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Detailed biological information on bees of the genus Andrena has been scarce (Linsley, MacSvvain, & Smith 1952b; Michener 1953a; Linsley 1958) and for hundreds of species little or nothing is known. Also most of the observations on Andrena life histories have been conducted in an opportunistic fashion, largely because of the difficulty in locating nests and the expense and time involved in necessary traveling. Studies have been conducted on the researcher's lawn, in a path on a college campus, near the tent on a

As a tropical archipelago, the Florida Keys provide an ideal environment to examine the historic and short-term processes that structure and influence biological diversity. Through a new survey of the ants of the Florida Keys, we increase our knowledge of the number of species to 94 representing 34 genera and 8 subfamilies. Through detailed collection information, we provide an in depth picture of the distribution of each species across the Keys. On the basis of these data and information on the native and known distributions of each species, we confirm the historical trend toward continued immigration of nonnative species into the Florida Keys and present these findings in the context of the proportion of native to nonnative species. We find a similar number of species introduced from the Old World and Neotropical mainland and discuss the probable immigration of mainland Florida species during the exposure of the Florida Shelf during the last glacial episode and the subsequent isolation of some populations as sea level rose following the last glaciation. Lastly, we discuss the possible threats to these populations due to rapid climate change and other human influences.

We studied the field host specificity of the microsporidia Thelohania solenopsae and Vairimorpha invictae and their prevalence in the imported fire ants, Solenopsis invicta and S. richteri. Terrestrial ants were sampled by using bait traps and/or nest sampling at preselected sites in Argentina and Brazil. The sampling included the genera Solenopsis, Pheidole, Camponotus, Crematogaster, Linepithema, Brachymyrmex, Paratrechina, Dorymyrmex, and Wasmannia. The samples were examined under a phase-contrast microscope for the presence of microsporidian infections. The bait trap sampling revealed that: (1) T. solenopsae infected only S. richteri, S. invicta, and Solenopsis sp. at 6-67% of the sites and in 1.5-29% of the traps; (2) V. invictae infected only S. invicta at 6% of the sites and in 3% of the samples. The nest sampling revealed that: (1) T. solenopsae infected S. invicta, S. richteri, and S. macdonaghi, at 41-67% of the sites and in 11-58% of the colonies; (2) V. invictae infected the same species at 15-50% of the sites and in 2-26% of the colonies. We detected T. solenopsae and V. invictae in equal percentages of S. invicta sites (41%); however, the percentage of colonies infected with V. invictae was 20% and with T. solenopsae only 11%. At S. richteri sites, in contrast, T. solenopsae occurred at 46% of the sites and 15% of the colonies and V. invictae occurred at only 15% of the sites and 2% of the colonies. In S. macdonaghi, T. solenopsae was detected at 67% of the sites and 58% of the colonies, and V. invictae was detected at 50% of the sites and 26% of the colonies. This is the first report of V. invictae infecting S. macdonaghi. The proportion of S. richteri and S. invicta infected with T. solenopsae was similar. In contrast, the proportion of S. invicta infected with V. invictae was higher than S. richteri. We conclude that the microsporidia, T. solenopsae and V. invictae, show a very high specificity for Solenopsis ants in the field. It appears that T. solenopsae infects S. invicta and S. richteri equally but V. invictae may be more adapted to infect S. invicta. Published by Elsevier Science (USA).