No abstract

Effect of temperature on the pathogenicity of Mediterranean native entomopathogenic nematodes (Steinernematidae and Heterorhabditidae) from natural ecosystems. Seven strains of entomopathogenic nematodes (EPNs) belonging to three species (Steinernema feltiae, S. ichnusae and Heterorhabditis bacteriophora) naturally isolated from Mediterranean countries (Southern Italy and Lebanon) were evaluated for their potential to infest greater wax moth (Galleria mellonella) larvae at different temperatures under laboratory conditions. The laboratory bioassay was conducted at six different temperatures ranging from 10°C to 35°C. Nematode Infective Juvenile (IJs) were put in contact with G. mellonella larvae in Petri dishes and mortality rates were recorded after 72 hours. The purpose of the study was to evaluate the temperature range in which the EPNs caused larval mortality; higher mortalities were recorded at 15°C and 20°C. All species failed at lower temperatures except for S. ichnusae ItS-SAR4, which caused 7% mortality. At 35°C S. ichnusae maintained its infectious activity (24%) along with H. bacteriophora ItH-LU1 (38%); both were isolated from Italy and were more efficient at high temperatures than the remaining Lebanese isolates.

The effects of entomopathogenic nematodes EPN (Steinernematidae and Heterorhabditidae) and fungi EPF (Beauveria bassiana) strains were evaluated in laboratory assays against larvae of four xylophagous pests: the Asparagus moth Parahypopta caestrum, the European goat moth Cossus cossus, the pine longhorn Arhopalus syriacus and the black Buprestid Capnodis tenebrionis. Due to their biology and ethology, these insects may be included in the category of pests residing in cryptic habitats. The control of these species is considered difficult, due to the inability of chemical pesticides to penetrate the cryptic habitats and reach the targets. The pathogenicity of the entomopathogenic nematodes and fungi was tested in vitro against the pests. Two experimental models were considered and aimed to imitate the natural environment of the pests, in Petri dishes filled with plant material and inside wood galleries respectively. Main results showed that the majority of the tested strains of nematodes and fungi affected the insects' survival rate. Steinernema feltiae and B. bassiana caused the highest percentage of larval mortality (80-100%). Considering the lack of effective chemical control means, the microbial control of the xylophagous pests by EPN and EPF reveals promising perspectives. Nematodes and fungi are able to penetrate the cryptic habitats because they are living organisms and may be horizontally transmitted by infected hosts. The distribution of EPF as preventive control method and the injection of EPN suspensions to reach and infect the larvae inside the wood galleries can be a combined sustainable control system.

Cedars of Lebanon Cedrus libani have been attacked since 1990s by a hymenopteran sawfly, Cephalcia tannourinensis (Chevin), causing considerable damage to the foliar buds. A biological control programme using entomopathogenic nematodes (EPNs) was conducted in vitro against C. tannourinensis prenymphs. Two EPNs strains belonging to the same species Heterorhabditis bacteriophora were used; one indigenous to the country (LIB04) and the other a commercial strain (HbCom). Four EPNs concentration rates (40, 100, 250, 480 infective juveniles) were tested against C. tannourinensis prenymphs. Higher mortality was noted for the indigenous strain, LIB04, independently from all concentrations (100%). Emergence of EPNs was observed following 12-17 days from the first contact between EPNs and C. tannourinensis prenymphs. This parameter indicated that EPNs succeeded to complete all their reproductive cycle inside the C. tannourinensis cadavers before emerging. Bioassays were realised in jars containing soil extracted from the forest in order to validate the scenario suggested for application in situ. Most C. tannourinensis prenymphs were attacked by the EPNs on the surface.

beetles (Coleoptera Curculionidae Scolytinae) associated with Pinus pinea in Lebanon: new records with remarks on their ecology, distribution and potential threat for forest stands. Five species of Scolytinae new to Lebanon were recorded on Pinus pinea: Hylurgus ligniperda (Fabricius), Hylurgus micklitzi Wachtl, Hylastes angustatus (Herbst), Hylastes attenuates Erichson, Carphoborus pini Eichhoff. Their ecology, distribution and potential phytosanitary risk are discussed in the context of stone pine conservation.