An Egyptian isolate of Streptomyces afghanensis was examined for the production of antiviral metabolites. Concentrated broth exudates of this microorganism were tested against tobacco mosaic virus (TMV), tomato mosaic virus (ToMV) and potato virus X (PVX) infecting Nicotiana tabacum L. cv. White Burley. Both concentrated metabolites and their acetone extract inhibited local lesion development of the tested viruses. In all cases, maximum antiviral effect was observed 2 hr after infection. The ultrafiltrate of broth culture reduced the number of local PVX lesions produced on the challenged half leaves in the case of later applications.

The pages: CP-51 and CP-54 of Bacillus cereus, together with P-4 and P-14 of B. sphaericus were tested against B. thuringiensis and B. sphaericus strains. P-4 and P-14 were more different in their host range than the other two phages. Results of the bioassay against Culex pipiens larvae presented the inhibition in the larvicidal effects of phage-infected bacteria. Such inhibitory action varied according to the phage and the entomopathogenic bacterial strains.

AbstractThe pages: CP‐51 and CP‐54 of Bacillus cereus, together with P‐4 and P‐14 of B. sphaericus were tested against B. thuringiensis and B. sphaericus strains. P‐4 and P‐14 were more different in their host range than the other two phages. Results of the bioassay against Culex pipiens larvae presented the inhibition in the larvicidal effects of phage‐infected bacteria. Such inhibitory action varied according to the phage and the entomopathogenic bacterial strains.ZusammenfassungWirkungen verschiedener Phagen von Bacillus spp. auf die larvizide Potenz von B. thuringiensis und B. sphaericusEs wurden die Phagen CP‐51 und CP‐54 von Bacillus cereus zusammen mit P‐4 und P‐14 von B. sphaericus gegen Stämme von B. thuringiensis und B. sphaericus getestet. P‐4 und P‐14 wiesen größere Unterschiede in ihrem Wirtskreis auf als die anderen zwei Phagen. Die Ergebnisse gegen Culex pipiens‐Larven zeigten eine Hemmung der larviziden Wirkung von mit Phagen infizierten Bakterien. Diese Hemmungswirkung variierte je nach Phagus und Bakterien‐Stamm.

Naturally present ditches of polluted and non-polluted mosquito breeding places were selected for this work. Water samples were collected before the spraying of the commercially used larvicides Bacillus thuringiensis H-14 and B. sphaericus 1593. Additional samples were obtained 72 h, 1 week, 2 weeks and 3 weeks after spraying. Phages for B. sphaericus only were detected after 72 h and thereafter. The larvicidal effect on Culex pipiens larvae was inhibited significantly with B. sphaericus in the presence of phage-containing filtered water samples. Such inhibition increased with time.

12 water and/or mud samples from different mosquito habitats were tested for the presence of phages specific to Bacillus spp. 37 plaque morphologies were detected on B. thuringiensis. H-14, B. thuringiensis Berliner, B. sphaericus 1593, B. sphaericus IF-114. Samples number 1, 11, 12, 5 and 10 decreased the mortality rates of B. thuringiensis H-14 when added to the larvicidal bioassay system of Culex pipiens. Samples number 5, 11, 9, 12 inhibited the larvicidal activity of B. sphaericus. Ultrafiltrates of water samples, which harbored high numbers of the detected phages exerted more inhibition in the larvicidal potentiality of the tested entomopathogenic bacteria.