The American Serpentine Leafminer (Liriomyza trifolii) is an important pest on a wide variety of hosts, but is most economically important on celery and chrysanthemums. Overwintered American Serpentine Leafminer pupae typically emerge as adults in spring. Depending on weather and location, there may be many generations in a season. There are two American Serpentine Leafminer Growing Degree Day Models, one with celery as a host crop and one with chrysanthemums. These models, developed by researchers, and available on the Pest Prophet app, are tools growers can use to predict next generation pupae and adults emergence after adults have been observed, based on temperature data.

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 the biofix date should be set when first adults are observed in the field, and should be re-set to predict to following generations.

Growing Degree Day Accumulation and Treatment

After the biofix is set, growing degree day accumulation can begin, using a lower threshold of 9.7C  and an upper threshold of 35C for the Celery model, and a lower threshold only of 10.6C for the Chrysanthemums model. Calculating growing degree days can be done using daily high and low temperatures, or using hourly temperature data using the Pest Prophet app. Pupation occurs at approximately 175 GDD (C) after biofix date, and adult emergence at  314 GDD (C) for the Celery model. Pupation occurs at approximately 140 GDD (C) after biofix date, and adult emergence at  282 GDD (C) for the Celery model.

Source:

Leibee, G. L. 1984. Influence of temperature on development and fecundity of Liriomyza trifolii (Burgess) (Diptera: Agromyzidae) on celery. Environ. Entomol. 13: 497-501.

Miller, G. W., and M. B. Isger. 1985. Effects of temperature on the development of Liriomyza trifolii (Burgess) (Diptera: Agromyzidae). Bull. Ent. Res. 75: 321-328.