Regional Variation in Insecticide Susceptibility in Odorous House Ants (Tapinoma Sessile)
Abstract
Odorous house ants (Tapinoma sessile) can be found across all of North America. They are an extreme nuisance pest, as its common name implies. In its natural environment, T. sessile is a submissive species, they usually stay in one localized colony and do not compete with other nearby species. They can usually be found in small, single queen colonies in acorns, leaf litter, and many other discrete sites. However, when introduced to urban environments,T. sessile flourish. They adapt invasive characteristics and grow from monogynous colonies to enormous polygynous colonies that may contain thousands of queens and millions of workers. They are infamous for invading man-made structures and impeding on both economic and esthetic thresholds. Tapinoma sessileare the #1 call-back ant for the pest management industry and are the cause of many control failures and customer dissatisfaction. Insecticide resistance has been found in many urban pests, including cockroaches and bedbugs. However, no study has been conducted on insecticide resistance with regards to certain social insects such as ants. This may be in part due to their reproductive biology, including the caste system. The goal of the study included in this thesis was to test T. sessile colonies in order to assess variation in insecticide susceptibility between colonies. The three main objectives were as follows: 1) to test if there was regional variation in susceptibility between T. sessilecolonies with regards to three commonly used insecticides for ant control, 2) to compare susceptibility between urban and natural colonies, and 3) to test if there were susceptibility differences between the worker and queen castes. With regards to both lambda-cyhalothrin and fipronil, there were no significant differences in susceptibilities between natural and urban colonies. However, urban colonies were significantly more tolerant than natural colonies with regards to dinotefuran. Because these results show that urban and natural colonies were not different with regards to lambda-cyhalothrin and fipronil, but there was a significant difference with regards to dinotefuran, this suggests that the local of T. sessile colonies is not a reliable predictor on their susceptibility to certain insecticides. However, with regards to comparing castes, queens were significantly more tolerant relative to their worker counterparts across all three insecticides. These results may explain why T. sessile are so difficult to control. Further research is needed to build a solid framework for effective odorous house ant control.
Degree
M.Sc.
Advisors
Buczkowski, Purdue University.
Subject Area
Entomology|Biology|Agricultural chemistry|Chemistry|Ecology|Organic chemistry|Urban planning
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