Date of Award

12-2010

Level of Access Assigned by Author

Campus-Only Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biological Sciences

Advisor

Francis A. Drummond

Second Committee Member

Andrei Alyokhin

Third Committee Member

William Glanz

Abstract

The ecology of Formica exsectoides was assessed throughout lowbush blueberry during a four-year study. Foraging workers collected a variety of prey species with Hymenoptera and Lepidoptera being the most common groups. Foragers traveled several meters (7-18 m) in a wide range of temperatures (14-35°C) and had little impact on other predators. Laboratory studies demonstrated that colonies feed readily on blueberry flea beetle larvae and spanworm larvae, two major blueberry pests. Colonies fed continuously on flea beetle larvae as densities increased. Carbon and nitrogen isotopic signatures were statistically similar for F. exsectoides and spiders, corroborating observations that this species is a major predator throughout blueberry. Overall, these results indicate F. exsectoides is an efficient predator throughout lowbush blueberry that has little impact on other beneficial arthropods, thus efforts to conserve colonies should be made. In order to learn more about this species, physical characteristics of mounds were evaluated. Mound temperatures as they relate to air and soil temperatures, and the role of colonies in increasing soil nutrients were examined. A six-year survey of lowbush blueberry fields was conducted to identify ant species diversity and richness. In addition, F. exsectoides abundance was evaluated during a one-year study, and laboratory investigations into the impacts of common insecticides on this species were conducted. Results indicated that fields with no chemical pesticide applications had significantly greater species richness and greater abundance of F. exsectoides. The edges and wooded areas surrounding fields had significantly greater species richness with F. exsectoides being most common on field edges. High densities of weedy vegetation were significantly correlated with increased densities of F. exsectoides, indicating a need for vegetation that supports honeydew-producing homopterans. In laboratory studies, workers were sensitive to phosmet, a highly toxic insecticide commonly sprayed throughout blueberry fields. Low toxicity insecticides such as acetamiprid and imidacloprid had little impact on worker survival in laboratory studies. Conservation of species diversity and F. exsectoides colonies may be accomplished through the reduction and judicious selection of insecticides, as well as allowing weedy vegetation growth throughout fields.

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