Essential oils can have an impact on pollen beetle (Meligethes spp.) host plant location behaviour.Highest repellency values were obtained for Mentha arvensis, Cymbopogon flexuosus, and Litsea cubeba

Daniel, Claudia

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C. DanielResearch Institute of Organic Agriculture, Ackerstrasse 21, CH-5070 Frick, Switzerland, claudia.daniel@fibl.orgwww.fibl.orgForschungsinstitut für biologischen LandbauInstitut de recherche de l’agriculture biologique      Research Institute of Organic AgricultureIstituto di ricerche dell’agricoltura biologicaInstituto de investigaciones para la agricultura orgánica E X C E L L E N C E  F O R  S U S T A I N A B I L I T YOlfactometer screening of repellent essential oils against the pollen beetle (Meligethes spp.).IntroductionOrganic agricultural methods to control pol-len beetle (Meligethes spp.) are limited and alternatives are needed. The beetles use olfac-tory cues to locate oilseed rape fields during immigration in spring. Non-host odors can have repellent effects on pollen beetles (Maucheline 2005). We compared the repellent effects of 15 differ-ent essential oils using a Y-tube-olfactometer. Material and methods� Y-tube-olfactometer described by Belz et al. 2013.� Essential oils diluted 1:10 in acetone; 40 µl applied on filter paper.� Filter papers + a flower cluster of oilseed  rape were placed in the odour containers of the olfactometer (control treatment: filter papers with acetone +flower).� Beetles  were released individually into the olfactometer. � The beetles’ choices were recorded. � Six replicates with six beetles each were conducted.� Repellency values (RV)  = nb of beetles on the untreated flower / total nb of beetles. � Wilcoxon signed rank test to test whether mean RV significantly differ-ent from 0.5.� To compare different essential oils: RV [arcsin√(x)] transformed, ANOVA: F14,72=5.03, p<0.0001; Tukey HSD tests (α=0.05); different letters show significant differences.Tested essential oils:� Cornmint (Mentha arvensis),� Orange (Citrus sinensis),� Wintergreen (Gaultheria procumbens),� Lemongrass (Cymbopogon flexuosus),� Eucalyptus (Eucalyptus globulus),� Fir needle (Abies sibirica),� Lemon (Citrus limon),� Tea-tree (Melaleuca alternifolia),� Clove (Syzygium aromaticum),� Star anise (Illicium verrum),� Grapefruit white (Citrus paradisi),� Texas cedarwood (Juniperus mexicana),� Litsea cubeba (Litsea cubeba),� Lavender oil (Lavendula angustifolia)� Pine oil product Heliosol (Omya Agro, Switzerland)Odour 1 Odour 2Results� On average, it took the beetles 39.8±0.6 s to make their choice.� 87.8% Meligethes aeneus, 12.2% M. viridescens.� Ten essential oils significantly repelled the beetles.� Highest repellency values were obtained for cornmint, lemongrass, Litsea and Heliosol.0%10%20%30%40%50%60%70%80%90%100%Cornmint Lemongrs. Litsea Heliosol Tea tree Grapefrt. Firneedle Staranise Lavender Clove Lemon Eucalypt. Wintergr. Orange Cedarwd.the untreated flower cluster the flower cluster+ essential oilababc aabc abc abcabcdabcdabcdabccd cd bcdd cdProportion of beetles choosing: 1.00* 0.92* 0.92* 0.92* 0.89* 0.86* 0.83* 0.83* 0.81* 0.81* 0.75 0.69 0.69 0.67 0.64Repellency value (*= significantely different from 0.5): ConclusionIn addition to a high repellency value, the price of an es-sential oil is a major factor to choose candidates for field application strategies. The cheapest essential oil in our ex-periments was grapefruit oil  (14.00 ¤ / kg). Lemongrass and Litsea oil are also reasonably priced (17.50 and 18.00 ¤ / kg). Cornmint oil is considerably more expensive (31.50 ¤ / kg) and lavender oil was by far the most expensive oil in our experiments (104.00 ¤ / kg). Based on the results of the experiments and on the prices of the essential oils, the development of a field application strategy will focus on cornmint oil, lemongrass oil and Litsea cubeba oil.Acknowledgements:A thousand thanks to Christian Urech who spent the splendid days of spring in the dark room patiently watching bee-tles speeding through the olfactometer. Many thanks to Brian Baker for language editing the manuscript Many thanks to qualiessentials gmbh for providing the essential oils. The project was funded by Migros Genossenschaftsbund and supported by Biofarm GenossenschaftReferences: Belz, E., Kölliker, M. & Balmer, O. (2013): Olfactory attractiveness of flowering plants to the parasitoid Microplitis mediator: potential implications for biological control. BioControl 58: 163–173Mauchline, A.L., Osborne, J.L., Martin, A.P., Poppy, G.M. & Powell, W. 2005: The effects of non-host plant essential oil volatiles on the behaviour of the pollen beetle Meligethes aeneus. Entomol Exp Appl 114: 181-188.Air flow

Olfactometer screening of repellent essential oils against the pollen beetle (Meligethes spp.)

