Investigation of fipronil resistance in German cockroach (Blattella germanica L.) populations in Antalya province

This study was conducted to determine the levels of resistance to fipronil in German cockroach (Blattella germanica L.) populations collected from various regions of Antalya Province. B. germanica is a significant public health pest commonly found in indoor environments and has a high potential to develop resistance to insecticides. In this study, field populations collected from 12 different locations were exposed to fipronil solutions at doses ranging from 0.25 to 140 ng/ml, selected according to the susceptibility levels of each population. Mortality rates were recorded 72 hours after treatment, and LD₅₀ values were calculated using Probit analysis. Resistance ratios (RR) were determined by dividing the LD₅₀ values of field populations by the LD₅₀ value of a susceptible reference population. The results showed that while fipronil remains an effective insecticide overall, low-level resistance has emerged in some populations. In nine out of twelve populations, LD₅₀ values ranged between 1 and 3 ng/ml. These findings indicate that the continuous and intensive use of fipronil alone may promote resistance development and emphasize the need for its integration into broader Integrated Pest Management (IPM) strategies. This thesis represents the first systematic investigation of fipronil resistance in B. germanica populations in Türkiye. The findings provide valuable data for reassessing local insecticide use practices and highlight the importance of establishing resistance monitoring programs.