{"paper_id":"0c88580b-0f4e-4dd4-87dc-342ecb1dd5be","body_text":"1 \n \nTitle: 1 \nThe floral illusion: A parasitic beetle mimics the scent of flowers to attract bees 2 \n 3 \nAuthors: 4 \nRyan M. Alam 1, Danny Kessler 1, Heiko Vogel 2, Katrin Luck 1, Anja David 1, Maritta Kunert 1, 5 \nMartin Kaltenpoth2, Sarah E. O’Connor1*, Tobias G. Köllner1* 6 \n 7 \nAffiliations: 8 \n1Department of Natural Product Biosynthesis, Max Planck Institute for Chemical Ecology, Hans-9 \nKnöll-Straße 8, D-07745, Jena, Germany. 10 \n2Department of Insect Symbiosis, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 11 \n8, D-07745, Jena, Germany. 12 \n*Corresponding author 13 \n 14 \nAbstract 15 \nAnimals are not known to biosynthesize floral signals to manipulate pollinators, although such 16 \nmimicry could profoundly shape plant-pollinator interactions. Larvae of t he poisonous European 17 \nblister beetle Meloe proscarabaeus parasitize multiple solitary bee species, yet the mechanism 18 \nenabling host attraction has remained unresolved. Here we show that these larvae lure bees by 19 \nemitting a bouquet of volatile compounds that closely resembles floral scent. Chemical analyses 20 \n.CC-BY 4.0 International licenseavailable under a \n(which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made \nThe copyright holder for this preprintthis version posted January 15, 2026. ; https://doi.org/10.64898/2026.01.15.699641doi: bioRxiv preprint \n\n2 \n \nreveal a complex blend of monoterpenoids derived from ( S)-linalool, a ubiquitous floral volatile. 21 \nBehavioral assays demonstrate that these compounds function as floral cues, eliciting attraction in 22 \nbees. Transcriptomic and functional analyses identify cytochrome P450 enzymes that oxidize (S)-23 \nlinalool, demonstrating that larvae biosynthesize these plant-like volatiles de novo. Together, these 24 \nfindings broaden the scope of interkingdom chemical mimicry and uncover a strik ing form of 25 \nsensory deception in which an insect chemically assumes the signal identity of a flower, revealing 26 \nthat animals can evolve biosynthetic pathways to exploit plant–pollinator communication. 27 \n 28 \nMain 29 \nMimicry, broadly defined as deceptive resemblance, is a widespread evolutionary strategy utilized 30 \nacross the tree of life 1. Since Bates’ seminal observations of visual mimicry among Amazonian 31 \nbutterflies in 1862 2, the concept has broadened to include decep tion across all major sensory 32 \nmodalities, including visual 3-5, tactile6, acoustic7, and chemical8-12. Although many studies focus 33 \non mimicry in predator -prey or host -parasite interactions 13-15, deceptive resemblance also plays 34 \nkey roles in other interspecific relationships. One striking example is phoresy, where one organism 35 \n(the phoront) uses another (the host) for transport to essential resources 16. Phoronts frequently 36 \nevolve morphological, behavioral, and/or chemical traits that imitate benign or mutualistic species, 37 \ndeceiving hosts into providing transport 8, 17 -19. Moreover, phoresy  has been proposed as an 38 \nevolutionary precursor to parasitism in certain systems 16, and complete dependence on a host for 39 \ndispersal can further drive the emergence of obligate parasitic relationships8.  