Pavement Ant (Tetramorium sp. E) Territoriality: Dominance, Competition and Implications for Control Methods
Abstract
Pavement ants (Tetramorium sp. E) are by far the most dominant species in urban areas, and are likely engaged in interspecific competition, which affects the abundance and diversity of other ant species. Ant abundance and diversity was monitored at the level of genus in Purdue Village and Copper Beech Apartments (West Lafayette, IN), along with temperature, humidity and habitat as possible factors. Temperature was found to be a significant factor affecting the abundance of ants, and humidity was not. The different habitats of the two locations corresponded to the presence of different genera. The number of pavement ants positively correlates with the number of cornfield ants (Lasius neoniger) in Copper Beech Apartments, but not in Purdue Village, which might suggest a dominant-subordinate relationship between these species in Copper Beech Apartments which does not exist in Purdue Village. Pavement ants are known for their large, intraspecific territorial battles, but the topic has been relatively unexplored. A large amount of preliminary work needs to be undertaken, including developing methods of mapping territories. The perimeter of buildings at each site was divided into distinct ‘territorial units’ of about 6 m and each unit baited to survey the ant population and collect pavement ants for aggression assays. The average sizes of the pavement ant colonies was 1.3 units in 2014, 1.6 units in 2015 and 1.7 units in 2016. Statistical analysis found that the sum of hostile adjacent pavement ant territories affected pavement ant numbers, suggesting that the predominant aspect of competitive pressure was intraspecific competition rather than interspecific competition. The territoriality of pavement ants provides an opportunity to study the effect of intraspecific competition on the efficacy of insecticides and control methods. Here, the surveys conducted in Chapter 2 and territorial maps constructed in Chapter 3 were used to assess that effect, by comparing Blanket (all pavement ant colonies around the building are treated) and Targeted baiting (only 1 pavement ant colony is treated) with thiamethoxam gel bait insecticide. Continuous treatment of the Blanket and Targeted Treatment buildings as well as surveys of all the sites for ant abundance was conducted until the end of the field season in 2016. Temperature was found to be the major factor influencing the percent reduction (p< 2e-16) in colony populations and both treatment methods were found to be just as effective at eliminating target colonies.
Degree
M.S.
Advisors
Bennett, Purdue University.
Subject Area
Ecology|Entomology
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