Filadelfo Guzman’s research while affiliated with Agricultural Research Service and other places
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We found that vittatalactone, specifically (3R,4R)-3-methyl-4-[(1S,3S,5S)-1,3,5,7-tetramethyloctyl]oxetan-2-one, is the male-produced aggregation pheromone of the western striped cucumber beetle, Acalymma trivittatum (Mannerheim), as was previously shown for the striped cucumber beetle, Acalymma vittatum (F.) (Coleoptera: Chrysomelidae). A synthetic mixture containing 9% of the authentic natural pheromone, is attractive to both sexes of both species in the field, as demonstrated by trapping using baited and unbaited sticky panels in California and earlier in Maryland. Females of both species do not produce detectable vittatalactone. This finding expands the usefulness of the synthetic vittatalactone mixture for pest management throughout the range of both A. vittatum and A. trivittatum. Development of vittatalactone time-release formulations combined with cucurbitacin feeding stimulants offer the potential for selective and environmentally-friendly cucurbit pest management tactics.
Spotted cucumber beetle (Diabrotica undecimpunctata howardi; also known as southern corn rootworm) is a pest feeding on many crops, including cucurbits, corn (maize), peanuts, beans, and other crops and wild plants in North America. On cucurbit crops, where it co-occurs with striped cucumber beetle (Acalymma vittatum), both are key pests that vector Erwinia tracheiphila, a destructive pathogen that causes bacterial wilt. Here we deployed synthetic vittatalactone, the male-produced aggregation pheromone of A. vittatum, as lures in the field, to measure attraction of the target and non-target insects. Both sexes of D. u. howardi were strongly attracted to the vittatalactone lures (5–7.5-fold compared to blank trap) throughout the growing season in Maryland and Virginia, USA. Moreover, D. u. howardi was more attracted to live A. vittatum males feeding on squash plants than to plants with females or without any beetles, confirming the genuine organismal cross-attraction between these two key pests. The kairomonal attraction to vittatalactone suggests that it functions as a “keystone semiochemical,” mediating the colonization of cucurbits by multiple herbivore species. Such cross attraction could allow for use of vittatalactone in management of multiple pest species, with potential reduction of pesticide use in cucurbit crops.
Sesquipiperitol is a sesquiterpene alcohol, some stereoisomers of which were found in several plant species. The biological role of these compounds in plants and their absolute configurations have not been reported. Recently, we found that 1S,6S,7R stereoisomer of sesquipiperitol was a key precursor in the biosynthesis of the harlequin bug, Murgantia histrionica, pheromone, which consists of two stereoisomeric zingiberenol oxides. In addition, the Tibraca limbativentris stink bug was shown to produce two sesquipiperitol stereoisomers as minor components in their male-produced sex pheromone, the main constituents of which were zingiberenols. To determine absolute configurations of plant- and stink-bug-produced sesquipiperitols, we undertook syntheses of all stereoisomers of this sesquiterpene alcohol. The syntheses were based on 1,10-bisaboladien-3-ols (aka zingiberenols) with known configurations at C-6 and C-7, the oxidation of which provided sesquipiperitone precursors with retention of configurations of these stereogenic centers. The foremost challenge of the synthetic endeavor was the assignment of absolute configurations of secondary carbinol centers, which was resolved by NMR analyses of corresponding Mosher's esters. Thus, the availability of all eight diastereomers allowed us to assign sesquipiperitols from Fitzroya cupressoides and Argyranthemum adauctum spp. jacobaeifolium plants 1S,6S,7R (16) and 1R,6R,7S (14) configurations, respectively. A chiral-phase gas-chromatographic method was developed to determine 1S,6S,7R and 1R,6S,7R (15) configurations of T. limbativentris sesquipiperitol pheromone components.
The brown marmorated stink bug, Halyomorpha halys, is an agricultural and urban pest that has become widely established as an invasive species of major concern in the USA and across Europe. This species forms large aggregations when entering diapause, and it is often these aggregations that are found by officials conducting inspections of internationally shipped freight. Identifying the presence of diapausing aggregations of H. halys using their emissions of volatile organic compounds (VOCs) may be a potential means for detecting and intercepting them during international freight inspections. Headspace samples were collected from aggregations of diapausing H. halys using volatile collection traps (VCTs) and solid phase microextraction. The only compound detected in all samples was tridecane, with small amounts of (E)-2-decenal found in most samples. We also monitored the release of defensive odors, following mechanical agitation of diapausing and diapause-disrupted adult H. halys. Diapausing groups were significantly more likely to release defensive odors than diapause-disrupted groups. The predominant compounds consistently found from both groups were tridecane, (E)-2-decenal, and 4-oxo-(E)-2-hexenal, with a small abundance of dodecane. Our findings show that diapausing H. halys do release defensive compounds, and suggest that volatile sampling may be feasible to detect H. halys in freight.
We recently synthesized all stereoisomers of 1,10-bisaboladien-3-ol and 10,11-epoxy-1-bisabolen-3-ol, including three stink bug pheromones, via a rhodium-catalyzed asymmetric addition of trimethylaluminum to diastereomeric mixtures of cyclohex-2-enones. However, yields of trans isomers were low, and scaling reactions using expensive catalysts were cumbersome. Now we describe a new synthesis of bisabolenol stink bug pheromones via (S)- and (R)-4-((R)-6-methylhept-5-en-2-yl)cyclohex-2-enones prepared by enantioselective Michael additions of methyl vinyl ketone to (S)- and (R)-citronellals and lithium hydroxide monohydrate-catalyzed stereoselective cyclizations of intermediate ketoaldehydes. Addition of methyllithium to these enones provided cis- and trans-1,10-bisaboladien-3-ols, which were separated by chromatography on silica and further converted to 10,11-epoxy-1-bisabolen-3-ols. Thus, we developed more convenient syntheses of pheromones of the rice stink bug, the harlequin bug, and brown marmorated stink bug.
