The response of Philaenus spumarius (Homoptera: Cercopidae) to fertilizing and shading its moorland host-plant (Calluna vulgaris)

abonos abonos nitrogenados ammonium nitrate azote calluna vulgaris chemical composition composition chimique ecologia ecologie ecology engrais escocia fertilizers grasslands herbage nitrate d'ammonium nitrate fertilizers nitrato de amonio nitrogen nitrogen content nitrogen fertilizers ombrage philaenus spumarius praderas reino unido scotland shading teneur en azote umbria united kingdom