Friday, May 4, 2012

Safe from the Harlequin

Cream Spot Ladybird, Calvia quatuordecimguttata
The threat to native Irish ladybird species from the invasive Harlequin Ladybird (Harmonia axyridis) has been outlined before in this blog, as has the presence of H. axyridis breeding sites in Ireland. Larvae of the Harlequin are voracious feeders and will readily consume the eggs of other coccinellids (1). However they will stop short when it comes to the eggs of the Cream Spot Ladybird (Calvia quatuordecimguttata), which are overwhelmingly rejected by Harlequin larvae when presented as a food source (2). The eggs are coated with a complex mixture of hydrocarbons, acid and alkenes that deter predation. Eggs treated with hexane to remove the coating immediately became more susceptible to attack.
Cream Spot Ladybird, Calvia quatuordecimguttata
Adult Cream Spots are quite different from other ladybird species in Ireland, having no black markings and orangish-brown elytra with 14 cream spots (3). They are found on a variety of plant species and are generalist feeders, feeding on both aphids and psyllids (4). However, their preferred food are pysllids and females feeding on these produced more than 4 times as many eggs than those feeding on aphids (5).

  1. Pell et al., 2008. BioControl 53 pp. 147-168
  2. Ware et al., 2008. BioControl 53 pp. 189-200
  3. McGavin, 2010. Pocket Nature Insects and Spiders p. 107
  4. Hodeck et al., 2012. Ecology and Behaviour of the Ladybird Beetles (Coccinellidae) p. 154
  5. Sem'yanov, 1980. Journal Entomologicheskoe Obozrenie 59 pp. 757-763

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