Crissman JR, Booth W, Santangelo RG, Mukha DV, Vargo EL, Schal C.
Abstract
The German cockroach, Blattella germanica (L.) (Blattodea: Blattellidae), is a major residential pest with the potential to vector various pathogens and produce and disseminate household allergens. Understanding population genetic structure and differentiation of this important pest is critical to efforts to eradicate infestations, yet little is known in this regard. Using highly polymorphic microsatellite markers, we investigated patterns of genetic diversity and differentiation within and among 18 apartments from six apartment complexes located in Raleigh, NC. No departure from panmixia was found between rooms within apartments, indicating that active dispersal resulting in gene flow may occur among rooms within apartment units. Alternatively, aggregations within apartments may exist in relative isolation under a metapopulation framework, derived from a recent, common source. Thus, in the event of population control practices leading to incomplete cockroach eradication within an apartment, recolonization of shelters and rooms is likely to occur from a genetically similar aggregation. A pattern of isolation-by-distance across the six apartment complexes indicated that dispersal was more common within complexes than among them, and F statistics suggested greater genetic similarity between apartments in a single building than between separate buildings of an apartment complex. Similarly, neighbor-joining tree and Bayesian clustering analyses were able to cluster only those apartments that were within a single building, indicating higher dispersal with associated gene flow within buildings than between them. The lack of any broader connectivity, as indicated by significant F(ST) and G-tests suggests that human-mediated dispersal of B. germanica between buildings of an apartment complex or between complexes occurs infrequently enough to have negligible effects on gene flow.
Abstract
The German cockroach, Blattella germanica (L.) (Blattodea: Blattellidae), is a major residential pest with the potential to vector various pathogens and produce and disseminate household allergens. Understanding population genetic structure and differentiation of this important pest is critical to efforts to eradicate infestations, yet little is known in this regard. Using highly polymorphic microsatellite markers, we investigated patterns of genetic diversity and differentiation within and among 18 apartments from six apartment complexes located in Raleigh, NC. No departure from panmixia was found between rooms within apartments, indicating that active dispersal resulting in gene flow may occur among rooms within apartment units. Alternatively, aggregations within apartments may exist in relative isolation under a metapopulation framework, derived from a recent, common source. Thus, in the event of population control practices leading to incomplete cockroach eradication within an apartment, recolonization of shelters and rooms is likely to occur from a genetically similar aggregation. A pattern of isolation-by-distance across the six apartment complexes indicated that dispersal was more common within complexes than among them, and F statistics suggested greater genetic similarity between apartments in a single building than between separate buildings of an apartment complex. Similarly, neighbor-joining tree and Bayesian clustering analyses were able to cluster only those apartments that were within a single building, indicating higher dispersal with associated gene flow within buildings than between them. The lack of any broader connectivity, as indicated by significant F(ST) and G-tests suggests that human-mediated dispersal of B. germanica between buildings of an apartment complex or between complexes occurs infrequently enough to have negligible effects on gene flow.
J Med Entomol. 2010 Jul;47(4):553-64.
Why is this cool?
Humans are thought to have started out as small tribes with little environmental impact. As time progressed and technology improved, it became possible for large masses of humans to congeal into cities and towns. A lot of research has been devoted to understanding the effects in terms of pollution from cities on less developed land, but I think a new line of research will involve determining the genetic changes in organisms to survive life in the city.
Today's article is a push that direction even though it is for disease prevention. The researchers sought to understand the genetic differences between several populations of roaches all within the same city, but located in different apartment complexes. They found that each apartment complex had its own distinct roach as measured by genetic differences at certain positions on the cockroach genome.
There are a myriad of reasons I think that studying organisms adapting to city survival is amazing. Let me give a quick list:
1. These organisms are acquiring all their nutrients from things we brought into the city and as such it might be a crude estimate of the necessary components of an ecosystem. This may be completely whack, but I don't know better just yet.
2. The city houses most of humanity and that number will only increase over time. As such it is important to understand what our uninvited guests are doing to stay with us.
3. If we can understand what these roaches, bedbugs, and squirrels are doing we can start thinking about constructing the city to invite the kinds of organisms that will make the city healthier or livable.
Man, squirrels and roaches are serious issues to me. Did you know that a roach will eat dead skin and hair. They have been documented to eat the eyelashes off of babies. Squirrels are more stupendous because they get all their nutrients from our trees and trash. This is a testament to our wastefulness and to a possible genetic difference between forest squirrels and city squirrels. A similar line of thinking goes for roaches, city ones must be different from wild roaches. Where do roaches even occur naturally?
Imagine that roaches are becoming more intelligent, but a crowd intelligence where a larger group means a larger group! It would be like Exterminators! Have you read that? It is about the ROACH REVOLUTION!!
Why is this cool?
Today's article is a push that direction even though it is for disease prevention. The researchers sought to understand the genetic differences between several populations of roaches all within the same city, but located in different apartment complexes. They found that each apartment complex had its own distinct roach as measured by genetic differences at certain positions on the cockroach genome.
There are a myriad of reasons I think that studying organisms adapting to city survival is amazing. Let me give a quick list:
1. These organisms are acquiring all their nutrients from things we brought into the city and as such it might be a crude estimate of the necessary components of an ecosystem. This may be completely whack, but I don't know better just yet.
2. The city houses most of humanity and that number will only increase over time. As such it is important to understand what our uninvited guests are doing to stay with us.
3. If we can understand what these roaches, bedbugs, and squirrels are doing we can start thinking about constructing the city to invite the kinds of organisms that will make the city healthier or livable.
Man, squirrels and roaches are serious issues to me. Did you know that a roach will eat dead skin and hair. They have been documented to eat the eyelashes off of babies. Squirrels are more stupendous because they get all their nutrients from our trees and trash. This is a testament to our wastefulness and to a possible genetic difference between forest squirrels and city squirrels. A similar line of thinking goes for roaches, city ones must be different from wild roaches. Where do roaches even occur naturally?
Imagine that roaches are becoming more intelligent, but a crowd intelligence where a larger group means a larger group! It would be like Exterminators! Have you read that? It is about the ROACH REVOLUTION!!
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Am I wrong? A misinterpretation of the data? Questions about what is what? Let me know.