Polyethylene tarping elevates temperature and reduces emergence of <i>Phloeosinus punctatus</i> LeConte (Coleoptera: Curculionidae) from giant sequoia debris piles

Abstract The western cedar bark beetle ( Phloeosinus punctatus LeConte) colonizes giant sequoia ( Sequoiadendron giganteum (Lindl.) J. Buchh.) branches and may build up large populations in broken or shed branches and woody debris, necessitating a possible need for intervention strategies. This study evaluates tarping treatments for managing P. punctatus populations in recently fallen branches in giant sequoia forests. A field experiment tested beetle emergence from debris piles relative to tarping treatments (covered or uncovered by a 4 mm clear polyethylene tarp) using a paired design, and the effects of several environmental factors on emergence were modelled. Tarping treatment resulted in a 53% reduction in mean beetle emergence; standardized beetle emergence was 9.8 ± 2.6 beetles/kg in the treatment group, 19.2 ± 5.6 beetles/kg in the control group and an average of 14.5 for the study. Mean temperatures were 21.8°C in tarped piles, compared to 19.7°C in control piles, indicating that tarping altered the thermal environment to impact emergence. No emergence occurred when the mean ambient temperature exceeded 24°C. Canopy openness also affected mean temperature in debris piles, with temperatures increasing sharply under more open canopy conditions. These results suggest that tarping is a simple and cost‐effective treatment for reducing P. punctatus populations in giant sequoia debris and may be a useful tool in integrated pest management strategies targeting this species.