Phototropism of Tuta absoluta, an important insect pest of fruit and vegetable crops, to blue-violet light wavelengths

Author of the article:ZHANG Gui-Fen, ZHANG Yi-Bo, ZHAO Jing-Na, XIAN Xiao-Qing, WANG Yu-Sheng, LIU Wan-Xue, WAN Fang-Hao,

Author's Workplace：State Key Laboratory for Biology of Plant Diseases and Insect Pests, Key Laboratory of Invasive Alien Species Control, Ministry of Agriculture and Rural Affairs, Key Laboratory of Integrated Pest Management of Crop, Ministry of Agriculture and Rural Affairs, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China

Key Words：light trap; physical pest control; pregnant female moth; trapping efficacy

Abstract：[Objectives]  To develop a more effective light trap for monitoring and controlling Tuta absoluta, an important insect pest of tomatoes in China. [Methods]  The phototropism of T. absoluta to five different wavelengths of blue-violet light; ultraviolet (380 nm), violet (405 nm and 425 nm) and blue (445 nm and 460 nm), was evaluated in greenhouses. The distance between the light tube and the ground was 20 cm. The overall number of moths, and the number of females and gravid females, trapped by light traps of each wavelength were counted daily. [Results]  All five wavelengths trapped male and female adults. Over 50 days, a total of 309.0 adults were trapped per trap per day by the 380 nm ultraviolet-light trap, 99.3 by the 405 nm violet-light trap, 47.0 by the 425 nm violet-light trap, 37.6 by the 460 nm blue-light trap, and 28.3 by the 445 nm blue-light trap. The ultraviolet 380 nm light trap captured significantly more (P<0.05) moths per day than the other wavelengths, followed by the 405 nm violet-light, 425 nm violet-light and 460 nm blue-light traps. The 445 nm blue-light trap captured significantly fewer (P<0.05) moths per day than the other wavelengths. All five wavelengths caught a higher proportion (> 65%) of female moths. The ultraviolet 380 nm light trap trapped the highest number of female adults per day (253.2 female individuals), which was respectively 3.67, 8.53, 14.72 and 11.46 times as many as were captured by the violet 405 nm and 425 nm light traps or the blue 445 nm and 460 nm light traps (P<0.001). The violet 405 nm light trap captured an average of 69.0 females per day, 4.01 times more than were captured by the blue 445 nm and 460 nm light traps (P<0.05). More than 84% of females captured were gravid; there was no significant difference in the proportion of gravid females attracted to the different wavelengths. [Conclusion]  Blue-violet light traps trap a higher proportion of female T. absoluta than males, most of which (84%) are gravid. Compared to violet and blue light, ultraviolet (380 nm) light is best for attracting T. absoluta to traps.