40 \nBlister beetles (Coleoptera: Meloidae) exemplify the intersection of mimicry, phoresy, and 41 \nparasitism. Most species parasitize solitary bees 20. In the subfamily Meloinae, gravid females 42 \n.CC-BY 4.0 International licenseavailable under a \n(which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made \nThe copyright holder for this preprintthis version posted January 15, 2026. ; https://doi.org/10.64898/2026.01.15.699641doi: bioRxiv preprint \n\n3 \n \ndeposit large egg clutches underground; the eclosed larvae (triungula) are highly mobile and either 43 \nclimb nearby vegetation to await hosts (Fig. 1A)8, 21, 22 or, in non-phoretic species, actively search 44 \nfor bee nests on the soil surface 23. These larvae commonly target solitary bees, rapidly attaching 45 \nto them, and are then transferred to the bee nest. Once in the nest, triungula dismount, consume 46 \nthe bee egg and provisions, and later complete several distinct  developmental stages before 47 \nemerging as adults the following year24. 48 \nHost-attraction strategies in kleptoparasitic phoretic Meloe species vary and often exploit host -49 \nspecific sensory cues. For instance, Meloe franciscanus triungula in North America aggregate on 50 \nvegetation and emit a blend of female bee sex pheromones to specifically attract male Habropoda 51 \nspp.8, 22. Alternatively, M. strigulosus larvae station themselves on flowers , where they intercept 52 \nforaging pollinators21. In contrast, triungula of the European Black oil beetle M. proscarabaeus 53 \ntypically form conspicuous orange aggregations on grasses and exhibit little host specificity, 54 \nsuggesting a generalist phoretic strategy 25. This behavioral divergence led us to hypo thesize that 55 \nM. proscarabaeus triungula use an alternative volatile cue to attract a broad range of pollinator 56 \nhosts. Here, we demonstrate that M. proscarabaeus larvae emit a complex bouquet of floral-scent 57 \nmonoterpenoids to deceive foraging bees. This dis covery reveals a previously undescribed form 58 \nof interkingdom chemical mimicry and expands the conceptual framework of sensory deception 59 \nand phoretic host attraction.  60 \n 61 \nLarvae emit floral monoterpenoids 62 \nTo characterize volatile emissions from M. proscarabaeus triungula, adult beetles were collected 63 \nin early spring (February–April 2024–25) from Jena, Thuringia, Germany, and maintained under 64 \n.CC-BY 4.0 International licenseavailable under a \n(which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made \nThe copyright holder for this preprintthis version posted January 15, 2026. ; https://doi.org/10.64898/2026.01.15.699641doi: bioRxiv preprint \n\n4 \n \ncontrolled conditions for mating and oviposition ( Supplementary Fig. 1). After approximately 65 \nthree weeks, egg clutches hatched synchronously, and aggregating triungula were harvested for 66 \nvolatile analysis  (Supplementary Fig. 2 ). Headspace solid -phase microextraction (HS -SPME) 67 \ncoupled with achiral gas chromatography -electron ionization -mass spectrometry (GC -EI-MS) 68 \nrevealed a complex volatile profile, comprising more than thirty C19–C27 saturated and unsaturated 69 \nlong-chain hydrocarbons (t r 20.95–29.22 min; Fig. 1B ; Supplementary Fig. 3 ), similar to 70 \ncompounds previously repo rted in M. franciscanus larvae22. However, in addition to these 71 \nhydrocarbons, we detected several structurally distinct monoterpenoids (t r 9.83–14.05 min; Figs. 72 \n1C and D), including cis- and trans- diastereoisomers of linalool oxide (furanoid) (1), linalool (2), 73 \nmultiple stereoisomers of lilac aldehyde ( 3), linalool oxide (pyranoid) ( 4), linalool-6,7-epoxide 74 \n(5), and lilac alcohol ( 6), and 8 -oxolinalool (7) and 8 -hydroxylinalool (8). Compound identities 75 \n(1–8) were confirmed by comparison with synthesized reference standards (Supplementary Fig. 76 \n4). 77 \n 78 \n.CC-BY 4.0 International licenseavailable under a \n(which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made \nThe copyright holder for this preprintthis version posted January 15, 2026. ; https://doi.org/10.64898/2026.01.15.699641doi: bioRxiv preprint \n\n5 \n \n 79 \nFig. 1 Lifecycle and volatile emissions of Meloe proscarabaeus triungula. (A) Lifecycle of the 80 \ntoxic European Black oil beetle M. proscarabaeus. After emerging and mating in the spring (i), 81 \ngravid females dig underground chambers (ii –iii) and oviposit thousands of yellow eggs (iv). 