Résumé:
Thaumetopoea pityocampa is one of the most important insect pests in the northeastern of Algeria, the Mediterranean area and the central of Europe. This pest has caused a lot of natural and human damages in the last years, it is also a public health problem. To understand the ecological behavior of the insect and to define its harmful effect and reduce its defoliation, we carried out a study based on the immune structure of the insect, on its nutritional behavior and on the effect of four essential oils on the mortality of the caterpillars during the larval stage of the insect. The most abundant cells identified in the hemolymph of the insect are prohemocytes, plasmocytes and granulocytes, the cells abundance increases from each larval stage to the next one. These cells participate in all immune reactions. They are identified during microscopic observations of the most forms of encapsulation, phagocytosis, melanization and cell nodulation reactions. Toxicological treatment with essential oils indicates larvicidal activity among the different oils used. Cedar and Eucalyptus oils are the most toxic insecticides for Thaumetopoea pityocampa caterpillars. The feeding behavior of the insect is achieved by studying the olfactory attractiveness of Thaumetopoea pityocampa larvae using different species of pine and cedar. We record variable preferences during the various tests.
