Abstract
A mixture of four volatile compounds, (Z)-3-hexenyl acetate, α-pinene, sabinene and n-heptanal, emitted from cabbage plants infested by diamondback moth [DBM; Plutella xylostella (L.)] larvae attracts Cotesia vestalis (Haliday), a major parasitoid of DBM larvae. The volatiles may affect other organisms, such as DBM conspecifics, other herbivores and carnivores. Here, we studied whether the volatiles affect the oviposition behavior of DBM females. In a climate-controlled room, five pots of komatsuna plants (Brassica rapa var. perviridis L. cv. Rakuten; leaf vegetable) were placed in an acrylic box. For the treatment, we placed a bottle-type dispenser of the volatiles (0.01% in a triethyl citrate solution) next to the center pot. For the control experiment, we used a container with plants and triethyl citrate only. The presence of the volatiles did not affect the number of eggs per plant. Interestingly, DBM females laid more eggs on the adaxial leaf surfaces in the treatment compared with the control. This is the first study showing that plant volatiles affect the oviposition site preference of herbivores on leaves. The results are discussed in relation to the application of attractants for DBM control in commercial greenhouses.
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
Introduction
Plants emit a specific mixture of volatiles in response to the damage caused by herbivorous arthropods, and a well-known ecological function of such volatiles is to attract carnivorous natural enemies of the currently infesting herbivorous arthropods (Dicke et al. 1990; Arimura et al. 2009; Takabayashi 2014). Cotesia vestalis (Haliday), a parasitic wasp of the diamondback moth [DBM; Plutella xylostella (L.)] larvae, and an effective biological control agent of DBM populations (Talekar and Shelton 1993), is attracted to volatiles from DBM larvae-infested cabbage plants (Shiojiri et al. 2000). The volatiles involved in attracting C. vestalis to DBM-infested cabbage plants are a mixture of (Z)-3-hexenyl acetate, α-pinene, sabinene and n-heptanal (Shiojiri et al. 2010). Interestingly, only this mixture (hereafter called attractants) attracts C. vestalis (Shiojiri et al. 2010).
We are studying the effective use of native C. vestalis to control DBM in greenhouses in the satoyama environment (the zone between the mountain foothills and arable flat land) using artificial attractants (Abe et al. 2007; Urano et al. 2011; Uefune et al. 2012; Shimoda et al. 2014). Under field conditions, C. vestalis females are more attracted to uninfested komatsuna plants placed near artificial attractants than to uninfested plants without the attractants (Uefune et al. 2012). Furthermore, the incidence of parasitism of DBM larvae by the wasps on komatsuna plants near artificial attractants is higher than that on komatsuna plants without the attractants under field conditions (Uefune et al. 2012).
Volatiles emitted by infested plants are exploited by natural enemies and by conspecific, and/or heterospecific, herbivores. Adult female herbivores are either attracted to the volatiles emitted by infested plants (Bolter et al. 1997; Horiuchi et al. 2003) or avoid them (Dicke 1986; De Moraes et al. 2001; Horiuchi et al. 2003; Oluwafemi et al. 2011). For example, Horiuchi et al. (2003) reported that Tetranychus urticae Koch are attracted to lima bean plants that are slightly infested by conspecifics but are repelled by those heavily infested by conspecifics. Herbivores in their larval stages also react to volatiles emitted by infested plants. Sixth stadium Spodoptera frugiperda (Smith) larvae are attracted to corn plants infested by conspecifics (Carroll et al. 2006).
We have reported that DBM females prefer to lay eggs on DBM-infested cabbage plants compared with uninfested ones (Shiojiri and Takabayashi 2003). If attractants stimulate the oviposition of female DBM, then the use of attractants for DBM control would be a double-edged sword: not only attracting C. vestalis from the surroundings but also stimulating the oviposition of female DBM that have invaded the attractant-treated greenhouses from the surroundings. For the application of artificial attractants to control DBM, understanding the oviposition preference of DBM females is important. The objective of this study was to determine whether the attractants mentioned before are involved in the oviposition preference of DBM females to plants. Based on the results, the possible use of artificial attractants for DBM control was discussed.