82 \nTriungula hatch after several weeks and form conspicuous orange aggregations on vegetation (v), 83 \nwhere they await con tact with a solitary bee host that inadvertently carries them to their nest to 84 \ncomplete their development to adulthood (vi). ( B) Total ion current (TIC) chromatogram of 85 \ntriungulin volatile profile, obtained via HS-SPME collection and achiral GC-EI-MS analysis. (C) 86 \n.CC-BY 4.0 International licenseavailable under a \n(which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made \nThe copyright holder for this preprintthis version posted January 15, 2026. ; https://doi.org/10.64898/2026.01.15.699641doi: bioRxiv preprint \n\n6 \n \nAlongside long -chain hydrocarbons (t r 20.95–29.22 min), M. proscarabaeus triungula emit a 87 \ncomplex bouquet of floral-scent monoterpenoids (tr 9.83–14.05 min, 1–8). Peak identification: 1a 88 \nand 1b) (5S)-linalool oxide (furanoid)‡, 2) (S)-linalool, 3a–c) (5S)-lilac aldehyde‡, 4a and 4b) (6S)-89 \nlinalool oxide (pyranoid)‡, 5a and 5b) (3S)-linalool-6,7-epoxide‡, 6a–c) (5S)-lilac alcohol‡, 7) (S)-90 \n8-oxolinalool, 8) (S)-8-hydroxylinalool. *Background; ‡Mixture of stereoisomers. (D) Structural 91 \nand stereochemical assignments of identified monoterpene volatiles were confirmed by 92 \ncomparison with synthetic standards using achiral and chiral GC-EI-MS.    93 \n 94 \nChiral GC -EI-MS analysis revealed that M. proscarabaeus triungula exclusively emit the ( S)- 95 \nenantiomer of linalool ((S)-2) (Supplementary Figs. 5 and 6) along with a range of (S)-2-derived 96 \nmetabolites bearing conserved stereochemistry at the C-3 position (Fig. 1D, Supplementary Figs. 97 \nS7–S20). Absolute configurations were verified by comparison with synthetic reference standards 98 \nderived from rac-, ( R)-, and ( S)-2. In total, triungula emitted 17 structurally  distinct 99 \nmonoterpenoids (1–8), all of which are known floral volatiles widespread among a ngiosperms26, 100 \n27 such as Berberis vulgaris, Prunus spp., and Salix spp.28-31, which serve as the main food source 101 \nfor pollinating bees in the spring, when M. proscarabaeus triungula also emerge. However, except 102 \nfor (S)-232 and linalool oxide 133, none of these monoterpenoids have been previously reported to 103 \nbe produced in an insect.  104 \n 105 \nFloral-scent mimicry attracts bees 106 \nSeveral monoterpenoids emitted by M. proscarabaeus triungula—including (S)-linalool ((S)-2) 107 \nand its derivatives (1 and 3–8)—are common floral volatiles known to attract pollinators, including 108 \n.CC-BY 4.0 International licenseavailable under a \n(which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made \nThe copyright holder for this preprintthis version posted January 15, 2026. ; https://doi.org/10.64898/2026.01.15.699641doi: bioRxiv preprint \n\n7 \n \nsolitary wild bees 28-31, 34. We hypothesized that by production and emission of these volatiles, 109 \ntriungula closely mimic a floral scent that , in turn,  can lure a br oad range of phoretic hosts. 110 \nAlthough M. proscarabaeus larvae primarily parasitize ground -nesting solitary bees 20, triungula 111 \nhave also been recovered from nests of social bee species 20, 35, suggesting that volatile emission 112 \nby these larvae may also mediate phoretic interactions with these unsuitable social insect hosts that 113 \ncan eject the larvae from the nest after transmission 36. Notably, the observation of M. 114 \nproscarabaeus triungula on both suitable and unsuitable bee hosts is consistent with a general 115 \nattraction strategy. 