Showing posts with label Aphids. Show all posts
Showing posts with label Aphids. Show all posts

Farming Herds Of Aphids


Yesterday’s post mentioned the farming characteristics of ant populations who look after herds of aphids. Now if you’re an ant this is serious husbandry information and continues to be a problem with our (human) interference in the natural scheme of things.

Now what about our interference in ant farming? Johansson and Gibb of Umeå U have had a look at our forestry practices on ant husbandry of aphids (1). They looked at the spruce forests in Sweden and how clear cutting affected the ant honeydew harvest.

They interviewed a large number of ants with a pretty invasive approach. Firstly theyweighed a large number on their way to work as well as a large number returning from herding duties. But that’s not all. They also put the squeeze on and made some worker ants give up their load.

The honeydew was then analyzed. So what is the effect of clear cutting? The sugar content is lower and the amino acid content is higher. That is the honeydew is a good indicator of the sap content being processed by the herds of aphids.

Does this matter, I can hear you asking. It does to the ants. The ants living in the clear-cut areas were physically disadvantaged as they grew smaller heads and could store less honeydew. In summary, clear cutting is bad news for ant populations.

Just as well we don’t allow ants to vote.

  1. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0032817;jsessionid=D119C2E7A6F74323C0BB82B5A949B8E6


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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