Comparison and Examination of Bombus occidentalis and Bombus impatiens (Hymenoptera: Apidae) in Tomato Greenhouses

Abstract

Experiments were conducted in commercial tomato, Lycopersicon esculentum Miller (Solanaceae), greenhouses to compare the relative foraging effort of two bumble bee species, Bombus occidentalis Greene and Bombus impatiens Cresson, to examine interspecific competition between B. occidentalis and B. impatiens, and to determine whether bumble bee colonies grew to their full population potential in commercial tomato greenhouses. B. impatiens colonies had more brood and workers and made more foraging trips per hour than B. occidentalis colonies. However, B. impatiens returned to the colony without pollen loads and left their colonies without dropping off their pollen loads more frequently than B. occidentalis greenhouse colonies. Our data also suggest that the presence of B. impatiens had a detrimental effect on B. occidentalis populations. Furthermore, B. occidentalis colonies did not grow to their full population potential in tomato greenhouses, with fewer workers in greenhouse colonies than in colonies placed outside in a natural environment, or in colonies that were physically enclosed and protected from external mortality. Together, this study suggests that B. impatiens is a better pollinator than B. occidentalis. It also shows that unknown factors are limiting the size of B. occidentalis colonies in tomato greenhouses.

Test of the invasive pathogen hypothesis of bumble bee decline in North America

“…These temporal associations add support to the hypothesis that N. bombi escaped into wild populations from heavily infected commercial colonies (2,3,18,19). Although the transmission mechanisms are unknown, it is known that worker bees from commercially reared colonies foraged at high frequencies outside of greenhouses (20,21), presumably preferring pollen and nectar from wild flowers over the pollen provided by cultivated tomato flowers (18,22). Commercial pollination of greenhouse tomatoes occurred mostly in the Pacific West region of North America and in Eastern Canada, which comprise the ranges of the declining Bombus s. s. species.…”

“…Colonies derived from those produced in Europe during the early 1990s were also used in open-field pollination and for field research in those regions (11). Moreover, B. impatiens, a stable species (4) currently reared for commercial pollination in eastern Canada and north central United States, is also known to have escaped commonly from greenhouses into the wild (18,20,23). Although overall infection rates are low in B. impatiens (4,24), infections do occur (6); thus, the species could still be a carrier of N. bombi.…”

A century of advances in bumblebee domestication and the economic and environmental aspects of its commercialization for pollination

“…For example, the species is only allowed for indoor use and there is the obligatory use of the so-called 'queen-excluder' that prevents young queens from escaping. Recent research in Canadian tomato greenhouses suggests that B. impatiens is a better pollinator, with a better development of its colonies than is B. occidentalis (Whittington and Winston, 2004). At present, B. impatiens is also used in Mexico.…”

Commercial Bombus impatiens as reservoirs of emerging infectious diseases in central México

“…At the end of the last century, private companies began to massively produce and distribute B. terrestris and B. impatiens colonies for commercial pollination of Solanum lycopersicum (i.e., tomato) (Whittington and Winston 2004), Capsicum annuum (i.e., bell pepper) (Shipp et al 1994) and Vaccinium angustifolium (i.e., cranberries) (Stubbs and Drummond 2001), among many other commercial species. In Europe alone, the annual market value of B. terrestris is estimated to be 55 million Euros (Meeus et al 2010a).…”

“…The intensive production and global dispersal of commercial B. impatiens can transmit hymenopteran diseases to naturally occurring honey bee and bumble bee populations (Whittington and Winston 2004;Singh et al 2010). Previous studies have demonstrated that wild bumble bees collected near greenhouses that have commercial B. impatiens colonies are more likely to be infected than naturally occurring colonies by Crithidia bombi, a protozoan pathogen that infest the bumble bee gut, the fungus Nosema bombi that causes a systemic infection, and the mite Locustacarus buchneri (Colla et al 2006;Morkeski and Averil 2010).…”