Caterpillar-induced plant volatiles attract conspecific adults in nature

Robotic mechanical wounding is sufficient to induce phenylacetaldoxime accumulation in Tococa quadrialata

This study investigated the accumulation of phenlyacetaldoxime (PAOx) and PAOx-Glc in Tococa quadrialata leaves in response to herbivore infestation and mechanical wounding. Results show that PAOx levels peaked at 24 h post-infestation, while PAOx-Glc remained present for several days. The accumulation of PAOx began as early as 3 h after herbivory, with PAOx-Glc significantly increased after 6 h. Mechanical wounding induced similar responses in PAOx and PAOx-Glc accumulation as herbivory, suggesting that continuous tissue damage triggers the production of these compounds. Interestingly, SpitWorm-treated leaves showed the highest levels of both PAOx and PAOx-Glc, indicating that herbivore-derived oral secretions (OS) play a role in the induction of these compounds. Additionally, JA-independent PAOx production was found to be associated with tissue damage rather than specific known signaling compounds. Emission of benzyl cyanide and 2-phenylethanol, PAOx-derived plant volatiles, was observed in response to herbivory and SpitWorm treatment providing plant-derived OS, further highlighting the role of herbivore cues in plant defense responses.

Volatile Semiochemicals Emitted by Beauveria bassiana Modulate Larval Feeding Behavior and Food Choice Preference in Spodoptera frugiperda (Lepidoptera: Noctuidae)

Beauveria bassiana is an entomopathogenic fungus that parasitizes and kills insects. The role of volatile organic compounds (VOCs) emitted by B. bassiana acting as semiochemicals during its interaction with lepidopterans is poorly explored. Here, we studied the effect of VOCs from B. bassiana and 3-methylbutanol (as a single compound) on the feeding behavior of L2 larvae of Spodoptera frugiperda in sorghum plants. Additionally, we assessed whether fungal VOCs induce chemical modifications in the plants that affect larval food preferences. Metabolomic profiling of plant tissues was performed by mass spectrometry and bioassays in a dual-choice olfactometer. The results showed that the larval feeding behavior was affected by the B. bassiana strain AI2, showing that the insect response is strain-specific. Furthermore, 80 µg of 3-methylbutanol affected the number of bites. The larval feeding choice was dependent on the background context. Fragment spectra and a matching precursor ion mass of 165.882 m/z enabled the putative identification of 4-coumaric acid in sorghum leaves exposed to fungal VOCs, which may be associated with larval deterrent responses. These results provide valuable insights into the bipartite interaction of B. bassiana with lepidopterans through VOC emission, with the plant as a mediator of the interaction.

Semiochemicals from Trichosanthes anguina (Cucurbitaceae) plants influence behavior in Diaphania indica

BACKGROUND

First to third instars of Diaphania indica (Saunders) (Lepidoptera: Crambidae) feed on the lower surface of leaves, while fourth and fifth instars gregariously consume leaves of Trichosanthes anguina L. After defoliating, the caterpillar also attacks flowers and fruits of the plant and finally, results in loss of crop yield. Therefore, behavioral responses of D. indica adults were investigated to volatiles from undamaged (UD), insect-damaged (ID, plants after feeding by D. indica larvae) and jasmonic acid (JA) treated T. anguina plants.

RESULTS

Females showed attraction to volatiles of UD and ID plants of three T. anguina cultivars [MNSR-1 (MNS), Baruipur Long (BAR) and Polo No. 1 (POLO)] in Y-tube olfactometer bioassays. Females did not show significant negative responses from volatiles of JA treated plants. Females were more attracted to volatiles of ID plants than UD plants. Females showed attraction to volatiles of UD or ID plants compared to JA treated plants. Females were attracted to certain synthetic blends resembling volatiles of insect-damaged MNS, BAR and POLO plants in olfactometer bioassays. Females could not distinguish among these three certain synthetic blends in olfactometer bioassays. A synthetic blend of 3Z-hexen-1-ol, α-pinene, hexyl acetate, benzyl alcohol and 6Z-nonenal at mole ratios of 1.47:1.20:1:1.82:1.21 was prepared at 20 mg/mL dichloromethane and 100 μL when used as lure in funnel traps resulted in the capture of the highest number of D. indica adults in field trails.

CONCLUSION

The earlier five-component chemical lure could be used in traps in an integrated pest management program of the insect pest, D. indica. © 2023 Society of Chemical Industry.

