Mismatched outcomes for biodiversity and ecosystem services: testing the responses of crop pollinators and wild bee biodiversity to habitat enhancement.

Supporting ecosystem services and conserving biodiversity may be compatible goals, but there is concern that service-focused interventions mostly benefit a few common species. We use a spatially replicated, multiyear experiment in four agricultural settings to test if enhancing habitat adjacent to crops increases wild bee diversity and abundance on and off crops. We found that enhanced field edges harbored more taxonomically and functionally abundant, diverse, and compositionally different bee communities compared to control edges. Enhancements did not increase the abundance or diversity of bees visiting crops, indicating that the supply of pollination services was unchanged following enhancement. We find that actions to promote crop pollination improve multiple dimensions of biodiversity, underscoring their conservation value, but these benefits may not be spilling over to crops. More work is needed to identify the conditions that promote effective co-management of biodiversity and ecosystem services.

A Novel Pollen Transfer Mechanism by Honey Bee Foragers on Highbush Blueberry (Ericales: Ericaceae).

Honey bees (Apis mellifera L. (Hymenoptera: Apidae)) are effective pollinators of many crops but are thought to be inefficient in pollinating blueberries (Vaccinium corymbosum L.) due to their inability to buzz pollinate. Nonetheless, commercial growers rent honey bee hives for pollination, resulting in the dominance of honey bee workers visiting flowers during bloom. The objective of this study was to examine where on the honey bee pollen is carried and how it is transferred from flower to bee to the stigma of other flowers. Examination of 90 honey bee workers foraging on blueberry flowers documented that blueberry pollen tetrads were present on all body parts. Relative amounts were as follows: head 12%, body 6%, legs 19%, and tarsi 63%. Quantities on the body subregions ranged from an average of 400 tetrads on the basitarsi to 16 on the fore tarsal claws. Thus, a single contact between many of the pollen-carrying body parts and a stigma has the potential to transfer significant amounts of pollen. The study also revealed that bee behaviors unrelated to the intentional collection of nectar and pollen, such as the frequent touching of stigmas by the claws, tarsi, or legs, while foraging, grooming, and walking across flower clusters, could result in pollen transfer. These contacts occurred 65.9% of the time a honey bee landed on a flower cluster. These findings have broad implications for future assessments of the efficiencies of various bee species in pollinating diverse crops and plants.

Fertilization of Epichloe typhina stromata by mycophagous slugs.

Epichloë typhina, a fungal endophyte of cool season grasses, is heterothallic and an obligate out-crosser. In areas of endemism, its spermatia are moved between stromata of the two opposite mating types through egg-laying activities of Botanophila flies. In western Oregon, where the fungus was inadvertently introduced into seed-production fields of Dactylis glomerata (= orchardgrass, cocksfoot), flies do not appear to be the sole vectors for E. typhina fertilization. Here we examined the role of the common agricultural slug pest Deroceras reticulatum and mycophagous slug species Prophysaon andersoni and Arion subfuscus in E. typhina spermatia transfer. Frass from P. andersoni, A. subfuscus and D. reticulatum fed stromata of one mating type was transferred to stromata of the opposite mating type, resulting in 100%, 93% and 25% stromata fertilization respectively. An experiment designed to mimic field conditions examined stromata fertilization on E. typhina-infected plants of opposite mating type in the presence of slugs. Treatments with P. andersoni and D. reticulatum had greater stromata fertilization compared to the no-slug control, but the slug treatments were not different. This appears to be the first report of mollusks vectoring viable spermatia leading to the cross fertilization of stromata of different mating types.