Applied entomology in Spanish greenhouse horticulture

Until 2007, greenhouse horticulture in Spain has suffered severe problems related to the use of pesticides against insect pests. Resistance of some key pests to the available active ingredients lead to a massive use of insecticides and, as a consequence, to severe problems with chemical residues on the fruits produced. Thanks to efforts in investigation by many institutes and companies, this problem has been resolved, making possible the large scale introduction of biological control and other alternative measures. During the crop season of 2009-2010, biological control is applied in approximately 59% of the total of 24,000 Ha in the province of Almeria. Bumblebee pollination has been applied in the total area of the tomato crops since 1995. The massive adoption of IPM has created the possibility to extend the use of bee or bumblebee hives also in other crops, in which, until only a few years ago, it was impossible to maintain pollinators alive due to the frequent use of incompatible pesticides. Considering the applications of pollinators and biological control agents together, it can be concluded that commercially introduced beneficial arthropods play an important role in about 88% of the total greenhouse area. One of the possible preventive measures against insect pests is the use of UV absorbing greenhouse covers. These materials transmit the light the plant needs for its photosynthesis and the visible light to man, but block UV, the most important visible colour for insects. The use of these materials may reduce the pest incidences but might also alter the activity of pollinators. This effect was investigated both through bioassays and field trials. It was concluded that the reduction of the activity under UV blocking materials is not significant with respect to bumblebees, but quite important for honeybees.