Light induces an increasing release of benzyl nitrile against diurnal herbivore Ectropis grisescens Warren attack in tea (Camellia sinensis) plants

Herbivore-induced plant volatiles (HIPVs) are critical compounds that directly or indirectly regulate the tritrophic interactions among herbivores, natural enemies and plants. The synthesis and release of HIPVs are regulated by many biotic and abiotic factors. However, the mechanism by which multiple factors synergistically affect HIPVs release remains unclear. Tea plant (Camellia sinensis) is the object of this study because of its rich and varied volatile metabolites. In this study, benzyl nitrile was released from herbivore-attacked tea plants more in the daytime than at night, which was consistent with the feeding behaviour of tea geometrid (Ectropis grisescens Warren) larvae. The Y-tube olfactometer assay and insect resistance analysis revealed that benzyl nitrile can repel tea geometrid larvae and inhibit their growth. On the basis of enzyme activities in transiently transformed Nicotiana benthamiana plants, CsCYP79 was identified as a crucial regulator in the benzyl nitrile biosynthetic pathway. Light signalling-related transcription factor CsPIF1-like and the jasmonic acid (JA) signalling-related transcription factor CsMYC2 serve as the activator of CsCYP79 under light and damage conditions. Our study revealed that light (abiotic factor) and herbivore-induced damage (biotic stress) synergistically regulate the synthesis and release of benzyl nitrile to protect plants from diurnal herbivorous tea geometrid larvae.

Dynamic environmental interactions shaped by vegetative plant volatiles

Covering: up to November 2022Plants shape terrestrial ecosystems through physical and chemical interactions. Plant-derived volatile organic compounds in particular influence the behavior and performance of other organisms. In this review, we discuss how vegetative plant volatiles derived from leaves, stems and roots are produced and released into the environment, how their production and release is modified by abiotic and biotic factors, and how they influence other organisms. Vegetative plant volatiles are derived from different biosynthesis and degradation pathways and are released via distinct routes. Both biosynthesis and release are regulated by other organisms as well as abiotic factors. In turn, vegetative plant volatiles modify the physiology and the behavior of a wide range of organisms, from microbes to mammals. Several concepts and frameworks can help to explain and predict the evolution and ecology of vegetative plant volatile emission patterns of specific pathways: multifunctionality of specialized metabolites, chemical communication displays and the information arms race, and volatile physiochemistry. We discuss how these frameworks can be leveraged to understand the evolution and expression patterns of vegetative plant volatiles. The multifaceted roles of vegetative plant volatiles provide fertile grounds to understand ecosystem dynamics and harness their power for sustainable agriculture.

The Role of Green Gram Plant Volatile Blends in the Behavior of Arctiid Moth, Spilosoma obliqua

This study investigated effects of volatile blends released from undamaged (UD), insect-damaged [ID, plants fed by larvae of Spilosoma obliqua Walker (Lepidoptera: Arctiidae)] and mechanically-damaged (MD) plants of three green gram cultivars [PDM 54, Pusa Baisakhi and Samrat] including synthetic blends on the behavior of conspecific adult moths in Y-tube olfactometer bioassays. Females showed attraction towards volatile blends of UD, ID and MD plants of these green gram cultivars against the control solvent (CH₂Cl₂). The components of volatile blends in UD plants of three green gram cultivars are not similar, but no any difference was found among three cultivars in term of the attractive effect on the insect moths when volatile blends from UD plants of these three cultivars were tested against one another. Females were more attracted towards volatile blends of ID plants of a particular cultivar compared to UD plants of the same cultivar. Total amount of volatiles was higher in ID plants than UD plants. Some herbivore-induced plant volatiles - (Z)-3-hexenal, 1-hexanol, (Z)-3-hexenyl acetate, 2-octanol and ocimene were attractive to the insect moths. Females were attracted towards three synthetic blends resembling amounts present in natural volatile blends of ID plants of these three cultivars in Y-tube olfactometer and wind tunnel bioassays, suggesting that involvement of host-specific chemical cues in long-range host location by S. obliqua females. If attraction of adult S. obliqua to these synthetic volatile blends is upheld by field trials then these blends may find practical application in detection and monitoring of S. obliqua populations.

