The Vertical Distribution and Monitoring Population of Thrips Palmi Karny (Thysanoptera: Thripidae) on Solanum Tuberosum (potato plant)

The study of vertical distribution and monitoring population of Thrips palmi Karny (Thysanoptera: Thripidae) on (potato plant) Solanum tuberosum was conducted at the field station of Lembang Vegetable Research Institute, West Java (alt. 1250 m) during dry season. The experiment was free from insecticide application. A total of 15 plant samples were taken diagonally from each plot and the number of nymphs and adults found on every leaf were recorded. Analysis of leaf nutrient contents was done at the Biotechnology Research Center, Bogor. Leaf factors observed were the protein content, total sugar, fat, mineral and thickness of leaves. Sample leaves were taken from three different positions: upper, middle and lower stratum, at four different ages of plant: 4, 6, 8 and 10 weeks after planting (WAP). The results showed that T. palmi invaded potato plants since the terminal shoots emergence stage. The adults were found on the upper leaves (first to fifth), while nymphs were mostly found on the middle leaves. Appropriate nutritional and physical factors of plant leaves caused the adults of T. palmi to choose the upper leaves as their food source and a place to lay eggs. Monitoring T. palmi populations are best done by observing middle leaves and the best time for monitoring is 0700-0800 or 1600-1700.