Fluctuation of Lymantria dispar (Lepidoptera: Lymantriidae) populations during gradation phase in sub-humid and semi-arid cork oak forest (Algeria)

Abstract

The last gypsy moth (Lymantria dispar (Linnaeus, 1758): Lepidoptera: Lymantriidae) gradation has been studied in sub-humid and semi-arid bioclimatic areas; respectively at Bouarfa and Tamentout cork oak (Quercus suber L.) forests. This study was to reveal the various aspects of the Lymantria dispar population dynamics. A analytical study focused on the egg masses of Lymantria dispar populations was conducted to determine the importance of their temporal evolution. The results analysis regarding the clutches and eggs of different generations allowed to synthesizing the evolution of the gypsy moth gradation in both cork oak forests explored. Progradation phase lasted from 2006 to 2007 in Bouarfa forest area, and 2006 to 2009 in the Tamentout cork oak forest. The peak of the infestation characterized both cork oak forests in respectively 2007 and 2009. Demotion phases were recorded during the period 2008 to 2010 in Bouarfa area and 2009 to 2011 in Tamentout cork oak forests. Actually, gypsy moth populations were in latency phase in all the areas surveyed.