The Mechanisms of Delayed Insecticidal Action of Streptothricin Antibiotics. III. The Mode of Delayed Insecticidal Action of Racemomycin-A

Abstract

Racemomycin-A (RM-A) showed delayed insecticidal activity against female adults (3d after adult emergence) of Musca domestica and Blattella germanica treated by the topical application method;the LD₅₀ values were 3.76 μg/insect (3 d) and 32.5 μg/insect (7d), respectively. RM-A also showed delayed insecticidal activity against the 3rd instar larva of Culex pipiens pallens and M. domestica treated by the immersion method;the LC₅₀ value for the former was 2.46 ppm (3d), but the insecticidal effect against the latter was weak. RM-A applied by the immersion method also inhibited the adult emergence of C. pipiens pallens and M. domestica, with IC₅₀ values of 1.41 and 199.5 ppm, respectively. Furthermore, RM-A exhibited insecticidal activity against female adults of B. germanica and larvae of Periplaneta fuliginosa treated by the bait method. The insecticidal activity of RM-A on adults of B. germanica was almost equal to that of boric acid bait agent (15%) at the concentration of 2.0%.