Phenology of Xylotrechus arvicola (Coleoptera: Cerambycidae) Adults in Spanish Vineyards
Abstract
Background and Aims: The longicorn beetle Xylotrechus arvicola (Olivier) (Coleoptera: Cerambycidae) is an important pest in vineyards of the Iberian Peninsula. Previous studies have reported that different varieties of grapevines Vitis vinifera exhibit varying susceptibility to infestation by this species.
Methods and Results: Adult X. arvicola captured were monitored using interception traps (CROSSTRAP) in vineyard plots cultivated with five different grapevine varieties (‘Tempranillo’, ‘Prieto Picudo’, ‘Mencia’, ‘Albarin’ and ‘Verdejo’) in the southern region of León province from 2017 to 2020. Tempranillo and Prieto Picudo had the highest number of X. arvicola captures, consistent with being the most susceptible varieties reported to be attacked by X. arvicola larvae. Verdejo had the lowest number of captures. In all varieties, the greatest period of adult emergence and subsequent captures occurred in June. However, in warmer springs, this emergence period started earlier, in May. The number of X. arvicola captured over time was significantly different between sexes, as well as in the interaction between captures and days across all varieties and years studied.
Conclusions: Our results provide valuable information for the integrated control and management of this pest. Placing traps in vineyards on the described dates and regularly monitoring them will help determine peak flight periods (i.e., the highest number of insects captured). This will allow for timely application of phytosanitary treatments, targeting the greatest number of insects. Further trials should be conducted in other vineyards with these types of traps and attractants to corroborate the results obtained.
1. Introduction
Cerambycid pests cause serious economic losses in wood exploitation all over the world [1–3]. Among the cerambycids that attack Vitis vinifera wood in vineyards, Vesperus xatarti (Dufour-Mulsant) has been considered a pest since the mid-19th century [4] and has subsequently been recorded in Spanish vineyards [5, 6]. Clytus arietis (L.) has been reported as a pest in Spanish [7, 8] and French vineyards [9]. In Australia, Acalolepta vastator (Newman) is an important vineyard pest [10], and Xylotrechus pyrrhoderus (Bates) causes damage in Chinese vineyards [11, 12], specifically in ‘′Cabernet Sauvignon’ and ‘Chardonnay’ varieties.
Xylotrechus arvicola (Olivier) is a cerambycid pest affecting vineyards in all major wine-producing regions of Spain, particularly La Rioja Alta and Alavesa [13, 14], Navarra [15] and Castilla y León [16]. Xylotrechus arvicola can spread across different vineyards with different training systems [17]. The activity of its larvae within the wood promotes the development of wood diseases (indirect damage), such as caused by Diplodia seriata De Not (Botryosphaeriales: Botryosphaeriaceae), Eutypa lata Tul and Tul (Xylariales: Diatrypaceae), Phaeoacremonium minimum Gams, Crous, Wingf., Mugnai (Diaporthales: Togniniaceae) and Phaeomoniella chlamydospora Crous and Gams (Diaporthales: Togniniaceae) [18].
Eggs of X. arvicola are laid by females under the rhytidome or in cracks of grapevine wood [19]. Most egg hatching occurs eight days after oviposition [20]. Egg-laying by X. arvicola females in the field and the viability of eggs laid extends over a longer period than for those kept in laboratory conditions [21, 22]. Eggs are white or cream, quite homogeneous and elongated, with a length of around 1.8 mm and a width of approximately 0.7 mm, on average [23]. The larvae are legless and white with an average size of 22 mm in the last stage, reaching up to 32 mm [24]. When the larva emerges from the egg, it penetrates the wood without any difficulty, boring galleries within the wood [25]. Grapevine wood attacked by X. arvicola larvae is more sensitive to external mechanical factors in vineyards such as strong winds, harvest weight and vibrations exerted by harvesting machines [26], in addition to becoming weaker and more prone to breakage [27]. The developmental stages in which X. arvicola can be most effectively controlled with insecticidal products are the adults and egg stages. However, the larva can also be controlled with an insecticide treatment during the first 24 h after hatching and before it penetrates the vine [20]. Once X. arvicola larvae penetrate the wood, they cannot be reached with foliar-applied chemicals that lack penetrative potential [20].
