Study On Thrips Species And Its Natural Enemies On Tobacco In Yunnan Province

Tobacco as an important economic crop in Yunnan Province, the area and the total yield ranks first in China. The quality and yield of tobacco, and tobacco growers’ income were affected seriously by insect pests. Thrips is one of the main pest of tobacco. Thrips is the common name of Thysanoptera insects. In addition to the direct feeding damage on tobacco, thrips can also transmit a variety of plant virus efficiently, resulting in greater economic loss than the direct feeding damage, and the tobacco production was seriously treatened. The research studied the tobacco thrips and its natural enemy species and its population dynamics in Yunnan Province. The results as follows:(1) The average damage level of tobacco plant at resettling stage was(49.80 ± 6.49) %; 2613 thrips were collected on the tobacco and weeds in tobacco field in Yunnan province, representing 3 families, 9 genera, 16 species. Thrips flavus and T. flavidulus were the dominant species, occupying 37.37% and 34.79% respectively; 1096 thrips were collected on tobacco, average 1.10 thrips per tobacco, which can be classified into 2 families, 4 genera, 11 species. T. flavidulus was the dominant species, occupying 47.90% of the total thrips number on tobacco. 124 predator enemies were collected in tobacco fields, Orius bifilarus and O. strigicollis were main thrips enemies on tobacco plant at resettling stage.(2) The average damage level of tobacco plant was(33.1 ± 1.15) % at seedling stage, of which tobacco in Jiangchuan County suffered the most serious damage, the average damage level reached(86.67 ± 2.03) %. 472 thrips were collected on tobacco, which can be classified into 1 family, 2 genera, 6 species. Frankliniella occidentalis was the dominant species of tobacco at seedling stage, occupying 76.69% of the total thrips number. None enemy was collected on tobacco at this stage.(3) The average damage level of tobacco flower was(37.19 ± 10.21) %. 385 thrips were collected on tobacco flowers in Yuxi city, which can be classified into 2 families, 4 genera, 8 species. T. hawaiiensis was the dominant species of tobacco flower, occupying 62.34% of the total number of thrips collected on tobacco flowers. O. bifilarus was the main natural enemy on tobacco flowers. A new record species in Yunnan province—Arorathrips mexicanus was found on Eleusine indica in tobacco field in Yuanjiang County.(4) Study on thrips and its natural enemy species and population dynamic on previous crops of tobacco, cabbage and radish. The result showed that: F. occidentalis was the dominant species, accounting for 40.15% and 59.11% of the total number of thrips on cabbage and radish respectively. F. intonsa, T. flavus and T. flavidulus were also collected on cabbage and radish, Mycterothrips consociatus was only collected 1 on cabbage. Thrips population on cabbage and radish reached the maximum value at full flowering stage, 58.36 and 51.82 thrips were collected per plant respectively. O. bifilarus was the main natural enemy on previous crops of tobacco, showed a certain control effect on thrips.(5) Study on thrips and its natural enemy species and population dynamic on tobacco. The result showed that: The dominant thrips species and its natural enemies were different at different growth stage of tobacco. T. flavidulus and F. occidentalis were the dominant thrips species on tobacco at root elongation stage, accounting for 39.69% and 37.40% of the total number of this stage respectively. Thrips number maintained a low level at fast growing and maturation stage with the increasing of nicotine content. F. occidentalis and T. hawaiiensis were the dominant thrips species respectively. The thrips population rised quickly at flowering stage, T. hawaiiensis was the dominant species, accounting for 70.04 % of the total number of this stage. Minute pirate bug, spiders, ladybug were collected on tobacco, and O. bifilarus was the main thrips enemy, showed a same change trend with thrips in the whole tobacco growth period.(6) The key of tobacco thrips adults was compiled, providing the identify information of tobacco thrips species.Investigation results on thrips and its natural enemy species, distribution and population dynamics on tobacco provided basic information for management of thrips and especially tobacco virus diseases transmitted by the thrips.