Predation of native coccinellids by the invasive alien Harmonia axyridis (Coleoptera: Coccinellidae): detection in Britain by PCR‐based gut analysis

Abstract

Abstract. 1. The harlequin ladybird, Harmonia axyridis, is an invasive alien species that arrived in Britain in 2003 and has spread across most of the country.2. This spread has been accompanied by a decline in some native coccinellid species, in particular, the two spot ladybird Adalia bipunctata and the ten spot ladybird Adalia decempunctata. One reason for this decline could be intraguild predation (IGP) of the Adalia species by H. axyridis.3. A DNA-based approach was used to look for evidence of coccinellid IGP in the wild. Adalia bipunctata-and A. decempunctata-specific Polymerase chain reaction primers were developed to analyse the gut contents of field collected H. axyridis larvae for the presence of Adalia DNA. Harmonia axyridis larvae (156) were collected from lime trees at four sites in eastern England over 3 years.4. Adalia bipunctata DNA was detected in 7.7% and A. decempunctata DNA in 4.5% of H. axyridis larvae. DNA from both Adalia species was detected in two larvae.5. This is the first demonstration of specific IGP interactions between H. axyridis and other coccinellid species in wild populations in Britain.

Harmonia axyridis (Coleoptera: Coccinellidae): Smelling the rat in native ladybird declines

“…Harmonia axyridis shows a strong habitat overlap with A. bipunctata, being also a generalist with a preference for deciduous trees Adriaens et al, 2008). A number of studies have documented asymmetric intraguild predation in favour of H. axyridis over A. bipunctata in the laboratory (e.g., Katsanis et al, 2013) and intraguild predation of A. bipunctata by H. axyridis has also been demonstrated in the fi eld (e.g., Hautier et al, 2011;Thomas et al, 2013): this has been suggested as a cause for the decline of A. bipunctata.…”

“…We frequently lack the context in which to assess which characteristics of H. axyridis make it so successful or pose a potential threat, because we lack studies of the same features of other non-invasive species (Sloggett, 2005(Sloggett, , 2012. Thus a number of studies show that H. axyridis is an intraguild predator of A. bipunctata in the fi eld (e.g., Hautier et al, 2011;Thomas et al, 2013;Rondoni et al, 2015). However, we do not know if this poses a unique threat to A. bipunctata or not, because there is no work on intraguild predation of A. bipunctata in the fi eld by native species of ladybirds: indeed there are relatively few laboratory studies (but see Hemptinne et al, 2000;Rondoni et al, 2012).…”

Molecular analysis of the gut contents of Harmonia axyridis (Coleoptera: Coccinellidae) as a method for detecting intra-guild predation by this species on aphidophagous predators other than coccinellids

“…This represents an intermediate sensitivity level, as other studies report primer pairs with higher sensitivity by a factor 2 to 10 3 (Chen et al, 2000;Traugott et al, 2006;Thomas et al, 2012). However, when considering the weight of both the predator and prey, there was a maximum difference of a factor 80 (when an adult of H. axyridis, approximately 36 mg, consumed 5 eggs of C. carnea, approximately 0.45 mg).…”

“…The diluted samples always contained a total concentration of 200 ng/µl DNA, and only 1 µl of this DNAsolution was used per PCR reaction. This kind of test is only a simulation of the natural situation, but provides useful information on the sensitivity of the primers that can be used for determining which primer set to use (Chen et al, 2000;Traugott et al, 2006;Thomas et al, 2012).…”

“…Recently, DNA-based field studies of IGP by H. axyridis on native coccinellids have been carried out in soybean fields in Canada (Gagnon et al, 2011b) and on linden trees in eastern England (Thomas et al, 2012). Hautier et al (2008Hautier et al ( , 2011 used GC-MS to provide evidence of IGP by H. axyridis on other ladybirds in potato fields and on linden trees in Belgium.…”