116 \nTo test whether M. proscarabaeus triungulin monoterpenoids attract solitary bees, we first 117 \nconducted dual -choice olfactometer assays with polylectic Osmia bicornis , a commercially 118 \navailable wild bee species (Fig. 2A; Supplementary Fig. 21). Live triungula, emitting a complex 119 \nblend of monoterpenoids and long-chain hydrocarbons attracted both male and female O. bicornis 120 \n(Fig. 2B). Similarly, volatile extracts obtained via dynamic headspace volatile (DHV) collection—121 \nwhich contained markedly reduced amounts of long -chain hydrocarbons —also attracted both 122 \nsexes of O. bicornis (Fig. 2C ). Notably, DH V collection captured the full triun gulin 123 \nmonoterpenoid profile, whereas parallel solvent-based extractions failed to recover these volatiles 124 \n(Supplementary Fig. 22).  125 \n.CC-BY 4.0 International licenseavailable under a \n(which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made \nThe copyright holder for this preprintthis version posted January 15, 2026. ; https://doi.org/10.64898/2026.01.15.699641doi: bioRxiv preprint \n\n8 \n \n 126 \nFig. 2 Triungulin -derived monoterpenoids attract solitary and social bees. (A) Dual-choice 127 \nY-tube behavioral assays were performed with solitary (Osmia bicornis and Colletes similis) and 128 \n.CC-BY 4.0 International licenseavailable under a \n(which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made \nThe copyright holder for this preprintthis version posted January 15, 2026. ; https://doi.org/10.64898/2026.01.15.699641doi: bioRxiv preprint \n\n9 \n \nsocial (Apis mellifera and Bombus terrestris) bee species. (B) Both male and female O. bicornis 129 \nwere attracted to live triungula. ( C) Volatile extracts from aggregating triungula, obtai ned via 130 \ndynamic headspace volatile (DHV) collection, also attracted male and female O. bicornis. (D) A 131 \nsynthetic blend of (S)-linalool ((S)-2)-derived monoterpenoids (1–8) elicited significant attraction 132 \nfrom female C. similis, A. mellifera, B. terrestris, and both sexes of O. bicornis. (E) Behavioral 133 \nassays with individual monoterpenoids showed sex -specific responses in O. bicornis. Control 134 \nassays with wheat in both Y -tube arms confirmed no side bias. All bees, except C. similis, were 135 \nflower-naïve. Numbers in bars indicate absolute choices. χ² test: ***p < 0.001, **p < 0.01, *p < 136 \n0.05, NS = not significant. §Mixture of stereoisomers; †Geranylacetone; tentatively identified using 137 \nthe NIST MS-Library v. 3.0 (2023). 138 \n 139 \nAs previously noted, M. franciscanus larvae attract male solitary bees by emitting a blend of long-140 \nchain hydrocarbons that mimic female bee sex pheromones 22. To determine whether triungulin -141 \nemitted monoterpenoids can independently elicit attraction—without the influence of co-occurring 142 \nlong-chain hydrocarbons—we exposed male and female O. bicornis to a synthetic blend of ( S)-143 \nlinalool derivatives (compounds 1–8; Fig. 2C ; Supplementary Fig. 23A ) lacking these 144 \nhydrocarbons. Both sexes were significantly attracted to this blend ( χ² test, p < 0.05). In contrast, 145 \nonly males, but not females , responded to an analogous blend of synthetic ( R)-linalool-derived 146 \nmonoterpenoids ( Supplementary Fig. 23B ), highlighting the importance of the natural 147 \nstereoisomeric composition of the triungulin volatile bouquet.  