Nesting site density and distribution affect Osmia lignaria (Hymenoptera: Megachilidae) reproductive success and almond yield in a commercial orchard

Abstract

1. The potential of commercially managed, native blue orchard bees, Osmia lignaria, to augment honey bees in orchard pollination depends on various factors, particularly how to enhance O. lignaria retention while optimising even pollination throughout orchards by varying their stocking density and nesting site distribution.2. In 2011, we investigated how artificial nest box density and the number of cavities within nest boxes influenced O. lignaria retention and reproduction in a 61 ha almond orchard pollinated by a mixture of O. lignaria and Apis mellifera in the southern Central Valley of California. We assessed how localised O. lignaria nesting affected total nut yield.3. Retention of O. lignaria females was significantly greater in orchard areas with high density nest boxes compared with areas with low density nest boxes. Females preferred to nest in high density (low cavity) nest boxes compared to low density (high cavity) nest boxes. All measures of O. lignaria reproductive success were greater in orchard areas with high density nest boxes than areas with low density nest boxes.4. Localised O. lignaria foraging and nesting activity influenced nut yield by producing more nuts in orchard areas with high density nest boxes compared with low density nest boxes, although differences in nut yield just failed to meet statistical significance.5. Results of this study show that the density and distribution of nest boxes for nesting O. lignaria females can strongly influence the reproductive success of an alternative, managed bee pollinator in a large production orchard.

Improvement of almond production usingBombus terrestris(Hymenoptera: Apidae) in Mediterranean conditions

“…Different authors have demonstrated that Bombus terrestris is an effective pollinator of raspberries and tomatoes (Ahmad et al, ; Willmer, Bataw, & Hughes, ). Regarding mason bees, different studies have focused on the efficiency of mason bees, such as Osmia cornuta (Márquez, Bosch, & Vicens, ; Monzón, Bosch, & Retana, ; Vicens & Bosch, ) and Osmia lignaria ( Artz, Allan, Wardell, & Pitts‐Singer, ; Boyle & Pitts‐Singer, ; Koh, Lonsdorf, Artz, Pitts‐Singer, & Ricketts, ) . The potential competition between different species of bumble bees ( Bombus vosnesenskii and Bombus melanopygus) and mason bees ( O. lignaria ) with the honey bee has been examined in at least one study, carried out in California by Brittain, Williams, Kremen, and Klein () in an almond orchard; these authors found no evidence of competition but rather an enhancement of the pollination activity of A. mellifera .…”

Yield in almond is related more to the abundance of flowers than the relative number of flowers that set fruit

“…Accordingly, almond orchards are planned and managed to improve relative fruit set by planting pollinizer rows on either side of the main cultivar rows to increase availability of compatible pollen (Dag et al 2000). The use of bees in almond orchards during flowering increases the likelihood of movement of pollen among trees (Artz et al 2013;Brittain et al 2013). Enhancing tree nutrition has also been reported to increase fruit set rates (Nyomora et al 1997(Nyomora et al , 1999.…”

Production of Solitary Bees for Pollination in the United States

“…Since the bees require some incubation to emerge, time can be lost by emerging them in the orchard, so releasing emerged bees (like the "bleed-off" in alfalfa leafcutting bees) has been tried successfully in almonds (M. Allan and S. Peterson, unpublished data). Additionally, offering many smaller nest sites improves establishment compared to fewer sites per unit of area (Torchio, 1984b;Artz et al, 2013). Recent work showed that nest box density and the number of cavities within nest boxes influenced blue orchard bee retention in almonds (Artz et al, 2013).…”

“…Additionally, offering many smaller nest sites improves establishment compared to fewer sites per unit of area (Torchio, 1984b;Artz et al, 2013). Recent work showed that nest box density and the number of cavities within nest boxes influenced blue orchard bee retention in almonds (Artz et al, 2013). Females completed more nests in high-density, low-cavity nest boxes compared to low-density, high-cavity nest boxes.…”