Interactions between the fungal pathogen Beauveria bassiana and three species of coccinellid: Harmonia axyridis, Coccinella septempunctata and Adalia bipunctata

The harlequin ladybird, Harmonia axyridis , has emerged as a model species for invasion biology, reflecting its remarkable capacity to outcompete native ladybird species when introduced into new habitats. This ability may be associated with its prominent resistance to pathogens and intraguild predation. We recently showed that the constitutive antibacterial activity present in the haemolymph of H. axyridis beetles can be attributed to the chemical defence compound harmonine. Here, we demonstrate that H. axyridis differs from other insects, including the native ladybird Coccinella septempunctata, by reducing rather than increasing the antimicrobial activity of its haemolymph following the injection of bacteria. However, both species produce new or more abundant proteins in the haemolymph, indicating that bacterial challenge induces innate immune responses associated with the synthesis of immunity-related proteins. Our results suggest that H. axyridis beetles can switch from constitutive chemical defence to inducible innate immune responses, supporting hypothesis that inducible antimicrobial peptides protect host beetles against pathogens that survive constitutive defences. These alternative antimicrobial defence mechanisms may reflect a trade-off resulting from fitness-related costs associated with the simultaneous synthesis of harmonine and antimicrobial peptides/proteins.

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Effect of the fungal pathogen, Beauveria bassiana, on the lysozyme activity in Spodoptera exigua larvae

Journal of Insect Physiology ◽

10.1016/0022-1910(94)90156-2 ◽

1994 ◽

Vol 40 (5) ◽

pp. 385-391 ◽

Cited By ~ 23

Author(s):

D.G. Boucias ◽

S.Y. Hung ◽

I. Mazet ◽

J. Azbell

Keyword(s):

Beauveria Bassiana ◽

Fungal Pathogen ◽

Spodoptera Exigua ◽

Lysozyme Activity

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Competition for Aphid Prey between Different Lady Beetle Species in a Laboratory Arena

Psyche A Journal of Entomology ◽

10.1155/2012/890327 ◽

2012 ◽

Vol 2012 ◽

pp. 1-9 ◽

Cited By ~ 6

Author(s):

Christy Leppanen ◽

Andrei Alyokhin ◽

Serena Gross

Keyword(s):

Native Species ◽

Harmonia Axyridis ◽

Coccinella Septempunctata ◽

Lady Beetle ◽

Macrosiphum Euphorbiae ◽

Beetle Species ◽

Lady Beetles ◽

Aphid Prey ◽

Aphid Consumption ◽

Asymmetric Interactions

Direct competition for aphid prey (Hemiptera: Aphididae) was evaluated between and among several lady beetle species (Coleoptera: Coccinellidae). The behavior of three native (Coccinella trifasciata, Coleomegilla maculata,andHippodamia convergens) and four nonnative (Coccinella septempunctata,Harmonia axyridis,Hippodamia variegata,andPropylea quatuordecimpunctata) lady beetles was observed in laboratory arenas. The beetles were kept alone, paired with conspecifics or paired with heterospecifics, and presented with potato aphids (Macrosiphum euphorbiae).Harmonia axyridiswas the most successful aphid predator in our study, being able to find aphids more quickly and consume more of them compared to most other lady beetle species. It was also by far the most aggressive of the tested species.Coccinella septempunctata, C. trifasciata,andC. maculatagenerally followedH. axyridisin aphid consumption. Prey discovery, consumption, and aggressive behaviors were dependent on which species were present in the arena. Except for the generally superiorH. axyridis, there was no obvious dominance hierarchy among the other tested species and no dichotomy between the native and non-native species. Asymmetric interactions between lady beetle species may affect their abilities to coexist in the same habitat.

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