Natural enemies of X. arvicola are still poorly studied [28]. Nevertheless, the use of microbial control agents (MCAs), such as fungi or bacteria, has been researched for its control. Rodríguez-González et al. [29] isolated and identified numerous antagonistic fungi (genus Trichoderma) from vineyard substrates and grapevine wood affected by X. arvicola, showing promising results [30].
Control of X. arvicola through cultural measures can be performed by removing the rhytidome from vines, but this technique is expensive and time-consuming, and therefore unsustainable for extensive cultivation [31]. Until now, in the field, only a few preventive treatments have been evaluated for X. arvicola control [19]. Insecticides with different modes of action [20, 32] have been evaluated under laboratory or semifield conditions [25] against all stages of X. arvicola growth.
Treatment of X. arvicola adults under field conditions is difficult due to their staggered emergence pattern [33]. The emergence period of X. arvicola ranges from June 15 to July 15 in vineyards of La Rioja (Spain), extending until August 15 under certain circumstances [34]. This period lasts from March to late July in vineyards of the Valladolid province, located in Castilla y León region [23], while in the Navarra region, Biurrun et al. [35] reported this period to extend from May 14 to August 26 in plantations of Prunus spinosa L. Also, the insect emergence is highly influenced by weather conditions such as increased temperature and decreased rainfall [36].
The capture, emergence and flight periods of this longhorn beetle in relation to the different host grapevine varieties have been little studied. Therefore, the objective of this study was to evaluate the timing of emergence of X. arvicola insects from different grapevine varieties to provide more information for the control of this insect through integrated pest management (IPM). By better understanding the flight periods of the insect in different varieties, we could further optimize its control by applying phytosanitary products.
2. Materials and Methods
2.1. Traps
Interception traps (CROSSTRAP, Econex, Murcia, Spain) were used to monitor X. arvicola adults in this study. This trap type was chosen because it was reported to have a greater number of X. arvicola catches in vineyards when compared to other traps [37]. In addition, this type of trap has been used in previous studies for the field evaluation of attractant compounds for X. arvicola adults [38]. The trap consisted of a polypropylene lid (33 cm in diameter) with a central carabiner attached to a steel spring. Two reinforced PVC sheets (80.0 × 30.0 cm2) were held in place by four steel springs in the upper section of the lid. In the lower section, the reinforced PVC sheets were held in place by a polypropylene funnel (30 cm in diameter) and four steel springs. The collection cup (12.5 cm diameter × 19 cm height) for the captured insects was in the lower section of the funnel (Figure 1) [39]. All panels were coated with Fluon barrier paint (Dyneon, 3M, Berkshire, England) as recommended by Graham et al. [40]. Lures were attached to the trap at the midpoint, and insects were trapped in a receiver (with walls sliding to retain insects, a grid at the bottom to evacuate water, and an approximate capacity of 1 L) at the base.
2.2. Lures
The lures used in this experiment were contained inside low-density polyethylene bags (95 mm × 60 mm × 50 μ thick; Transpack, Southampton, England) with a press seal. Ethanol (Ethanol Absolute; VWR Chemicals Prolabo, Fontenay-sous-Bois, France) (1 mL) was impregnated onto a folded cotton pad (50 mm diameter; Kent Express Dental Supplies, Gillingham, England), which had previously been placed inside each polyethylene bag.
2.3. Experimental Vineyards
This experiment was conducted from May 20 to July 31, from 2017 to 2020, in five blocks, with the Tempranillo, Prieto Picudo, Mencia, Albarin and Verdejo varieties. The blocks were all located in a vineyard in Gordoncillo (42°08′14.9″ N 5°25′41.6″W) (León, Castilla y León, Spain) and were chosen based on evidence of damage by X. arvicola, such as larval galleries observed in pruning cuts and exit holes of X. arvicola adults on trunks and branches of vines. The five blocks were planted with the same spacing (3.0 m between rows and 1.5 m between plants). The experimental blocks were surrounded by blocks of other varieties. The five blocks had the same age (25 years old), vine training system (bilateral cordon, spur pruning over two branches per trunk at 0.6 m above the ground), soil characteristics (calcareous soils, low in minerals and poor in organic matter), location (747 m above sea level), annual average temperature (11.7°C) and average annual rainfall (500 mm).
