COS 54-1
Native bee assemblages and development near canola fields in the South Central US
Canola (Brassica napus) is an oilseed crop harvested for biofuel and cooking oil and is planted in rotation with winter wheat in the South Central US. Production of canola has increased from 0 hectares 10 years ago, to over 93,000 hectares in 2013 in Oklahoma alone, but the influence of increased production on native insect pollinators is not known. Canola blooms early in spring, prior to many native plants and provides floral resources for many bee species. However, many fields are treated with insecticides which are harmful to bees around the time of bloom. We documented bee abundance and diversity from 2011-2013 using blue-vane traps in canola-wheat and canola-wheat-pasture landscapes to evaluate the bee assemblages around canola fields. Trap nests for twig nesting bees were used to assess bee reproductive success in these landscapes as well.
Results/Conclusions
Our data show six species are extremely abundant around canola year to year and bee species richness is highest in canola fields near pasturelands and lowest in wheat fields near canola without pasturelands. Nest boxes were most populated in areas with canola and without pasture, likely due to nest resource availability, but parasitization of nests by other insects was also highest in these areas. Presence of pastures positively correlated with bee abundance and richness around canola fields, potentially exposing more bees to insecticides during forage flights.