Light Trap Density for Capturing the Tomato Leafminer Moth “Tuta absoluta” in Greenhouses

Tomato leafminer, Tuta absoluta (Meyrick), is considered as the most important tomato pest in the world. The pest is also devastated tomato fields and considered as a big threat for tomato production especially in greenhouses in Iran. The exceptional speed and extent of T. absoluta enforced to use several pest control methods for controlling the damages. The strategies might be applied a complex of different approaches from cultural to biological and finally chemicals control. Chemical pesticides are often used to control this pest, which not only pose a risk for environment, but also is harmful for public health (due to the fresh use of the product). Therefore, the use of other pests control methods should be considered. Mass trapping of the adults are could significantly reduce the percentage of infested leaves and fruits. Given that the adults are nocturnal, they fly towards a light source, since the night light traps are developed to capture adult. The use of light traps is one of the low-cost and low-risk methods for capturing adult’s moths, and as a consequence of reducing the pest damages.
Methods and Materials: Cylindrical transparent containers (8.5 cm diameter and 15 cm height), which were made from clear plastic (polyethylene terephthalate (PET)) were chosen as traps. For entering the attracted moths, several holes (0.5 cm in diameter) were embedded in the traps walls, except the below part (2.5 cm) that some 0.5% detergent solution were poured in there to entrap the captured moths. Then a BLB bulb was installed in each trap as light sources. The traps were installed at about 70 cm above the infested plants, with four different density (2, 4, 6 and 8 in a 1000 m2 of greenhouses) to find out the best density of traps. The comparisons were done in a completely randomized design with six replications (six days). The light of the traps were turn on from the sunset until next morning. The numbers of captured moths from each trap were recorded and were analyzed using generalized linear models.

In the greenhouse assessment in Hormozgan province, the mean numbers of moths were 27.75 in the two-trap and 14.39 in the four-trap, while for the four-trap were 11.67 compare to the six- traps 7.87, and finally for the six-trap were 112.67 compare to the eight-trap 113.33. In Qazvin province, the average numbers of moths were 10.93 in the two-trap compare to 13.61 for the four traps, while, the number of moths for the four-trap were 11.38 and for the six-trap were 11.91. In the Markazi province (Greenhouse complex of Aveh), the mean numbers of moths were 27.70 for the two-trap treatment and 18.95 for the four-trap treatment. In the second step, the mean numbers of moths were 8.25 in the four-trap compare to 9.47 for the six-traps. Mass tapping is an approach of pest control methods in several crops. This technique is non-poisonous and non-hazardous to natural enemies as a part of the integrated pest control program, and environmentally friendly. The light traps can captured not only males, but also a large number of females. Therefore, light traps are more effective than conventional pheromone-baited water traps in reducing the damage especially at low/moderate T. absoluta population density. Up to now most of the used light traps for capturing T. absoluta, were installed on the ground. However, the adult’s moths can fly very well (250 matters in two hours) and could fly from one place to another place and disperse easily and quickly. The present study demonstrates the success of mass trapping of T. absoluta by hanging up the light traps above the infested tomato plants.

installing the light trap up to the height of the host plants could capture more adults and could reduce the damages. Based on the results we can say that, during the growing season, four traps light with a BLB source is sufficient for 1000 m2 of greenhouses that should be installed above the plants canopy. This technique can be used in the IPM programs in greenhouses. Where, the isolation of area will strongly raise the chances of the mass trapping methods by reducing the possibility of immigration of adult’s pests from adjacent area. Of course, combination with other pest control methods should also be considered.