148 \nConsidering that O. bicornis is likely a n unsuitable host for M. proscarabaeus triungula—as it 149 \ntypically nests in pre-existing cavities in wood, hollow stems, loess, clay, or masonry37—we next 150 \ntested the synthetic (S)-2-derived blend in dual-choice assays with wild-caught females of Colletes 151 \n.CC-BY 4.0 International licenseavailable under a \n(which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made \nThe copyright holder for this preprintthis version posted January 15, 2026. ; https://doi.org/10.64898/2026.01.15.699641doi: bioRxiv preprint \n\n10 \n \nsimilis, a ground -nesting solitary bee, and with workers of the eusocial generalists Bombus 152 \nterrestris and Apis mellifera (Fig. 2D). These assays confirmed the attraction of C. similis and 153 \nadditionally revealed that triungula can also attract unsuitable social bee hosts, a capacity that may 154 \nenhance their phoretic dispersal. For instance, M. strigulosus triungula have been observed to 155 \ndetach from unsuitable hosts during inter -floral movements21. Such a “hop-on, hop-off” strategy 156 \nlikely increases dispersal efficiency and may similarly occur in M. proscarabaeus. 157 \nWhile the sex pheromones of A. mellifera and B. terrestris have been described previously as long-158 \nchain hydrocarbon derivatives38, 39 and do not include monoterpenoids, certain colletid bees40, such 159 \nas Colletes cunicularius 32, use (S)-2 as a mate attractant . However, we could not detect 160 \nmonoterpenoids in either sex of C. similis or O. bicornis (Supplementary Fig. 24). Together with 161 \nthe observation that triungulin monoterpenoids attract several distantly related bee species, this 162 \nsupports the conclusion that bee attraction to triungulin monoterpenoids is based on floral scent 163 \nmimicry rather than the imitation of bee sex pheromones. In addition, the bright orange coloration 164 \nand shape of the larval aggregates may also visually mimic floral signals , a possibility further 165 \nsupported by the contrasting appearances of M. franciscanus and closely related M. violaceus41 166 \ntriungula, which are markedly darker8, 20. Indeed, increasing evidence indicates that mimics exploit 167 \nmultiple sensory channels simultaneously, enhancing the effectiveness of the deception42. 168 \nWe next investigated each compound ( 1–8) individually in dual -choice assays using naïve male 169 \nand female O. bicornis (Fig. 2D). All monoterpenoids except (3 S)-linalool-6,7-epoxide ((3S)-5) 170 \nand (5S)-lilac alcohol ((5S)-6) elicited significant attraction in males (χ² test, 0.001 > p < 0.05). 171 \nFemales were not attracted to (3 S)-5 and, unlike males, showed no preference for ( S)-2, (5 S)-172 \nlinalool oxide (furanoid) ((5S)-1), or (S)-8-hydroxylinalool ((S)-8) (p > 0.05). However, (5S)-lilac 173 \naldehyde ((5 S)-3), (6 S)-linalool oxide (pyranoid) ((6 S-4), (5 S-6), and ( S)-8-oxolinalool (( S)-7) 174 \n.CC-BY 4.0 International licenseavailable under a \n(which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made \nThe copyright holder for this preprintthis version posted January 15, 2026. ; https://doi.org/10.64898/2026.01.15.699641doi: bioRxiv preprint \n\n11 \n \nwere significantly attractive to females (0.01 > p < 0.05). The observed attraction of female bees 175 \nto the monoterpenoid blend as well as several of the individual components support the hypothesis 176 \nthat mimicry of floral scent in M. proscarabaeus larvae can bypass male bees and directly lure 177 \nfemale hosts, unlike triungula of M. franciscanus who only attract intermediary male Habropoda 178 \nhosts and then have to move to females during copulation in order to reach the nest . The direct 179 \nattraction of females by M. proscarabaeus larvae likely enhances their chances of nest entry and 180 \nsuccessful development.  