Our Liviiif; Resources — Noii-iuilive Species 



449 



Africanized and European honeybees exhib- 

 it different foraging strategies (largely tropical 

 versus temperate attributes). Africanized honey- 

 bee colonies in Africa, and now in much of the 

 Neotropics. are attuned to finding and exploit- 

 ing isolated mass-tlowering tropical trees, and 

 also use pollen and nectar from the nocturnal 

 flowers of bat-pollinated flowering plants. 

 Some tropical Apis species even migrate to fol- 

 low nectar and pollen flows across the floral 

 landscape. Consequently, these bees depend on 

 increased colony mobility (reproductive s wann- 

 ing and abandoning the hive) as behavioral 

 responses to seasonal tloral richness or dearths. 

 EHBs are better at hoarding vast amounts of 

 honey and surviving long, cold winters. 



Although preliminary evidence for behav- 

 ioral differences between the two races have 

 been documented in the Neotropics (French 

 Guiana, Venezuela, Panama; see reviews by 

 Taylor 1977: Seeley 1985; Roubik 1989). the 

 behavioral ecology of AHBs and their interac- 

 tions with EHBs and thousands of species of 

 native U.S. bees remain largely unknown. 

 Africanized honeybees have slightly shorter 

 developmental times than do European bees, 

 enabling them to produce more bees per unit 

 time compared with EHBs. Africanized bees 

 will also accept smaller cavities to nest in than 

 European bees. This behavior increases poten- 

 tial competition for nesting sites with birds and 

 other animals and also increases the potential 

 for greater numbers of honeybee colonies in an 

 area. Africanized honeybees commonly aban- 

 don their hives, often 15%-30% annually or 

 even much greater in some localities. 

 Absconding colonies may travel as far as 170 

 km (about 100 mi) before selecting a new nest- 

 ing site (USDA 1994). Thus they have been able 

 to rapidly colonize new areas in the Neotropics. 



The most often-discussed characteristic sep- 

 arating the two races is the AHBs" propensity to 

 vigorously defend their colony and nest site. 

 Although all honeybees respond to threats to 

 their colonies, AHBs respond more quickly and 

 in much greater numbers than do EHBs. In 

 comparison to EHBs, greater numbers of AHBs 

 will pursue intruders for much greater distances 

 to defend their colonies. Recent research report- 

 ed that 3 to 4 times as many AHBs responded 

 and left 8 to 10 times more stings in a black 

 leather measuring target in stinging experiments 

 (USDA 1994). 



Biochemical comparisons of AHB and EHB 

 venoms indicate they are nearly identical. 

 Nineteen stings per I kg (2.2 lb) of human vic- 

 tim body weight is the predicted median lethal 

 dose (Schumacher et al. 1992). Massive sting- 

 ing incidents by AHBs are more likely to result 

 in toxic envenomation. Reported 1993 stinging 

 incidents in Mexico have involved more than 60 



1994 United States 



Texas 



Venezuela 



Guyana 

 ^ / Surinam 



Ffencli Guiana 



human fatalities (one death per 1.4 million). 

 From 1988 to 1992, the Mexican national 

 African Bee Program eliminated 1 17,000 AHB 

 swarms in densely populated urban areas 

 (Guzman-Novoa and Page 1994). To date, the 

 worst U.S. stinging incident occurred in July 

 1992, when a 44-year-old man mowing his lawn 

 experienced a massive bee attack resulting in 

 800-1,000 stings (McKenna 1992). 



Ecological Implications 



Competition among nectar- and pollen-feed- 

 ing invertebrate and vertebrate pollinators, 

 resource partitioning, insect and plant commu- 

 nity interactions, and ecosystem processes are 

 affected by introduced EHBs and AHBs, with 

 important short- and long-term ecological and 

 perhaps evolutionary consequences. The influ- 

 ence of exotic honeybees on individual species 

 or communities of native tropical (or temperate) 

 plants or animals can only have one of three 

 outcomes: the native species will suffer, bene- 

 fit, or remain more or less unaffected. The key 

 to understanding these seemingly obvious out- 

 comes is, however, based on obtaining suffi- 

 cient information to delineate the very complex 

 short- and long-term competitive dynamics 

 between introduced bees, native bees and polli- 

 nators, and native plants in diverse, interacting, 

 natural communities. 



Fig. 1. Migration of Africanized 

 honeybees. 



■ Counties having AHBs 

 n AHB-infesled counties 



Fig. 2. Confirmed presence of 

 Africanized honeybees in (colored) 

 counties of Arizona. New Mexico, 

 and Texas, January 15, 1994. 



