The Oak Ambrosia Beetle (Monarthrum dentiger) is an important pest on pine and spruce trees. Overwintered Oak Ambrosia Beetle larvae typically emerge in spring, before pupation. After adults emerge, they can be targeted by traps or insecticide treatments. The Oak Ambrosia Growing Degree Day Model, developed by researchers at Oregon State University, and available on the Pest Prophet app, is a tool growers can use to predict adult emergence.

Initiating the Biofix

To properly use the model, the biofix must first be set. This is the date that will serve as the starting point for growing degree day accumulation. For this type of model January 1st is the standard biofix to start accumulation (for the Northern Hemisphere). This can be used to predict when adults will emerge and pheromone traps can be used.

After adults are observed and confirmed, the biofix can be adjusted in order to improve accuracy of the model for predicting later life stages.

Growing Degree Day Accumulation and Treatment

After the biofix is set, growing degree day accumulation can begin, using a lower threshold of 52F and an upper threshold of 100F. This can be done using daily high and low temperatures, or using hourly temperature data using the Pest Prophet app. Pupation occurs at approximately 423 GDD(F). Adults typically emerge at 815 GDD (F) after the Jan. 1st biofix. These adults can be targeted for traps or insecticide treatments. The model can also be used to predict emergence of the next generation.

Source:

Sone, K, T. Mori, and M. Ide. 1998. Life history of the oak borer, Platypus quercivorus (Murayama). Appl. Entomol. Zool. 33:67-75.