Materials and methods
Plants and insects
Komatsuna plants (Brassica rapa var. perviridis L. cv. Rakuten) were cultivated in a greenhouse (25 ± 3 °C, 60 ± 10% RH, 16 L:8 D). Five plants were reared from seeds per plastic pot (upper diameter: 9 cm, lower diameter: 7 cm, depth: 7 cm) for 4–5 weeks. Then, 12 pots were placed in a plastic tray (37 cm × 27 cm × 6 cm depth) containing water for the plants. These pots were used for the experiments.
DBM larvae were collected in a field near Kyoto, Japan, and mass-reared on potted komatsuna plants in a climate-controlled room (25 ± 3 °C, 60 ± 10% RH, 16 L:8 D) to obtain adults. Eggs were collected every day, and hatched larvae were reared on cut plants in small cages (25 cm × 15 cm × 10 cm high). Newly emerged adults of DBM were maintained separately in acrylic cages (35 cm × 25 cm × 30 cm high) and provided a 50% (v/v) honey solution as food in a climate-controlled room (25 ± 3 °C, 60 ± 10% RH, 16 L:8 D) to ensure mating. After 4 days, DBM females were used for experiments.
Attractants
Pure (Z)-3-hexenyl acetate, n-heptanal, α-pinene and sabinene (RC Treatt, Suffolk, UK; Wako Chemicals Co. Ltd., Osaka, Japan; Tokyo Kasei Kogyo Co. Ltd., Tokyo, Japan) compounds were mixed in a 1.8:1.3:2.0:3.0 ratio, respectively (Shiojiri et al. 2010). The mixture was dissolved in triethyl citrate (TEC) to achieve slow volatilization. The above ratio was adjusted to that released by an infested cabbage plant as herbivore-induced volatiles using a gas chromatograph equipped with a flame ionization detector.
To expose the blend to DBM females, we used a bottle-type dispenser described in Uefune et al. (2012). The glass bottle (diameter: 35 mm, height: 55 mm) of the dispenser was filled with 20 g of the attractant blend, which was the mixture dissolved to 0.01% in TEC. Bottles of the same type containing 20 g of pure TEC were used as controls. The lids of the bottles have a hole (diameter: 12 mm) through which a piece of polypropylene thread (diameter: 12 mm, length: 70 mm) was strung. The purpose of the thread was to facilitate the evaporation of the chemicals. We used the 0.01% dose for the experiments because C. vestalis females are attracted to uninfested plants placed near dispensers containing 0.01% of the blend compared with uninfested plants only (Uefune et al. 2012).
Oviposition experiments
Each komatsuna pot, containing five komatsuna plants, was placed in a plastic cup (diameter: 9 cm, depth: 4.5 cm). Then, five komatsuna pots were placed in an acrylic box (60 cm × 60 cm × 60 cm) in the “dice five” formation in a climate-controlled room (25 ± 2 °C; 50–70% RH; 16 L:8 D). For treatment experiments, we placed a dispenser containing 0.01% of the artificial attractants next to the center pot. The other plants are referred to as plants without the attractants. The distance between the center plant and the surrounding four plants was 20 cm. We conducted control experiments where we again placed five plants in the “dice five” formation, but the dispenser near the center pot contained TEC only.
There were two windows (40 cm × 40 cm, covered with nylon gauze), so that the volatiles would not saturate the interior of the box. We released three male and female pairs of DBM in the box at 16:00. We counted the number of eggs laid on the plants 24 h later. We also recorded the distribution of the eggs on the leaves. The experiments were repeated six times. In each experiment, we used a newly cleaned box.
Statistical analyses
To determine whether there were differences in the oviposition preferences of DBM females between plants with and without artificial attractants, we used randomized-block two-way ANOVAs. We added 0.5 to the number of eggs on leaves because we had zero data, and then used a Box–Cox transformation before the analyses. The adaxial proportion of eggs on the leaf surfaces was angular transformed before the analyses. Statistical analyses were conducted with the JMP software package (version 11.2.1; SAS Institute, Cary, NC, USA).