During 2017, in each block, an area of 972 m2 (18 m long × 54 m wide) was divided into two sections of 486 m2, with four trap-lures (eight traps per variety). During 2018, 2019 and 2020, the evaluated area for each variety was 648 m2 (18 m long × 36 m wide) forming one block containing six trap-lures for each variety.
Lures (polyethylene bags containing dental rolls baited with 1 mL of ethanol) were changed every 10 days during the experiment. Traps were first attached to a 1.5 m PVC pipe, hanging the trap out of an L-shaped arm, with 18 m between each trap. All traps were monitored every 3 days.
2.4. Insect Emergence and Varieties
Emergence of X. arvicola was measured by counting the beetles found in the interception traps. These were identified and sexed in the laboratory, according to the description of Moreno et al. [23].
2.5. Statistical Analysis
For data analysis, the mean number of trapped insects (males, females and total) was calculated per day per trap (i.e. number of captures obtained divided by the 3-day monitoring period). The captures within the same range of days (3-day monitoring) were compared among varieties and years.
Analysis 1. Insect captures by sex and variety: A completely randomized experiment using a generalized linear model (GLM) procedure with five vineyard varieties, two sexes (males and females), and six replicates was subjected to one-way analysis of variance (ANOVA). Differences (p ≤ 0.05) between males, females and totals among varieties were examined by mean comparisons using Tukey’s tests. Differences (p ≤ 0.05) among adult insects captured (males and females) in the same variety and different years were examined by mean comparisons using Tukey’s tests.
Analysis 2. Insect captures by sex and years in relation to days since trapping started on May 20 where May 20 was Day 1 (DAY) were assessed: ANOVA, followed by a Fisher’s LSD test (significance at p ≤ 0.05), was used to examine the average number of insects (males and females) captured in the same variety and year in relation to DAY. ANCOVA was used to examine the effect of DAY on the capture of X. arvicola in different varieties and years (fixed factor) on the number of captures (males and females) as a covariate. Linear regression coefficients for the interactions between captures and days were tested using an F-test (significance at p ≤ 0.05).
All analyses were conducted using SPSS software, Version 24 (IBM SPSS Statistics, 1968, Armonk, NY, USA).
3. Results
3.1. Insect Captures by Sex and Variety
During 2017, significantly more male insects were captured in the varieties Tempranillo, Prieto Picudo and Albarin than in Verdejo (p = 0.003, Table 1). Significantly more female insects were captured in Tempranillo, Prieto Picudo, Mencia and Albarin than in Verdejo (p = 0.002, Table 1). Significantly more total (males + females) insects were captured in Tempranillo, Prieto Picudo and Albarin (F = 6.122, df = 4,35, p = 0.001) than in Verdejo (Figure 2(a)).
