The Geisenheim VineyardFACE facility was established in 2011 at Geisenheim University, Germany (49°59′N, 7°57′E; 96 m above sea level) and consists of six ring-frame structures, each with an inner diameter of 12 m. Three rings are under elevated CO₂ (eCO₂, ca. 508 ppm) and three under ambient CO₂ (aCO₂, ca. 411 ppm) concentration. Each ring contains seven rows of grapevine Vitis vinifera L. ‘Riesling' and ‘Cabernet-Sauvignon' plants, with a total of 32 grapevine plants per variety in each ring. For a detailed description of the Geisenheim VineyardFACE facility, see publications by Reineke and Selim (2019) and Wohlfahrt et al. (2018). The vineyard is managed according to the principles of good agricultural practice and integrated pest management in viticulture. Recapture experiments were conducted in 2020 from May 18–27th and June 26th–July 7th (L. botrana and E. ambiguella). In 2021, experiments were conducted from July 28th–August 23rd (L. botrana). During these experimental periods, grapevine plants were in the developmental stages BBCH 55-57, BBCH 73-77, and BBCH 75-81 after Lorenz et al. (1995). Weather conditions and CO₂ concentrations during the experimental periods are shown in Supplementary Table 1.

The L. botrana and E. ambiguella colonies were maintained at Geisenheim University, Geisenheim, Germany, and regularly supplemented with additional genotypes either collected in local vineyards or received from other laboratory strains outside Geisenheim. Larvae were cultured in groups in plastic boxes (20 × 15 cm and 9 cm high) in an insect rearing room (24 ± 1 °C; 40 ± 12 % relative humidity; light/dark photoperiod: 16:8 h) and were fed ad libitum with a modified semi-synthetic diet according to the general-purpose diet of Singh and Moore (1985). Pieces of corrugated cardboard were offered for pupation. Pupae were then removed from the crevices, sexed under a binocular (LeicaR, EZR4 W), and stored individually in small plastic containers. They were inspected daily to monitor adult emergence. To test hypothesis 2, the effect of temperature during rearing was studied with L. botrana, comparing two daily fluctuating thermal regimes designed to simulate current (‘ambient') and predicted future (‘elevated') thermal conditions. Temperatures of the climate chambers (Memmert HCP 240 Humidity Chamber, 241 L; 115 VAC) were based on the publication of Iltis et al. (2018) for comparability purposes. Both thermal regimes were composed of six segments, each lasting 4 h, 65 % relative humidity, and a light/dark photoperiod of 16:8 h (650 lx; for details, please see Table 1).

Table

titre du tableau
time of day (h)	light	temperature
		ambient	elevated
7–11	on	18	22.9
11–15	on	22	27.8
15–19	on	25	30.5
19–23	on	23	28.3
23–3	off	19	24.2
3–7	off	16	21.4

To assess the success of MD field experiments were performed using a modified cage method (Hoffmann and Doye, 2017). Four nylon mesh cages (Figure 1; BugDorm NHBS, Bonn, Germany) with a size of 47.5 × 47.5 × 93 cm and a mesh size of 650 µm were installed in each elevated and ambient ring of the FACE facility (Figure 2) as well as in two external control vineyards, one with and one without MD. In the second year, experiments were performed only in the non-disrupted external control vineyard. In all FACE rings and in the disrupted vineyards, RAK® 1+2 dispensers containing the sex pheromone components (Z)-9-dodecen-1-yl acetate and (E,Z)-7,9-dodecadien-1-yl acetate (BASF, Ludwigshafen, Germany) were distributed along rows with a density of 500 dispensers per hectare. For the recapture experiments in the field, we used ten male moths and one synthetic pheromone lure in a delta trap (first year, 2020; Temmen, Hattersheim, Germany) or ten male moths and two females in a small metal cage (second year, 2021; traps with glue; Figure 1) per BugDorm. Moths used for the experiments were 24–72 h old. Two days after release, the numbers of trap-captured and non-captured males were counted.

In the first year, all tested moths were raised in the insect-rearing room under constant temperature. In the second year, half of the moths had been raised under ambient and the other half under elevated temperature, as described in Table 1. For an overview of the tested treatments in both years, see Table 2. In the first year, twelve replicates per treatment and moth species were obtained for the first-generation flight period, and 29–33 replicates for the second-generation flight period. In the second year, ten replicates per treatment were obtained for the second-generation flight period.