Odorant Receptor PxylOR11 Mediates Repellency of Plutella xylostella to Aromatic Volatiles

Insects can use plant volatiles to guide certain behaviors, such as courtship, mating, host positioning, and habitat selection. Plutella xylostella is a global agricultural pest and has always been closely studied, but relatively few studies assess the molecular mechanism of P. xylostella exposed to plant volatiles. In this study, we analyzed the role of the odorant receptor PxylOR11 when P. xylostella is exposed to plant volatiles. Our analysis of tissue expression demonstrated that PxylOR11 is expressed in the antennae and that expression levels in female moths were significantly higher than in male moths. Functional analyses using the Xenopus oocyte expression system demonstrated that PxylOR11 was tuned to three aromatic compounds: benzyl alcohol, salicylaldehyde, and phenylacetaldehyde. Electroantennogram analyses revealed that these three aromatic compounds can induce electrophysiological responses in the antennae of P. xylostella, and that the electroantennograms response value of female moths was significantly higher than that of male moths. Dual-choice bioassays demonstrated that the three aromatic compounds have a repellent effect on female P. xylostella. These results suggest that PxylOR11 has a role in mediating the repellent effect of aromatic volatiles on P. xylostella and can be used as a potential target to design novel olfactory regulators controlling P. xylostella.

Patterns of Herbivory in Neotropical Forest Katydids as Revealed by DNA Barcoding of Digestive Tract Contents

Many well-studied animal species use conspicuous, repetitive signals that attract both mates and predators. Orthopterans (crickets, katydids, and grasshoppers) are renowned for their acoustic signals. In Neotropical forests, however, many katydid species produce extremely short signals, totaling only a few seconds of sound per night, likely in response to predation by acoustically orienting predators. The rare signals of these katydid species raises the question of how they find conspecific mates in a structurally complex rainforest. While acoustic mechanisms, such as duetting, likely facilitate mate finding, we test the hypothesis that mate finding is further facilitated by colocalization on particular host plant species. DNA barcoding allows us to identify recently consumed plants from katydid stomach contents. We use DNA barcoding to test the prediction that katydids of the same species will have closely related plant species in their stomach. We do not find evidence for dietary specialization. Instead, katydids consumed a wide mix of plants within and across the flowering plants (27 species in 22 genera, 16 families, and 12 orders) with particular representation in the orders Fabales and Laurales. Some evidence indicates that katydids may gather on plants during a narrow window of rapid leaf out, but additional investigations are required to determine whether katydid mate finding is facilitated by gathering at transient food resources.

Feeding Volatiles of Larval Sparganothis pilleriana (Lepidoptera: Tortricidae) Attract Heterospecific Adults of the European Grapevine Moth

Plants release volatiles in response to caterpillar feeding. These herbivore-induced plant volatiles (HIPVs) attract natural enemies of the herbivores and repel or attract conspecific adult herbivores in a tri-trophic interaction which has been considered to be an indirect plant defense against herbivores. Recently, we demonstrated the attraction of male and female European grapevine moth, Lobesia botrana (Denis & Schiffermüller) (Lepidoptera: Tortricidae) to a blend of phenylacetonitrile and acetic acid, two compounds identified as HIPVs in heterospecific apple-leafroller interactions. The ecological basis of our findings is not clearly understood. Thus, this work was undertaken to investigate HIPVs in the grapevine-leafroller interaction and study the response of heterospecific adults L. botrana, to these volatiles. We collected headspace volatiles emitted from uninfested grapevines and grapevines infested with larvae of a generalist herbivore, the grapevine leafroller moth, Sparganothis pilleriana (Denis & Schiffermüller), and analyzed them using gas chromatography/mass spectrometry. Infested grape leaves released three compounds (phenylacetonitrile, indole, and 2-phenylethanol) not found from uninfested leaves. Nine different blends, comprising a full factorial set of the three compounds with each blend containing acetic acid, were tested in a field-cage trial. Only lures containing phenylacetonitrile caused a significant increase in trap catches compared to the other lures and blank traps. Electroantennographic tests show that L. botrana can detect the compounds. The results confirm our hypothesis that phenylacetonitrile is released during grapevines infestation with herbivores, and attracts adult L. botrana.

