TY - JOUR

T1 - Landscape context and management effects on an important insect pest and its natural enemies in almond

AU - Eilers, Elisabeth Johanna

AU - Klein, Alexandra-Maria

PY - 2009/12

Y1 - 2009/12

N2 - Pest control mediated by organisms such as parasitoids is a valuable ecosystem service, particularly with regard to high costs, low effectiveness, and detrimental effects of some agrochemicals. This study examined infestation rates and abundance of pests and their natural enemies in organic and conventional almond orchards in California, differing in landscape context, understory plant cover, and plant species richness. Parasitoids of the commercially most important insect pest of almond, the Navel Orangeworm (NOW) were studied by rearing NOW in collected overwintering nuts. The indirect impact of vertebrate natural enemies of NOW were estimated by counting empty nut shells with feeding marks by wild birds and various mammals, found at the orchard floor. Mean nut infestation by NOW ranged from 0.8% to 37% per orchard and was reduced by parasitism rates, ranging from 0% to 22%, and vertebrate nut damage, ranging from 2% to 96% per orchard. The parasitoids were facilitated by a high proportion of natural habitat surrounding the orchards and high proportion of understory ground cover with vegetation. The vertebrate natural enemies were facilitated by a high proportion of natural habitat surrounding the orchards and plant species richness in the orchard understory. In conclusion, this study shows that pest control mediated by vertebrates and invertebrates promoted by near natural habitats can lower pest pressure by NOW larvae in overwintering almond. In case of the vertebrate nut damage this service might only be temporal and turn into a dis-service during and after harvest because the vertebrates continue to feed on the nuts and may also cause injuries to the trees.

AB - Pest control mediated by organisms such as parasitoids is a valuable ecosystem service, particularly with regard to high costs, low effectiveness, and detrimental effects of some agrochemicals. This study examined infestation rates and abundance of pests and their natural enemies in organic and conventional almond orchards in California, differing in landscape context, understory plant cover, and plant species richness. Parasitoids of the commercially most important insect pest of almond, the Navel Orangeworm (NOW) were studied by rearing NOW in collected overwintering nuts. The indirect impact of vertebrate natural enemies of NOW were estimated by counting empty nut shells with feeding marks by wild birds and various mammals, found at the orchard floor. Mean nut infestation by NOW ranged from 0.8% to 37% per orchard and was reduced by parasitism rates, ranging from 0% to 22%, and vertebrate nut damage, ranging from 2% to 96% per orchard. The parasitoids were facilitated by a high proportion of natural habitat surrounding the orchards and high proportion of understory ground cover with vegetation. The vertebrate natural enemies were facilitated by a high proportion of natural habitat surrounding the orchards and plant species richness in the orchard understory. In conclusion, this study shows that pest control mediated by vertebrates and invertebrates promoted by near natural habitats can lower pest pressure by NOW larvae in overwintering almond. In case of the vertebrate nut damage this service might only be temporal and turn into a dis-service during and after harvest because the vertebrates continue to feed on the nuts and may also cause injuries to the trees.

KW - Ecosystems Research

KW - Ecosystem services

KW - Ecosystem disservices

KW - Biology

KW - Amyelois transitella

KW - Biological control

KW - Birds

KW - Parasitoids

KW - Rodents

KW - Didactics of sciences education

UR - http://www.scopus.com/inward/record.url?scp=70350011797&partnerID=8YFLogxK

U2 - 10.1016/j.biocontrol.2009.07.010

DO - 10.1016/j.biocontrol.2009.07.010

M3 - Journal articles

VL - 51

SP - 388

EP - 394

JO - Biological Control

JF - Biological Control

SN - 1049-9644

IS - 3

ER -