Degree-day model for adult emergence of the red sunflower seed weevil

Wednesday, November 16, 2022

1:42 PM – 1:54 PM PT

Location: Vancouver Convention Centre, Meeting Room 110

Presenting Author(s)

JP

Jarrad R. Prasifka

Research Entomologist
USDA-ARS
Fargo, North Dakota

Co-Author(s)

Shawna Pantzke

Graduate Student
Rutgers, The State University of New Jersey
New Brunswick, New Jersey
Beth E. Ferguson

Postdoctoral Research Scientist
Rutgers, The State University of New Jersey
Berlin, New Jersey
Joseph P. Rinehart

Research Biologist
USDA-ARS
Fargo, North Dakota
Deirdre A. Prischmann

Professor
North Dakota State University
Fargo, North Dakota

The red sunflower seed weevil, Smicronyx fulvis LeConte, is a univoltine seed-feeding pest of cultivated sunflowers. Previous research suggests that peak populations of this pest can be avoided by planting early or early-maturing sunflower hybrids. However, no validated method to predict adult emergence has been available for this pest. Emergence of adult weevils under controlled temperatures in the laboratory allowed estimation of a lower developmental threshold and accumulated degree days for first adult emergence and 50% emergence. When the model was tested in field plots, weevils generally emerged earlier than predicted, likely because measured soil temperatures (in a state-wide weather network) are slightly cooler than what many overwintering weevils experience. This first degree-day model for S. fulvus could be improved with additional emergence (validation) data, but also by using ambient temperatures, which are more accessible than soil temperature data.