Results
The number of eggs
The treatments (the treated experiments vs the control experiments) did not affect the number of eggs laid on leaves of komatsuna (df = 1, 10, F = 0.0398, P = 0.8459, randomized-blocks two-way ANOVA) (Fig. 1). Further, the locations of the komatsuna pots did not affect the number of the eggs (df = 4, 40, F = 0.6922, P = 0.5018, randomized-blocks two-way ANOVA). The interaction between the treatments and locations was also not significant for the number of eggs (df = 4, 40, F = 0.9086, P = 0.4683, randomized-blocks two-way ANOVA) (Fig. 1).
Egg distribution on a leaf
The treatments affected the adaxial proportion (%) of eggs laid on the leaf surface (df = 1, 7.456, F = 11.7686, P = 0.01, randomized-blocks two-way ANOVA). The proportion was significantly higher on plants in the treated boxes than on those in the control boxes (Fig. 1). By contrast, the locations of the komatsuna pots did not affect the adaxial proportion of the eggs (df = 4, 28.28, F = 0.7357, P = 0.5754, randomized-blocks two-way ANOVA). The interaction between the treatments and locations was also not significant for the adaxial proportion (df = 4, 28.28, F = 0.5052, P = 0.7322, randomized-blocks two-way ANOVA) (Fig. 1).
Discussion
Shiojiri and Takabayashi (2003) reported that, in an acrylic box (30 cm × 25 cm × 30 cm), which was smaller than that used in this study, DBM females laid more eggs on DBM-infested cabbage plants than on uninfested ones. However, in this study, the mixture of (Z)-3-hexenyl acetate, n-heptanal, α-pinene and sabinene, which attract C. vestalis at a 0.01% dose (Uefune et al. 2012), did not affect the number of eggs that were oviposited by DBM females. Thus, the compounds that attract C. vestalis would not be involved as active principals from DBM-infested plants that stimulate DBM oviposition on infested plants. Zakir et al. (2013) reported the effects of volatiles from infested plants on the oviposition of Spodoptera littoralis females. A significant reduction in oviposition by females was found on undamaged cotton and alfalfa plants adjacent to S. littoralis larvae-damaged cotton plants that attract parasitoids and predators.
Badenes-Perez et al. (2011) studied the amounts of an oviposition stimulant of DBM females, glucosinolates, on the surface of three Crucifer species, Barbarea rupicola, B. verna and B. vulgaris. They found higher concentrations (twofold–tenfold) of glucosinolates on the abaxial surface than on the adaxial surface of B. rupicola and B. verna leaves. However, there were no differences in oviposition by DBM between adaxial and abaxial surfaces on the Barbarea species or on B. vulgaris. Thus, glucosinolates are not involved in the site preferences by DBM females. In this study, 44 ± 0.06% (mean ± SE) of eggs were laid on the adaxial leaf surfaces of komatsuna plants in control boxes. However, when DBM females were exposed to the artificial attractants in treated boxes, the proportion, 75 ± 0.05% (mean ± SE), of eggs on the adaxial leaf surfaces was greater than that in the control boxes. To our knowledge, this is the first study showing that volatiles emitted by infested plants affect oviposition sites on leaves.
A possible adaptive function of the change would be to avoid damage caused by conspecific and heterospecific larvae. Philips et al. (2014) reported that DBM larvae move to the undersides of leaves after hatching. The first-instar larvae mine the spongy mesophyll tissue, whereas older larvae feed from the lower leaf surface and usually consume all of the tissue except the wax layer on the upper surface (Talekar and Shelton 1993). Such larvae would eventually have negative effects (injury and predation) on newly deposited DBM eggs on the abaxial surface of a leaf. Because the presence of the attractants indicates that there are DBM larvae on a plant, a change in the leaves’ preferred oviposition sites in response to the attractants could, in part, be explained by the avoidance of negative effects by currently inhabiting DBM larvae. Larvae of Mamestra brassicae and Spodoptera litura, which infest a wide range of plant species including crucifer plants, have been reported to induce volatiles in plants (Menzel et al. 2014; Sugimoto et al. 2014). Early stages of larvae of these two species are known to stay on the abaxial leaf surface. Whether volatiles induced by these herbivores also affect the distribution of DBM eggs will be studied in the future.