181 \nConsidering that M. proscarabaeus triungula usually aggregate on vegetation but sometimes climb 182 \nto reach flowers, we hypothesized that  larval monoterpenoids have a dual rol e: facilitating both 183 \nhost attraction and larval aggregation. Indeed, olfactometric as says showed that triungula were 184 \nsignificantly attracted to a synthetic blend of ( S)-linalool-derived monoterpenoids ( 1–8), 185 \nsupporting a dual role for these volatiles in bee attraction and larval clustering ( Supplementary 186 \nFig. 25 , Supplementary Table 1 ). This result suggests an intriguing evolutionary scenario in 187 \nwhich triungula likely originally relied on floral volatiles as  cues to locate flowers, where they 188 \ncould await pollinating insect hosts. The emission of such scents by the larvae may have initiall y 189 \nmerely amplified the natural floral signal. However, ultimately, this also led to the aggregation of 190 \ntriungula, allowing clustered larvae to generate a substantially stronger bouquet than solitary 191 \nindividuals and thereby reduc e their dependence on actual flowers. In fact, M. proscarabaeus 192 \nlarvae typically emerge in the spring near bee nests in areas that have few ground-flowering plants 193 \nand where early-flowering shrubs and trees, which act as main food source for pollinating bee s, 194 \nare often several hundred meters away. Thus, flower mimicry may have helped M. proscarabaeus 195 \nto occupy new ecological niches. Remarkably , this host -attraction strategy also targets  a 196 \n.CC-BY 4.0 International licenseavailable under a \n(which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made \nThe copyright holder for this preprintthis version posted January 15, 2026. ; https://doi.org/10.64898/2026.01.15.699641doi: bioRxiv preprint \n\n12 \n \nfundamental behavioral mechanism essential for the survival of pollinating insects, limiting their 197 \npotential for rapid coevolutionary escape. 198 \n 199 \nTriungula biosynthesize monoterpenoids  200 \nFollowing eclosion, larvae of M. proscarabaeus consistently emit floral-scent monoterpenoids 1–201 \n8. However, it remained unclear whether these volatiles were sequestered, maternally transferred, 202 \nor biosynthesized de novo. However, as larvae do not feed on plants following eclosion 20, the 203 \nsequestration of floral monoterpenoids seems rather unlikely. T o determine if larval 204 \nmonoterpenoids 1–8 were maternally derived, we analyzed the volatile profiles of adult females 205 \nand their eggs, using HS -SPME GC-EI-MS (Supplementary Figs. 26 and 27). However, apart 206 \nfrom the emission of (S)-linalool ((S)-2) by eggs (Supplementary Fig. 28), we could detect no 207 \nother floral monoterpenoids in eggs or adults. This result, together with the conserved ( S) 208 \nstereochemistry at the linalool C -3 position among compounds 1 and 3–8, led us to hypothesize 209 \nthat triungula biosynthesize these monoterpenoids from (S)-2 (Fig. 3A).    210 \n 211 \n 212 \n.CC-BY 4.0 International licenseavailable under a \n(which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made \nThe copyright holder for this preprintthis version posted January 15, 2026. ; https://doi.org/10.64898/2026.01.15.699641doi: bioRxiv preprint \n\n13 \n \n 213 \nFig. 3 Triungula biosynthesize a range of ( S)-linalool-derived floral monoterpenoids. (A) 214 \nProposed biosynthetic pathway of floral-scent volatiles in triungula showing early P450-mediated 215 \noxidation of central precursor ( S)-linalool ((S)-2) to epoxide (3 S)-5 and diol ( S)-8. Spontaneous 216 \nring-closure of labile epoxide (3S)-5 subsequently affords linalool oxides (5S)-1 and (6S)-4, while 217 \nfurther oxidation of ( S)-8 furnishes intermediate (S)-7 that cyclizes to lilac aldehyde (5 S)-3. 