The Effect of some Factors on the Efficacy of Pheromone Traps for Capturing Leopard Moth in Walnut Orchards

The leopard moth, Zeuzera pyrina (L.) (Lepidoptera, Cossidae), is an important xylophagous pest on different trees such as walnut, Juglans regia (L.), which weaken the host trees by canalling in the trunks. Regarding type of damage and host range of the pest, it is so difficult to control. Catching of the male moths by traps containing sex pheromone lures is a promising method to control the pest. There are many factors influencing potential of pheromone traps. Some of these factors, such as trap shape, trap color and height of trap placement, can be manipulated by the user or grower. One of the components of the pheromone blend of leopard moth is (E, Z)-2, 13-octadecadien-1-ol acetate, which seems to be the pheromone compound of the current clearwing moth Synanthedon tipuliformis (Clerck) (Sesiidae).
Separate experiments were conducted in walnut orchards (each having more than 10 years of damage history and area of 0.5-3.5 ha) of Najaf-Abad County (Isfahan, Iran). Pheromone traps were placed on the trees in late April. The traps were inspected at 5-day intervals until late July. The number of catched lthe moth males was recorded and also, during the growth season average of the capturing per trap per night was calculated. Lures were replaced monthly. In the present study the effects of four factors (pheromone type, trap shape, trap color and height of trap placement) on the number of catched leopard moth males were evaluated. The experiments for different factors were conducted as follows: 1. Pheromone type and lures of pheromones of S. tipuliformis and Z. pyrina, both of which were provided from Agriscense Company, were compared. 2. Trap shape, four shapes (cylindrical or standard, delta, wing and funnel) were compared. The experiment was conducted using white-colored traps placed at the height of 1.5m above the ground and had S. tipuliformis lures. 3. Trap color, three separate experiments were conducted as follows: delta traps with 3 colors (white, yellow and green), delta traps with 6 colors (white, yellow, green, glossy gray, normal gray and red), cylindrical traps with 4 colors (green, yellow, with and normal gray). In the experiments, traps with height of 2m above the ground had S. tipuliformis lures. 4. Height of trap placement, two separate experiments with delta and cylindrical traps were conducted for comparison of three placement heights of 1.5, 3 and more than 6 meters above the ground. The experiment was conducted using white - colored traps which had S. tipuliformis lures. All above experiments were conducted in a randomized complete block design with three or four replications. Analysis of variance was performed after data transformation, using log (x). In all experiments means were compared using Tukey̕s test, except for the experiment of pheromone type, which compared using t-student test.
In the present study the catching was started on 4th of May and lasted till 26 July. During 105 nights of trapping, traps, which were continuing lures of S. tipuliformis and Z. pyrina, were captured in total 77 and 7 leopard moth males, respectively. Means of capturing per trap per night were 0.18 and 0.01, respectively. Results showed that catching of male moths were significantly higher on traps containing lures of S. tipuliformis than those containing lures of Z. pyrina. In comparison to shape of traps, significantly the highest catches belonged to funnel trap. The superiority of the funnel traps could be related to its specific structure. Comparison of 6 colors with delta traps showed that green and yellow colors had the highest and the lowest catching, respectively. However, in comparison of 4 colors with cylindrical trap, the highest and the lowest catching belonged to normal gray and yellow, respectively. In the present study, ranking of trap colors changed by trap shape. The phenomenon might be related to the interactions between the factors of traps̕ shape and color. In the experiments of height of trap placement, the highest catching was obtained at the height more than 6 m with both delta and wing traps. It shows that the amount of catching is increasing by increasing in the height of trap placement.
Pheromone traps could be used as a useful method for catching leopard moths males. However efficacy of the pheromone traps was influenced by several factors, including type of pheromone, trap shape, trap color and height of trap placement.