COS 75-1
Developmental synchrony, and recurrent insect outbreaks caused by temperature-driven changes in system stability

Wednesday, August 12, 2015: 8:00 AM
347, Baltimore Convention Center
Ottar N. Bjornstad, Entomology, Penn State University, University Park, PA
William A. Nelson, Biology, Queen's University, Kingston, ON, Canada
Takehiko Yamanaka, Institute for Agro-Environmental Sciences, NARO, Tsukuba, Ibaraki 305-8604, Japan

Insect species often undergo regular outbreaks in population density.  Identifying the causal mechanism for such outbreaks in a particular species has proven difficult. The tea tortrix Adoxophyes honmai exhibits exceptionally regular outbreak cycles on Japanese tea plantations caused by lock-step developmental synchrony of each generation. We apply time series analysis and parameterize a temperature-dependent stage-structured model for the system to understand the outbreak cycles.


Wavelet analysis of a 51 year long time series confirms that there is a threshold in outbreak amplitude each spring when temperature exceeds 15°C, and a secession of outbreaks each fall as temperature decreases. This is in close agreement with our independently parameterized mathematical model that predicts the system crosses a Hopf bifurcation from stability to sustained cycles as temperature increases. Our study is a unique illustration of how temperature may drive a plant-herbivore system to instability.