Table

The BugDorm (A) includes a glue trap under two female L. botrana moths that were placed in a small metal cage, as displayed in photo (B). The hatched circles indicate sleeve openings in the BugDorm. Figure by Anna Rummel, photo by Mirjam Hauck.

The impact of elevated atmospheric CO₂ concentration on the efficacy of mating disruption in the different areas was evaluated using one-factorial generalized linear models (GLM) of the binomial family with logit-link. For multiple comparisons of means, Tukey contrasts (general linear hypotheses and multiple comparisons: glht, multcomp package) (Hothorn et al., 2008) were used. The interaction between temperature and CO₂ was evaluated using two-factorial GLM of the binomial family with logit-link and glht with Tukey contrasts for multiple comparisons of means. All evaluations were done using R version 4.1.1 (RStudioTeam, 2020), adopting a significance level of α = 0.05.

Using synthetic pheromone lures, recapture rates of L. botrana and E. ambiguella, respectively, did not differ significantly between elevated and ambient atmospheric CO₂ concentrations in the VineyardFACE facility (Figure 3). During the first-generation flight period, the highest recapture rates of males were obtained in areas without mating disruption (‘external control_MD-’; Figure 3; A: χ² ₃ = 57.5, p < 0.0001, B: χ² ₃ = 40.4, p < 0.0001). They were significantly higher than the recapture rates in the MD-treated VineyardFACE facility and the external control_MD+. Recapture rates did not differ significantly between the MD-treated VineyardFACE facility and the external control_MD+. During the second-generation flight periods highest recapture rates of males were obtained in areas without mating disruption (‘external control_MD-’; Figure 3 C: χ² ₃ = 29.7, p < 0.0001), D: χ² ₃ = 51.2, p < 0.0001). They were significantly higher than the recapture rates in the MD-treated VineyardFACE facility but not than those obtained in the external control_MD+. Regarding both E. ambiguella and L. botrana, recapture rates were not significantly different between the MD-treated (‘external control_MD+’) and not treated (‘external control_MD-’;) external control areas.

Using females as pheromone sources, recapture rates of L. botrana did not differ significantly between elevated and ambient atmospheric CO₂ concentrations in the VineyardFACE facility – independent of the temperature the moths were reared at (Figure 4; temperature: χ²₁ = 0, p = 1; CO₂: χ²₂ = 50.4, p < 0.0001; CO₂ * temperature: χ²₂ = 8.7, p = 0.01). The highest recapture rates were obtained in the non-disrupted external control area (external control_MD-). The difference in recapture rates between the eCO₂ VineyardFACE rings and the non-disrupted external control area is only approaching significance among moths from the standard temperature regime (p = 0.05, z = 2.80; Figure 4).

Table

Recapture rates were assessed under ambient and elevated CO₂ concentration in the VineyardFACE facility under mating disruption and two external control areas under ambient CO₂, with (‘control_MD+’) and without (‘control_MD-’) mating disruption. Identical letters indicate that values did not differ significantly.

From a practical point of view—and especially from an ecological one—our results are good news. They indicate that MD will not be negatively affected by future elevated CO₂ concentrations. Furthermore, we did not detect a negative impact of elevated temperature. We have to keep in mind, though, that we did not study the immediate impact of elevated temperature during pheromone perception, only the effect during development before the perception events. Technically, experiments on the interactive effects of climate change factors are very challenging. Nevertheless, investigating these interactions is crucial to realistically anticipate the overall impact of climate change on MD to secure its future use as a sustainable pest management method.

We want to thank Mirjam Hauck, Olivia Herczynski, and Birgit Breckheimer very much for their help during these experiments.

ARe, JGr, ARu, and CB designed the experiments. CB and ARu conducted the experiments and gathered the data. CB, ARu, and ARe evaluated the data. CB, JGa, JGr, ARu, and ARe wrote the manuscript. All authors read and approved the manuscript.

The experiments were part of the KLIMAKOM project (funding code: 281B204416), which was supported by funds from the Federal Ministry of Food and Agriculture (BMEL) based on a decision of the Parliament of the Federal Republic of Germany via the Federal Office for Agriculture and Food (BLE) under the innovation support program. The VineyardFACE facility receives financial support from the Hessian Agency for Nature Conservation, Environment and Geology.