Behavioral responses of the pine wood nematode to terpenes.

Abstract

Wehave tested various chemicals for their modifying effects on the behavior of the pine woodnematode. Several compounds containing the oleyl group, i.e., ethylene glycol monooleate, 1-monoolein, oleic acid and oleyl alcohol were attractive.X) Allyl isothiocyanate, naringenin, 1-tyrosine, 1-tryptophan and calcium chloride were also attractive, while capsaicin and magnesium chloride exhibited repellency.2)As a continuation of these works, we tested behavioral responses of the nematode to terpenes. The results are presented in this paper. MATERIALS AND METHODSTest chemicals. Commercially available terpenes (analytical grade) were used without further purification.Bioassay. The procedure for behavioral tests was de-scribed in detail in the preceding paper.2) Agar plates in petri dishes were perforated to makea pair of holes, and filled with agar containing the test chemical and untreated agar respectively. A pad of absorbent cotton impregnated with a suspension of the nematodes reared on colonies of Botrytis cinerea was placed in the center of the agar plates.After incubating in darkness at 25°C for 3 days, the number of nematodes in the treated and untreated agar discs were counted and analysed statistically. All the test compounds had been previously dissolved in ethanol and water was added to provide ethanol concentration below 6%. A preliminary check showed that the effect of ethanol was negligible below 10%. The test was not performed for concentrations higher than 10~3m, since the chemicals could not be maintained in suspension. RESULTSAll the chemicals were first tested at 10~3m. If a significant activity was noted, the concentration waslowered successively by an order of magnitude. The results obtained with 26 terpenes are presented in Table I. Abietic acid and phytol were attractive at the order of 10~5 m, followed by /?-myrcene and geraniol, which were active at 10~4m. carene and camphene,were weakly attractive.3) Our results coincided with his concerning the high attractancy of /?-myrcene, but jS-pinene was repellent in our test system. Behavioral effects of monoterpenes on insects have been frequently reported. In particular, ipsenol, a monoterpene structurally related to /?-myrcene, was found to be an aggregation pheromoneof Ipsproconfusus, one of the bark beetles which infest pine.4) Reports on the behavioral activity of diterpenes have not often appeared, but the present work disclosed the remarkable attractiveness of phytol and abietic acid to the nematode. Recently, the latter compoundwas found to be a feeding stimulant to the larch saw fly.5) Abietic acid is contained in the pine resin, and this might be connected with infestation of the pine by the nematode.

Rapid Diagnosis of the Infection of Pine Tree with Pine Wood Nematode (Bursaphelenchus xylophilus) by Use of Host-Tree Volatiles

“…xylophilus was inconsistent. β-Myrcene has been reported to be a strong attractant, , but it did not show any attractiveness in our experiments. β-Pinene has been reported as a weaker attractant and as a repellent .…”

“…β-Myrcene has been reported to be a strong attractant, , but it did not show any attractiveness in our experiments. β-Pinene has been reported as a weaker attractant and as a repellent . The mixture of α-pinene, β-pinene, and longifolene was attractive to B.…”

“…A 0.1 mM solution of the compounds was prepared by serial dilutions in hexane (Sigma-Aldrich). The chemical concentrations were determined by referring to the results by Tominaga et al…”

Volatiles from a Mite-Infested Spruce Clone and Their Effects on Pine Weevil Behavior

“…In addition, Shulaev et al (1997) postulated that methyl salicylate (MeSA) is involved in plant -plant communication, and recent studies have proved its involvement in systemic acquired resistance in plants (Park et al 2007). Effects of plant volatiles on the behavior of forest pests are of both fundamental interest to biologists and great practical interest to foresters (Tominaga et al 1984;Nordlander 1990Nordlander , 1991Byers 1992;Wibe et al 1997;Thiery and Marion-Poll 1998;Byers et al 2000;Huber et al 2000;Bichão et al 2003;Miller et al 2003;Asaro et al 2004). Our results show that some of the volatiles released by mite-infested spruces significantly decreased the attraction of the pine weevil H. abietis to host volatiles from spruce.…”

Scientific Opinion on comments provided by Portugal on the phytosanitary risk associated with Pinus pinea for the spread of pine wood nematode

“…Nevertheless, this does not necessarily imply that nematode-infested beetles would infect this pine when feeding, because the departure of the nematodes from the insect's body is controlled by an interaction of various factors such as volatile chemicals and CO 2 emitted by the host (Edwards and Linit, 1992;Kishi, 1995). The volatile compound β-myrcene has been found to play a decisive role in promoting the exit of PWN from vector's body to enter the host (Tominaga et al, 1984;Ishikawa et al, 1986;Linit, 1998, 2001), and this volatile is much more abundant in P. pinaster needles and branches than in P. pinea (Tiberi et al, 1999;Macchioni et. al., 2003).‖ 3.1.2.2.…”