Résumé:
The white grub of crops causes considerable damage on several crops. It is considered
a serious threat to agriculture in Algeria. Faced with this dangerous insect, farmers are
oriented towards chemical control. The objective of this study is to propose alternative
solutions based on the use of natural products in order to carry out biological control.
The first part concerns the search for indigenous entomopathogens capable of
controlling white grub populations. It focuses on the one hand on the isolation and
identification of an entomopathogenic fungus present on a mummified larva of this insect and
on the other hand, the demonstration of the larvicidal activity of this pathogen.
The results obtained showed the existence of a single species of entomopathogenic fungus,
namely: Fusarium sp .. The pathogenicity test of this strain confirms its causality in the
induction of symptoms observed on the host. In addition, virulence tests on larvae highlight
the effectiveness of this indigenous entomopathogen, with a mortality rate of over 60%.
The second part of our work focuses on verifying the effectiveness of essential oils
from four aromatic plants: Lavandula sp., Origanum sp., Salvia sp. and Thymus sp. on white
grub larvae.
The results obtained in vitro show that the larvae of the white grub are sensitive to the effect
of EOs of Salvia sp. and Origanum sp. in comparison with that of the HEs of Lavandula sp.
and Thymus sp .. The use of sage and oregano to control this pest has shown mortality rates of
over 50% for Salvia sp. on the 10th day at a dose of 0.5% and on the 6th day at a dose of 1%
for Origanum sp ..
