Predation by the hoopoe (Upupa epops) on pupae of Thaumetopoea pityocampa and the likelyinfluence on other natural enemies

Abstract

The hoopoe (Upupa epops L.) is an insectivorousbird often preying on larvae and pupae of the pineprocessionary caterpillar (Thaumetopoeapityocampa Denis & Schiffermuller), the mostimportant defoliator of pines in Southern Europe andNorthern Africa. The first half of the breeding seasonof this migratory bird coincides with the pupal stageof the insect. Bird predation of pupae was quantifiedin two years in a Pinus nigra stand of northernItaly by periodic counting of the empty cocoons lefton the soil surface after extraction. The predationrate, estimated on 20 pupation sites representing thewhole stand, was 74.1% in 1993 and 68.3% in 1994.Predation was higher in the upper part of the soil andthen progressively decreased with increasing depth.The hoopoe may also prey on cocoons containing pupaeinfected by pathogenic fungi or parasitoids. Anexclosure experiment showed that the bird mayinterfere with these other mortality factors. Threepupal parasitoids, the ichneumonids Erigorgusfemorator Aubert and Coelichneumon rudis (Boyerde Fonscolombe) and the pteromalid Conomoriumpityocampae Graham, were significantly less frequentin the exposed sites. The fungus Beauveriabassiana (Balsamo) Vuillemin and the most abundantpupal parasitoid, Villa brunnea Becker (Diptera:Bombyliidae), caused the highest pupal mortality atboth protected and exposed sites. The bird seems to bean incompletely additive mortality factor acting onthe pest and it can also alter the relativemortalities imposed by the other natural enemies.