218 \nEnzymatic reduction of aldehyde (5S)-3 generates alcohol (5S)-6. (B) Differential gene expression 219 \nanalysis identified a cytochrome P450 reductase (MpRed)  and P450 -encoding transcripts 220 \nupregulated in larvae relative to adult females. Relative (Rel.) expression values are based on reads 221 \nper kilobase of transcript per million reads mapped (RPKM) values obtained by RNA -seq (for 222 \nabsolute RPKM values, see Supplementary T able 4 ). ( C) Functional characterization of 223 \n.CC-BY 4.0 International licenseavailable under a \n(which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made \nThe copyright holder for this preprintthis version posted January 15, 2026. ; https://doi.org/10.64898/2026.01.15.699641doi: bioRxiv preprint \n\n14 \n \nCYP347BT1 in S. cerevisiae expressing either CYP347BT1 and MpRed or MpRed alone in the 224 \npresence of (S)-2. Reaction products were analyzed using GC-EI-MS. Peak identification: 1a and 225 \n1b) (5 S)-linalool oxide (furanoid), 2) ( S)-linalool, 4) (6 S)-linalool oxide (pyranoid), 5) (3 S)-226 \nlinalool-6,7-epoxide. Note: Only traces of (6 S)-4 and (3 S)-5 were detected. *Background. ( D) 227 \nFunctional characterization of CYP345BZ1 in S. cerevisiae expressing either CYP345BZ1 and 228 \nMpRed or MpRed alone in the presence of (S)-2. Reaction products were analyzed using GC-EI-229 \nMS. Peak identification: 8) (S)-8-hydroxylinalool.     230 \n 231 \nAs compounds 2 and 5, and 3, 7, and 8 are known intermediates in the biosynthesis of linalool 232 \noxides (1 and 4) and lilac alcohol ( 6), respectively, we hypothesized that two cytochrome P450 233 \n(P450) enzymes generate structural diversity within the triungulin monoterpenoid bouquet by 234 \noxidizing (S)-linalool ((S)-2) to (S)-8 and (3S)-5. To test this, we extracted RNA from aggregating 235 \ntriungula and adult females, and generated a de novo transcriptome assembly. Differential gene 236 \nexpression analysis identified 15 transcripts annotated as P450 or P450 -like, with elevated 237 \nexpression in triungula but not in adult females, along with a putative  P450 reductase ( MpRed) 238 \n(Fig. 3B).  239 \nEach candidate P450 was individually co-expressed with MpRed in Saccharomyces cerevisiae and 240 \nscreened for biosynthetic activity in vivo  in the presence of ( S)-2. One candidate , designated 241 \nCYP347BT1 according to P450 nomenclature, epoxidized (S)-2 to primarily yield linalool oxide 242 \n(furanoid) stereoisomers, (2 S,5S)- and (2R,5S)-1, along with trace amounts of (3 S)-linalool-6,7-243 \nepoxide ((3S)-5) and linalool oxide (pyranoid) diastereomers (6S)-4 (Fig. 3C). Another candidate 244 \ndesignated CYP345BZ1, catalyzed the terminal allylic C-H hydroxylation of (S)-2 to produce (S)-245 \n.CC-BY 4.0 International licenseavailable under a \n(which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made \nThe copyright holder for this preprintthis version posted January 15, 2026. ; https://doi.org/10.64898/2026.01.15.699641doi: bioRxiv preprint \n\n15 \n \n8-hydroxylinalool (S)-8 (Fig. 3D). Together, these results confirm that M. proscarabaeus triungula 246 \nindependently biosynthesize floral-scent monoterpenoids. 247 \nConsistent with in vivo  assays, HS -SPME and DH V collection  extracts of triungula contained 248 \nrelatively low amounts of (3 S)-5 and (6S)-4, compared to linalool oxide (5 S)-1 (Fig. 1B and C). 249 \nFurthermore, GC -EI-MS analysis indicated that (3 S)-5 undergoes both 5 - and 6 -exo-tet 250 \nintramolecular cyclization to form (5 S)-1 and (6 S)-4, respectively, during analysis 251 \n(Supplementary Fig. 29), congruent with the spontaneous degradation of synthetic (5S)-5 to (5S)-252 \n1 and (6S)-4 over time (Supplementary Fig. 30). The formation of both (2 R,5S)- and (2S,5S)-1 253 \nstereoisomers from ( S)-2 in the presence of CYP347BT1 and MpRed further suggests that 254 \nCYP347BT1-mediated epoxidation proceeds non -stereoselectively, initially generating labile 255 \nintermediates (3S,6S)- and (3S,6R)-5 from (S)-2.  