I'm interested in various aspects of conservation biology and ecological interactions. My main field of research is pollination ecology of wild and cultivated plants. The effects of biodiversity on ecosystem functioning and stability, landscape ecology and especially the effects of native-habitat destruction on population dynamics. I started in September 2005 as a Visiting Researcher financed by the Alexander von Humboldt foundation in the Kremen lab. Claire and I are working on a project to understand if orchard management at habitat and landscape scale can increase the availability of wild pollinators and natural enemies and to understand if, how, and to which extant, wild pollinators can augment almond pollination.

The Almond Project
“Understanding plant-pollinator and herbivore-parasitoid interactions in changing environments”

Insects help to provide crop pollination and can reduce pest pressure (via parasitoid-predator/pest interactions) in agricultural systems. California is the fifth globally most important agricultural producer with almond as one of the most important agricultural commodity. Bee pollination is a key process and essential to almond production. Hence Californian’s almond producers rely on renting honeybees to ensure production. This is a risky strategy because weather during almond blooming is often cold and rainy reducing the foraging activity of honeybees. Furthermore, colony numbers have generally declined and unknown causes are leading to unpredictable colony collapse. Wild, non-managed bees, like Andrena cerasifolii and syrphid flies (unpublished data) may augment pollination services to almonds in years when colony numbers are low or when honeybees do not forage because of cool and rainy or windy weather conditions as some of the wild pollinators forage also during cool weather. Up to now, we have little information on the habitat requirements for most of these wild pollinating species and we do not know to what extent they contribute to almond pollination and we even do not know if the wild species are effective pollinators for almond.
The navel orangeworm (NOW), Amyelois transitella, is a primary pest of almond nuts in California and several parasitic wasps (e.g. Copidosoma sp., Goniozus sp., Macrocentrus sp., Trichogramma sp.) attack the eggs, larvae, and pupae. Diversity of parasitoids can sometimes be increased when agricultural fields boarder natural habitats and the availability of wild pollinating insect species changes with agricultural management and landscape context as shown for other crop species like watermelons, tomatoes, and sunflowers in the proposed study area in California. A pilot study conducted in 2004 suggested also for almonds that wild pollinators are available when organic orchards are adjacent to natural habitats. We do not know if the management practices in the orchards or the natural habitat adjacent to the orchards or a combination of both provided the habitat for the wild pollinators. We also do not know if a large proportion of natural habitats adjacent to almond orchards are needed to increase wild pollinator or parasitic wasp diversity and density or if small habitat patches (e.g. flowering or riparian strips including nesting resources around or incorporated in large orchards) can help to increase numbers of wild pollinators or natural enemies of NOW. The overall goal of the project is to understand if orchard management at habitat and landscape scale can increase the availability of wild pollinators and natural enemies and to understand if, how, and to which extant wild pollinators can augment almond pollination.