The aptness of entompathogenic bacteria against sawtoothed grain beetle (Oryzaephilus surinamensis [L.]) (Coleoptera: Silvanidae) in dates under laboratory conditions

Objective: The sawtoothed grain beetle, Oryzaephilus surinamensis (L). is known as one of the most devastating insect pests in stored date fruits, infrequently found in newly harvested date fruits and raisins but developed a high plenty in dry fruits particularly after long storage. Indiscriminate use of pesticides and fumigants to control insects have resulted in insecticide resistance, environmental hazards, residual toxicity, and pest resurgence so the control trends have been changed and particularly biological control agents like entomopathogenic bacteria Photorhabdus temperata and Xenorhabdus nematophila being used to manage sawtoothed grain beetle. Methods: During present study, the pathogenicity of P. temperata and X. nematophila was evaluated against this crucial pest of stored grains. The bacterial concentrations, 1 × 104, 1 × 105, 1 × 106, 1 × 107 and 1 × 108 cells/ml of both bacteria were prepared and used for the experiments. The prepared solutions were applied directly to the date fruits infested with sawtoothed grain beetles and data were recorded. Results: Significant results were observed for both bacterial treatments as the highest concentration of 108 cells/ml showed to be very effective against the beetle in terms of fecundity, adult emergence, and mortality. In terms of fecundity, 8.66 to 4.33 mean number of eggs were produced at bacterial P. temperata concentrations of 1 × 104 and 1 × 108 cells/ml, respectively. Similarly, the F1 adult emergence for P. temperata was recorded 15.33 and 9 adults at concentrations of 1 × 104 and 1 × 108 cells/ml, respectively. Results showed a similar trend for the X. nematophila species. Conclusions: These results indicate that utilizing bacteria as biological control agents can be advantageous for reducing insect populations in storage facilities and preventing the loss of grains and date fruits that have been stored in storage.