Essential oils can have an impact on pollen beetle (Meligethes spp.) host plant location behaviour. Lavender oil (Lavendula angustifolia) showed the highest repellency value in a previous laboratory study that compared five different essential oils (Mauchline et al., 2005). However, lavender oil is one of the most expensive essential oils – a fact that could seriously hamper on-farm implementation of this strategy. To find a cheaper essential oil with comparable efficacy to lavender oil, we compared the essential oils of Mentha arvensis, Eucalyptus globulus, Melaleuca alternifolia, Citrus sinensis, Citrus paradisi, Citrus limon, Juniperus mexicana, Abies sibirica, Illicium verum, Gaultheria procumbens, Cymbopogon flexuosus, Syzygium aromaticum, and Litsea cubeba using a Y-tube-olfactometer. Essential oils were diluted 1:10 in acetone and 40 µl of the dilution were applied on a 3.1cm2 filter paper. Filter papers were placed in the odour containers of the olfactometer together with a flower cluster of spring oilseed rape with 5 open flowers and 10-15 buds. The control treatment involved filter papers treated only with acetone. Hungry pollen beetles were released individually into the olfactometer. The beetles’ choices were recorded. Flowers and essential oils were changed between replicates. Six replicates with six beetles each were conducted. Highest repellency values were obtained for Mentha arvensis, Cymbopogon flexuosus, and Litsea cubeba

