Joint research project

Extent of damages to Pine forests in Lebanon and South Italy caused by endemic and alien insect species and their associated nematodes.

Project leaders
Alberto Troccoli, Elise Noujeim
LIBANO - CNRS-L - National Council for Scientific Research of Lebanon
CNR/CNRS-L biennio 2018-2019 2018-2019
Biology, agriculture and food sciences
Thematic area
Biology, agriculture and food sciences
Status of the project

Research proposal

Mediterranean stone pine (Pinus pinea L.) is one of the most important forest tree species in the Mediterranean basin. In Lebanon it extends over 12,740 hectares, nearly 10 % of total forest cover. In Italy it is cultivated virtually everywhere, except in mountainous areas and covers 134.000 ha where Pinus pinea are mixed with other pines (Seigue 1985). It's very important for pine nut production, control of soil erosion, landscape, amenity, and recreation. While stone pine forests in Lebanon are getting older, the intensive forestry practices (pruning, clearing and cone harvesting) and severe droughts are adding threats to pine trees that are becoming more susceptible to many pests.
Along the Mediterranean basin, pinewoods have been affected by the Dry Cone Syndrome (DCS) that reduced pine nut production. DCS comprises a drastic conelet loss in the tree crown before ripening, as well as a strong decrease of pine nut kernel yield per harvested cone weight. Since first reports in Italy at beginning 21st century, DCS has spread all over Mediterranean countries and has been associated definitively to the cone insect pest Leptoglossus occidentalis (Roversi et al., 2011; Bracalini et al., 2013; Lesieur et al., 2014), a seed-feeding bug (Hemiptera: Coreidae) introduced accidentally from North America.
The latest problem of Dry Cone Syndrome occurred in Lebanon and was addressed by international and national experts, FAO and the Ministry of Agriculture. This problem was associated with the Alien invasive insect pest L. occidentalis, which was firstly detected in Lebanon (Arsoun) in February 2015 (Nemer, 2015). Leptoglossus occidentalis (Nemer, 2015) is a new important pest for pine insect fauna in Lebanon. The bugs suck on young developing cones and may cause abortion of young conelets, fusion of seeds to cone scales as well as direct damage by depletion of the lipid and protein content of the seed up to its complete emptying (Bates et al. 2000a, b, 2002). It has been estimated that one adult female can destroy up to 310 seeds in a lodgepole pine orchard (Forest Genetics Council of British Columbia, FGC, 2011). In Lebanon, the parasitoids of L. occidentalis were only marginally studied and weren't detected to date. It is of great importance finding natural enemies of L. occidentalis that play an important role in integrated pest management in the future, and/or introducing other biological control (Alarm Pheromones, bio-agents...) in order to prevent serious damage to forest resources.Leptoglossus occidentalis was introduced in Italy, probably with importing lumber, in 1999, reported in Veneto region (Villa et al., 2001). Then it was found in Lombardy, Friuli Venezia Giulia, Trentino, Sicily and Emilia-Romagna (Taylor et al., 2001; Bernardinelli & Zandigiacomo, 2001). In the autumn of 2006, it was spotted in Umbria and later in the South of the Country becoming one of the major pests of the pines. Since the introduction of L. occidentalis into Italy, production of pine nuts has decreased rapidly, not only in Italy but also in other European areas (Roversi, 2009), and in 2009 cone harvests declined by as much as 95% from Italian stone pine forests (OEPPDEPPO, 2011). Little is known about its biology, ecology and natural enemies in southern Italian pinewoods.
Leptoglossus occidentalis is threatening pines in Lebanon and Italy, but another problem occurred in the pine forest of the capital Beirut that constitutes more than 75 percent of the available urban green space in the city. Beirut forest in a pine forest that have been threatened by xylophagous insects since February 2017 that induced the death of 400 trees, insects found could probably be affiliated to the Cerambycidae and Buprestidae families but they are not yet identified on the genera and species level.
In the preliminary assessment of insects conducted in the "Maten" region precisely Arsoun (March-September 2014) one major observation was the abundance of Cerambycids which are borers that affect weak trees in addition to a relatively high abundance of Tomicus destruens (Scolytinae) (Nemer, 2014) that has been recorded to cause serious problem till present in all pine stands in Lebanon. In Lebanon Kawar et al. (2000) and Nemer (2001, 2009, 2014) have reported the presence of many woodborers and shoot borers particularly Ernobius sp. (Anobidae) that was found to be associated with the dry brown tip symptom.
On the other hand pinewood pest like Cerambycidae, Curculionidae (including subfamily Scolytinae) in addition of being directly harmful to pine trees, some of them are also vector species for the pinewood parasitic nematode (PWN) Bursaphelenchus xylophilus which causes the pine wilt disease. In Lebanon, pine wilt nematode Bursaphelenchus sp. has never been reported to date (Nemer, 2015) although there is one report of one specimen of Monochamus sutor sutor in one location in Lebanon (Moussa et al, 2016) that could be a potential vector of PWD under some natural and artificial conditions (Akbulut et al, 2007). In Italy the cerambycid beetle Monochamus galloprovincialis has been reported as insect vector of B. mucronatus. As this beetle is also a well-known vector of the pest B. xylophilus, it is crucial to conduct targeted surveys in infested pinewoods in Lebanon and South Italy, to identify main pine pests, potentially considered as vectors for pine nematodes, study their biology and conduct preliminary biological methods to control them.

Research goals

The main objectives of this research work will focus on the economic impacts of the insect pests on the pine forests in both countries Italy and Lebanon. An evaluation of their biological control methods will be also assessed.
A. Evaluate the yield loss incurred by the invasive species Leptoglossus occidentalis and evaluate preliminary test for different control methods.
B. Identification of xylophagous species of Beirut woods, study their bioecology, evaluation of their impact on the forest resources, evaluate the presence of natural enemies, and set up integrated control strategies.
C. Extraction and characterization of nematodes from pine woods in Lebanon and Italy by applying EPPO/OEPP standard procedures.

Last update: 27/11/2021