Table 2.
Toxicity of monoterpene volatiles against MPB from cohort 2.
| Cohort 2 | |||||
|---|---|---|---|---|---|
| Monoterpenes | N | LC50 [μl/L] (f.l.) | Hill slope ± SE | χ2 (df) | Mean Weight [mg] ± SD |
| (−)-Limonene | 120 | 32 (22–47)a | −2.2 ± 0.5 | 1.4 (2) | 10.03 ± 0.19 |
| (+)-Limonene | 120 | 60 (52–70)b | −5.9 ± 1.6 | <0.1 (1) | 9.68 ± 0.23 |
| (+)−3-Carene | 120 | 76 (63–90)bc | −4.5 ± 1.0 | 0.4 (1) | 9.47 ± 0.19 |
| Myrcene | 119 | 77 (55–108)bc | −1.6 ± 0.3 | 1.5 (2) | 9.76 ± 0.22 |
| (−)-β-Phellandrene | 120 | 97 (75–124)cd | −3.0 ± 0.7 | 9.1 (3) | 9.52 ± 0.22 |
| (−)-β-Pinene | 120 | 130 (105–160)d | −4.9 ± 1.4 | <0.1 (1) | 9.52 ± 0.18 |
| (+)-β-Pinene | 120 | 131 (108–158)d | −6.7 ± 1.9 | 0.6 (3) | 9.45 ± 0.20 |
| (+)-α-Pinene | 120 | 131 (106–161)d | −5.0 ± 1.4 | 3.5 (3) | 9.99 ± 0.19 |
| (−)-α-Pinene | 120 | 248 (187–330)e | −2.2 ± 0.5 | 0.6 (1) | 9.73 ± 0.21 |
| Terpinolene | 120 | >500 | 9.73 ± 0.21 | ||
Dose-response models of the logit-transformed mortality data were used to determine the LC50 values, 95% fiducial limits (f.l.), and Hill slope for each monoterpene tested. LC50 values denoted with the same letter were not significantly different. Multiple comparisons between LC50 values were conducted via pairwise t-tests on the log (LC50) values of the Hill equation, using a pooled standard error, and correcting for experiment-wise error by the Benjamini–Hochberg procedure. The goodness-of-fit test χ2 (degree of freedom) was used to assess the fit of the dose-response model. Less than 50% of the beetles died at all doses of terpinolene. The mean weight of the beetles tested for each compound in cohort 2 was not significantly different and the mean weight of the beetles tested with a given monoterpene was the same at all doses (ANOVA, p-value = not significant). As sex was not a significant factor in mortality for all monoterpenes tested, the data for both sexes was combined.