Integrating Kaolin into Ambrosia Beetle (Coleoptera: Curculionidae: Scolytinae) Pest Management in Ornamental Tree Nurseries

Invasive ambrosia beetles (Coleoptera: Curculionidae) are an expensive problem for ornamental tree production.  Available chemical measures are not completely effective, and due to the length of the beetle dispersal period and product breakdown, repeated treatments can become costly in terms of application expense and non-target impacts.  Additional options are needed to reduce application frequency and to provide an acceptable level of protection.  Applications of kaolin, alone and in combination with bifenthrin, were sprayed onto baited trees at research sites in Mississippi and Tennessee in 2014-15, and the number of new ambrosia beetle galleries were compared over time with negative (untreated) and positive (bifenthrin-treated) control trees.  While kaolin trees were better-protected than untreated trees during the first observation period, they rapidly lost their coating after rain events and subsequently there was no significant difference from untreated controls.  Kaolin + bifenthrin trees retained their coating longer, but were not significantly different from bifenthrin trees.  When combined with an insecticide containing a surfactant, kaolin applications can contribute an additional deterrence to ambrosia beetles, but the effect is not synergistic.  Further research is needed on the variety of other positive impacts kaolin applications may provide to ornamental tree production.