Biochar prepared from Ficus nitida as a carrier for frankincense essential oil (Boswellia sacra) to control some stored product insects

The insecticidal activity of biochar that prepared from Ficus nitida tree residues at 500 and 700οC °C was evaluated against some stored product insects Tribolium castaneum, Rhyzopertha dominica and Oryzaephilus surinamensis, alone and as a carrier for the frankincense essential oil (Boswellia sacra) after 0, 15 and 30 days storage periods. The results showed the O. surinamensis was the most susceptible and the biochar prepared at 500οC was the most active against all tested insects. Also, the toxicity increased with increasing storage period only against R. dominica. The formula was more toxic than biochar or oil alone, especially against T. castaneum. The elemental analysis showed low carbon and high oxygen contents in the biochar 500 and the FTIR analysis showed a large number of functional groups on biochar 500 compared to biochar 700 which may attribute to the slightly higher toxicity of biochar. SEM images of the ventral surface of treated O. surinamensis showed the adhesion of biochar on all body parts, Moreover, the sensilla within the external surface of the elytra are partly absent. Our results suggest the promising use of biochar against some stored product insects and can be effectively loaded with other safe chemicals, more studies are needed to understand its effects on insects.