Abstract
Onion thrips (Thrips tabaci Lindeman) represent a major limiting factor for greenhouse sweet pepper (Capsicum annuum L.) cultivation in Uzbekistan, causing severe cosmetic damage and vectoring damaging plant viruses. Widespread reliance on chemical insecticides has exacerbated resistance issues and disrupted integrated pest management (IPM) efforts. This study evaluated the efficacy of the entomopathogenic nematode (EPN) Steinernema feltiae (Filipjev) against the soil-dwelling pupal stages of T. tabaci under controlled commercial greenhouse conditions in Tashkent Region, Uzbekistan. Three application rates (25, 50, and 75 infective juveniles [IJs]/cm²) were administered as soil drenches and compared against an untreated control and a chemical benchmark (spinosad). Population reduction was monitored over a four-week post-treatment period using blue sticky traps and foliage sampling. Steinernema feltiae applied at 50 and 75 IJs/cm² resulted in significant reductions in adult emergence of 68.4% and 74.2%, respectively, after 21 days compared to the untreated control. Although spinosad produced faster initial knockdown of foliar thrips, nematode treatments sustained stable suppression of emerging generations without inducing phytotoxicity or disrupting predatory mite populations. These findings confirm that soil-applied S. feltiae provides viable, environmentally benign biological control of T. tabaci pupae in Central Asian greenhouse pepper systems, serving as a critical component in local sustainable crop protection programs.
