Tomato Pinworm (Keiferia lycopersicella) is an important pest on tomatoes in California and other regions. Overwintered Tomato Pinworm larvae typically emerge in late winter/ early spring and the first adults may be seen soon after. There can be 7-8 generations in a year, depending on the weather. Insecticide treatments targeting 1st or 2nd generation larvae, or pheromone mating disruption targeting adults are typically the best way to control Tomato Pinworm populations for the entire growing season. Researchers have developed the Tomato Pinworm Growing Degree Day Model, available on the Pest Prophet app.  It is a tool growers can use to predict occurrence of different life cycles based on adult trap catches and field-specific 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 Tomato Pinworm, this biofix is the first date of consistent, sustained adult moth catches using pheromone traps in the field. Traps should be placed in early spring, or late winter, and checked on a regular basis. Once adult moths have been trapped for a few weeks in a row, the date of the first catch should be used as the biofix.

Growing Degree Day Accumulation and Treatment

After the biofix is set, growing degree day accumulation can begin, using a lower threshold of 10.2C and an upper threshold of 35C. This can be done using daily high and low temperatures, or using hourly temperature data using the Pest Prophet app. The first egg hatch and larval stage will peak at approximately 92 GDD (C) after adult moth catch. Pupation occurs at approximately 322 GDD (C) after biofix, with adults emerging at approximately 455 GDD(C). These predictions can be used to time insecticide treatments or pheromone mating disruption applications.

For best results in second generation of Tomato Pinworm in a given season, the biofix should be reset when new pheromone traps have successfully capture adult moths in late spring/ early summer.

Source:

Lin, S. Y. H., and J. T. Trumble. 1985. Influence of temperature and tomato maturity on development and survival of Keiferia lycopersicella (Lepidoptera: Gelechiidae). Environ. Entomol. 14: 855-858.