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Development of an economic rearing and transport system for an arid adapted strain of the predatory mite, Neoseiulus californicus

Final Report Summary - EUROMITE (Development of an economic rearing and transport system for an arid adapted strain of the predatory mite, Neoseiulus californicus, for spider mite control)

Spider mites of the genus Tetranychus are important pests for many food and ornamental crops; the mites can be controlled, at moderate temperatures and high humidity, by the predatory mite Phytoseiulus persimilis. However, at low humidity levels and high temperatures, control is not up to par. The species Neoseiulus californicus is relatively efficient against spider mites in such conditions, and was therefore selected as a potential predator by the EUROMITE project team.

EUROMITE aimed to identify an arid adapted strain and develop an economic rearing and transport system that would allow growers to take advantage of this valuable natural enemy. Given that the species is native to various different geographic and climatic regions, the identification of substantial variation among strains was possible, allowing for the selection of the most appropriate strain. The undertaken research was a multi-institutional, multinational, collaborative project, organised in five distinct work packages (WPs) with specific objectives.

Firstly, strains were collected and reared, in order to determine which were most suited for EUROMITE purposes. Diagnostic tools allowing for the differentiation of populations were also evaluated, and innovative proposals were developed, based on morphological and morphometrical characters. Morphological measurements were proposed to be repeated in the future in order to define whether the morphological differences that were pinpointed by the present study would be conserved. Secondly, life history experiments were used for the identification of the most arid adapted strain and the analysis of its efficiency under semi-field and field conditions. The obtained results were publicised in three scientific papers.

In addition, the project identified bacteria that exhibited differences in performance. All N. californicus strains were screened for the presence of these microorganisms and the fitness effects of various bacteria in selected strains were determined. A commercial rearing and transport system was subsequently developed based on these findings. Finally, the marketing potential of the proposal in Europe was analysed and the economic benefits of N. californicus for growers of selected crops were identified, based on literature reviews, field surveys and interviews with stakeholders. This research component focused on three crops which were vulnerable to the two-spotted spider mite (TSSM). Finally, a methodology for the provision of economical and quantitative estimates was developed.