|Cooper, William - Rodney
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/6/2012
Publication Date: 2/6/2013
Citation: Cooper, W.R., Spurgeon, D.W. 2013. Temperature-dependent egg development of Lygus hesperus (Hemiptera: Miridae). Journal of Economic Entomology. 106(1):124-130.
Interpretive Summary: The western tarnished plant bug, Lygus hesperus, is a major pest of fruits, vegetables, forages, and cotton in the western United States, but certain aspects of its temperature-dependent biology are poorly understood. Researchers at the USDA-ARS Western Integrated Cropping Sysstems Research Unit in Shafter, CA developed accurate models describing the effects of temperature on western tarnished plant bug development. Studies of temperature-dependent development of plant bug eggs showed that eggs developed faster as temperatures increased from 50 to 90 degrees F, but development slowed with further increases in temperature. They also showed that egg development rates are influenced by the egg’s host substrate. This study provides accurate models for temperature-dependent development of western tarnished plant bug eggs and supplements development rate models recently reported for the development of immature plant bugs and adult reproductive organs. Collectively, these models will be useful to researchers investigating seasonal plant bug population dynamics and overwintering ecology, and provide temperature thresholds for calculating degree-days which allow growers to time management decisions with specific stages of insect development.
Technical Abstract: Lygus hesperus Knight (Hemiptera: Miridae) is a key agricultural pest in the western United States, but certain aspects of its temperature-dependent development are poorly defined. Accurate models describing the relationships between temperature and development of L. hesperus would facilitate the study of Lygus seasonal population dynamics and overwintering ecology. We used non-linear biophysical models to describe the development of L. hesperus eggs oviposited in green bean pods and semitransparent agarose and held under constant temperatures from 10 to 37.8 degrees C. The agarose substrate was used because it is less susceptible than green beans to deterioration at low and high temperature extremes, and because it allowed the observation of phases of embryonic development that are hidden from view from eggs developing in plant material. The models indicated that both low- and high- temperature inhibited development of each observed embryonic phase regardless of oviposition substrate. Development rates asymptotically approached zero with decreasing temperature in the lower thermal range, and decreased with increasing temperatures above 32.2 degrees C. Eggs oviposited in agarose developed slower than eggs oviposited in green bean pods suggesting that egg development rates were influenced by the type of host-substrate. Our temperature-dependent development rate models for L. hesperus eggs supplement non-linear models recently reported for L. hesperus nymphal and adult reproductive development, and should be useful in planning and interpreting field studies of L. hesperus population dynamics and overwintering ecology.