Companion planting with French marigolds protects tomato plants from glasshouse whiteflies through the emission of airborne limonene - Fig 2

The percentage of whiteflies on tomato (n = 200) when given the choice between four un-accompanied “Elegance” tomato seedlings or four “Elegance” seedlings intercropped with either flowering marigold plants (Fig 2A) or limonene dispensers (Fig 2B). Whitefly eggs were also recorded for each replicate (Fig 2C and 2D). Values were transformed to percentages and the Pearson’s chi-squared test was used to test differences in settling and oviposition behaviour. Significant differences are annotated onto the graph for each treatment with the following format; “*” indicates a p value of p df = 1 for all reps, Fig 2A, rep 1 X 2 = 21.26, p = X 2 = 3.43, p = 0.064; rep 3 X 2 = 17.01, p = X 2 = 11.17, p = 0.001; rep 5 X 2 = 5.95, p = 0.015; rep 6 X 2 = 15.72, p = X 2 = 2.92, p = 0.087; rep 2 X 2 = 8.33, p = 0.004; rep 3 X 2 = 0.985, p = 0.321; rep 4 X 2 = 8.33, p = 0.004; rep 5 X 2 = 5.32, p = 0.021; rep 6 X 2 = 0.501, p = 0.479. Fig 2C, rep 1 X 2 = 13.82, p = X 2 = 0.323, p = 0.570; rep 3 X 2 = 12.65, p = X 2 = 1.65, p = 0.198; rep 5 X 2 = 2.05, p = 0.152; rep 6 X 2 = 9.51, p = 0.002. Fig 2D, rep 1 X 2 = 2.31, p = 0.128; rep 2 X 2 = 0.731, p = 0.398; rep 3 X 2 = 6.876, p = 0.009; rep 4 X 2 = 2.97, p = 0.084; rep 5 X 2 = 0.02, p = 0.887; rep 6 X 2 = 2.49, p = 0.114. On average over the 6 replicates, 21.93% of whiteflies settled on tomato intercropped with marigold and 36.12% whiteflies settled on tomato intercropped with limonene dispensers. 31.44% of eggs were laid on marigold intercropped tomato and 37.24% were laid on limonene intercropped tomato. Average distribution (n = 6) of whiteflies in limonene and marigold treatments were compared to ascertain whether marigold control was significantly more effective at repelling whitefly, however this was not the case (X 2 = 2.016, p = 0.156, df = 1).