Wednesday, May 10, 2017

Aphids - Advantages of Cloning versus Sex

The Blackfly and Greenfly (Aphids) are abundant in the garden at the moment. I attempted focus stacking (first photo) some on a red campion stalk. The stacked photo is not that successful photographically as they are very shiny and moving and so the stacking has accentuated the reflections. However, it has shown their amazing biology well. In most colonies, all the aphids are female. Without males, no energy is expended finding mates, courting, and the laying and incubation of eggs. Parthenogenesis, the development of unfertilised eggs, enables female aphids to give birth to live young as soon as they are adult - you can see one emerging in the first photo. Some of the females in these clones will have wings to disperse the colony.
 Parthenogenesis  produces clones of individuals very rapidly and this is obviously an advantage but aphid colonies do not go on reproducing themselves indefinitely. At a certain time clonal reproduction ceases and  males and egg-laying females appear, mate and produce fertilised eggs. You can see a male (winged) on the rose bud greenfly colony
The last two days were very cold and overcast in Cambridgeshire and this Four-spotted Chaser emerged on Monday morning and was still in the same position on Tuesday until mid afternoon when the wind turned more southerly giving a bit of warmth. The irises are full of exuvia -6 or 7 so far this year. 

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Ann Miles Photography - My Favourite Images of the Past10 years or so