| Insects | 2017 year | F | df | p | ||||
|---|---|---|---|---|---|---|---|---|
| Tempranillo†‡ | Prieto Picudo | Mencía | Albarin | Verdejo | ||||
| ♂ | 3.2 ± 0.9abA | 4.7 ± 0.9aA | 1.3 ± 0.4bcB | 3.4 ± 0.8aA | 0.9 ± 0.4 cA | 5.009 | (4, 35) | 0.003 |
| ♀ | 4.0 ± 0.6aA | 3.1 ± 0.7aA | 3.5 ± 0.9aA | 3.0 ± 0.3aA | 0.4 ± 0.3bA | 5.420 | (4, 35) | 0.002 |
| Totals | 7.3 ± 1.2ab | 7.9 ± 1.2a | 4.8 ± 1.1b | 6.4 ± 1.1ab | 1.3 ± 0.6c | 6.122 | (4, 35) | 0.001 |
| F | 0.529 | 2.043 | 5.299 | 0.158 | 1.098 | |||
| df | (1, 14) | (1, 14) | (1, 14) | (1, 14) | (1, 14) | |||
| p | 0.479 | 0.175 | 0.037 | 0.697 | 0.312 | |||
| Insects | 2018 year | |||||||
| Tempranillo | Prieto Picudo | Mencía | Albarin | Verdejo | ||||
| ♂ | 7.6 ± 1.3aA | 8.3 ± 0.8aA | 6.5 ± 1.2aA | 7.3 ± 1.9aA | 5.8 ± 1.9aA | 0.449 | (4, 25) | 0.772 |
| ♀ | 7.3 ± 0.6aA | 7.8 ± 0.9aA | 7.0 ± 0.8abA | 5.5 ± 1.2abA | 4.3 ± 1.0bA | 3.290 | (4, 25) | 0.048 |
| Totals | 15.0 ± 1.6ab | 16.2 ± 1.1a | 13.5 ± 1.5ab | 12.8 ± 1.4ab | 10.2 ± 2.7b | 3.161 | (4, 25) | 0.050 |
| F | 0.057 | 0.156 | 0.118 | 0.687 | 0.475 | |||
| df | (1, 10) | (1, 10) | (1, 10) | (1, 10) | (1, 10) | |||
| p | 0.816 | 0.701 | 0.738 | 0.427 | 0.506 | |||
| Insects | 2019 year | |||||||
| Tempranillo | Prieto Picudo | Mencía | Albarin | Verdejo | ||||
| ♂ | 2.2 ± 0.6aA | 2.2 ± 0.7aA | 2.2 ± 1.1aA | 2.3 ± 0.3aA | 0.5 ± 0.5aA | 1.238 | (4, 25) | 0.320 |
| ♀ | 3.0 ± 0.7aA | 2.5 ± 0.4aA | 2.5 ± 0.6aA | 2.2 ± 0.4aA | 0.3 ± 0.2bA | 4.538 | (4, 25) | 0.007 |
| Totals | 5.2 ± 1.1a | 4.6 ± 0.6a | 4.6 ± 1.0a | 4.5 ± 0.7a | 0.8 ± 0.6b | 4.437 | (4, 25) | 0.008 |
| F | 0.839 | 0.164 | 0.075 | 0.102 | 0.094 | |||
| df | (1, 10) | (1, 10) | (1, 10) | (1, 10) | (1, 10) | |||
| p | 0.381 | 0.694 | 0.790 | 0.756 | 0.765 | |||
| Insects | 2020 year | |||||||
| Tempranillo | Prieto Picudo | Mencía | Albarin | Verdejo | ||||
| ♂ | 3.5 ± 1.1aA | 1.5 ± 0.7abA | 2.8 ± 1.4abA | 1.6 ± 0.7abA | 0.5 ± 0.3bA | 4.570 | (4, 25) | 0.013 |
| ♀ | 1.6 ± 0.3aA | 1.8 ± 0.4aA | 2.1 ± 0.5aA | 1.6 ± 0.8aA | 1.1 ± 0.5aA | 0.454 | (4, 25) | 0.769 |
| Totals | 5.2 ± 1.3a | 3.3 ± 0.9ab | 5.0 ± 1.5ab | 3.3 ± 1.4ab | 1.6 ± 0.5b | 4.480 | (4, 25) | 0.018 |
| F | 2.738 | 0.164 | 0.191 | 0.000 | 1.290 | |||
| df | (1, 10) | (1, 10) | (1, 10) | (1, 10) | (1, 10) | |||
| p | 0.129 | 0.694 | 0.671 | 1.000 | 0.282 | |||
- †Means followed by different lowercase letters in the same insect sex (male, female and total) and year were significantly different among varieties (ANOVA, LSD p < 0.05).
- ‡Means followed by different capital letter in the same variety and year were significantly different between the sexes (ANOVA, LSD, p < 0.05).
