Student Poster Display
Plant-Insect Ecosystems
Student
Student Competition
Natasha May Weppler
PhD Candidate
University of Guelph
Harriston, Ontario, Canada
Jocelyn L. Smith
Assistant Professor
University of Guelph
Ridgetown, Ontario, Canada
Julie Ann Peterson
Professor
University of Nebraska
North Platte, Nebraska
Yasmine Farhan
Research Associate
University of Guelph
Ridgetown, Ontario, Canada
Alisson Da Silva
University of Nebraska
North Platte, Nebraska
Western bean cutworm, Striacosta albicosta (Smith; Lepidoptera: Noctuidae), poses a significant threat to corn (Zea mays) and dry beans (Phaseolus vulgaris) in North America. The use of integrated refuges can allow for sub-lethal exposure of the highly mobile S. albicosta larvae to the sole effective Bacillus thuringiensis (Bt) protein, Vip3A, transformed into corn hybrids (Bt corn). This sub-lethal exposure is a key mechanism in driving resistance. S. albicosta larvae exhibit three distinct movement phases as they develop on corn plants: 1) 1st instars move from egg to tassel, 2) 2-3rd instars move from tassel to ear, and 3) 4-6th instars move from ear to ear and plant to plant. Field experiments were conducted in 2022-2024 to determine instar-specific movement in integrated versus structured refuge configurations. Protein-marked larvae were released at the central corn plant in plots 6 x 9 m in size for each movement phase. Destructive sampling was conducted after 14 and 19 days for the second and third movement periods, respectively, to determine the survival and distance that larvae moved in different refuge configurations. In 2022, 28% of larvae were recovered from non-Vip3A plots, traveling an average of 21.5 and 84.0 cm during the second and third movement phases, respectively. For the 2023 and 2024 experiments, destructive sampling was conducted 48 h after release to increase the resolution of the experiment. Results from 2023 suggest structured refuges reduce sub-lethal exposure compared to integrated refuges which may reduce the risk of Vip3A resistance evolution in S. albicosta.