natural Enemies

An increase in pesticide-resistant pests (such as the prevalence of Q-biotype whiteflies), more stringent pesticide applicator regulations, and pressure from retailers is putting effective pest management at risk. The practice of purchasing bulk beneficial insects (predators and/or parasitic wasps) to manage pests is already common practice in Northeastern USA, Canada, Europe, and other parts of the world, but has yet to be adopted by growers in Texas. The reason for this lack of adoption in Texas may be due to several factors, such as many effective insecticide options still available, semi-open greenhouses with warm year-round temperatures resulting in constant pest pressure, and cost-effectiveness.

The purpose of this research objective is to determine cost-effective means of pest management that are effective in Texas. Our current research focuses mainly on poinsettias, since they are grown as a mono-crop with limited target pests (namely whiteflies) as a model system for developing biological control in Texas.

Part 1: Determining Starting Populations and Retailer Thresholds

Biological control can rarely result in 100% pest suppression; then again, the same applies to insecticidal control as well. The purpose of this objective was to determine the starting densities of whiteflies on poinsettias when growers receive them and the densities of whiteflies when they go to the retailer. In short, we found very few whiteflies at the start of the crop but reasonably high numbers at the retailer: 50% or higher plants, 4 – 40 immatures on average per poinsettia. The results of this objective have been published and are available here: