Mitespotting: approaches for Aculops lycopersici monitoring in tomato cultivation.

Aculops lycopersici is a major pest in tomato cultivation worldwide, and lately its relevance in German tomato cultivation has increased markedly. Aculops lycopersici causes damage to tomato plants by feeding on the surface of leaves, stem and fruits and can lead to the loss of whole plants. Given the small size of the pest, A. lycopersici infestation may go unnoticed for quite a length of time. When discovered symptoms can be easily confused with those of diseases. In addition to these issues A. lycopersici has a very high reproduction rate. In this study, fluorescence measurements were performed on the stem of A. lycopersici-inoculated potted tomato plants and these were compared with a visual bare eye assessment and a sticky tape imprint method for classification of these plants as either infested or healthy. The best correct classification rate was achieved with sticky tape, but this method is time intensive, which makes it unsuitable for large-scale monitoring in practice. Classification based on a ridge regression performed on stem fluorescence measurements was at least as good as the classification based on the visual assessment, and detection was robust against symptoms of drought stress. In a second trial the specificity of stem fluorescence measurements for A. lycopersici against Trialeurodes vaporariorum was tested successfully. The fluorescence method is promising as this method allows for high automation and thereby has the potential to increase monitoring efficacy in practice considerably. The relevance of the tested monitoring methods for practical tomato cultivation and the next steps to be taken are discussed.