Brigham Young University Science Bulletin, Biological Series


Fifty-three arthropod species were studied in an area affected by an underground nuclear detonation. These were represented by 10 species of ants, 17 beetles, 5 orthopterans, 4 scorpions, 6 solpugids, and 11 spiders (Table 16). Relative populations were determined prior to the detonation and at three periods after the detonation–(1) one and two months after (August and September 1962), (2) 11 months after (June 1963), and (3) 13 months after (August 1963). One and two months after the detonation, the number of species was reduced from the expected by 48 percent, by 52 percent after 11 months, and by 66 percent after 13 months. Greatest reduction of specimens occurred with spiders, followed by ants and beetles. Fewest changes occurred in the number of scorpions. Populations of each group changed significantly in each period. Reductions from 30 percent to 100 percent occurred in all groups in all periods after the detonation except for the scorpions one and two months after, when an increase of 160 percent was noted. After 11 months spiders had increased 33 percent (Table 17).

Within specific sectors, populations did not vary significantly from the expected except in a few instances. In August and September 1962, immediately after the detonation, populations of arthropods in sectors 3, 4, and 5 were much higher than expected. This represented the area from approximately 65m to 140m from ground zero. The increase may have been due primarily to the physical transport and initial survival of those arthropods living closer to ground zero than 65m. Similarly, slight increases were noted in sectors 7 and 9, but these likely were not significant. In June 1963 in sector 5 and in August 1963 in sector 3, slight increases in populations were noted. These may have been due to seasonal differences correlated with vegetative type, and are also not considered significant.