Flora and fauna in the southeast are coming back to life as the spring season continues, including ladybugs as they can be found in abundance this time of year.
Provincial Insect and Vertebrate Pest Management Specialist, Dr. James Tansey explains these beetles, part of the Coccinellidae family, overwinter in large groups in sheltered areas like leaf litter and hollow logs.
“They like each other's company, especially overwintering. They find protection in these spots and they tend to share them. They're hunkered down in these areas over the course of the winter. They'll be covered by snow and protected from some of the harsher cold conditions. Once that snow melts and they're allowed to leave these places, they can sometimes be found in pretty large numbers.”
Tansey continues, noting they typically overwinter in their adult stage, as some species of ladybug can live up to three years from egg to adulthood.
An interesting curiosity is that true to their name, some species of ladybugs are primarily made up of females, due to an intercellular parasite called Wolbachia.
“It's like a bacterium. What these do in some cases is they will limit mating between male and female that have different strains of the Wolbachia. And some Wolbachia will actually be male killing pathogens. So there are some ladybug species that are actually 98 to 99 percent female because of this Wolbachia.”
Tansey says this does not seem to limit their population growth.
Native vs. invasive ladybugs: Species, traits, and competition
While there are 475 different species of ladybugs, with several present on the prairies, Tansey explains they are not hugely diverse. The vast majority are predators feeding on aphids and other soft bodied insects, with the few plant-feeding species present in Mexico and Central America.
Tansey notes two invasive species that are present on the prairies, the first originating from southeast Asia called the Asian Ladybug or Harlequin Ladybug due to its different colour morphs. No established populations of this variety have been observed in the prairies; however, it continues to work its way across the continent.
The second is the seven-spot ladybird, originating from Europe, Asia, and Africa.
“It's become very well established on the prairies. I'm willing to bet that most of the time, when people encounter ladybugs, it's going to be that particular species.”
Tansey describes this variety, saying they are a relatively larger species of ladybug, red to orange in colour with three conspicuous dots on them.
“Those two are invasive and the reason that they're an issue is they are predators, and they will happily munch on the eggs of other ladybug species and actively outcompete native ladybug species. There is some concern for a few of our native ladybug species, including the nine spotted ladybug and the transverse ladybug, which is in pretty serious decline in large part due to competition with these invasive species.”
This variety of species means some differences in colour, pattern, and size. Tansey says a good way to determine whether a ladybug is in its adult stage is by its anatomy. The body of a ladybug is comprised of three main components, the head, the pronotum, and the abdomen.
As with all other insect groups, only adults have fully developed wings, so any ladybug with wings, regardless of its size, is an adult.
He explains ladybugs have four wings, the spotted part of the thorax making up two of them, called the elytra.
“Their four wings have become hard to be protective structures and those are called elytra. And that's really conspicuous of all beetles. That's really one of the distinguishing characteristics of beetles.”
The other two wings are the membranous wings underneath the elytra.
The ecological importance of ladybugs as natural pest controllers
While ladybugs are a more charismatic fauna, Tansey notes they also serve a significant role in their ecosystem. As they are predators, they are extremely important in regulating plant pests. An example is their aphid-including diet.
“Aphids can be very important plant pests. In agricultural systems and gardening systems, many managed systems, ladybugs can affect biological control of some of these pests and are considered natural enemies of some of these important crop pests.” He continues “Because they are generalist predators, of course, they can have regulating impacts on other herbivores in natural systems as well. And these natural systems evolved with these native ladybugs on the prairies as well.”
Tansey notes a resource containing more in-depth information about the Coccinellidae family, called the “Key to Ladybeetles” by D.J. Larson, available as a free online PDF. He explains it provides a dichotomous key of the ladybug species present in Saskatchewan, complete with pictures.
“It looks like a real ton of work went into this, so I'd encourage people to take a look at it.”
Another resource he mentions is Bug Guide. He also encourages people to reach out to their local entomologists saying, “there's a few of us in the province, and we'd be happy to talk about all things bug.”