3 research outputs found
Persistence Of Active Compounds Of Essential Oils Of Clausena Anisata (Rutaceae) And Plectranthus Glandulosus (Labiateae) Used As Insecticides On Maize Grains And Flour
Maize occupies an important place in the resolution of food insecurity
problems in the sub-Saharan region of Africa. However due to poor
post-harvest technologies, more than 35% of annual crop yield is often
lost during storage as a consequence of insect attack. While chemical
pesticides constitute an efficient tool for reducing these losses,
current excessive usage runs the risk of modifying the quality and
safety of foods produced from these grains. The use of essential oils
of plant origin for grain storage has been advocated as a non invasive
method with limited or no effect on the quality and safety of the
grains or their products. This study was carried out as an evidence of
bioactivity of two essential oils of Clausena anisata (Willd.) Hook
and Plectranthus glandulosus Hook F. against adults of Tribolium
castaneum Herbst and Sitophilus zeamais Motschulsky, which are two
important stored product insect pests in Northern Cameroon. Because of
the low persistence of the insecticidal activities of these plants,
their essential oils to achieve a complete protection of the stored
products must be applied at frequent delays. The present investigation
focuses on the occurrence of residues of these oils on treated maize
grain and flour. The doses of crude essential oils used to treat adults
of S. zeamais and T. castaneum in a contact and inhalation process were
their LD99s. After the evaluation of their insecticidal activity the
persistence of each essential oil was observed every 2 days till 14
days. After the disappearance of their insecticidal activities,
essential oil was re-extracted and their residual compounds were
identified from treated grain and flour. The major compounds of C.
anisata are, estragole, α-humulene, germacrene D and
(E)-nerolidol. In P. glandulosus they are: fenchone, α-terpinolene
and piperitenone oxide. After 14 days, only 64.24% of compounds of C.
anisata were recovered on treated flour and 55.16% on grains.
Concerning P. glandulosus, 48.94% was recovered on grains and 61.23% on
flour