Montana codling moth trap-based biofix compared to two fixed biofix models, 2018-2020

Codling moth (Cydia pomonella) is the primary insect pest of apple and pear trees in Montana and can destroy an entire crop if uncontrolled. Understanding the moth's life cycle is important for determining management methods and timing of treatments. The purpose of this study was to compare trap-based biofix (first consistent moth capture in the spring) to two temperature based trap-free models for fixed biofix developed in other apple producing regions. Trap-free models determine a date for fixed biofix using temperature accumulation data (growing degree days) from nearby weather stations. Trap-free models compared in the present study were developed and are used in Washington state and Utah state; compared to Montana, Washington is similar latitude but lower elevation, and Utah is similar to higher elevation, but lower latitude. Results presented here suggest that the Washington state model for fixed biofix more closely aligns with Montana trap-based biofix in the 3 years of the study. Generally, trap-based biofix in Montana occured after the Washington state model fixed biofix growing degree date; we surmise that low evening temperatures and frequent high winds in some parts of the state and certain years could influence trap catch.苹果蠹蛾（Codling moth, Cydia pomonella）是美国蒙大拿州苹果与梨树的首要害虫，若未采取防控措施，可导致整片果园绝收。明晰该虫的生活周期，对于确定防控方案与施药时机至关重要。本研究旨在对比基于诱捕的始见日（trap-based biofix，即春季首次持续捕获到成虫的日期），与另外两种由其他苹果产区开发的无诱捕固定始见日温度模型。无诱捕模型通过整合邻近气象站的温度累积数据（生长度日，growing degree days, GDD）来计算固定始见日。本研究对比的两款模型均由美国华盛顿州与犹他州开发并应用。与蒙大拿州相比，华盛顿州纬度相近但海拔更低，犹他州则海拔更高、纬度更低。本研究为期三年，结果显示华盛顿州的固定始见日模型与蒙大拿州基于诱捕的始见日匹配度更高。总体而言，蒙大拿州的诱捕始见日晚于华盛顿州模型基于生长度日计算的固定始见日；我们推测，该州部分区域及部分年份的夜间低温与频繁强风，可能会对诱捕捕获效果产生影响。