LABORATORY PERFORMANCE OF 0.05% FIPRONIL AND 2.15% IMIDACLPORID GEL BAITS AGAINST GERMAN COCKROACH BLATTELLA GERMANICA

: Introduction: Application of insecticidal baits is one of the most common and effective strategies for controlling German cockroach, (Blattella germanica L.) The current study was designed to investigate the susceptibility level of German cockroach to fipronil and imidacloprid gel baits in laboratory situation and to recommend its usage in Iran. Methods: This experimental study was conducted on eight German cockroach strains. Tests were conducted on newly emerged adult males (Ultimately 3 weeks old). Adult male German cockroachs starved for 12 hours, and then ingested fipronil and imidacloprid gel baits for 2 hours. After given time was over, we removed the bait and replaced it with mice foods. Mortality was recorded at 12 intervals for 6 days. Data were pooled and assessed by probit regression analysis. Results: Feeding assays revealed that in all strains mortality rate after 2 hours ingestion of fipronil and imidacloprid gel baits for 144 hours (6 days) was 100%. In all strains more than 60% mortality in imidacloprid ingested gel bait after 24 hours and 100% mortality (except Shahmorady and Zanjan dormitory strains) after 48 hours was observed. Whereas, in some strains 10-30% mortality in fipronil ingested gel bait was seen and in some strains no mortality after 24 hours while most of them had a rate of 60% mortality after 48 hours. These observations indicate that the imidacloprid gel bait operates faster than the fipronil gel bait as is expected. The susceptible strain showed LT50 of 47.13 and 11.31 h for fipronil and imidacloprid gel baits, respectively. The result of this investigation indicated that all feral strains are susceptible to fipronil and imidacloprid gel baits. Conclusion: Considerins the ever-increasing infestation of human habitations with German cockroach, and its resistance to conventional insecticides(esp. pyrethroides), its intensity in the future. is increasingly growing Toxic fipronil bait can be an appropriate substitute for controlling this hygiene pest in Iran.