Response of predominant rodent borne diseases to difethialone anticoagulant rodenticide under laboratory conditions.

Susceptibility level to difethialone 0.0025% anticoagulant rodenticide by bioassay method were studied (during 2009 & 2010) to the Norway rat Rattus norvegicus and the roof rat Rattus rattus trapped from Giza and Menoufia Governorates (G) where anticoagulant rodenticides were used to control rodents for long periods. Complete mortality was obtained for both species at two Governorates within 3 days no-choice feeding test period, indicated to be susceptible to difethialone. The bait consumption and corresponding active ingredient intake was more in R. rattus than R. norvegicus. The mean intake values for R. rattus were 3.1 & 2.29 mg/kg at Giza G and 2.63 & 2.65 mg/kg at Menoufia G for males and females and for R. norvegicus 1.93 & 2.29 mg/kg at Giza and 2.14 & 2.09 mg/kg at Menoufia for males and females, respectively. Within 2 days no-choice feeding test period, difethialone caused mortality ranged between 70-80% for both species. The higher intake values of active ingredient for died animals was recorded for R. rattus males at Giza G (2.23 mg/kg), while the lower value was recorded for R. norvegicus females of at Menoufia G (1.37 mg/kg). Within one-day no-choice feeding test period, difethialone caused mortality ranged between 60-70% for R. norvegicus and 50-60% to R. rattus. The higher intake values for died animals were recorded for R. rattus males at Giza G (1.45 mg/kg), while the lower value was recorded for R. norvegicus males at Giza (0.75 mg/kg).