...using the logic of ecology

ecological control for aphids and whitefly (by jonathan radford)

Millions of dollars are lost across the globe every year due to crop damage caused by aphids and other plant pests. Aphids and whitefly have created havoc all over the world. The problem is not only due to the direct damage they cause to plants but also because we humans have sprayed them with just about every insecticide at our disposal on the food crops that we consume for the past 40 years in an attempt to eradicate them. Aphids and Whitefly are sap-sucking insects that gather on the underside of leaves and on the stems of lush plants. Although the direct damage they cause does harm the plant, the viruses carried by them are far more menacing and cause the real damage.

Up until just recently the main solution to this problem was to spray host plants with extremely toxic pesticides, which curiously, also kill natures own way of dealing with the problem - the parasitic wasp. There are hundreds of species of parasitic wasp, some feed on caterpillars and grubs and several species lay their eggs on aphids and whitefly resolving a huge problem for the gardener. In Italian gardens there will usually be an orangery, greenhouse or conservatory- used to over-winter tender plants. These include; lemons, oranges and geraniums etc. They are also used for establishing early crops of tomatoes and other solanums .

Whitefly tend to gather in large numbers in these warmer spaces and can soon become a major nuisance to the plants, weakening the plant and bringing diseases. Controlling the conservatory with a toxic spray is clearly not an intelligent control, given that it also an ideal place for the owner to have breakfast or socialise in the evening etc. However by using these minute parasitic wasps to do the job we can avoid using harmful sprays and they are totally harmless and almost invisible to the naked eye. This is clearly by far the most ecological solution and they are now widely available,
even online (Click HERE).

The eggs of the wasp are laid inside the pests body and the body of the pest (aphid, whitefly, cabbage worm, tomato hornworm etc) the body then becomes both the food and an ideal place for the larvae to develop. The fully developed larva then laves the body of the pest by making a tiny hole from which it emerges as an adult wasp to continue its good work. There are two main groups of these wasps, the first being the Braconids which feed on various species of aphids, webworms, hornworms, armyworms, leaf rollers and many others. Whereas the Chalcid group favour small grubs and caterpillars, such as the cabbage worm, tomato worm, codling moth - amongst many others.

Curiously these wasps have been in use since 1926, when they were first discovered and, although their use is largley restricted to greenhouses, they are extremely useful and fascinating creations. I often wonder what would have happened if research into ecological treatments such as these had received the same monstrous amount of investment as the pesticide industry?