Scientific Investigation on the Efficacy of Isolated Nomuraea rileyi and Spinosad against Corn Pests under Laboratory and Field Conditions in Egypt

Abstract

The entomopathogenic fungus, Nomuraea rileyi and commercial BT spinosad were tested on some corn pests: Ostrinia nubilalis, Chilo agamemnon and Sesamia cretica under laboratory and field conditions. Results showed that the N. rileyi LC₅₀ of O. nubilalis, C. agamemnon and S. cretica, 124, 146 and 159 conidia/ml under laboratory conditions. The corresponding figure for Spinosad was 166, 179 and 185 microgram/ ml (g/ml. Under field conditions, results showed that during the season 2011, percentage of O. nubilalis, S. cretica and C. agamemnon infestations were significantly decreased in plots treated with N. rileyi to 253.2, 212.4 and 242.3 individuals after 120 days after the first application as compared to 973.3 in the control.  When spinosad was applied in the field, the percentage of infestations was significantly decreased to 263.3 as compared to 991.3 individuals in the control during both seasons. During the harvest season, the corn weight was significantly increased to 382245.6 and 394060.4 kg/Feddan (Feddan=2400m²) in the plots treated with the fungus N. rileyi as compared to 281040.9 and 271073.2 Kg/Feddan in the control plots. Among plots treated with spinosad the yield significantly increased to 300060.7 and 312984.1 kg/Feddan during season 2011 and 2012, respectively.