> Is there any significant evidence that one has used to put these worries at rest?

By anyone's measure, the Africanized honey bees of South America are correctly categorized as "invasive." And yet, their impact on native bees and plants has been negligible. 

> Very little effort has been made to investigate bee population dynamics among intact wilderness areas. The presence of newly-arrived feral Africanized honey bee (AHB), Apis mellifera (Apidae), populations was studied for 10-17 years in areas previously with few or no escaped European apiary honey bees. Here I describe and interpret the major results from studies in three neotropical forests: French Guiana, Panama and Yucatan, Mexico (5° to 19° N. latitude). The exotic Africanized honey bees did not produce a negative effect on native bees, including species that were solitary or highly eusocial.

Roubik, D. W. (2009). Ecological impact on native bees by the invasive Africanized honey bee. Acta Biológica Colombiana, 14(2), 115-124.

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html