The graphs show the sticky card weekly whitefly counts for all 3 growers and the percentage of poinsettia plants each week that were found to have whitefly present (very rarely was there more than 1-2 whiteflies found per plant).

Grower B purchased 2 varieties of poinsettia that from the outset were infested with whiteflies. The biocontrol agents did not give effective control early on, but there was some suggestion that the cuttings were treated with pesticides on the rooting bench before the grower received them. If this was the case, then the lack of parasitism makes sense. The case for pesticide residues being the culprit is supported by the fact that a few weeks after the trial was stopped and pesticides were used to control the whitefly, we actually started to see significant numbers (up to 50% ) of parasitized whitefly (the parasitism would have taken place before the pesticides were used and the wasps were then protected inside the whitefly nymph.). As the initial pesticide residues declined to levels that were not toxic to the Eretmocerus, we started to see parasitism taking place. If this is the case, it emphasizes how whitefly management by propagators can affect the biocontrol program in the end crop