Saturday, June 9, 2012
Aphids, also known as greenfly, are extremely successful sap sucking insects with a phenomenal rate of reproduction, which makes them major agricultural and horticultural pests. Within a month or so the little family group of 15 individuals in the photo below have the capacity to leave many hundreds of descendants, thanks to their ability to reproduce without sex. They give birth to live parthenogenetic young, which are clones of their parent and can themselves begin to reproduce within a few days of birth.
This individual has given birth to one offspring which is already feeding on the host plant, while a second is just about to be born. These already have the developing embryos of the next generation developing inside them.
This aphid parent is giving birth while still feeding - you can see its sylets, like a hypodermic syringe, inserted into the vein of the leaf. Winged aphids like this disperse widely between crops.
Many aphids only undergo sexual reproduction as winter approaches, leaving genetically variable eggs that will include some that are better adapted to endure the rigours of winter. These well adapted survivors will hatch and clone themselves in spring.