Rainfall and overhead irrigation are important mortality factors for DBM (Kobori and Amano 2003; Talekar and Shelton 1993 and citations therein). Thus, for plant fitness, the increase in the number of eggs on the adaxial surface of a leaf caused by the attractants would be favorable for the plants, because eggs on the adaxial surface are more exposed to risk of water. In open agricultural fields and greenhouses, this shift would facilitate DBM control. The use of attractants for the parasitic wasp C. vestalis would, therefore, not be a double-edged sword as discussed in the introduction, but could produce twice the beneficial effect when used to control DBMs in greenhouses.
References
Abe J, Urano S, Nagasaka K, Takabayashi J (2007) Release ratio of Cotesia vestalis to diamondback moth larvae (Plutella xylostella) that suppresses the population growth of diamondback moth feeding Brassica leaf vegetables in a greenhouse. Bull NARC West Reg 6:125–132 (in Japanese with English summary)
Arimura G, Matsui K, Takabayashi J (2009) Chemical and molecular ecology of herbivore-induced plant volatiles: proximate factors and their ultimate functions. Plant Cell Physiol 50:911–923. doi:10.1093/pcp/pcp030
Badenes-Perez FR, Reichelt M, Gershenzon J, Heckel DG (2011) Phylloplane location of glucosinolates in Barbarea spp. (Brassicaceae) and misleading assessment of host suitability by a specialist herbivore. New Phytol 198:549–556. doi:10.1111/j.1469-8137.2010.03486.x
Bolter CJ, Dicke M, Van Loon JJA, Visser JH, Posthumus MA (1997) Attraction of colorado potato beetle to herbivore-damaged plants during herbivory and after its termination. J Chem Ecol 23:1003–1023. doi:10.1023/B:JOEC.0000006385.70652.5e
Carroll MJ, Schmelz EA, Meagher RL, Teal PEA (2006) Attraction of Spodoptera frugiperda larvae to volatiles from herbivore-damaged maize seedlings. J Chem Ecol 32:1911–1924. doi:10.1007/s10886-006-9117-9
De Moraes CM, Mescher C, Tumlinson JH (2001) Caterpillar-induced nocturnal plant volatiles repel conspecific females. Nature 410:577–580. doi:10.1038/35069058
Dicke M (1986) Volatile spider-mite pheromone and host-plant kairomone, involved in spaced-out gregariousness in the spider mite Tetranychus urticae. Physiol Entomol 11:251–262. doi:10.1111/j.1365-3032.1986.tb00412.x
Dicke M, Sabelis MW, Takabayashi J, Bruin J, Posthumus MA (1990) Plant strategies of manipulating predator-prey interactions through allelochemicals—prospects for application in pest control. J Chem Ecol 16:3091–3118. doi:10.1007/BF00979614
Horiuchi J, Arimura G, Ozawa R, Shimoda T, Takabayashi J, Nishioka T (2003) Comparison in response of Tetranychus urticae (Acari: Tetranychidae) and Phytoseiulus persimilis (Acari: Phytoseiidae) to volatiles emitted from lima bean leaves with different level of damages made by T. urticae or Spodoptera exigua (Lepidoptera: Noctuidae). Appl Entomol Zool 38:109–116. doi:10.1303/aez.2003.109
Kobori Y, Amano H (2003) Effect of rainfall on a population of the diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae). Appl Entomol Zool 38:249–253. doi:10.1303/aez.2003.249
Menzel TR, Huang T-Y, Weldegergis BT, Gols R, van Loon JJA, Dicke M (2014) Effect of sequential Induction by Mamestra brassicae L. and Tetranychus urticae Koch on lima bean plant indirect defense. J Chem Ecol 40:977–985. doi:10.1007/s10886-014-0499-9
Oluwafemi S, Bruce TJA, Pickett JA, Ton J, Birkett MA (2011) Behavioral responses of the leafhopper, Cicadulina storeyi China, a major vector of maize streak virus, to volatile cues from intact and leafhopper-damaged maize. J Chem Ecol 37:40–48. doi:10.1007/s10886-010-9891-2