In 2018, no significant differences were observed in the capture of males and females among the varieties evaluated (Table 1). No significant differences were found in the total (males + females) insect captures among the varieties evaluated (Figure 2(b)).
In 2019, no significant differences were found in the capture of males between any of the varieties evaluated. Significantly more female insects were captured in Tempranillo, Prieto Picudo and Mencía compared to Verdejo (p = 0.007, Table 1). Significantly more total (males + females) insects were captured in Tempranillo, Prieto Picudo and Albarin (F = 4.437, df = 4,25, p = 0.008) than in Verdejo (Figure 2(c)).
In 2020, no significant differences were found in the capture of males and females among the varieties evaluated (Table 1). No significant differences were observed in the total (males + females) insect captures among the varieties evaluated (Figure 2(d)).
Comparing the captures of males and females within the same variety across different years, captures of males and females obtained in 2018 in Tempranillo, Prieto Picudo, Mencía and Verdejo varieties were significantly higher than those obtained in the same varieties in the years 2017, 2019 and 2020. Meanwhile, the captures of males and females obtained in 2018 in the Albarin variety were only significantly higher than those obtained in the same variety in 2019 and 2020 (Table 1).
3.2. Insect Captures by Sex and Year in Relation to Days
In 2017, captures of males in relation to DAY were significantly greater (p = 0.023) in Mencía compared to captures of females in this variety and year. DAY for males was significantly greater in Prieto Picudo (p = 0.011), Albarin (p = 0.007) and Verdejo (p = 0.009) compared to DAY for females (Table 2). Meanwhile, DAY for females was significantly greater than for males in Tempranillo (p ≤ 0.001) and Mencía (p = 0.006). The Captures × DAY interaction yielded linear regression coefficients that were not significantly different between males and females in all varieties studied.
| Variety (year) | df | Mean square | F | p | Variety (year) | df | Mean square | F | p | Variety (year) | df | Mean square | F | p | Variety (year) | df | Mean square | F | p | Variety (Year) | df | Mean square | F | p | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Tempranillo (2017) | Captures | 1 | 0.307 | 0.146 | 0.704 | Prieto Picudo (2017) | Captures | 1 | 2.077 | 0.315 | 0.577 | Albarin (2017) | Captures | 1 | 0.072 | 0.017 | 0.897 | Mencía (2017) | Captures | 1 | 14.074 | 5.529 | 0.023∗∗ | Verdejo (2017) | Captures | 1 | 0.362 | 1.626 | 0.209 |
| Days | 1 | 34.453 | 16.444 | ≤ 0.001∗∗ | Days | 1 | 46.633 | 7.079 | 0.011∗∗ | Days | 1 | 34.209 | 8.089 | 0.007∗∗ | Days | 1 | 21.235 | 8.342 | 0.006∗∗ | Days | 1 | 1.671 | 7.514 | 0.009∗∗ | |||||
| Captures × days | 1 | 0.149 | 0.071 | 0.791 | Captures × days | 1 | 0.305 | 0.046 | 0.831 | Captures × days | 1 | 0.329 | 0.078 | 0.782 | Captures × days | 1 | 3245.258 | 0.736 | 0.408 | Captures × days | 1 | 0.126 | 0.565 | 0.456 | |||||
| Total | 48 | Total | 48 | Total | 48 | Total | 48 | Total | 48 | ||||||||||||||||||||
