TrackTrap: An R-based computational tool for modeling pest phenology with automated weather integration

Understanding pest phenology is fundamental to integrated pest management (IPM), as constant pest monitoring provides timely information needed for informed management decisions throughout the growing season. Conventional tools and techniques for pest phenology modeling rely on routine trap monitoring to identify the reference event (biofix) and on growing degree days (GDD) to track subsequent developmental progress since the biofix. Manual compilation, cleaning, and processing of weather data from multiple sources can be time-consuming, error-prone tasks that can further delay the development and application of phenology models. Several resources on CRAN (Comprehensive R Archive Network) provide only partial support for pest monitoring workflows, with limited integration of raw trap data processing, automated weather retrieval, GDD calculation, and pest phenology visualization within a single package. In this paper, we present TrackTrap, an open-source R package that automates this workflow by using two meteorological Application Programming Interfaces (APIs), namely Daymet and Open-Meteo, to retrieve location-specific weather information for a user-specified date. As an alternative, users may instead provide weather data manually as a CSV file downloaded from the California Irrigation Management Information System (CIMIS). Following the user’s inputs, TrackTrap then processes JSON responses from Open-Meteo, weather data retrieved via the daymetr package for Daymet, or CSV data manually downloaded from the CIMIS website. Using pest-specific developmental thresholds stored in the package’s built-in database or user-supplied values, TrackTrap computes cumulative GDD using the simple-average method with a horizontal upper-temperature cutoff when specified or without an upper cutoff when explicitly selected. TrackTrap provides researchers and pest control advisors (PCAs) with an automated, reproducible script to compute degree-days beginning the day after biofix and visualize trap catches against accumulated degree days. The software and resources for accessing TrackTrap are freely available in the Zenodo and GitHub repositories.