Spider mite control in arid conditions
Spider mites are a formidable pest of many food and ornamental crops. At high humidity and moderate temperatures, the predatory mite Phytoseiulus persimilis provides adequate control but when the humidity dips and temperatures rise, the level of control is below par. As growing conditions for many of the spider mite's crops fall into the low-humidity, high-temperature bracket, the EU-funded project Euromite investigated an alternative for biological spider mite control. The project team selected the species Neoseiulus californicus as, although it is less voracious than Phytoseiulus, it needs a minimum of 60 % humidity and temperatures in the range 15–30 ˚C. Selection of the most efficient strain for arid conditions was a relatively easy task as the mite is native to a range of geographic and climatic regions. Project scientists evaluated a range of diagnostic tools allowing for the differentiation of morphological and morphometric characters of candidate mites. The idea was to make sure the physical characteristics pinpointed by the present study could be conserved. Interestingly, bacterial partners are associated with the predatory mite and the fitness of the microbes was assessed for the selected strains as well as the microorganisms' influence on the host. Overall, work was done on three crops vulnerable to the two-spotted spider mite, a common pest in the European horticulture industry. Economic commercial rearing and transport methods were based on these findings. Euromite completed research on a biological control mechanism and assessed the marketing potential and economic benefits for Europe. This study will help to provide safer and healthier crops in southern Europe, the source of most of the continent's fruit and vegetables. In the rest of Europe, horticultural production under glass and plastic also stand to benefit from application of this host/parasite relationship.
