Pattern and shape effects of orchid flower traps on attractiveness of Thrips palmi (Thysanoptera: Thripidae) in an orchid farm

Abstract

Thrips palmi Karny is widely distributed and causes damage to orchid flowers. Orchid varieties in the genera Dendrobium and Mokara are different in shape. This study determined if different trap patterns which reflect flower shape may affect the attractiveness to thrips. The shapes of Dendrobium and Mokara orchid flowers were characterized and the numbers of flowers per raceme were counted in inflorescences in order to design realistic trap patterns. Four patterns (A, B, C and D) of flower traps were made by increasing the petal area. The mean number of T. palmi in flower pattern A was significantly lower than for flower patterns B, C and D (p < 0.05). The numbers of T. palmi in flower traps increased with flower petal area (r = 0.63, p < 0.05), but decreased with increasing length of flower contour (r = -0.56, p < 0.05). Six patterns (B1, B2, B3, B4, B5 and B6) of inflorescence traps were created by increasing the number of flowers per raceme. The numbers of T. palmi increased with increased numbers of flowers per raceme, pattern area and length of contour (r = 0.74, p < 0.05). Thus, inflorescence patterns and sizes affected the numbers of T. palmi attracted. The results of this research indicated that not only the patterns but also the sizes of traps were important factors for attractiveness to thrips. This information may be useful in designing and monitoring control programs for T. palmi.