| Variety (year) | df | Mean square | F | p | Variety (year) | df | Mean square | F | p | Variety (year) | df | Mean square | F | p | Variety (year) | df | Mean square | F | p | Variety (year) | df | Mean square | F | p | |||||
| Tempranillo (2018) | Captures | 1 | 0.819 | 0.084 | 0.774 | Prieto Picudo (2018) | Captures | 1 | 0.841 | 0.055 | 0.816 | Albarin (2018) | Captures | 1 | 0.398 | 0.041 | 0.841 | Mencía (2018) | Captures | 1 | 0.656 | 0.063 | 0.803 | Verdejo (2018) | Captures | 1 | 0.082 | 0.013 | 0.911 |
| Days | 1 | 4.218 | 0.431 | 0.515 | Days | 1 | 4.007 | 0.262 | 0.612 | Days | 1 | 2.349 | 0.241 | 0.626 | Days | 1 | 1.339 | 0.129 | 0.722 | Days | 1 | 5.213 | 0.810 | 0.373 | |||||
| Captures × days | 1 | 0.940 | 0.096 | 0.758 | Captures × days | 1 | 2.010 | 0.131 | 0.719 | Captures × days | 1 | 0.048 | 0.005 | 0.944 | Captures × days | 1 | 0.261 | 0.025 | 0.875 | Captures × days | 1 | 1.244 | 0.193 | 0.662 | |||||
| Total | 48 | Total | 48 | Total | 48 | Total | 48 | Total | 48 | ||||||||||||||||||||
| Variety (year) | df | Mean square | F | p | Variety (year) | df | Mean square | F | p | Variety (year) | df | Mean square | F | p | Variety (year) | df | Mean square | F | p | Variety (year) | df | Mean square | F | p | |||||
| Tempranillo (2019) | Captures | 1 | 0.334 | 0.135 | 0.715 | Prieto Picudo (2019) | Captures | 1 | 0.159 | 0.072 | 0.789 | Albarin (2019) | Captures | 1 | 0.069 | 0.047 | 0.829 | Mencía (2019) | Captures | 1 | 0.028 | 0.010 | 0.921 | Verdejo (2019) | Captures | 1 | 0.089 | 0.482 | 0.491 |
| Days | 1 | 4.049 | 1.644 | 0.206 | Days | 1 | 1.837 | 0.835 | 0.366 | Days | 1 | 5.405 | 3.697 | 0.061 | Days | 1 | 7.749 | 2.795 | 0.102 | Days | 1 | 0.305 | 1.662 | 0.204 | |||||
| Captures × days | 1 | 0.058 | 0.023 | 0.879 | Captures × days | 1 | 0.661 | 0.300 | 0.586 | Captures × days | 1 | 0.048 | 0.033 | 0.857 | Captures × Days | 1 | 0.079 | 0.029 | 0.867 | Captures × days | 1 | 0.068 | 0.370 | 0.546 | |||||
| Total | 48 | Total | 48 | Total | 48 | Total | 48 | Total | 48 | ||||||||||||||||||||
| Variety (year) | df | Mean square | F | p | Variety (year) | df | Mean square | F | p | Variety (year) | df | Mean square | F | p | Variety (year) | df | Mean square | F | p | Variety (year) | df | Mean square | F | p | |||||
| Tempranillo (2020) | Captures | 1 | 2.604 | 1.450 | 0.235 | Prieto Picudo (2020) | Captures | 1 | 0.379 | 0.746 | 0.392 | Albarin (2020) | Captures | 1 | 0.016 | 0.012 | 0.914 | Mencía (2020) | Captures | 1 | 1.061 | 0.723 | 0.400 | Verdejo (2020) | Captures | 1 | 0.320 | 1.071 | 0.306 |
| Days | 1 | 8.583 | 4.779 | 0.034∗∗ | Days | 1 | 3.031 | 6.013 | 0.018∗∗ | Days | 1 | 4.978 | 3.733 | 0.060 | Days | 1 | 7.576 | 5.159 | 0.028∗∗ | Days | 1 | 0.341 | 1.141 | 0.291 | |||||
| Captures × days | 1 | 0.861 | 0.479 | 0.492 | Captures × days | 1 | 0.079 | 0.157 | 0.694 | Captures × days | 1 | 0.021 | 0.016 | 0.900 | Captures × Days | 1 | 0.731 | 0.498 | 0.484 | Captures × days | 1 | 0.098 | 0.327 | 0.570 | |||||
| Total | 48 | Total | 48 | Total | 48 | Total | 48 | Total | 48 | ||||||||||||||||||||
- ∗∗p ≤ 0.05.