256 \n 257 \nConclusion 258 \nOur results reveal a  hitherto undescribed form of interkingdom aggressive chemical mimicry in 259 \nwhich M. proscarabaeus triungula collectively emit a complex bouquet of floral -scent 260 \nmonoterpenoids to lure solitary and social bees. Behavioral assays show that these volatiles act as 261 \nfloral-scent mimics rather than pheromone analogs, enabling attraction of male and female solitary 262 \nbees, promoting s uccessful phoretic dispersal , and coordinating larval aggregation . We identif y 263 \ntwo P450  enzymes, CYP347BT1 and CYP345BZ1, that generate committed biosynthetic 264 \nprecursors ((3S)-5 and (S)-8) responsible for the suite of (S)-linalool-derived monoterpenoids (1, 265 \n3, 4, 6, and 7). Together, these findings broaden the evolutionary framework of mimicry by 266 \n.CC-BY 4.0 International licenseavailable under a \n(which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made \nThe copyright holder for this preprintthis version posted January 15, 2026. ; https://doi.org/10.64898/2026.01.15.699641doi: bioRxiv preprint \n\n16 \n \ndemonstrating how an insect can independently produce plant-like signals to manipulate inter- and 267 \nintraspecific interactions.  268 \n 269 \nData availability:  270 \nAll data required to evaluate the conclusions proposed herein are present in the Manuscript or 271 \nassociated Supplementary Information. Genes characterized in this study are deposited in the 272 \nNCBI GenBank with the following accession number s: MpRed ( PX569140), CYP347BT1 273 \n(PX569141), and CYP345BZ1 (PX569142) and s equencing data are available at 274 \nhttps://doi.org/10.17617/3.7TXB4J. 275 \n 276 \nAcknowledgements 277 \nWe thank Daniel Veit and Angela Lehmann (MPI-ICE) for the design and construction of volatile 278 \ncollection and behavioral bioassay apparatuses, Sarah Heinicke (MPI-ICE) for assistance with GC-279 \nEI-MS data acquisition, Prof. David Nelson (UTHSC) for kindly annotating P450 genes, 280 \nCYP345BZ1 and CYP347BT1, and Drs Klaus Gase, Mohamed Omar Kamileen, Maite Colinas, 281 \nSong Wu (MPI-ICE), and Hannah M. Rowland (MPI-ICE/UOL) for helpful discussion.  282 \n 283 \nFunding 284 \nThis work was supported by funding from the Max Planck Society.  285 \n 286 \n.CC-BY 4.0 International licenseavailable under a \n(which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made \nThe copyright holder for this preprintthis version posted January 15, 2026. ; https://doi.org/10.64898/2026.01.15.699641doi: bioRxiv preprint \n\n17 \n \nAuthor contributions  287 \nConceptualization: R.M.A., M.Ka., S.E.OC., and T.G.K.; Data curation: R.M.A., H.V., and 288 \nT.G.K.; Formal analysis:  R.M.A., D.K., H.V., and T.G.K.; Funding acquisition:  S.E.OC.; 289 \nInvestigation: R.M.A., D.K., H.V., K.L., and A.D.; Methodology: R.M.A., D.K., M.Ku., and 290 \nT.G.K.; Project administration: R.M.A. and T.G.K.; Resources: S.E.OC.; Supervision: S.E.OC. 291 \nand T.G.K.; Validation: R.M.A., D.K., K.L., and T.G.K.; Visualization: R.M.A. and T.G.K.; 292 \nWriting – original draft: R.M.A. and T.G.K.; Writing – review and editing: R.M.A., D.K., H.V., 293 \nM.Ka., S.E.OC., and T.G.K.  294 \n 295 \nCorresponding authors: 296 \nCorrespondence and requests for materials should be addressed to oconnor@ice.mpg.de and 297 \nkoellner@ice.mpg.de  298 \n 299 \nEthics declarations 300 \nCompeting interest: 301 \nThe authors declare that they have no competing interests.  302 \n 303 \n 304 \n 305 \n 306 \n.CC-BY 4.0 International licenseavailable under a \n(which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. 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