Hesperomyces virescens

Hesperomyces virescens

Hesperomyces virescens
(photo: Katie Murray)

Laboulbeniales are a group of fungi that infect many different insect species, including ladybirds. Hesperomyces virescens is a species of Laboulbeniales that is transmitted between ladybirds during mating, although it can sometimes spread between individuals that rub against each other when they cluster together in groups during overwintering. Infections of the fungus can be seen fairly easily because it appears as yellow, finger-like projections on the surface of the ladybird. Due to the sexual spread of this fungus, it is more often found on the underside and between the legs of males, and on the top of the wing cases of females, as these are the areas that come into contact during mating. Individuals with very heavy infections can be covered with small yellow spines, and can almost resemble miniature hedgehogs!

In the UK this sexually-transmitted fungus has historically been seen on native species, particularly 2-spot ladybirds and only in the London area. Recently, we have seen this fungus infecting the invasive alien harlequin ladybird in London and Oxfordshire. The UK Ladybird Survey monitors the changes in distribution of ladybirds and their natural enemies, and we would now like to also monitor the spread of this fungus in both native species and also the invasive alien harlequin ladybird. We want to find out where in the UK the disease has spread to, which species of ladybirds are infected and what proportion of ladybirds have the infection.

Advice for looking and finding it:

At this time of year ladybirds are beginning to overwinter. This usually means they huddle together in leaf litter or other sheltered places like your house, shed, garage or other outbuildings. This is especially true for harlequins, which are often found clustering in houses. Checking these aggregations is a good way to have a look for the fungus, particularly if you’re evicting the ladybirds anyway! Many ladybirds will have only a few yellow projections, so you may have to look carefully.

What to do:

We want your reports whether the ladybirds you find are infected or not. Although we are particularly interested in harlequin ladybirds, we would also like to know about native species, such as the 2-spot ladybird. Having records of multiple species will allow us to compare infection by the fungus in both native species and the harlequin ladybird. Please submit a photograph with your record if you can, as this will allow us to confirm your identification or help you if you are unable to identify the ladybird species. We are also interested in how many ladybirds you have seen and how many have the infection from your sample.

Questions you may have:

Does the fungus make the ladybirds sick?
  • We don’t know – most of the research on this species suggests not but we are interested in investigating this question as part of ongoing research into the effect of native parasites on invasive alien species. It is possible that it could affect the lifespan or the number of eggs a female can produce over her lifespan, but we still need to investigate this further.
Can I catch it?
  • No, this fungus is specific to arthropods (insects, crustaceans, centipedes, millipedes & spiders) and so will not be able to transfer to a human.
Did this fungus come with the harlequin when it invaded?
  • It is unlikely the harlequin brought this fungus with it when it arrived in the UK and more likely that the fungus has transferred from the native 2-spot population in the UK.
Is the harlequin particularly susceptible to this disease?
  • We don’t know. This is another aspect of research that is currently ongoing – that’s why we need your records!