In 2018, captures of males in relation to DAY were not significantly greater in all varieties studied compared to captures of females in this year (Table 2). DAY for males were captured was not significantly greater in all varieties compared to DAY for females. The Captures × DAY interaction yielded linear regression coefficients that were not significantly different between males and females in all varieties studied.
In 2019, captures of males in relation to DAY were not significantly greater in all varieties studied compared to captures of females in this year (Table 2). DAY for males were captured was not significantly greater in all varieties compared to DAY for females. The Captures × DAY interaction yielded linear regression coefficients that were not significantly different between males and females in all varieties studied.
Finally, in 2020, captures of males in relation to DAY were not significantly greater in all varieties studied compared to captures of females in this year. DAY for males were captured was significantly greater in Tempranillo (p = 0.034) and Mencía (p = 0.028) compared to DAY for females (Table 2). Meanwhile, DAY for females were captured was significantly greater than for males in Prieto Picudo (p = 0.018). The Captures × DAY interaction yielded linear regression coefficients not significantly different between males and females in all varieties studied.
4. Discussion
During the 4 years evaluated, Tempranillo had the greatest number of total insects captured in 2019 and 2020, while Prieto Picudo had the greatest number of total insects captured in 2017 and 2018. These varieties have a greater susceptibility to being attacked by X. arvicola, as described in previous studies by Ocete and Del Tío [13] and Moreno et al. [41] for Tempranillo and Rodriguez-González et al. [37] for Prieto Picudo. The different sensitivity of the varieties to being attacked by X. arvicola may be due to the varying holocellulose and lignin contents of each variety. Tempranillo, Viura and Cabernet Sauvignon are varieties with low holocellulose and high lignin contents, and they have the highest proportion of affected vines, while Mencia has low lignin and high holocellulose contents, and fewer vines were attacked [23]. Other authors have described how these organic polymers (holocellulose and/or lignin) are related to the feeding preference of insects in their hosts. Thus, for example, Becker [42] describes that holocellulose, made up of cellulose and hemicellulose, is a very desirable compound for xylophagous insects, although only between 20% and 35% of cerambycids can assimilate it. On the other hand, lignin is less consumed by coleopteran larvae [42]. Among the insects that can digest this compound, another cerambycid, Hoplocerambyx spinicornis (Newman 1842), can digest part of the lignin with the help of microorganisms found in its digestive tract [43].
According to Peláez et al. [44], the appearance of X. arvicola adults in vineyards may be delayed if the spring has been cold. Climatic data obtained from Inforiego [45] from the nearest weather station to the studied vineyards (Mayorga de Campos, Valladolid, Spain) recorded an average temperature of 14.7°C for spring (from March 21 to June 21) in 2017, and 13.3°C in 2020, which was warmer than the springs in 2018 (11.7°C) and 2019 (12.3°C). This is consistent with the X. arvicola captures recorded during 2017 in the current study compared to the other years evaluated. Captures began in May and ended in late June or the beginning of July, while in 2018, the first captures were delayed until June, ending in July. In 2019, with a slightly higher spring temperature (12.3°C) than in 2018 (11.7°C), the same general emergence pattern was observed, except for a few captures obtained during May in Mencia and Albarin. The results obtained in all varieties studied, in relation to the emergence period of X. arvicola adults, confirm that the rate of development and emergence of X. arvicola in these vineyards is strictly related to the accumulated temperature. The explanation for the fact that 2018 was the year with the highest number of captures may be due to the spring with colder temperatures (average temperature of 11.7°C from March 21 to June 21), which delayed the emergence of insects, with no captures occurring during the month of May, and all insect emergences being concentrated after the date of trap placement in the vineyards (May 20). Fierke and Stephen [46] described that the temperature insects accumulate is like the energy needed to move from one stage to the next during their development. Similar behaviour has been described in other cerambycid pests, relating optimal temperature to emergence from the host, as in Monochamus saltuarius Gebler (Coleoptera: Cerambycidae) [47], or in X. arvicola [48].