RAHMANN G & AKSOY U (Eds.) (2014) Proceedings of the 4th ISOFAR Scientific Conference. ‘Building Organic Bridges’, at the Organic World Congress 2014, 13-15 Oct., Istanbul, Turkey (eprint ID 24164)   1035 Olfactometer screening of repellent essential oils against  the pollen beetle (Meligethes spp.)  CLAUDIA DANIEL1 Key words: Meligethes aeneus, Meligethes viridescens, essential oil, lavender, cornmint, lemongrass Abstract Essential oils can have an impact on pollen beetle (Meligethes spp.) host plant location behaviour. We compared the effects of essential oils of Mentha arvensis, Eucalyptus globulus, Melaleuca alternifolia, Citrus sinensis, Citrus paradisi, Citrus limon, Juniperus mexicana, Abies sibirica, Illicium verum, Gaultheria procumbens, Cymbopogon flexuosus, Syzygium aromaticum, and Litsea cubeba using a Y-tube-olfactometer. Essential oils were diluted 1:10 in acetone and 40 µl of the dilution were applied on a 3.1cm2 filter paper. Filter papers were placed in the odour containers of the olfactometer together with a flower cluster of spring oilseed rape with 5 open flowers and 10-15 buds. The control treatment involved filter papers treated only with acetone. Hungry pollen beetles were released individually into the olfactometer. Six replicates with six beetles each were conducted. Highest repellency values were obtained for Mentha arvensis, Cymbopogon flexuosus, and Litsea cubeba.  Introduction Organic agricultural methods to control pollen beetle (Meligethes spp.) are limited. Although effective insecticides are available for organic producers (Spinosad), their use is often restricted by guidelines of producers associations. In Swiss organic production (Bio Suisse) the use of insecticides in oilseed rape is interdicted. Therefore, alternative non-insecticidal methods to control pollen beetles are needed. Experiments in UK showed that essential oils can have an impact on pollen beetle host plant location behaviour (Mauchline et al., 2005; Mauchline et al., 2008; Mauchline et al., 2013). In a laboratory study that compared five different essential oils, lavender oil (Lavendula angustifolia) showed the highest repellency value (Mauchline et al. 2005). Lavender oil is relatively expensive, and cost is an impediment for farms to adopt it as a repellent. We compared 15 different essential oils using a Y-tube-olfactometer to see if any of lower cost would have similar efficacy. Material and methods  The pollen beetles used in all experiments were collected in an untreated winter oilseed rape field in north-western Switzerland. Beetles were denied food for 40 hours before starting the experiment.  Spring oilseed rape flowers (variety Hero) used as odour source were produced in a nearby greenhouse. Flower clusters with 5 open flowers and approximately 10-15 closed buds were cut immediately before starting the experiments and were permanently supplied with water.  The experiments were conducted using a Y-tube-olfactometer (Belz et al., 2013). Odour sources were placed in the odour containers of the olfactometer. Pollen beetles were released individually into the olfactometer using flexible forceps. The measurement started as soon as the beetle crossed the first line (1.5 cm from the release point; 10 cm distance to the Y-junction) and stopped as soon as the beetle crossed the finish line (4 cm behind the Y-junction). The choice of the beetle was recorded. The beetle was removed from the olfactometer for determination of species (M. aeneus, M. viridescens) and sex. Beetles that failed to cross the finish line within 90s after crossing the first line, were removed from the olfactometer and were not included in the analysis. Each replicate consisted of six responding pollen beetles. Odour sources (=flowers and repellent odours) were replaced after each replicate. Six replicates (= total 36 beetles) were conducted per treatment. The sequence of the tested substances was randomized between each replicate to avoid influence of the time of day. Experiments were conducted between 7:30 and 16:30 h. The experimental room was kept at 22±3°C, 50±10% rh relative humidity.  The following essential oils, supplied by qualiessentials gmbh (Germany), were used in the experiments: cornmint oil (Mentha arvensis), orange oil sweet (Citrus sinensis), wintergreen oil (Gaultheria procumbens), lemongrass oil (Cymbopogon flexuosus), eucalyptus oil (Eucalyptus globulus), fir needle oil (Abies sibirica), lemon oil (Citrus limon), tea-tree oil (Melaleuca alternifolia), clove oil (Syzygium aromaticum), star anise oil                                                  1Research Institute of Organic Agriculture (FiBL), Switzerland, www.fibl.org, eMail: claudia.daniel@fibl.org  DANIEL C Olfactometer screening of repellent essential oils against the pollen beetle (Meligethes spp.)   1036 (Illicium verrum), grapefruit oil white (Citrus paradisi), Texas cedarwood oil (Juniperus mexicana), Litsea cubeba oil (Litsea cubeba), lavender oil (Lavendula angustifolia). In addition to the essential oils, the product Heliosol (Omya Agro, Switzerland) was tested. Heliosol is a pine oil based product used as wettening and sticking agent for plant protection purpose. Essential oils and Heliosol were diluted 1:10 in acetone and 40 µl of the dilution were applied on a 3.1 cm2 filter paper (MN713, Macherey-Nagel, Germany). After 30 minutes, when the acetone had evaporated, the filter papers were placed together with a flower cluster in the odour containers of the olfactometer. The control used filter papers treated only with acetone with a flower cluster. Statistical analysis: Repellency values (RV) were calculated per replicate according to Mauchline et al. (2005): [RV = number of beetles on the untreated flower / (number of beetles on the untreated flower + number of beetles on the treated flower)]. In order to test if the essential oils had a significant effect compared to the “untreated” control, a Wilcoxon signed rank test was performed to test whether mean RV was significantly different from 0.5. In order to compare the efficacy of different essential oils, the RV were [arcsin√(x)] transformed. Normality of data and homogeneity of variance were tested. RV were compared by an ANOVA followed by a Tukey HSD post hoc tests (α=0.05). Results and discussion Behaviour of beetles in the olfactometer: