Lady Beetle: Beneficial or Invasive?
By Andrea Peck
It's hard to imagine that a ladybug could be threatening. Maybe annoying or even irritatingbut
only if you haven't had your morning cup of coffee and you've just recovered from the flu or
something like that. Even then, it's more likely that you would just refrain from getting excited
over the sight of one. In our family, we usually point them out, “there's a lady bug!” For some
reason they attract inordinate attention. I blame it on the kindergarten curriculum.
The real term is lady beetle, by the way. You probably know this. The lady beetle is not a bug at
all, she is a beetle according to the people involved in Scientific Categorization and
Organization. For some reason, she has always reminded me of Mary Poppins, but there is no
line item for that, so we are stuck with lady beetle. There are many kinds of lady beetles, but it
is the harlequin lady beetle ( Harmonia axyridis) that seems to be overstaying it's welcome and
giving the beetle the name, ‘bug.'
Since 1910, the Harlequin lady beetle, also called the Asian lady beetle, has been introduced into a number of countries as a biological warfare against the much maligned terrorist group: aphids. A bit dramatic, I know. But, technically, if you are a farmer, aphids may pose a very real threat to your income and ability to bring home the bacon and fry it up in the pan.
Unfortunately, this particular breed of lady beetle is becoming invasive. Let's just say that one
reason is that this girl doesn't know when to step away from the aphid buffet table. Of course,
this is why she was selected for the job. The problem comes when there are no aphid
delectables left for the native or local lady beetles.
But, we cannot blame the healthy appetite of the harlequin lady beetle entirely. In fact, other
evidence suggests that “alien” insects, those that are introduced to an area, are far less likely to
be predated upon by native predators. In fact, one study showed that where 1 in 9 native lady
beetles were predated upon, only 1 in 100 of the Harlequin beetles were subject to the same
fate. Predators included any type of insect or animal, including parasites or pathogens.
Another study noted that the Harlequin lady beetle preferred warm weather locales and urban areas. Seems snooty to me, but the researchers conjectured that the weather, combined with the ability to overwinter inside buildings, was less lifestyle choice and more about proliferation of
the species. They added that the lady beetle has had difficulty establishing itself in coniferous
woodland, which has allowed the native species a respite from the dominant Harlequin.
Combine the above with the usual suspects the ability to reproduce with abandon and eat a
wide variety of foods and you've got trouble.
The scientific community is involved in the situation at this point the Harlequin has become
problematic across the globe. The situation may ride on the head of a red, flying pin like
creature, but nevertheless, researchers have found a silver lining in it all. By studying the lady
beetle and considering what has led to its overpopulation, scientists may gain insight into the
“how” of invasives in any form plant, animal or insect. Additionally, researchers exuberantly
noted the usefulness of the public in gaining concrete data.
That means you!