First in situ biocontrol attempt against Cephalcia tannourinensis on Cedrus libani

Alarming outbreaks of the insect defoliator Cephalcia tannourinensis are threatening the survival of the cedars of Lebanon, Cedrus libani. As a first in situ biocontrol attempt against this cedar web-spinning sawfly, inundative treatment using entomopathogenic nematodes (EPNs) were applied from 2014 to 2016 in Tannourine cedars forest. The treatments consisted of applying three times per year a commercial strain of Heterorhabditis bacteriophora in treated sites and tap water in control sites. The success of this treatment was assessed by monitoring the C. tannourinensis populations by measuring the density of underground larvae, emerging adults and the associated foliar damage. High fluctuations of the pest’s population occurred during the years of treatment in all sites. No statistical difference resulted between the EPNs treated sites and the control sites for the density of underground larvae or emerging adults. Although foliar damage in EPNs treated sites decreased significantly, the EPNs inundative treatments against C. tannourinensis in the Tannourine forest is still at experimental phase. Nevertheless, this study provides better guidance for future strategic biocontrol plans against insect forest pests. © (2024), (Agri Overseas). All rights reserved.