Whitefly Killer introduction programmes use the parasitic wasp; Encarsia formosa and provide the most efficient method of introducing this highly effective parasite of glasshouse whitefly.
Encarsia formosa develops more quickly than whitefly in optimum conditions. Most of its population are female and they both parasitize whitefly larva and host feed on them, feeding on the honeydew and body fluids of the whitfly larvae. Encarsia wasps are tiny with a yellow abdomen and black upper body. They parasitize whitefly larvae ,which turn black after being parazitised.
Temperature and day length have a big impact on their activity levels. The ideal temperature range for the adult wasps to be active is between 20-25.c. There will be activity at lower temperatures than this but it will be slower and their life cycle will be much longer. The wasps only fly in the day and low light levels will reduce their activity.
Encarsia wasps have a very efficient flying pattern and will search plants looking for whitefly, once they find the whitefly larvae, they will stay in this area until all have been paraztised or host fed on.
Professional growers have found that introducing Encarsia in glasshouses with programmes of introductions is the most effective method. This ensures populations of Encarsia are maintained to counter whitefly populations at times when plants are vulnerable to attack from whitefly and they help ensure Encarsia are present when whitefly appears. If there are already very high numbers of whitefly present before Encarsia introductions have started , control of the pest can take a longer period of time.