The German cockroach (Blattella germanica) is world’s most common cockroach pest found in human households worldwide. These insects have an affinity for human dwellings and are not found in natural habitats outdoors.
The earliest record of this specie in Europe is about 250 years old. German cockroach is thought to have spread to different parts of the world from Central Europe between the late 19th to early 20th centuries. Interestingly, close relatives of German cockroach are not in Europe but thought to be in Africa and Asia.
To resolve the paradox of European spread but Asian phylogenetic affinity of German cockroach, researchers undertook genomic analysis by sampling genome-wide markers of 281 cockroaches from 17 countries across six continents.
The study revealed that German cockroach (Blattella germanica) evolved from the Asian cockroach (Blattella asahinai) about 2 thousand years ago in India or Myanmar. The researchers reconstructed two main spread routes of German cockroach following origination in Bay of Bengal region. One group spread westward to the Middle East about 1200 years ago while the other group spread eastward about 390 years ago which coincided with and the European colonial period. The later younger spread of the German cockroach coincided with European advances in long-distance transportation and temperature-controlled housing and played key role in its successful worldwide dispersal and establishment in new regions.
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Reference:
- Tang, Q. et al. 2024. Solving the 250-year-old mystery of the origin and global spread of the German cockroach, Blattella germanica. Proc. Natl Acad. Sci. USA 121, e2401185121. Published 20 May 2024. DOI: https://doi.org/10.1073/pnas.2401185121
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 evolved from the Asian cockroach (Blattella asahinai) about 2 thousand years ago in India or Myanmar. ){kind=link}