When released into the olfactometer, the pollen beetles needed a few seconds to get on their feet and to orient themselves towards the airflow. Once they started to walk, they moved forward until they reached the junction of the two arms. Irritated either by the light, which was placed directly above the junction or by the disturbance in the airflow, most beetles stopped or walked a vertical looping in the junction. After a few seconds, they started walking into one arm of the olfactometer, usually at a rapid pace. On average, it took the beetles 39.8±0.6 s to cover the distance (14 cm) from the first line to finish line. Beetles rarely moved back into the other olfactometer arm. A total of 772 beetles were released into the olfactometer. Out of these beetles, 232 individuals (=30%) failed to cross the finish line within 90s after crossing the first line. They were removed and not included in the analysis. A total of 540 beetles were responsive. Beetles showed best reaction early in the morning. This might be due to the daily activity pattern of pollen beetles: food foraging behaviour is probably stronger in the morning. Field collected beetles were used for the experiments. Determination of sex and species was done after the beetles had passed the olfactometer. Out of the 540 responding beetles, 474 individuals were Meligethes aeneus, 66 individuals (=12.2%) were Meligethes viridescens. The sex ratio (M:F) of 0.47 was identical for both species.  Pollen beetle choice in the olfactometer: Ten out of the 15 tested essential oils in a 1:10 dilution significantly repelled the pollen beetles and showed a repellency value (RV) significantly greater than 0.5 (Table 1; Wilcoxon signed rank test, p<0.05). The essential oils from cedarwood, orange, wintergreen, eucalyptus and lemon did not have a significant effect on pollen beetle choice. The RV was not significantly different from 0.5 (Wilcoxon signed rank test, p>0.05). However, all tested essential oils had a mean RV > 0.5. Thus, none of the tested essential oils was attractive for the pollen beetles. Cornmint had the highest RV (1.00): none of the beetles chose the olfactometer arm with cornmint essential oil. Lemongrass and Litsea essential oils, as well as the pinolene based plant protection product Heliosol also showed high repellency values of 0.92. Lavender oil was less repellent: RV was 0.81. These results are in accordance with the literature: Maucheline et al (2005) compared different essential oils at 10% dilution and observed the following mean RV: 0.97 for peppermint (Mentha piperita), 0.97 for lavender, 0.95 for Tea tree, and 0.9 for eucalyptus.  Prices of different essential oils: In addition to a high repellency value, the price of an essential oil is a major factor to choose candidates for field application strategies. Prices of essential oils fluctuate during the year, depending on origin and harvesting time of plants. Prices given in Table 1 are rough estimations by qualiessentials gmbh. The cheapest essential oil in our experiments was grapefruit oil. Lemongrass and Litsea oil are also reasonably priced. Cornmint oil is considerably more expensive and lavender oil was by far the most expensive oil in our experiments.  Conclusions Based on the results of the experiments and on the prices of the essential oils, the development of a field application strategy will focus on cornmint oil, lemongrass oil and Litsea cubeba oil. Acknowledgements  A thousand thanks to Christian Urech who spent the splendid days of spring in the dark room patiently watching beetles speeding through the olfactometer. Many thanks to Brian Baker for language editing the RAHMANN G & AKSOY U (Eds.) (2014) Proceedings of the 4th ISOFAR Scientific Conference. ‘Building Organic Bridges’, at the Organic World Congress 2014, 13-15 Oct., Istanbul, Turkey (eprint ID 24164)   1037 manuscript Many thanks to qualiessentials gmbh for providing the essential oils. The project was funded by Migros Genossenschaftsbund and supported by Biofarm Genossenschaft.  Table 1: Repellency values (± se) of different essential oils tested in the Y-tube-olfactometer containing “flower clusters + filter paper + acetone” and “flower clusters + filter paper +essential oil diluted 1:10 in acetone” and estimation of price per kg of the essential oils. Essential oil RV±se Wilcoxon Test Tukey HSD-Test Prices of essential oils Cornmint 1.00±0.00 * D 31.50 € / kg Lemongrass 0.92±0.06 * CD 17.50 € / kg Litsea 0.92±0.06 * CD 18.00 € / kg Heliosol 0.92±0.04 * CD 18.00 € / kg Tea tree 0.89±0.06 * BCD 32.00 € / kg Grapefruit 0.86±0.03 * ABC 14.00 € / kg Fir needle 0.83±0.06 * ABCD 28.50 € / kg Star anise 0.83±0.06 * ABCD 22.50 € / kg Lavender 0.81±0.05 * ABCD 104.00 € / kg Clove 0.81±0.08 * ABC 30.00 € / kg Lemon 0.75±0.08 n.s. ABC  Eucalyptus 0.69±0.07 n.s. ABC  Wintergreen 0.69±0.11 n.s. ABC  Orange 0.67±0.06 n.s. AB  Cedarwood 0.64±0.05 n.s. A   Statistical analysis: Wilcoxon signed rank test testing if RV is different from 0.5 with p<0.05; Tukey: Data transformed [arcsin√(x)], Four-way-ANOVA: essential oil: F14,72=5.03, p<0.0001; temperature: F1,72=21.57, p<0.0001; humidity: F1,72=0.12, p<0.13; position of olfactometer arms: F1,72=7.73, p=0.007; Tukey HSD post hoc tests α=0.05, different letters show significant differences. References  Belz, E., Kölliker, M. & Balmer, O. (2013): Olfactory attractiveness of flowering plants to the parasitoid Microplitis mediator: potential implications for biological control. BioControl 58: 163–173 Mauchline, A.L., Osborne, J.L., Martin, A.P., Poppy, G.M. & Powell, W. 2005: The effects of non-host plant essential oil volatiles on the behaviour of the pollen beetle Meligethes aeneus. Entomol Exp Appl 114: 181-188. Mauchline, A.L., Birkett, M.A., Woodcock, C.M., Pickett, J.A., Osborne, J.L. & Powell, W. 2008: Electrophysiological and behavioural responses of the pollen beetle, Meligethes aeneus, to volatiles from a non-host plant, lavender, Lavandula angustifolia (Lamiaceae). Arthropod-Plant Interactions 2: 109-115. Mauchline, A.L., Cook, S.M., Powell, W. & Osborne, J.L., 2013: Effects of non-host plant odour on Meligethes aeneus during immigration to oilseed rape. Entomol Exp Appl 146: 313-320. DANIEL C Olfactometer screening of repellent essential oils against the pollen beetle (Meligethes spp.)   1038  

