Atracción del trips Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) con trampas de luz en un cultivo de Gerbera jamesonii (G.)

Abstract

Flower thrips Frankliniella occidentalis (P.) may cause severe economic losses due to its periodic occurrence, the damage caused by sucking sap and spreading plant diseases through the transmission of viruses, mainly in horticultural crops and ornamental plants, such as roses, gerbera and carnation. Monitoring through sticky colored traps provides a simple method of obtaining estimates of thrips population densities. These traps may measure a far more rapid estimate of pest population than labor-intensive absolute methods of counting individuals, as these traps continuously catch a higher number of thrips throughout the time. The utility of these sticky colored traps methods as tools for monitoring thrips population has been assessed in greenhouses, taking into consideration the traps attractiveness and the capture rate according to species. This work was conducted once a serious damage on flowers (Frankliniella occidentalis) caused by thrips was observed, mainly in a Gerbera jamesonii crop located in a greenhouse for cut flowers production in the Argentine Agricultural Experiment Station (EEA) of the National Institute for Agricultural Technology (INTA) of Concordia, Province of Entre Rios (Argentina). The main purpose of this work was to evaluate the effectiveness of sticky light traps of two colors (yellow and blue, both of them selected due to its known attractiveness to various thrips species and different light intensities (25 and 40 watt bulb)) on the capture of flower thrips. These traps were made from cardboard boxes (22 × 30 × 20 cm) with an opening (10×15 cm) through which light passes and covered with a plastic wrap coated with adhesive material on which the adults thrips become trapped (The Tanglefoot Company Adhesive Pest Management & Tree Protection Products, USA). The trial consisted of the following four treatments: (i) yellow light trap with 25 watt bulb; (ii) yellow light trap with 40 watt bulb; (iii) blue light trap with 25 watt bulb and (iv) blue light trap with 40 watts bulb. Each treatment was replicated four times. Four sticky light traps were positioned on both sides of the Gerbera jamesonii flowerbeds to half-height of cut flowers. For each trial, the trap placement in each experimental design was at random. The bulbs were turned on at sunset and turned off in the morning when the traps were removed and carried to the laboratory and the number of adult thrips caught was counted. On the one hand, yellow light traps with both intensities (25 and 40 watt bulbs) became significantly more attractive to F. occidentalis adults in comparison to the capture rate on the blue ones with the same intensity; and, on the other hand, both yellow and blue sticky light traps were much more efficient for the capture of thrips F. occidentalis with 40 watt intensity bulbs. One reason why thrips would respond to various visual stimuli (a more effective response to w color and its high intensity) would be related to its response to the different changes of physiological features of plants. These changes would play a significant important role in sending a visual signal (color and intensity), which would lead Frankliniella occidentalis (P.) to change the search behavior as to its feeding sources and oviposition.