MAPPING NANTUCKET PINE TIP MOTH (LEPIDOPTERA: TORTRICIDAE) PHENOLOGY IN GEORGIA

Abstract

Thermal requirements for the Nantucket pine tip moth (NPTM), Rhyacionia frustrana (Comstock), to complete one generation were estimated using published data and new observations representing six unique combinations of location and year. Estimates ranged from 690 degree-days (DD) to 818 DD using a lower threshold of 9.5° C and an upper threshold of 33.5° C. Selected values within the range of estimates were used along with historical temperature data to produce maps of NPTM phenology in Georgia. The map based on the midpoint of the range of estimates (754 DD) was most closely compatible with previous observations of NPTM phenology and major physiographic boundaries. With an estimated mean thermal requirement of 754 DD, the NPTM will complete two to four generations per year in Georgia. This study demonstrates a technique that could be applied to map the phenology of any multivoltine insect for which data on thermal requirements for development are available.