as positive control in the analysis. Negative effect sizes indicate weaker responses to T-tC and DHC than to pure tC, as also seen in A. Responses with CI:s below zero were regarded as significantly weaker than the response to pure tC at the specified dose. doi:10.1371/journal.pone.0085381.g006 df = 8; p,0.001) followed by Dunnet’s T3. Traps baited with only pheromone had the highest catch. In contrast to Trial 1, traps with -verbenone as the only inhibitor did not reduce catches significantly compared to the pheromone control. However, adding 1-hexanol as a second inhibitor in combination with -verbenone significantly reduced trap catches, confirming this synergy from Trial 1. Adding tC or T-tC at 0.5 or 5 mg/day in combination with 1hexanol and -verbenone significantly reduced trap catches further. This observation confirmed the results from Trial 1 regarding the importance of tC as a second synergist in reducing the attraction to the pheromone. There was no significant difference in catch between traps with T-tC or tC included in the inhibitory blend, except for in the traps with the lowest release rate of tC. Thus, the addition of this lowest release rate of tC resulted in trap catches that were not significantly different from the treatments including only 1-hexanol and -verbenone as inhibitors. Importantly, the lack of difference between tC and T-tC indicates that trap catch of I. typographus was neither influenced significantly by impurities in the technical grade treatment, nor by the effectively lower release of tC from the technical grade preparation due to the ca. 28% lower tC content. 7 NHV Blend for Protection against Ips typographus Synthesis of DHC The starting material 2-methylenetetrahydrofuran was synthesized from 2–tetrahydrofuran by treatment with potassium hydroxide, in moderate yields according to Armitage et al.. The formed 2-methylenetetrahydrofuran was used in a Diels-Alder reaction with methyl vinyl ketone in analogy with Ireland and Habich, yielding the product 7-methyl-1,6 dioxaspirodec-7-ene in 63% yield. Trial 3: Test of DHC The inhibitory effect of DHC on pheromone trap catch was evaluated in Trial 3 and compared to the inhibitory effect 
of pure tC. A total of 2 812 beetles were caught in 15 replicates. Also in this trial catches among the traps, including a pheromone only control and three inhibitory treatments, differed significantly by ANOVA followed by Tukey HSD on arcsin!. The trap with pheromone alone caught significantly more beetles than the other treatments . The treatment including tC in combination with 1hexanol and -verbenone had significantly lower catch than the treatment including DHC . The treatment with tC also had a significantly lower trap catch than the treatment with only -verbenone and 1-hexanol as antiattractants, whereas this was not the case for the treatment with DHC . Single-sensillum Recordings To provide a mechanistic explanation for the similar reduction in trap catch by the presence of T-tC and tC, 21385929 but lower reduction by DHC, SSR from the trans-conophthorin sensitive ORN class were performed. The tC neuron responded the strongest and was most sensitive to pure tC. The response threshold for this stimulus was below the 1 ng dose. GW 501516 price Somewhat weaker responses, but not significantly different, were elicited by T-tC, which probably only reflected the lower purity of the compound. DHC also elicited responses, 22924972 but the sensitivity to this compound was almost 100 times lower. Accordin as positive control in the analysis. Negative effect sizes indicate weaker responses to T-tC and DHC than to pure tC, as also seen in A. Responses with CI:s below zero were regarded as significantly weaker than the response to pure tC at the specified dose. doi:10.1371/journal.pone.0085381.g006 df = 8; p,0.001) followed by Dunnet’s T3. Traps baited with only pheromone had the highest catch. In contrast to Trial 1, traps with -verbenone as the only inhibitor did not reduce catches significantly compared to the pheromone control. However, adding 1-hexanol as a second inhibitor in combination with -verbenone significantly reduced trap catches, confirming this synergy from Trial 1. Adding tC or T-tC at 18083779 0.5 or 5 mg/day in combination with 1hexanol and -verbenone significantly reduced trap catches further. This observation confirmed the results from Trial 1 regarding the importance of tC as a second synergist in reducing the attraction to the pheromone. There was no significant difference in catch between traps with T-tC or tC included in the inhibitory blend, except for in the traps with the lowest release rate of tC. Thus, the addition of this lowest release rate of tC resulted in trap catches that were not significantly different from the treatments including only 1-hexanol and -verbenone as inhibitors. Importantly, the lack of difference between tC and T-tC indicates that trap catch of I. typographus was neither influenced significantly by impurities in the technical grade treatment, nor by the effectively 7190624 lower release of tC from the technical grade preparation due to the ca. 28% lower tC content. 7 NHV Blend for Protection against Ips typographus Synthesis of DHC The starting material 2-methylenetetrahydrofuran was synthesized from 2–tetrahydrofuran by treatment with potassium hydroxide, in moderate yields according to Armitage et al.. The formed 2-methylenetetrahydrofuran was used in a Diels-Alder reaction with methyl vinyl ketone in analogy with Ireland and Habich, yielding the product 7-methyl-1,6 dioxaspirodec-7-ene in 63% yield. Trial 3: Test of DHC The inhibitory effect of DHC on pheromone trap catch was evaluated in Trial 3 and compared to the inhibitory effect of pure tC. A total of 2 812 beetles were caught in 15 replicates. Also in this trial catches among the traps, including a pheromone only control and three inhibitory treatments, differed significantly by ANOVA followed by Tukey HSD on arcsin!. The trap with pheromone alone caught significantly more beetles than the other treatments . The treatment including tC in combination with 1hexanol and -verbenone had significantly lower catch than the treatment including DHC . The treatment with tC also had a significantly lower trap catch than the treatment with only -verbenone and 1-hexanol as antiattractants, whereas this was not the case for the treatment with DHC . Single-sensillum Recordings To provide a mechanistic explanation for the similar reduction in trap catch by the presence of T-tC and tC, but lower reduction by DHC, SSR from the trans-conophthorin sensitive ORN class were performed. The tC neuron responded the strongest and was most sensitive to pure tC. The response threshold for this stimulus was below the 1 ng dose. Somewhat weaker responses, but not significantly different, were elicited by T-tC, which probably only reflected the lower purity of the compound. DHC also elicited responses, but the sensitivity to this compound was almost 100 times lower. Accordin