Biological control in the polytunnel - anyone?

[chasingmytail]

I think there is evidence of whitefly in the polytunnel. I also need to check for aphids tomorrow. Reading the bio control you need to do this pre-infestation.

As my plants are looking very good I have toms, cucs, peppers, chillies, aubergines and very young rocket I am concerned that if I dont assume all will go wrong and prepare now theres going to be devastation.

It takes over a week for the bio control to arrive and its not cheap however does it make economic sense to order now? I think the bugs only last 2 weeks plus its costly. Assume there will be aphids later on. Use Encarsia to control whitefly naturally in greenhouses and conservatories.

Has anyone worked out the cheapest way of doing this I have a small polytunnel and should I order both sets now?

[fishpond]

I had an infestation of whitefly (it was bad and out of control) in my heated greenhouse this year(10 x 8), never used Encarsia before, but ordered some of the 'net.
Still a few but nowhere near as bad.
Very surprised to get 4 lots of 5 cards in 4 weeks--I thought it was expensive at the time but it works out really cheap for what you get.
I also noticed some greenfly skins amongst the peppers, so I introduced 4 lady bird larva from the garden into the greenhouse.
I have now got 4 x ladybirds that are quite large and healthy and few if any greenfly.
Note:- The encarsia last until the temperature drops below 50f
If you do not do the whitefly now, you will be amazed at how quickly they go from 1 or 2 to zillions.
Mine were even spreading into the garden.

[Penellype]

With all biological controls, there is no point in using them as a preventative measure before you see evidence of pests. Whether it is ladybirds, encarsia, nematodes or any other predator, if they have no prey to eat they will soon die and you will have wasted your money. The time to buy them is when you notice the first signs of an infestation, so hopefully they will arrive before things get totally out of control.

[chasingmytail]

I bought both the white fly and the aphids control. It wont arrive until next Friday so by then I assume there will be an infestation