OLFACTOMETER SCREENING OF REPELLENT ESSENTIAL OILS AGAINST THE POLLEN BEETLE (MELIGETHES SPP.)

Laboratory Screening of essential oils against pollen beetle: The objective of our experiments was to find a cheaper essential oil with comparable efficacy to lavender oil. We compared the essential oils of Mentha arvensis, Eucalyptus globulus, Melaleuca alternifolia, Citrus sinensis, Citrus paradisi, Citrus limon, Juniperus mexicana, Abies sibirica, Illicium verum, Gaultheria procumbens, Cymbopogon flexuosus, Syzygium aromaticum, and Litsea cubeba using a Y-tube-olfactometer

www.ippc2015.deBERLIN 2015XVIII. International Plant Protection Congress24–27 August 2015 • Berlin (Germany)ABstrActs© fotolia.com/Beboy/St. Körber/drob/S. Mathews/T. Nyshko/jola B.Oral Presentations Non-Chemical Control Options II  86 O NOC II-6 Olfactometer screening of repellent essential oils against the pollen beetle (Meligethes spp.) C. Daniel Research Institute of Organic Agriculture (FiBL), Crop Sciences, Frick, Switzerland  claudia.daniel@fibl.org  In organic farming, pollen beetles (Meligethes spp.) are difficult to control due to the ban of insecticides. Alternative methods are therefore needed. The beetles use olfactory cues to locate oilseed rape fields in early spring. Essential oils were shown to have an impact on host plant location behaviour. Lavender oil (Lavendula angustifolia) showed the highest repellency value in a laboratory study that compared five different essential oils (Mauchline et al., 2005). However, lavender oil is one of the most expensive essential oils - a fact that could seriously hamper on-farm implementation of this strategy. The objective of our experiments was to find a cheaper essential oil with comparable efficacy to lavender oil. We compared the essential oils of Mentha arvensis, Eucalyptus globulus, Melaleuca alternifolia, Citrus sinensis, Citrus paradisi, Citrus limon, Juniperus mexicana, Abies sibirica, Illicium verum, Gaultheria procumbens, Cymbopogon flexuosus, Syzygium aromaticum,  and Litsea cubeba using a Y-tube-olfactometer. Essential oils were diluted 1:10 in acetone and 40 µl of the dilution were applied on a filter paper. Filter papers were placed in the odour containers of the olfactometer together with a flower cluster of spring oilseed rape. Hungry pollen beetles were released individually into the olfactometer. The beetles’ choices were recorded. Flowers and essential oils were changed between replicates. Six replicates with six beetles each were conducted. Ten out of the 15 tested essential oils significantly repelled the pollen beetles; none of the tested essential oils was attractive for the pollen beetles. Highest repellency values were obtained for Mentha arvensis (100% repellency), Cymbopogon flexuosus (92% repellency), and Litsea cubeba (92% repellency). Lavender oil was less effective and repelled only 81% of the beetles. With an average price of 17.5 and 18 € / kg, Cymbopogon flexuosus and Litsea cubeba oil are considerably less expensive than lavender oil (104 €/kg). Mentha arvensis oil has an average price of 31.50 € / kg. Based on the results of the experiments and on the prices of the essential oils, the development of a field application strategy will focus on Cymbopogon flexuosus, Litsea cubeba and Mentha arvensis oil. Mauchline, et al. 2005: Entomol Exp Appl 114: 181-188.     

Olfactometer screening of repellent essential oils against the pollen beetle (Meligethes spp.)

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