Interactions between Amblyseius swirskii and Amblydromalus limonicus

Abstract: In Japan, fruit vegetables are mostly grown in small greenhouses with no temperature control. In the primary cropping system, they are planted in early spring and harvested in late autumn. Thrips and whiteflies are important agricultural pests in greenhouses. Amblyseius swirskii Athias-Henriot and Amblydromalus limonicus Garman and McGregor are generalist predators of thrips and whiteflies with different characteristics. Amblyseius swirskii prefers relatively high temperatures, whereas A. limonicus prefers low temperatures. As a long cultivation period involves low- and high-temperature periods, only one of the two species cannot control the pests throughout the season. Amblyseius swirskii works well during summer, whereas A. limonicus works well during relatively cool seasons; therefore, the combined application of these two species in fields may be effective for pest control. However, the interspecific interactions between these two species remain unknown. Therefore, in this study, we aimed to evaluate the interactions between Amblyseius swirskii and A. limonicus. First, we evaluated their dispersal behaviours in a laboratory and observed a difference in the dispersibility of the two species. We also tested their compatibility in a capsicum field. The frequency of leaves with two or more mites was very low, with only two leaves containing more than one A. limonicus species. Our findings suggest that the combination of these two mites is effective for pest control as they complement each other very well in fields.