Susceptibility of Periplaneta americana (Blattodea: Blattidae) to two isolates of Steinernema rarum (Rhabditida: Steinernematidae) of the province of Cordoba, Argentina

The effect of Steinernema rarum (Doucet) ((OLI) and N105 strains) from Cordoba province on the American cockroach Periplaneta americana (L.) was evaluated. Two doses: 3,200 and 6,400 infective juveniles (IJs) / host were used and a control group was considered. Forty-nine insects per treatment were evaluated. Infections were maintained at 25 +/- 1 degrees C. Dead insects were recorded every 24 h during 15 days. Steinernema rarum (OLI) caused a mortality of 67% and 89%, for 3,200 and 6,400 Jls, respectively. With isolate N105, mortality never exceeded 65%. The two isolates completed their life cycle with the production and emergence of Jls in P. americana: for S. rarum (OLI), 255,215 +/- 3 x 10(4) and 328,102 +/- 3 x 10(4) , for D3200 and D6400, respectively; for S. rarum N105, 142,451 +/- 3 x 10(4) and 188,253 +/- 3 x 10(4) , D3200 and D6400, respectively. Significant differences between strains for the average number of Jls (F-3,F-126 = 5,26; p <= 0,001) were registered. Based on these results, Blattodea is incorporated into the range of hosts of S. rarum (OLI) and it is disclosed that P. americana is the first host for S. rarum N105 in laboratory.