Aboveground thrips infestation influences root growth in ThryvOn and non-ThryvOn cotton

Tobacco thrips (Frankliniella fusca Hinds) are a severe pest of cotton seedlings that cause significant economic losses annually in the USA. In previous studies, we have observed that higher thrips infestations are linked to a reduction of cotton root length, highlighting the need to better understand the relationship between thrips infestation levels and cotton root development. The use of a new Bt cotton (ThryvOn) has proven to control damaging thrips populations. However, it is unknown if ThryvOn has greater root growth relative to non-ThryvOn when infested with equivalent levels of thrips. Greenhouse experiments were conducted with both ThryvOn and non-ThryvOn (DP1646) cotton. Seedlings were infested with 5, 10, or 15 female adult F. fusca, while controls were not infested. After 12 days, aboveground biomass was measured, and root parameters were analyzed using WinRHIZO root-scanner and software. Our results confirmed that root development is reduced with thrips infestation. More specifically, we noticed that thrips infestation reduces root length, volume, projected area, and surface area for both cotton lines. Aboveground biomass was not reduced on ThryvOn cotton. Therefore, ThryvOn is tolerating thrips infestation better than non-ThryvOn cotton, supporting more sustainable and productive farming practices.