Influence of planting date on the relationship between populations of Frankliniella flower thrips and predatory bug Orius niger in cotton

The influence of three planting dates [mid-March (early-planted), 15 April-15 May (normal-or timely planted) and mid-June (late-planted)] of cotton variety SG 125 on the relationship between populations of Frankliniella flower thrips (Thysanoptera: Thripidae) and the predatory bug, Orius niger (Wolff) (Hemiptera: Anthocoridae) were investigated in Adana province in the Eastern Mediterranean region of Turkey in 2003 and 2004. To facilitate emergences of cotton seedlings in early-plantings, cotton rows were mulched after sowing. Adult Frankliniella occidentalis (Pergande) dominated the thrips populations in flowers and colonized the flowers rapidly with high numbers in early-and normal-planted cotton, while adult F. intonsa (Trybom) were significantly more abundant on flowers in late-planted cotton (P <= 0.05). The significantly higher but short-lasted larval developments were detected only in late-planted cotton in both years (P <= 0.05). Although some scarring and silvering damage on leaves and bolls caused by larval feedings occurred in the late-planted cotton, Frankliniella flower thrips did not have any detrimental effect on plant developments and cotton yields in any of the plantings. Early- and mulch-planted cotton produced significantly higher numbers of fruiting parts and also cotton yield, followed by normal-planted cotton (P <= 0.05). We commented that the lower cotton yield in late-planted cotton were due to physiologically caused abscissions of the fruiting parts under unfavourable climatic conditions. O. niger was an effective predatory insect of Frankliniella thrips in the flowers especially in normal-planted cotton, as it was detected in significantly high numbers and thrips-to-predator ratios were lower. It is suggested that early planting of cotton in March could be a good cultural practice in the Mediterranean region.