|CRAMER, MARIA - Pennsylvania State University|
|DEMCHAK, KATHY - Pennsylvania State University|
|MARINI, RICH - Pennsylvania State University|
Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2019
Publication Date: 5/1/2019
Citation: Cramer, M.E., Demchak, K., Marini, R., Leskey, T.C. 2019. UV-blocking high-tunnel plastics reduce Japanese beetle (Popillia japonica) in red raspberry. HortScience. 54(5):903-909. https://doi.org/10.21273/HORTSCI13820-18.
Interpretive Summary: Japanese beetle can be a significant pest of raspberries with most growers spraying insecticides for their management. Here, we evaluated how high tunnel structures that utilize ultraviolet (UV)-blocking plastics may affect Japanese beetle abundance and damage, as many insects are responsive to UV light. A range of UV-blocking plastics were evaluated in 2016 and 2017. We found that plastic that blocked >90% of the UV range usually had significantly lower beetle populations than the plastics that blocked the least UV. Overall, it appears that using a UV-blocking plastic can reduce Japanese beetle abundance and feeding damage on raspberries. This approach could benefit growers by reducing the cost of insecticides and decreasing exposure risk for non-target organisms.
Technical Abstract: Insecticides are the primary tool raspberry growers use to control Japanese beetle (Popillia japonica), but reliance on pesticides is costly, and there are risks to non-target species. Based on observations that Japanese beetle was less abundant on raspberries in high tunnels than in fields, we investigated the effects of plastics that transmit different amounts of ultraviolet (UV) light on Japanese beetles. Many insects are sensitive to light in the UV-A range and use it for navigation. High tunnel plastics that block varying percentages of UV radiation are increasingly available. We grew two primocane-fruiting red raspberry cultivars, ‘Polka’ and ‘Josephine’, in tunnels with six different covering treatments. Five were plastics which blocked the UV range to varying degrees, and one was a no-plastic treatment. In 2016, beetles were counted and removed from the plants by hand daily. In 2017, beetles were removed by hand every four to five days. Foliage temperature was measured in each tunnel twice in 2017 with an infrared thermometer. Spectral transmittance characteristics of the plastics were measured with a spectroradiometer in 2015 or 2016, and 2018. Mean beetle counts by date and for the whole season were compared for the plastics and cultivars. Japanese beetle numbers were significantly higher in the no-cover treatment than under all-plastic treatments. The plastic that blocked >90% of the UV range usually had significantly lower beetle populations than the plastics that blocked the least UV. Overall, it appears that using a UV-blocking plastic can reduce Japanese beetle aggregation and feeding damage on raspberries, and reduce the need for other control. This could benefit growers by reducing the cost of insecticides and decreasing exposure risk for non-target organisms.