Impact of some plant powders on Sitophilus granarius (L.) and Rhizopertha dominica (Fab.) for protecting wheat grain.

This study was carried out in the laboratory to investigate the insecticidal potency of some plant powders (Eucalyptus globulus Labill, Lantana camara, Schinus terebinthifolius Raddi, Malaleuca alternifolia, Terminalia arjuna, Ficus nitida, Taxodium distichum, Origanum majorana, Stems and covers of wheat kernels Triticum aestivum L) against the adult stage of Sitophilus granarius (L.) and Rhizopertha dominica (Fab). Mortality percentages were registered at three exposure periods (3, 6, and 9 days). Obtained results showed an increase in the mortality percentages of S. granarius and R. dominica in relation to the increase in concentration from 0.0625 to 1.0 g/g and of the exposure time from 3 to 9 days. Data revealed that O. majorana, with the lowest LC50 value (0.136 g), was the most toxic to S. granarius while M. alternifoli with LC50 value had the lowest toxic for the same insect pest. Among the tested plant powders for insecticidal activity, T. arjuna was the most effective in controlling adult R. dominica, with the LC50 of 0.140 g/g; while the least was in M. alternifolia with the LC50 of 0.306 g/g. The median lethal time (LT50) required to kill 50% was recorded. Although the mortality time of all treatments was decreased with increasing concentrations, differences in the median lethal time were found between the plant powders. The tested botanical powders represent valuable tools with the potential of integration into the management of both tested insect pests. [ABSTRACT FROM AUTHOR]