Assessment of Rice Gall Midge, Orseolia oryzae (Wood Mason) Biotype Using Gene Differentials in Rudrur, Nizamabad District, Telangana State, India

Abstract

The rice gall midge (Orseolia oryzae) remains a major constraint to rice production in Telangana, where recent outbreaks have raised concerns about shifts in virulence and the possible emergence of new biotypes. To generate reliable, locality-specific information for resistance deployment, a structured biotype characterization study was carried out for three consecutive kharif seasons (2023–2025) at the Regional Sugarcane and Rice Research Station (RS&RRS), Rudrur. Twenty standard rice gall-midge differential lines of 5 groups, representing Gm1-Gm11 resistance sources and unknown sources were evaluated under natural field infestation using established biotype identification protocols. Consistent reactions were recorded across seasons, with all Group II differentials (Gm2 - Gm10) showing uniform susceptibility, while differentials carrying Gm1, Gm3, Gm4, Gm8, and Gm11 expressed stable resistance. The susceptible check TN1 exhibited high silver-shoot incidence each year, confirming adequate pest pressure. The cumulative resistance susceptibility pattern observed across Groups I-V corresponded closely with the diagnostic profile of Biotype 3. These findings provide the first comprehensive evidence on the prevailing gall-midge biotype in the Rudrur region of Northern Telangana and offer a robust foundation for selecting suitable resistant varieties and designing sustainable pest-management strategies for the state’s rice ecosystems.