Volatiles Emission by Crotalaria nitens after Insect Attack

Plants are known to increase the emission of volatile organic compounds upon the damage of phytophagous insects. However, very little is known about the composition and temporal dynamics of volatiles released by wild plants of the genus Crotalaria (Fabaceae) attacked with the specialist lepidopteran caterpillar Utetheisa ornatrix (Linnaeus) (Erebidae). In this work, the herbivore-induced plant volatiles (HIPV) emitted by Crotalaria nitens Kunth plants were isolated with solid phase micro-extraction and the conventional purge and trap technique, and their identification was carried out by GC/MS. The poly-dimethylsiloxane/divinylbenzene fiber showed higher affinity for the extraction of apolar compounds (e.g., trans-β-caryophyllene) compared to the Porapak™-Q adsorbent from the purge & trap method that extracted more polar compounds (e.g., trans-nerolidol and indole). The compounds emitted by C. nitens were mainly green leaf volatile substances, terpenoids, aromatics, and aldoximes (isobutyraldoxime and 2-methylbutyraldoxime), whose maximum emission was six hours after the attack. The attack by caterpillars significantly increased the volatile compounds emission in the C. nitens leaves compared to those subjected to mechanical damage. This result indicated that the U. ornatrix caterpillar is responsible for generating a specific response in C. nitens plants. It was demonstrated that HIPVs repelled conspecific moths from attacked plants and favored oviposition in those without damage. The results showed the importance of volatiles in plant-insect interactions, as well as the choice of appropriate extraction and analytical methods for their study.

Designing a species-selective lure based on microbial volatiles to target Lobesia botrana

Sustainable, low impact control methods, including mating disruption and microbial insecticides against L. botrana have been available for decades. Yet, successful implementation has been restricted to only a few grapevine districts in the world. A limiting factor is the lack of a female attractant to either monitor or control the damaging sex. Volatile attractants for both female and male insects can be used to assess when L. botrana populations exceed economic thresholds, and to decrease the use of synthetic pesticides within both conventional and pheromone programs. Rather than using host-plant volatiles, which are readily masked by background volatiles released by the main crop, we tested the attractiveness of volatiles that signify microbial breakdown and more likely stand out against the background odour. A two-component blend of 2-phenylethanol (2-PET) and acetic acid (AA) caught significant numbers of both sexes. Catches increased with AA and, to a minimal extent, 2-PET loads. However, a higher load of 2-PET also increased bycatches, especially of Lepidoptera and Neuroptera. Major (ethanol, ethyl acetate, 3-methyl-1-butanol) or minor (esters, aldehydes, alcohols and a ketone) fermentation volatiles, did surprisingly not improve the attraction of L. botrana compared to the binary blend of 2-PET and AA alone, but strongly increased bycatches. The most attractive lure may thus not be the best choice in terms of specificity. We suggest that future research papers always disclose all bycatches to permit evaluation of lures in terms of sustainability.

Leafroller-induced phenylacetonitrile and acetic acid attract adult Lobesia botrana in European vineyards

We recently identified unique caterpillar-induced plant volatile compounds emitted from apple leaves infested with the larvae of various leafroller species. In subsequent field tests, binary blends of phenylacetonitrile+acetic acid and 2-phenylethanol+acetic acid were found to be attractive to a range of tortricid leafroller species (Tortricidae: Tortricinae) in both the Southern and Northern Hemispheres. In this work, the caterpillar-induced plant volatiles from the apple-leafroller system were tested in two vineyards in Spain and Hungary for their attractiveness to the grape frugivore Lobesia botrana (Tortricidae: Olethreutinae). As seen for Tortricinae species, a binary blend of phenylacetonitrile+acetic acid attracted significantly more male and female L. botrana to traps than acetic acid or blank lures. Traps baited with other caterpillar-induced plant volatile compounds (benzyl alcohol, 2-phenylethanol, indole, and (E)-nerolidol, each as a binary blend with acetic acid) did not catch significantly more moths than traps containing acetic acid alone. The catches of male and female moths support an optimistic future for new products in female tortricid surveillance and control that are based on combinations of kairomone compounds released from larval-damaged foliage.

Recruiting on the Spot: A Biodegradable Formulation for Lacewings to Trigger Biological Control of Aphids

Upon herbivory, plants release herbivore-induced plant volatiles (HIPVs), which induce chemical defenses in the plant as well as recruit natural enemies. However, whether synthetic HIPVs can be employed to enhance biological control in a cultivated crop in the field is yet to be explored. Here we show that a biodegradable formulation loaded with induced and food-signaling volatiles can selectively recruit the common green lacewing, Chrysoperla carnea, and reduce pest population under field conditions. In apple orchards, the new formulation attracted lacewing adults over a 4-week period, which correlated well with independent assessments of the longevity of the slow-release matrix measured through chemical analyses. In barley, lacewing eggs and larvae were significantly more abundant in treated plots, whereas a significant reduction of two aphid species was measured (98.9% and 93.6% of population reduction, for Sitobion avenae and Rhopalosiphum padi, respectively). Results show the potential for semiochemical-based targeted recruitment of lacewings to enhance biological control of aphids in a field setting. Further research should enhance selective recruitment by rewarding attracted natural enemies and by optimizing the application technique.

