Effect of narrow-banded blue LED device on host plant settlement by greenhouse whitefly and currant-lettuce aphid

Abstract

Manipulating phytophagous insects with light-based repelling techniques has shown its potential to be a useful tool in integrated pest management systems in the future. Underlying optical mechanisms can be applied in field and in protected cultivation, with reflecting materials or emitting light sources, such as LEDs. Many pest insects are characterised by their cryptic lifestyle to avoid intervening pest protection measurements. In addition, there is a high degree of resistance mechanisms against insecticides in certain species. The idea of most light-repelling techniques is to reduce the immigration and the settlement of pest species on hostplants before population growth even starts. We conducted experiments with narrow-banded blue LEDs arranged around the plants and emitting radiation towards the sky. For compact rosette Lactuca sativa and upright-branched Euphorbia pulcherrima, we tested the suitability of the measure on settlement of Trialeurodes vaporariorum in 2 choice experiments. In further choice experiments with reduced number of untreated plants, T. vaporariorum and Nasonovia ribisnigri were evaluated for the effect on hostplant settlement of the light barrier on lettuce plants under more practical conditions. The light barrier shows high repellent impact on hostplant settlement by greenhouse whitefly, independent of different plant architectures. The modified choice experiment showed strong decrease in hostplant settlement for greenhouse whitefly. For currant-lettuce aphid, tendencies are shown, but no statistical effect could be demonstrated. Possible applications and differences between the insect species used for the experiments are discussed.