Do microsporidia function as "biological weapon" for Harmonia axyridis under natural conditions?. (20th May 2015)

• Record Type: Journal Article
• Authors: Gegner, Tobias; Otti, Oliver; Tragust, Simon; Feldhaar, Heike
• Is Part Of: Insect science. Volume 22:Number 3(2015:Jun.)
• Page Start: 353
• Page End: 359
• Publication Date: 2015-05-20
• Subjects: Insects -- Periodicals; Entomology -- Periodicals; 595.705
• DOI: 10.1111/1744-7917.12224
• Languages: English
• ISSNs: 1672-9609

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>Invasive alien species, such as the multicoloured Asian ladybird <italic>Harmonia axyridis</italic>, are often regarded as major drivers of biodiversity loss. Therefore understanding which characteristics or mechanisms contribute to their invasive success is important. Here the role of symbiotic microsporidia in the hemolymph of <italic>H. axyridis</italic> was investigated in the context of intraguild predation between wild‐caught <italic>H. axyridis</italic> and the native ladybird species <italic>Coccinella septempunctata</italic>. The microsporidia were recently discussed to contribute to the unpalatability of <italic>Harmonia</italic> for other coccinellids during intraguild predation and to function as "biological weapons". In the present study, visual detection of microsporidia in hemolymph samples revealed that 73.5 % of <italic>H. axyridis</italic> were infected. Intraguild predation experiments between larvae of the two species showed a significant competitive advantage for <italic>H. axyridis</italic>, even against larger larvae of <italic>C. septempunctata</italic>. Adult <italic>C</italic>. <italic>septempunctata</italic> always killed and fed on <italic>H. axyridis</italic> larvae. However only 11.4 % (4 of 47) of <italic>C. septempunctata</italic> that fed on infected <italic>H. axyridis</italic> died within 4 months. In contrast to previous studies this suggests that microsporidia or harmonine, the chemical defense compound of <italic>H. axyridis</italic>, do not lead to death of <italic>C. septempunctata</italic> preying on larvae of <italic>H. axyridis</italic>. Instead our results support the idea that competitive advantage during intraguild predation greatly facilitates the success of <italic>H. axyridis</italic> and that this may help this highly invasive species to outcompete native species. The impact of microsporidia on <italic>Harmonia</italic> itself as well as on interspecific interactions require further studies.</p> </abstract>