Uygulama sonrası zararlı salgınlarına karşı koruma için Beauveria bassiana etkinliğinin depolanmış ürünler üzerinde kalıcılığı

Abstract

This study was carried out to determine the post-treatment efficacy of three local Beauveria bassiana isolates by applying them against adults of three common stored-product pests, Sitophilus oryzae L. (Coleoptera: Curculionidae) Rhyzopertha dominica F. (Col.: Bostrichidae) and Oryzaephilus surinamensis L. (Col.: Silvanidae). For the biological tests, wheat grains were mixed with fungal spores at 1000 ppm (w/w) concentration, then 20 adults were release 1, 15 and 28 days after the treatments. The tests carried out with S. oryzae; the mortality rate was initially 33.3-41.6% and 68.3-76.6%; and declined to 6.6-18.3% and 13.3-21.6% on the 7th and 14th day, respectively, when released 28 days later. The initial mortality of R. dominica was 46.6-50.0% and 93.3-95.0%; and became 10.0-18.3% and 16.6-28.3% when released 28 days later. Oryzaephilus surinamensis mortality on 7th and 14th day was initially 41.6-46.6% and 70.0-85.0%, and decreased to 8.3-15.0% and 13.3-20.0%, respectively, when released 28 days later. Mortality rates at the end of each incubation period, for all testing isolates and insect species, were significantly reduced when waiting time of spores on wheat was prolonged. For all incubation periods, similar mortality rates were obtained from all isolates and similar efficiacy loss was observed. All the results together indicate that the responsible factors for time-dependent loss of activity in B. bassiana isolates should be determined and in line with these data precautions need to be taken.