Abstract
Geotrogus deserticola (Blanch.) belongs to the Scarabeidae family and the Melolonthini group. In Algeria, Melolonthini and more specifically Geotrogus deserticola (Blanch) especially in the south west part of Algeria, cause damage to the roots of most vegetables including the cereals (Delassus and Pasquier, 1930, Delassus, Lepigre and Pasquier 1933).
Investigations upon the assessment of the different damage carried out each year 1984 by the National Institute of Vegetable Protection show that the density of Geotrogus deserticola (Blanch) can reach 100 larvae/m(2) depending upon the study site.
In order to have the capacity to do experiences upon this species, we should, as a first stage, establish a breeding device this latter was more damty than to try an experience upon an insect with a long cycle. Its supply conditions varied from one stage to another. Now a day, the technique seems to be satisfactory.
It consists upon the insulation, individually, all the larvae in recipients with au appropriated dimensions including a light ground, supplied by the roots and maintained in a good climate and moisture conditions (from 20 to 30 C, 5 to 20%H for the young larvae and from 20 to 25 C, 5 to 10% HR for the old larvae).
Researches upon the biological cycle shows that the cycle lasts for two years with the emergency of adults in spring. The accouplement is done at the ground surface. The laying starts two or three weeks after the accouplement It is undespread upon three to four days. In three weeks, the first instar (L1) appears. The first molt is observed at September of the first year. The resistance of the second instar (L2) can surpass one year. The second molt is observed at September of the second year.
The lifetime of L3 is six months. The nymphose, which lasts one month, happened on March. The emergency of a new imagos takes place in spring (April-March).