Our Ladybirds

The Symbol Of The Dutch Foundation Against Senseless Violence            photo credit: Ziko

Ladybirds, or ladybugs, are a regular sign of summer and have long provided entertainment in counting the spots on their wing cases. They are bright and colorful and are popular as logos. Perhaps the most interesting is the picture of a ladybird used as symbol by the Dutch Foundation For Senseless Violence where it is on a tile embedded in the sidewalk where a particularly nasty and senseless crime has taken place.

The term “lady” comes from the religious connotation and in the Netherlands the name refers to “The Lord’s” animal, so we see it as a rather benign creature. Even in the nursery rhyme where we urge it to “fly away home” to take care of its children, we are looking on it as benevolent fellow creature.

But let’s look at its children. A different picture emerges.  The rose lovers amongst us are already aware that the larvae munch their way through lots of aphids every day. They have voracious appetites and the aphids have to breed like crazy to keep up.

Of course, it isn’t just our roses that have aphids. For some strange reason, the world seems to becoming more and more addicted to soya beans and that’s fine with the aphids who see acre after acre of grazing stretch out before them. It is also easy pickings for the ladybird larvae.

The fields in Québec are the focus of Gagnon et al who decided to look at the darker side of ladybird larval lifestyle (1). They identified four species of ladybirds were using the fields as cafeterias for their kids. However, the ladybird kids weren’t very well brought up. They did eat what was in front of them, as good kids should, but if that happened to be a different strain of lady bird, too bad, it went the way of the aphids.

This has the fancy name in intraguild predation (IGP) and simply means dog-eat-dog when the predators are hungry. Gagon et al analyzed the DNA from the stomachs of a large group of each species of larvae and showed that they were very catholic (with a small “c”) in their eating habits. There was a year-to-year difference and this was put down to the aphid supply chain, but it was recognized that IGP provided a better nutrition source. Ladybird eggs were also a delicacy.

So ladybirds have a dark side. Maybe it’s wise not to look too deeply into a lady’s past.

  1. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0028061

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