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We examine how cost and benefit components of resource profitability affect recruitment in the giant tropical ant, Paraponera clavata. To vary resource profitability, we changed the quantity of artificial nectar baits presented to foragers and the distance of nectar baits from the nest. Both distance to and amount of resource affected quantitative aspects of recruitment. At increased distances foragers were less likely to recruit, and fewer workers were recruited to the resource area. The amount of nectar affected the tendency of foragers to recruit, but had no effect on the number of ants recruited. Variation in resource distance was also associated with qualitative changes in recruitment strategy. Foragers at distant sites recruited from the canopy rather than from the nest, and often transferred nectar to other workers for transport to the nest. Nectar transfer and extra-nidal recruitment significantly reduced the time required for resource collection. It may also have increased the ability of workers to specialize in specific foraging tasks. A portion of the colony's foraging force specialized spatially by remaining in distant foraging areas without returning to the nest. The flexible recruitment system of P. clavata increases colonial net energetic gain rates by concentrating foraging effort on resources yielding the highest net energetic rewards, and increases the competitive abilities of individual colonies at resource sites by decreasing collection times.

We tested the hypothesis that in a genetically mixed assemblage of worker honey bees, individual workers would behave differently toward unfamiliar sisters than toward unfamiliar nonsisters. Groups of worker honey bees of mixed genetic composition were assembled by collecting pupae from separate colonies and placing the worker bees together on eclosion. A total of 10 workers, 5 from each of two kin groups, were used to form each group. When the workers were 5 days old, a worker of one of the two kin groups was introduced into the mixed group. This worker had previously been held in a group of its sisters, without contact with queen or nonsister bees. The system used by honey bees to recognize nest mates has been the subject of many studies. Early reports, such as that of Kalmus and Ribbands (3), emphasized the importance of odor cues acquired from the environment in establishing differences between colonies that could be used by guard bees in discriminating between nest mates and nonnest mates. Similar findings were later presented concerning the recognition of queens (4) by nest mates. The finding that genotypically correlated cues could be used by sweat bees to identify nestmates (5) stimulated more refined tests for genotypically correlated recognition cues (recognition phenotypes) in the honey bee (1, 6, 7). In the absence of environmentally derived recognition signals, the honey bee queen and workers still possess recognition cues; these cues are more similar among bees that are closely related genetically. Buckle and Greenberg (8) provided an elegant model of the process by which individual sweat bees learn the recognition characteristics of their nest mates. Their model provides a conceptual framework in which learning can be studied in the honey bee.Central to the environmental odor hypothesis is the process of mixing of individual odors, presumably by contact among individuals, to produce a group odor. Such a process may also yield a colony "gestalt" of genotypically correlated odors (9, 10). We used genotypically mixed groups of Apis mellifera to test the hypothesis that a gestalt group odor is present.The presence and use of genetically correlated (similar among relatives) cues by the honey bee presents something of a paradox when the mating system and sperm utilization of this species are considered. Honey bee queens are known to mate many times prior to onset of egg laying (11). Thus, from the standpoint of a worker bee, the colony is potentially a constantly changing mixture of full and half sibs. Under such circumstances, workers should have the capacity to learn the cues of surrounding bees, rather than relying on a comparison of their own cues with those of surrounding bees. However, under certain circumstances, such as the rearing of a new queen (12-14), the capacity to recognize full sisters within genetically mixed groups might become important. Until now, no study has specifically addressed the issue of whether such preferential treatment occurs in the context of nest-mate recognitio...

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