Automatic extraction of Psylliodes chrysocephala larvae versus sorting by hand
An easy but not widely used method for estimating the number of P. chrysocephala larvae was tested in this study. The Funnel-Method can be considered as a modified Berlese-Funnel-Method with no heat supply. The passive extraction of cabbage stem flea larvae by using a funnel and a catching vessel generated nearly the same results as the manual dissection. The big advantage of using the Funnel-Method is that distinctly less labour time is needed; the disadvantage is that the extraction needs about 21 days until all larvae have left the plant tissue and that larval development stages cannot be related to the collection date. The results of this study indicate that the Funnel-Method is a cheap and simple tool for practical use of estimating the total number of larvae per plant, but with a time delay before results are available.