Biological and ecological characteristics of Gypsy Moth, Lymantria dispar L.(Lep. Lymantriidae) in the gradation phase's in Blideen Atlas forest (Algeria)

Abstract

The gypsy moth, a pest of hardwood forests is now found throughout the Northern Hemisphere. It is among the most studied "for science" basic and applied aspects of regulation of molting, vision larval pheromones, insect diseases, insecticides, biological control, and dynamics population, its polyphagia and polymorphism. This work focuses on the behavior of gypsy moth chronological in its natural environment. We conducted larval sampling only in the cork oak forests, the pupae in three stations and the counting of spawning in the different sites surveyed. The results concerning counts layings show the existence of significant variables mean values from one station to another it is results from the variable quality of food that directly affects female fertility. The recorded values are respectively 32 and 20 eggs-mass per cork oak tree and chestnut, while in e altitude Holm oak forest average of 14 eggs-mass per tree. Another important result shows that the emergence of L. dispar in Holm oak forest altitude is later than cork oak forests; the offset is recorded in the range of about twenty days This shift is directly related to average temperatures that varied altitudinal a plant, they are higher in low altitude. The biometric and statistical study performed on our samples shows the existence of six larval stages put in evidence with statistical tests. Finally, the sex ratio of L. dispar shows a dominance of females on cork oak and chestnut with respective values of 0.63 and 0.67, whereas in Holm oak altitude the sex ratio tends to be balanced (0.98) the results presented are dependent on supply conditions. This study provides information on the biology and ecology of L. dispar causing important damage to the cork oak forest in particular.