Dynamics and impact of Coccinella septempunctata as another invasive ladybird beetle in North America


Abstract: Harmonia axyridis is the second species of Coccinellidae recently to cause much alarmin North America as an invasive non-native species. The first was Coccinella septempunctata,which spread (both naturally and with human assistance) from the early 1970s through the early1990s to attain high densities throughout North America. This establishment and rapid rangeexpansion is striking; numerous attempts previously to introduce C. septempunctata to NorthAmerica as a generalist biocontrol agent (classical biological control) seemingly had failed. Ipresent a brief account here of C. septempunctata in North America, with focus on possible nontargeteffects beyond pest (aphid) suppression. I consider in particular ideas and evidenceassociated with four major mechanisms hypothesized to result in adverse effects on nativecoccinellids: exploitative competition among larvae, intraguild predation, habitat compression/shift, and interspecific hybridization. These mechanisms need to be evaluated further. Thechallenge has intensified with the establishment now of H. axyridis, which may join withC. septempunctata in having far reaching effects in North America.

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