Evidence of sexual attraction by pheromone in the cedar web-spinning sawfly

Abstract

The cedar web-spinning sawfly, Cephalcia tannourinensis Chevin (Hymenoptera: Pamphiliidae), is a pest that has been causing serious damage to cedar (Cedrus libani) forests in Lebanon since 1990. The existence of a sex pheromone was shown in field experiments in a cedar forest in Lebanon and in laboratory tests in olfactometers with and without airflow. More males were caught in traps baited either with virgin females or with a hexane extract of the whole female body than in traps baited either with males alone or with mixed males and females. Male and female C. tannourinensis were active during the day. Mating and pheromone production were observed to occur during midday hours (1000–1400) in the field and under laboratory conditions. Olfactometer tests with extracts prepared from different body parts of the female indicated that the pheromone is produced in the abdominal region, and tests with different dilutions of female extract showed that the male response is dose-dependent.

Comparison of indigenous and exotic entomopathogenic nematode strains for control of the cedar web-spinning sawfly,Cephalcia tannourinensis in vitro

“…LIB04 was cultured on last instar Galleria melonella (L.) according to Kaya and Stock (1997) and stored at 10°C (10,000 IJs/mL) for a maximum of three weeks prior to use. Since rearing of C. tannourinensis under laboratory conditions is difficult (Nemer, Kawar, Kfoury, & Frerot, 2007), Cephalcia prenymphs were collected from the soil under the cedars in the Tannourine forest during the summer season. They were then transferred to Petri dishes (D = 9 cm) containing humid soil collected in the Tannourine forest.…”

Stand structure and regeneration of Cedrus libani (A. Rich) in Tannourine Cedar Forest Reserve (Lebanon) affected by cedar web-spinning sawfly (Cephalcia tannourinensis, Hymenoptera: Pamphiliidae).

“…Contrastingly, there was no significant differences in dasometric parameters for the other species, especially the Juniperus sp. The severe outbreak of Cephalcia tannourinensis in 1997 in TCNFR caused the death of a high number of adult trees (Nemer et al 2007, Sattout & Nemer 2008. This seems to be clearly related to the higher number of young individuals and the lower DBH value of infested stands (DBH = 5.65 cm) compared to larger trees (DBH = 27 cm) in non-infested stands.…”

“…In 1999, the infestation of the Tannourine Hadath el Jebbeh cedar forest reached a very high level and it was spreading and threatening the surrounding cedar forests in Lebanon. Consequently, aerial treatments with the insect growth regulator diflubenzuron (Dimilin SC 48 ® mixed with the oil adjuvant, Citrole) were carried out between 1999 and 2004, and resulted in considerable suppression of the cedar web-spinning sawfly population (Nemer et al 2007, Sattout & Nemer 2008. Following the outbreak in 1999, the adult density of web-spinning sawfly was assessed on a yearly basis using yellow sticky traps.…”

“…Then, the eggs hatch, the larvae pass through three instars during the months of June and July before hibernating in the soil. While developing, the larvae feed on the needles of the new cedar buds (SETS 2007, Nemer et al 2007). The feeding of the larvae on the new shoots during spring and early summer infers the severity of the damage that is done by the cedar web-spinning sawflyand its potential impact on the cedar growth.…”

The influence of soil properties on the development of Cephalcia tannourinensis Chevin (Hym. Pamphiliidae) infesting the cedar forests in Lebanon

“…The larval diapause can last for more than one year; and a five year diapause was recorded for some species within the same genus (Gruppe, 1996). Aerial spraying with the insect growth regulator diflubenzuron was carried out in 1999-2004 resulting in considerable suppression of the cedar webspinning sawfly population (Nemer and Nasr, 2004) but for ecological reasons development of more environmentally friendly techniques to manage populations are required (Nemer et al, 2007;Abdo et al, 2008). The danger of the spread of this insect to other cedar forests in Lebanon and the Mediterranean region led to the initiation of a UNEP/GEF project entitled "Integrated Management of Cedar Forests in Lebanon in Cooperation with Other Mediterranean Countries" that aims to develop an action plan for integrated management of forests including assessment of insects in cedar forest in the Mediterranean region with particular emphasis on the Tannourine-Hadath El-Jebbeh cedar forest.…”