Minimizing the impact of invasive Coptotermes sp. (Heterotermitidae) on urban tree canopies using a recurrent inspection-elimination program.

Abstract

Invasive subterranean termite species within the genus Coptotermes (Heterotermitidae) are important structural pests. However, they also cause extensive damage in live trees and pose serious risks to tree health as a result. The urban tree canopy in areas with established populations of Coptotermes are therefore at risk of loss of trees over time, and many urban forests within municipality parks in their introduced range may experience tangible canopy alteration. This can have wide-reaching negative impacts on the ecology of these parks and to the public that utilize them. This 5-yr long study utilized eight parks (1,304 trees) to demonstrate how a simple visual monitoring/bait approach can identify and eliminate termite colonies infesting trees and maintain minimal termite activity within public green spaces. Here, we demonstrate that the systematic direct application of an experimental above-ground chitin synthesis inhibitor (CSI) bait formulation to trees can eliminate termite activity and protect trees. However, owing to high termite pressure, colony reinfestation is likely over time, and municipalities may have to establish perennial programs that would include regular monitoring and treatment as needed. Such a long-term strategy would minimize tree loss, while using a termite-specific formulated pesticide with a low amount of active ingredient. This pilot study demonstrates that it can be achieved, but ultimately, the success of this approach relies on technically competent staff that can readily identify the signs of active Coptotermes infestation in trees and access to above ground CSI bait formulations.