Potential for A. limonicus to control whitefly in greenhouse ornamental crops under cool weather conditions: Preliminary tests in a commercial greenhouse

Abstract: Amblydromalus limonicus is sold commercially for whitefly control. With the purported advantage of better functioning under low temperatures than other whitefly natural enemies, it has the potential to be an important part of a whitefly biocontrol program in cooler months. However, its adoption within the ornamental industry has been slow; its relatively high cost means growers are unlikely to experiment with it. However, price becomes less important if the efficacy is better and more reliable than alternatives. Thus, commercial greenhouse trials were conducted to determine the potential of A. limonicus for whitefly control in fall/winter compared to other management tactics. In studies over the fall/winter in a long-term crop (Mandevilla), Year 1 data showed A. limonicus + parasitic wasps brought Bemisia whitefly (Bemisia tabaci) levels down to near zero, reducing pressure faster than the parasitic wasps alone. In Year 2, when compared to A. swirskii, A. limonicus performed better, but chemical intervention was still needed due to high initial Bemisia whitefly pressure. These studies suggest that A. limonicus could play a role in controlling species of whitefly under cool weather conditions when other whitefly biocontrol agents are less effective. However, coupling with other strategies (i.e. preventative dips of cuttings, use of trap plants) is likely necessary, both in terms of efficacy and to reduce costs.