Eavesdropping on gall-plant interactions: the importance of the signaling function of induced volatiles

The galling insect manipulates the host plant tissue to its own benefit, building the gall structure where it spends during most of its life cycle. These specialist herbivore insects can induce and manipulate plant structure and metabolism throughout gall development and may affect plant volatile emission. Consequently, volatile emission from altered metabolism contribute to eavesdropping cueing. Eavesdropping can be part of adaptive strategies used by evolution for both galling insects and the entire-associated community in order to cue some interaction response. This is in contrast to some herbivores associated with delayed induced responses, altering plant metabolites during the short time while they feed. Due to the different lifestyles of the galling organism, which are associated with different plant tissues and organs (e.g leaves, flowers or fruits), a distinct diversity of organisms may eavesdrop on induced volatiles interacting with the galls. Furthermore, the eavesdropping cues may be defined according to the phenological coupling between galling organism and host plant, which results from the development of a gall structure. For instance, when plants release volatile-induced defenses after galling insects' activity, another interactor may perceive these volatiles and change its behavior and interactions with host plants and galls. Thus, natural enemies could be attracted by different volatiles emitted by the gall tissues. Considering the duration of the life cycle of the galling organism and the gall, the temporal extent of gall-induced volatiles may include more persistent volatile cues and eavesdropping effects than the volatiles induced by non-galling herbivores. Accordingly, from chemical ecology perspective we expect that galling herbivore-induced volatiles may exhibit robust effects on neighboring-plant interactions including those ones during different plant developmental or phenological periods. Information about multitrophic interactions between insects and plants supports the additional understanding of direct and indirect effects, and allows insight into new hypotheses.

Volatiles of Grape Inoculated with Microorganisms: Modulation of Grapevine Moth Oviposition and Field Attraction

Semiochemicals released by plant-microbe associations are used by herbivorous insects to access and evaluate food resources and oviposition sites. Adult insects may utilize microbial-derived nutrients to prolong their lifespan, promote egg development, and offer a high nutritional substrate to their offspring. Here, we examined the behavioral role of semiochemicals from grape-microbe interactions on oviposition and field attraction of the grapevine moth Lobesia botrana (Denis & Schiffermüller). The volatile constituents released by grape inoculated with yeasts (Hanseniaspora uvarum (Niehaus), Metschnikowia pulcherrima (Pitt.) M.W. Miller, Pichia anomala, Saccharomyces cerevisiae Meyen ex E.C. Hansen, and Zygosaccharomyces rouxii (Boutroux) Yarrow), sour rot bacteria (Acetobacter aceti (Pasteur) Beijerinck and Gluconobacter oxydans (Henneberg) De Ley), and a fungal pathogen (Botrytis cinerea Pers.) all endemic of the vineyard were sampled by solid-phase microextraction and analyzed by gas-chromatography coupled with mass spectrometry. Ethanol, 3-methyl-1-butanol, and ethyl acetate were the most common volatiles released from all microbe-inoculated grapes. In addition, acetic acid was released at a substantial amount following bacteria inoculation and in a three-way inoculation with yeasts and the fungus. 2-phenylethanol, a compound reported to attract tortricid moths when used in combination with acetic acid, was found at a relatively low level in all microbial combinations as well as in the control grape. While grapes inoculated with a consortium of yeasts stimulated oviposition in comparison with uninoculated berries, the phytopathogenic fungus deterred egg-laying. Nonetheless, the highest preference to lay eggs was measured when the yeasts were co-inoculated with the fungus. The lowest preference was obtained when grapes were inoculated with sour rot bacteria and their binary co-inoculation with yeasts and the fungus. Interestingly, oviposition on berries simultaneously inoculated with all the three microbial groups was unaffected. Lures loaded with either acetic acid or 2-phenylethanol were not attractive when placed in traps as single component in vineyards, but a binary blend attracted both sexes of grapevine moth in significant numbers. Further addition of the three most common volatiles released by infected berries (ethanol, 3-methyl-1-butanol, and ethyl acetate) did not significantly increase moth catch with this binary blend. The ecological implications of the grape-microorganism and grapevine moth interaction as well as the possibility to develop a pest monitoring system based on microbial volatiles are discussed.