The greatest capture periods of X. arvicola took place in June in all vineyards and varieties studied, with varying number of X. arvicola captured (males, females and totals) between years, and the greatest number of captures was in 2018. This range of dates presenting the greatest captures (June 1 to June 30) in our study is consistent with the emergence period of X. arvicola in the field described by other authors in vine-producing regions and crops. Among these, we can highlight Soria et al. [34], who described the emergence period between late June and mid-July in vineyards of La Rioja; Moreno [23], describing the emergence period from March until the end of July in vineyards of Valladolid (Castilla y Leon); Rodríguez-González et al. [37] doing the same in vineyards located in the southeast of León province and describing this emergence period between June 1 and mid-July; or Biurrun et al. [35], describing the emergence period between May 14 and August 26 in P. spinosa L. orchards in Navarra. Captures of insects (males or females) in relation to days were not significantly higher between sexes in all varieties and years studied (except in the Mencia variety, 2017). Also, no significant differences were found in the Captures × Days interaction, which suggests that sex ratios did not differ during the emergence period in these vineyards and varieties, in contrast to García-Ruiz [33], who reported for X. arvicola the phenomenon known as protandry, by which adult males emerge before females, and females predominate at the end of the emergence period.
5. Conclusion
The grapevine varieties Tempranillo and Prieto Picudo had the highest number of X. arvicola captured, corresponding to the higher susceptibility of these varieties to be attacked by X. arvicola larvae, as described by previous studies. The fewest captures were recorded in Verdejo. In all V. vinifera varieties studied in this wine-producing area over four years, the greatest period of insect emergence and subsequent capture occurred during June. Nevertheless, this emergence period begins early in May when warmer springs occur. Captures of insects (males or females) in relation to days were not significantly different between sexes, and in the interaction Captures × DAY in all varieties and years studied, so we can deduce that the phenomenon known as protandry was not observed in these vineyards and varieties. Our results provide valuable information for the integrated control and management of this pest. Placing traps in vineyards on the dates described and conducting periodic trap observations will allow us to know when the peak of flight occurs (the greatest number of insects captured), so that if a phytosanitary treatment is needed, it can be as effective as possible because it will target the greatest number of insects. While the variety effects may be true, it cannot be certain that they can be generalized to all locations where this cerambycid is found and the grapevine varieties studied. Therefore, further trials should be carried out in other vineyards with these types of traps and attractants to corroborate the results obtained.
Conflicts of Interest
The authors declare no conflicts of interest.
Funding
This research was funded by the projects ‘Solución global para mejorar la producci´on vitivin´ıcola frente al cambio climático basada en robótica, en tecnología IT y en estrategias biotecnológicas y del manejo del viñedo (Acronym: GLOBALVITI; Reference: IDI-20160746)’.
Acknowledgements
We would like to thank the Diputación de León, Servicio de Desarrollo Rural y Medio Ambiente, for the project ‘Control integrado del taladro de la vid Xylotrechus arvicola en la provincial de León’, as well as ‘Gordonzello’ wine cellar, and ‘Pago de Carraovejas’, for the projects ‘Solución global para mejorar la producción vitivinícola frente al cambio climático basada en robótica, en tecnología IT y en estrategias biotecnológicas y del manejo del viñedo’ (Acronym: GLOBALVITI; Reference: IDI-20160746) and ‘Estudio de nuevos factores relacionados con el suelo, la planta y la microbiota enológica que influyen en el equilibrio de la acidez de los vinos y en su garantía de calidad y estabilidad en climas cálidos (Acronym: LOWpHWINE 2020; Reference: IDI-20210391)’. We also would like to thank the research program of the Universidad de León (2022) for the grant awarded to Daniela Ramírez Lozano, the Ministry of Education, Culture and Sports (Spain) and for the grant awarded to Laura Zanfaño González (FPU 20/03040) and the Junta de Castilla y Leon for the financial aid supporting the predoctoral hiring of research personnel, cofinanced by the European Social Fund, as established by ORDEN EDU/875/2021, awarded to Andrea Antolín Rodríguez.
Open Research
Data Availability Statement
The data used to support the findings of this study are available from the corresponding author upon reasonable request.
