Progress 12/01/00 to 11/30/03
Outputs
We used two classes of molecular genetic markers to characterize the breeding system in both undisturbed and urban populations of the eastern subterranean termite, Reticulitermes flavipes. Of 56 colonies investigated in undisturbed habitats in the Piedmont, microsatellite analysis indicated that 43 (77%) were simple families headed by a single pair of reproductives. The remaining 13 colonies were inbred families descended from a single reproductive pair. All colonies had limited foraging ranges with only a single inbred colony having workers foraging over a distance of 15 m. In an urban habitat, we investigated 41 colonies found near buildings in an apartment complex. Thirty (73.2%) of these colonies were simple families, whereas 11 (26.8%) were inbred families descended from simple families. Comparisons of the coefficients of relatedness and inbreeding to values generated by computer simulations suggested that the simple families from both habitats were headed by
pairs of outbred primary reproductives. In contrast, the inbred colonies were most likely headed by a small number of secondary reproductives - on the order of 2 females and 1 male - who were the direct descendants of the primary reproductives. A population in an undisturbed habitat in the Coastal Plain region had a slightly different composition, although colonies in this area were also fairly localized. Six (30%) of the 20 colonies were simple families, whereas the remaining 14 were inbred families descended from simple families. Analysis of gene flow using the microsatellite markers indicated a lack of genetic differentiation at the scale of 1 - 40 km with only very weak differentiation between the Piedmont and Coastal Plain sites (160 km), suggested no major barriers to flow of nuclear genes at these spatial scales. However, analysis of mtDNA sequence data showed significant differentiation at spatial scales of 10-40 km, suggesting that dispersal by females may be more limited
than dispersal by males. On a more local scale, there was no significant isolation by distance at either the nuclear or mtDNA markers, indicating that reproduction by budding is not a common mode of colony proliferation in these habitats. Detailed studies of colony social and spatial organization in field plots in undisturbed habitats indicate that colonies have fairly localized foraging areas, generally less than 100 m2, the size of the foraging area does not seem to be related to the social organization of colonies, and distinct colonies can occasionally merge. These results help clarify colony social and spatial organization of R. flavipes, a major economic pest throughout the central and eastern U.S. This information will play a key role in future efforts to refine exiting termite management strategies and in the development of safer, more efficient control technologies.
Impacts
These results have made a significant contribution to our understanding of colony social and spatial organization in the eastern subterranean termite, a major economic pest throughout the eastern part of the U.S. This information will aid in the development of more effective ways to manage these highly destructive pests.
Publications
- DeHeer, C. J. and E. L. Vargo. 2004. Colony genetic organization and colony fusion in the termite Reticulitermes flavipes as revealed by foraging patterns over time and space. Molecular Ecology, in press.
- Vargo, E. L. 2003. Genetic structure of Reticulitermes flavipes and R. virginicus (Isoptera: Rhinotermitidae) colonies in an urban habitat and tracking of colonies following treatment with hexaflumuron bait. Environmental Entomology 32: 1271-1282.
- Vargo, E. L. 2003. Hierarchical analysis of colony and population genetic structure of the eastern subterranean termite, Reticulitermes flavipes, using two classes of molecular markers. Evolution, in press.
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Progress 10/01/01 to 09/30/02
Outputs
We have made excellent progress in all our objectives and are on schedule for all portions of the work. We have completed characterization of the breeding system in both undisturbed and urban populations. Of 56 colonies investigated in the Piedmont, microsatellite analysis indicated that 43 (77%) were simple families headed by a single pair of reproductives. The remaining 13 colonies were inbred families descended from a single reproductive pair. All colonies had limited foraging ranges with only a single inbred colony having workers foraging over a distance of 15 m. In an urban habitat, we investigated 35 colonies found near buildings in an apartment complex. Twenty-four (69%) of these colonies were simple families, whereas 11 (31%) were inbred families descended from simple families. Comparisons of the coefficients of relatedness and inbreeding to values generated by computer simulations suggested that the simple families from both habitats were headed by pairs of
outbred primary reproductives. In contrast, the inbred colonies were most likely headed by a small number of secondary reproductives - on the order of 2 females and 1 male - who are the direct descendants of the primary reproductives. A population in an undisturbed habitat in the Coastal Plain region had a slightly different composition, although colonies in this area were also fairly localized. Six (30%) of the 20 colonies were simple families, whereas the remaining 14 were inbred families descended from simple families. Analysis of gene flow using the microsatellite markers indicated a lack of genetic differentiation at the scale of 1 - 40 km with only very weak differentiation between the Piedmont and Coastal Plain sites (160 km), suggested no major barriers to flow of nuclear genes at these spatial scales. However, analysis of mtDNA sequence data showed significant differentiation at spatial scales of 10-40 km, suggesting that dispersal by females may be more limited than
dispersal by males. On a more local scale, there was no significant isolation by distance at either the nuclear or mtDNA markers, indicating that reproduction by budding is not a common mode of reproduction in these habitats. Detailed studies of colony spatial organization in field plots in undisturbed habitats indicate that colonies have fairly localized foraging areas, generally less than 100 m2, and the size of the foraging are does not seem to be related to the social organization of colonies.
Impacts
This research is making a significant contribution to our understanding of colony and population genetic structure in the eastern subterranean termite, a major economic pest throughout the eastern part of the U.S. This information will aid in the development of more effective ways to manage these highly destructive pests.
Publications
- No publications reported this period
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Progress 10/01/00 to 09/30/01
Outputs
We have made excellent progress in all our objectives and are on schedule for all portions of the work. We have completed characterization of the breeding system in undisturbed populations. Of 56 colonies investigated in the Piedmont, microsatellite analysis indicated that 22 (40%) were simple families headed by a single pair of reproductives. The remaining 44 colonies were inbred families descended from a single reproductive pair. All colonies had limited foraging ranges with only a single inbred colony having workers foraging over a distance of 15 m. The 22 colonies investigated in the Coastal Plain region had a very similar composition. Colonies were also fairly localized. Six (27%) of the colonies were simple families, whereas the remaining 16 were inbred families descended from simple families. Analysis of the coefficients of relatedness and inbreeding suggested that the simple families from both locations were headed by a pair of outbred primary reproductives.
In contrast, the inbred colonies were headed by a small number of secondary reproductives inbred for only 1-2 generations, and were not comprised of large numbers of secondaries inbreeding for many generations. Analysis of gene flow using the microsatellite markers indicated a lack of genetic differentiation at the scale of 1 - 40 km with only very weak differentiation between the Piedmont and Coastal Plain sites (160 km), suggested no major barriers to flow of nuclear genes at these spatial scales. However, analysis of mtDNA sequence data showed significant differentiation at spatial scales of 10-40 km, suggesting that dispersal by females may be more limited than dispersal by males. On a more local scale, there was no significant isolation by distance at either the nuclear or mtDNA markers, indicating that reproduction by budding is not a common mode of reproduction in these habitats. We have transects in place to characterize populations around structures, which will be done this
coming field season. Investigation of levels of gene flow are nearly completed for the undisturbed sites and will be done for the urban sites concomitantly with characterization of the breeding system. The detailed grids necessary for the final objective, determination of the relationship between social organization and size of foraging area, are in place and these studies will be completed this coming summer.
Impacts
This research is making a significant contribution to our understanding of colony and population genetic structure in the eastern subterranean termite, a major economic pest throughout the eastern part of the U.S. This information will aid in the development of more effective ways to manage these highly destructive pests.
Publications
- No publications reported this period
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Progress 10/01/99 to 09/30/00
Outputs
n/a
Impacts
(N/A)
Publications
- No publications reported this period
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