Population fluctuations of sucking pests and their effects in terms of yield and quality on some cotton varieties

It was aimed to determine preferences of the pests in different cotton varieties by monitoring population dynamics of the pest populations in the early and late cotton varieties. The experiments were carried out in 2014-2016 to assess relationship between leave hairiness and population density of pest. Effects of quality and yields were identified and it was also aimed that varieties which less preferred by the pests were determined and finally reducing unnecessary pesticide spraying. Özbek105, GSN12, Carmen, Claudia, Gloria, Flash, PG2018, Carizma varieties were used as plant materials. Thrips tabaci Lind, Frankliniella intonsa Tryb, and F. occidentalis (Perg) belonging to family Thripidae; Aphis gossypii (Glov) belonging to family Aphididae; Asymmetrasca decedens (Paoli) belonging to family Cicadellidae; Bemisia tabaci (Genn) belonging to family Aleyrodidae; Creontiades pallidus Rumb belonging to family Miridae were observed on cotton plants. Differences in population dynamic of the pest were detected. While T. tabaci and B. tabaci prefer hairy leaf varieties of Özbek105, GSN12 and PG2018, the pests did not prefer hairless varieties (Gloria, Claudia Carmen and Flash). The highest population density of T. tabaci were detected on Özbek105 variety (in 2014: 2,1 individuals/leaf; in 2015: 0,9 individuals/leaf; in 2016: 0,6 individuals/leaf;), the lowest population diversity of T. tabaci were detected on Claudia variety (in 2014: 0,9 individuals/leaf; in 2015: 0,4 individuals/leaf in 2016: 1,1 individuals/leaf) The highest population density of F. occidentalis was observed on the hairy cotton varieties, but it was proposed that this was related to the flowering stage of the cotton varieties. The highest population density of A. decedens was obtained on Gloria and Claudia (year 2014: 2,6 and 2,7 individuals/leaf, year 2015: 6,5 individuals/leaf, year 2016: 3 and 3.4 individuals/leaf). Because A. gossypii didn't reach to the economic threshold level and also detected low level of its population, the pest preferences of plant varieties could not be identified. No significant difference has been detected for C. pallidus among the varieties. When the chemical treated and untreated plots compared, statistically significant differences were found for cotton yields. The lowest yield in 2014 was obtained from variety Gloria in untreated and treated plots as 171,13 kg/da, and 99,48 kg/da respectively. The highest yield in 2014 was detected in PG2018 variety in untreated and treated plots as 318 kg/da ve 268,60 kg/da respectively. In 2015, the lowest yield in treated plots was 244,60 kg/da in variety Carmen; the highest yield in treated plots was 244,60 kg/da in variety Carmen. The untreated plots, the lowest yield was 124,70 kg/da in variety Claudia, the highest yield was 221,04 kg/da in variety Özbek105. In the year 2016, treated and untreated plots, the lowest yield was 287,55 and 138,22 kg/da in variety Carmen respectively, the highest yield was 525,75 kg/da in variety PG2018 and 274,72 kg/da in Carizma respectively. Eight different cotton varieties were evaluated for the fiber quality parameters in treated and untreated plots. Statistically differences among the varieties could be detected for the micronair, fiber length and SCI between treated and untreated plots. On the other hand, statistically differences were obtained for the fiber strength and fiber mature among cotton varieties. Keywords: Cotton, Gossypium hirsitum, Sucking Pests, Population Fluctuation, Yield, Quality