Philips CR, Fu Z, Kuhar TP, Shelton AM, Cordero RJ (2014) Natural history, ecology, and management of diamondback moth (Lepidoptera: Plutellidae), with emphasis on the United States. J Integr Pest Manage 5:D1–D11. doi:10.1603/IPM14012
Shimoda T, Mitsunaga T, Uefune M, Abe J, Kugimiya S, Nagasaka K, Sano K, Urano S, Suzuki Y, Yano E, Takabayashi J (2014) A food-supply device for maintaining Cotesia vestalis, a larval parasitoid of the diamondback moth Plutella xylostella, in greenhouses. Biocontrol 59:681–688. doi:10.1007/s10526-014-9611-x
Shiojiri K, Takabayashi J (2003) Effects of specialist parasitoids on oviposition preference of phytophagous insects: encounter-dilution effects in a tritrophic interaction. Ecol Entomol 28:573–578. doi:10.1046/j.1365-2311.2003.00539.x
Shiojiri K, Takabayashi J, Yano S, Takafuji A (2000) Flight response of parasitoid toward plant-herbivore complexes: a comparative study of two parasitoid-herbivore systems on cabbage plants. Appl Entomol Zool 35:87–92. doi:10.1303/aez.2000.87
Shiojiri K, Ozawa R, Kugimiya S, Uefune M, van Wijk M, Sabelis MW, Takabayashi J (2010) Herbivore-specific, density-dependent induction of plant volatiles: honest or “cry wolf” signals? PLoS One 5:e12161. doi:10.1371/journal.pone.0012161
Sugimoto K, Matsui K, Iijima Y, Akakabe Y, Muramoto S, Ozawa R, Uefune M, Sasaki R, Alamgir KM, Akitake S, Nobuke T, Galis I, Aoki K, Shibata D, Takabayashi J (2014) Intake and transformation to a glycoside of (Z)-3-hexenol from infested neighbors reveals a mode of plant odor reception and defense. Proc Natur Acad Sci USA 111:7144–7149. doi:10.1073/pnas.1320660111
Takabayashi J (2014) Infochemical webs and tritrophic interactions. eLS. doi:10.1002/9780470015902.a0021912
Talekar NS, Shelton AM (1993) Biology, ecology, and management of the diamondback moth. Annu Rev Entomol 38:275–301. doi:10.1146/annurev.en.38.010193.001423
Uefune M, Choh Y, Abe J, Shiojiri K, Sano K, Takabayashi J (2012) Application of synthetic herbivore-induced plant volatiles causes increased parasitism of herbivores in the field. J Appl Entomol 136:561–567. doi:10.1111/j.1439-0418.2011.01687.x
Urano S, Uefune M, Abe J, Takabayashi J (2011) Analytical model to predict the number of parasitoids that should be released to control diamondback moth larvae in greenhouses. J Plant Interact 6:151–154. doi:10.1080/17429145.2011.555007
Zakir A, Sadek MM, Bengtsson M, Hansson BS, Witzgall P, Anderson P (2013) Herbivore-induced plant volatiles provide associational resistance against an ovipositing herbivore. J Ecol 101:410–417. doi:10.1111/1365-2745.12041
Acknowledgements
This research was partly supported by the Bio-oriented Technology Research Advancement Institution, by JST “Science and Engineering Entrepreneurship Development Program for Vigorous Researchers (SEED-V)” and by Grants-in-Aid for Scientific Research from MEXT (Grant numbers 15K07230 and 26292030).
Author information
Authors and Affiliations
Corresponding author
Additional information
Handling Editor: Miriama Malcicka.
Masayoshi Uefune and Kaori Shiojiri have contributed equally to this work.
Rights and permissions
About this article
Cite this article
Uefune, M., Shiojiri, K. & Takabayashi, J. Oviposition of diamondback moth Plutella xylostella females is affected by herbivore-induced plant volatiles that attract the larval parasitoid Cotesia vestalis . Arthropod-Plant Interactions 11, 235–239 (2017). https://doi.org/10.1007/s11829-016-9484-2
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11829-016-9484-2