The arrival of the invasive alien harlequin ladybird in Britain and Ireland provided a new emphasis for research on ladybird-parasite interactions. Parasites of native ladybirds seem to find the harlequin less attractive, so will they adapt to this invader? We want to know!
There are very few predators of ladybirds. Ladybirds contain various mildly toxic and foul-tasting chemicals – their bright coloration is a warning to deter predation. But parasites do attack them, including some fascinating fungal pathogens. Two natural enemies are often considered among the most important causes of mortality in adult predatory ladybirds: the braconid wasp, Dinocampus coccinellae, and pathogenic fungi within the genus Beauveria.
|Dinocampus coccinellae adult and pupa with harlequin ladybird host.|
Photo: Richard Comont
The wasp Dinocampus coccinellae lays eggs in adult ladybirds – a single wasp larva hatches within the ladybird and begins to feed on the host. Eventually it emerges to spin a cocoon between the legs of the ladybird in which it has developed. This parasite-host interaction can be observed in the field: the parasite cocoon is particularly conspicuous in the spring when it can be seen attaching 7-spot ladybirds (and others) to various surfaces such as fence posts and trees.
The wonderful ladybird parasite Dinocampus coccinellae - a fascinating overview @katiemurray88 #ECE2014 pic.twitter.com/rBdCWE1XZ1
— Helen Roy (@UKLadybirds) August 8, 2014
The fungus: Beauveria
The most common pathogen attacking ladybirds is the fungus Beauveria bassiana which causes ‘white muscardine’ disease in many insects. It persists as tiny spores, usually in soil but also on tree bark or leaves. The fungus spreads by infecting overwintering ladybirds in sheltered spots such as crevices or leaf litter. Scientists at CEH have shown that ladybirds avoid places with lots of fungal spores and move away from ladybirds that succumb to the disease.
|Beauveria bassiana infection (late stage) of (left to right) harlequin, 7-spot|
and 2-spot ladybird adults. Photo: Helen Roy
Tiny scuttle flies can attack ladybird pupae. There is also a beautiful yellow fungus that grows as fruiting bodies on the surface of ladybirds.
Helping our scientists
Send your records by emailing firstname.lastname@example.org or upload sightings of Dinocampus to iRecord at www.brc.ac.uk/irecord/enter-Dinocampus-records
The free iRecord Ladybirds mobile phone app for iPhones and Android devices makes it very easy to upload your records of ladybirds to the UK Ladybird Survey.
Harlequin ladybirds escape enemies while native species succumb 3 Dec 2013
Staff page and research interests of Dr Helen Roy
Posted by Paulette Burns