New project PE 020 aimed to gain a greater level of understanding regarding supplementary feeding strategies. It was designed to evaluate the speed of M. pygmaeus growth from six combinations of release rate and feeding strategies on cv Mecano and cv Angelle.
The standard application was one M. pygmaeus per square metre released on cv Mecano three weeks after the delivery of plants and fed with Artemia cysts at four-week intervals. Three variations were M. pygmaeus release rate halved, release date made earlier or cultivar changed to cv Angelle. The Artemia in all cases were released at feeding stations or from a dispenser.
The trial established that predator growth was significantly greater on cv Angelle than on cv Mecano, with population growth rates higher when supplementary food was provided. The impact was difficult to fully interpret because in-crop observations suggested a high natural mortality rate of the predator, which may have masked smaller differences between the strategies. This points to the need for in-house checking of macrobiologicals prior to distribution within the crop.
Parallel studies have indicated that the state of hydration of Artemia cysts/eggs could be critical to their value as a food material and this is currently being examined in project PE 020a.
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