Overview of research
The first orientation trials with A. swirskii have taken place in chrysanthemum crops. A. swirskii was released in two crops on one practising enterprise, from June to September inclusive, in a trial area measuring 500 m2. The level of thrips infestation in this period was generally low (on average approx. 20 thrips per sticky trap). Three weeks after the planting date, 100 predatory mites per m2 were scattered over each crop (see photographs). This amounted to densities of 1.6 and 1.7 predatory mites per branch. After four weeks, A. swirskii was still traceable in both crops. However, the population size had not increased. On average, 1.5 predatory mites were found per branch. Young mites were also found in the crop, indicating that A. swirskii is able to reproduce in chrysanthemum crops. The extent to which these low densities of predatory mites are able to combat thrips is not clear.
Greenhouse trials by WUR Greenhouse Horticulture also found that A. swirskii was able to establish itself in the crop but that there was no strong population growth.
In comparison with Amblyseius cucumeris, A. swirskii did have a more marked effect on thrips. With A. swirskii, the thrips damage increased by 30% less than when A. cucumeris was used.
Results
A. swirskii can establish itself in chrysanthemum crops.
A. swirskii was more effective in combating thrips than A. cucumeris.
