Harmonia axyridis (Coleoptera: Coccinellidae): Smelling the rat in native ladybird declines
In the last two decades a huge amount of research has focused on the invasive harlequin ladybird, Harmonia axyridis, particularly on potential or actual deleterious effects that have arisen after it has colonised new regions. A focus of this work has been real or anticipated declines in native ladyb...
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| Format: | Article |
| Language: | English |
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Institute of Entomology, Biology Centre, Czech Academy of Science
2017-10-01
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| Series: | European Journal of Entomology |
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| Online Access: | https://www.eje.cz/artkey/eje-201701-0058_Harmonia_axyridis_Coleoptera_Coccinellidae_Smelling_the_rat_in_native_ladybird_declines.php |
| _version_ | 1818963515911700480 |
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| author | John J. SLOGGETT |
| author_facet | John J. SLOGGETT |
| author_sort | John J. SLOGGETT |
| collection | DOAJ |
| description | In the last two decades a huge amount of research has focused on the invasive harlequin ladybird, Harmonia axyridis, particularly on potential or actual deleterious effects that have arisen after it has colonised new regions. A focus of this work has been real or anticipated declines in native ladybird abundance since the introduction of H. axyridis, for which it is deemed responsible. Scientists have generally painted a very bleak picture of the effects of H. axyridis on native species: in this paper I argue that the picture painted is often too bleak. I use the case of the 2-spot ladybird, Adalia bipunctata, the species most often invoked as threatened by H. axyridis, to illustrate my point. While there is little question that H. axyridis has led to a decline in A. bipunctata populations in Europe, it seems likely that prior to the invasive ladybird's arrival A. bipunctata occurred in artificially high numbers in the urban environments in which it was typically studied. Pollution in towns and cities led to enhanced numbers of prey aphids on plants there which initially favoured A. bipunctata, and later H. axyridis. Thus one species, A. bipunctata, that has benefitted from an association with humans has been replaced by another, H. axyridis, just as brown rats replaced black rats in Europe and North America. Viewed with a longer perspective, A. bipunctata has more likely declined back to pre-industrial levels: the artificially high level from which it has declined recently was not a 'natural' one, and thus its decline from this level does not imply that it is now threatened or endangered. More broadly, we need a wider perspective, encompassing other ladybirds, longer timeframes and better comparisons with other (non-ladybird) invasive species to more clearly assess whether H. axyridis really poses as much of a threat as is often proposed. |
| first_indexed | 2024-12-20T12:46:27Z |
| format | Article |
| id | doaj.art-403517e7cc8c41cabed54142d890f9d9 |
| institution | Directory Open Access Journal |
| issn | 1210-5759 1802-8829 |
| language | English |
| last_indexed | 2024-12-20T12:46:27Z |
| publishDate | 2017-10-01 |
| publisher | Institute of Entomology, Biology Centre, Czech Academy of Science |
| record_format | Article |
| series | European Journal of Entomology |
| spelling | doaj.art-403517e7cc8c41cabed54142d890f9d92022-12-21T19:40:17ZengInstitute of Entomology, Biology Centre, Czech Academy of ScienceEuropean Journal of Entomology1210-57591802-88292017-10-01114145546110.14411/eje.2017.058eje-201701-0058Harmonia axyridis (Coleoptera: Coccinellidae): Smelling the rat in native ladybird declinesJohn J. SLOGGETT0Maastricht Science Programme, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands; e-mail: j.sloggett@maastrichtuniversity.nlIn the last two decades a huge amount of research has focused on the invasive harlequin ladybird, Harmonia axyridis, particularly on potential or actual deleterious effects that have arisen after it has colonised new regions. A focus of this work has been real or anticipated declines in native ladybird abundance since the introduction of H. axyridis, for which it is deemed responsible. Scientists have generally painted a very bleak picture of the effects of H. axyridis on native species: in this paper I argue that the picture painted is often too bleak. I use the case of the 2-spot ladybird, Adalia bipunctata, the species most often invoked as threatened by H. axyridis, to illustrate my point. While there is little question that H. axyridis has led to a decline in A. bipunctata populations in Europe, it seems likely that prior to the invasive ladybird's arrival A. bipunctata occurred in artificially high numbers in the urban environments in which it was typically studied. Pollution in towns and cities led to enhanced numbers of prey aphids on plants there which initially favoured A. bipunctata, and later H. axyridis. Thus one species, A. bipunctata, that has benefitted from an association with humans has been replaced by another, H. axyridis, just as brown rats replaced black rats in Europe and North America. Viewed with a longer perspective, A. bipunctata has more likely declined back to pre-industrial levels: the artificially high level from which it has declined recently was not a 'natural' one, and thus its decline from this level does not imply that it is now threatened or endangered. More broadly, we need a wider perspective, encompassing other ladybirds, longer timeframes and better comparisons with other (non-ladybird) invasive species to more clearly assess whether H. axyridis really poses as much of a threat as is often proposed.https://www.eje.cz/artkey/eje-201701-0058_Harmonia_axyridis_Coleoptera_Coccinellidae_Smelling_the_rat_in_native_ladybird_declines.phpcoleopteracoccinellidaeadalia bipunctataharmonia axyridisalien invasivehabitat compressionnative species declineurbanization |
| spellingShingle | John J. SLOGGETT Harmonia axyridis (Coleoptera: Coccinellidae): Smelling the rat in native ladybird declines European Journal of Entomology coleoptera coccinellidae adalia bipunctata harmonia axyridis alien invasive habitat compression native species decline urbanization |
| title | Harmonia axyridis (Coleoptera: Coccinellidae): Smelling the rat in native ladybird declines |
| title_full | Harmonia axyridis (Coleoptera: Coccinellidae): Smelling the rat in native ladybird declines |
| title_fullStr | Harmonia axyridis (Coleoptera: Coccinellidae): Smelling the rat in native ladybird declines |
| title_full_unstemmed | Harmonia axyridis (Coleoptera: Coccinellidae): Smelling the rat in native ladybird declines |
| title_short | Harmonia axyridis (Coleoptera: Coccinellidae): Smelling the rat in native ladybird declines |
| title_sort | harmonia axyridis coleoptera coccinellidae smelling the rat in native ladybird declines |
| topic | coleoptera coccinellidae adalia bipunctata harmonia axyridis alien invasive habitat compression native species decline urbanization |
| url | https://www.eje.cz/artkey/eje-201701-0058_Harmonia_axyridis_Coleoptera_Coccinellidae_Smelling_the_rat_in_native_ladybird_declines.php |
| work_keys_str_mv | AT johnjsloggett harmoniaaxyridiscoleopteracoccinellidaesmellingtheratinnativeladybirddeclines |