Index of host habitat preference explored by movement-based simulations and trap captures

Animal species likely have different strengths of host habitat preference (HHP) that might be characterized by a standardized index ranging from 0 (no preference) to 1 (maximum preference). We hypothesized that in some species, HHP may result from individuals dispersing out of the host habitat having a probability of turning back at the boundary, or after entering host habitat by reducing speed or increasing size of turning angles. Computer simulations of individuals moving between various sized patches of host and nonhost habitat were conducted based on these three behaviours hypothesized to affect HHP. In the rebounding model, simulations resulted in equilibria of animal numbers inside and outside of host habitat that depend on sizes of these areas, initial number and the rebounding probability. Curvilinear regression of simulation results suggested an equation that predicted numbers in the host habitat and was solved for rebounding probability. A modified equation that sampled population densities (e.g., insect pheromone trap catches) inside and outside host habitat areas gave the rebounding probability, an index of HHP, without requiring the sizes of the areas. Simulations with traps and moving animals verified that the modified equation could predict the index correctly. The modified equation also estimates an index of HHP from sampled densities due to speed reductions and a combination of this and rebounding. Changes in angular turning size upon entering host habitat, however, did not affect habitat preference. Using pheromone trap captures, we found that the lesser date moth Batrachedra amydraula has a HHP for date Phoenix dactylifera plantations of 0.96. Host habitat preference indexes also were calculated from sampled insect densities reported in the literature. The new index of HHP is useful to characterize habitat patches of many organisms and aid understanding of animal spatial distributions and speciation processes. In addition, the index can be applied in studies of invasive species, trap crops of pest insects and conservation management.

Survey of conspecific herbivore-induced volatiles from apple as possible attractants for Pandemis pyrusana (Lepidoptera: Tortricidae)

BACKGROUND

Studies were conducted to identify volatiles released by apple foliage untreated or sprayed with a yeast and from untreated and sprayed foliage with actively feeding larvae of Pandemis pyrusana Kearfott. Field studies then evaluated various combinations of these volatiles when paired with acetic acid as possible adult attractants.

RESULTS

The most abundant volatiles released following herbivore feeding were four green leaf volatiles (GLVs) and acetic acid. Nineteen volatiles were found to be released in significantly higher amounts from foliage with herbivore damage than from intact leaves. The combination of yeast followed by herbivore injury increased the levels of methyl salicylate and phenylacetonitrile compared with herbivory alone. Levels of acetic acid released were not significantly different among the four treatments. Only phenylacetonitrile and 2-phenylethanol with acetic acid caught similar and significantly more total and female moths than acetic acid alone. Moth catches with 12 other volatiles plus acetic acid were not significantly higher than with acetic acid alone, and were lower than with acetic acid and 2-phenylethanol.

CONCLUSION

These data show that herbivore injury does not create a unique chemical signal for adults to locate oviposition or rendezvous sites. Instead, moths may cue to the aromatic-acetic acid combination as a nutritional cue to locate sugary resources. © 2017 Society of Chemical Industry.

Caterpillar-Induced Plant Volatiles Attract Adult Tortricidae

Binary and ternary combinations of volatile organic compounds identified earlier from caterpillar-infested apple foliage caught more than one thousand individuals of both sexes of several adult tortricid leafroller species in several days of trials conducted in apple orchards in southern British Columbia. A series of combinations with phenylacetonitrile, benzyl alcohol, and/or 2-phenylethanol and acetic acid enabled substantial catches of both sexes of eye-spotted budmoth, Spilonota ocellana, oblique-banded leafroller, Choristoneura rosaceana and three-lined leafroller, Pandemis limitata. These findings suggest that new monitoring aides can be developed to seasonally track populations, enabling practical applications in surveillance of female leafroller populations for the first time. It may also be possible to develop suppression tools based on combinations of kairomone compounds originally identified from leafroller larval-damaged apple trees, given the level of attraction. The discovery of these adult tortricid attractants (aromatic compounds plus acetic acid) raises new ecological questions about evolved direct plant defences against herbivores. Larval feeding-induced attraction of adult herbivores produces signals that are potentially harmful to the plant by increasing herbivory in the same family and probably feeding guild, but evidence for effects on plant fitness is needed.