Bishop, D.B. 1998 . Differential Effects of the Allegheny Mount Ant, Populations and their Interactions in ... Michigan State University 119 pp.

Notes: [Title continues: Jack Pine Forests. Ph.D. Thesis; Catherine M. Bristow, Advisor.] Allegheny mound ants, Formica exsectoides Forel (Hymenoptera: Formicidae) are one of the most common mound building ants in the eastern United States. They readily tend honeydew producing Homoptera and are very aggressive towards non-tended homopterans and other arthropod species, including natural enemies of homopterans. A survey in north central Michigan in 1993 indicated that the homopteran community differed markedly between areas of jack pine (Pinus banksiana L.) forests with and without this ant. Tended homopteran species dominated areas with F. exsectoides while a non-tended aphid was most common in areas without it. In addition, invertebrate predator populations were generally larger and of different composition, consisting primarily of generalist predators in areas without mound ants. I tested the hypothesis that the presence of F. exsectoides alters the homopteran community by (1) providing enemy-free space for tended homopterans against their specialist predators and (2) by preying upon non-tended homopterans. I tested hypothesis 1 by conducting a combination of ant-exclusion, predator-inclusion studies using the two most common tended homopterans in mound ant areas, Cinara banksiana Pepper & Tissot (Aphidae) and the pine tortoise scale, Toumeyella parvicornis (Cockerell) (Coccidae). Allegheny mound ants provided enemy-free space for the aphid against its specialist mirid (Pilophorus spp.) predators. Pine tortoise scales received less effective enemy-free space against their specialist predator; early instars of Hyperaspis binotata Say (Coleoptera: Coccinellidae) hid under gravid scales and escaped ant attack while feeding on scale eggs and crawlers. Later instars feeding in the open used glandular secretions and long, waxy tufts to repel ant attack. Mound ants readily attacked and removed the most abundant predator in non-mound ant areas, lacewing larvae, when encountered. Since both tended aphids and pine tortoise scales were virtually absent from non-mound ant areas implies that generalist predators in non-ant areas may play a key role in reducing populations of these homopterans. Hypothesis 2 was tested using ant-exclusions with the non-tended woolly aphid, Schizolachnus piniradiatae (Davidson) (Aphididae). Woolly aphids were attacked by ants every time they were encountered, and by the end of 72 h, woolly aphid numbers on ant-present branches were less than those on ant-excluded branches.