Tuesday, October 14, 2008

Aphids Upon Aphids

I am less and less disgusted by my kale's aphid infestation. I am restraining myself from blasting them off with a squirt of water from my hose, or brushing them off with my fingers. Acutally, I am waiting for the legions of lacewings and lady beetles to come and devour them. But so far, no one has shown up. So now there are layers and layers of aphids, huddled together, sucking. Why?

My research brought me to the wondrous revelations of Gordon's Aphid Page. I found out that there are 4,000 species of aphids in the world, 1,350 of them in North America (mine are cabbage aphids).

It's their sex life, however, that will really stretch your mind. First of all, they can reproduce parthenogenetically (that is, unmated females produce young from unfertilised eggs) AND can also reproduce by sexual mating. They bear live young (are viviparous) AND lay eggs (are 0viparous), at different times of the year. Ponder this:
Ova within a viviparously reproducing female start to develop immediately after ovulation, this occurs long before birth (even human females are born with all the ova they will ever need throughout their life, though they remain undeveloped for many years.) This means that an embryo can exist inside another larger and more mature embryo. In fact a newly born Summer aphid can contain within herself not only the developing embryos of her daughters but also those of her grand-daughters which are developing within her daughters. Parthenogenesis combined with this 'telescoping of generations' give aphids an exceedingly rapid turn-over of generations meaning they can build up immense populations very quickly.
Hence my infestation.

Still hoping for some predators.

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