Two stereoisomeric zingiberenols in ginger were identified as (3R,6R,7S)-1,10-bisaboladien-3-ol (2) and (3S,6R,7S)-1,10-bisaboladien-3-ol (5). Absolute configurations were assigned by utilizing 1,10-bisaboladien-3-ol stereoisomers and two gas-chromatography columns: a 25 m Hydrodex-β-6TBDM and 60 m DB-5MS. The C-6 and C-7 absolute configurations in both zingiberenols match those of zingiberene present abundantly in ginger rhizomes. Interestingly, zingiberenol 2 has recently been identified as a male-produced sex pheromone of the rice stink bug, Oebalus poecilus, thus indicating that ginger plants may be a potential source of the sex pheromone of this bug.
Preparation of a complete stereoisomeric library of 1,10-bisaboladien-3-ols and selected 10,11-epoxy-1-bisabolen-3-ols was pivotal for the identification of the aggregation pheromone of the brown marmorated stink bug, Halyomorpha halys. Herein, we describe syntheses of the remaining 10,11-epoxy-1-bisabolen-3-ols, and provide additional evidence on the assignment of relative and absolute configurations of these compounds by single-crystal X-ray crystallography of an intermediate, (3S,6R,7R,10S)-1-bisabolen-3,10,11-triol. To demonstrate the utility of this stereoisomeric library, we revisited the aggregation pheromone of the harlequin bug, Murgantia histrionica, and showed that the male-produced pheromone consists of two stereoisomers of 10,11-epoxy-1-bisabolen-3-ol. Employment of eight cis-10,11-epoxy-1-bisabolen-3-ol stereoisomeric standards, two enantioselective GC columns, and NMR spectroscopy enabled the identification of these compounds as (3S,6S,7R,10S)-10,11-epoxy-1-bisabolen-3-ol and (3S,6S,7R,10R)-10,11-epoxy-1-bisabolen-3-ol, which are produced by M. histrionica males in 1.4:1 ratio.
We describe a novel and straightforward route to all stereoisomers of 1,10-bisaboladien-3-ol and 10,11-epoxy-1-bisabolen-3-ol via the rhodium-catalyzed asymmetric addition of trimethylaluminum to diastereomeric mixtures of cyclohex-2-enones 1 and 2. The detailed stereoisomeric structures of many natural sesquiterpenes with the bisabolane skeleton were previously unknown because of the absence of stereoselective syntheses of individual stereoisomers. Several of the bisabolenols are pheromones of economically important pentatomid bug species. Single-crystal X-ray crystallography of underivatized triol 13 provided unequivocal proof of the relative and absolute configurations. Two of the epoxides, (3S,6S,7R,10S)-10,11-epoxy-1-bisabolen-3-ol (3) and (3R,6S,7R,10S)-10,11-epoxy-1-bisabolen-3-ol (4), were identified as the main components of a male-produced aggregation pheromone of the brown marmorated stink bug, Halyomorpha halys, using GC analyses on enantioselective columns. Both compounds attracted female, male, and nymphal H. halys in field trials. Moreover, mixtures of stereoisomers containing epoxides 3 and 4 were also attractive to H. halys, signifying that the presence of additional stereoisomers did not hinder attraction of H. halys and relatively inexpensive mixtures can be used in monitoring, as well as control strategies. H. halys is a polyphagous invasive species in the U.S. and Europe that causes severe injury to fruit, vegetables, and field crops and is also a serious nuisance pest.
We describe a novel and straightforward route to all stereoisomers of 1,10-bisaboladien-3-ol and 10,11-epoxy-1-bisabolen-3-ol via the rhodium-catalyzed asymmetric addition of trimethylaluminum to diastereomeric mixtures of cyclohex-2-enones 1 and 2. The detailed stereoisomeric structures of many natural sesquiterpenes with the bisabolane skeleton were previously unknown because of the absence of stereoselective syntheses of individual stereoisomers. Several of the bisabolenols are pheromones of economically important pentatomid bug species. Single-crystal X-ray crystallography of underivatized triol 13 provided unequivocal proof of the relative and absolute configurations. Two of the epoxides, (3S,6S,7R,10S)-10,11-epoxy-1-bisabolen-3-ol (3) and (3R,6S,7R,10S)-10,11-epoxy-1-bisabolen-3-ol (4), were identified as the main components of a male-produced aggregation pheromone of the brown marmorated stink bug, Halyomorpha halys, using GC analyses on enantioselective columns. Both compounds attracted female, male, and nymphal H. halys in field trials. Moreover, mixtures of stereoisomers containing epoxides 3 and 4 were also attractive to H. halys, signifying that the presence of additional stereoisomers did not hinder attraction of H. halys and relatively inexpensive mixtures can be used in monitoring, as well as control strategies. H. halys is a polyphagous invasive species in the U.S. and Europe that causes severe injury to fruit, vegetables, and field crops and is also a serious nuisance pest. T he bisabolane skeleton is a recurring structural motif in the semiochemistry of stink bugs (Hemiptera: Pentatomidae). Bisabolene epoxides comprise male-specific pheromones of Nezara viridula 1,2 and Chinavia (=Acrosternum) spp. 3,4 The related zingiberene, β-sesquiphellandrene, and α-curcumene constitute part of the Thyanta pallidovirens pheromone, 5 and β-sesquiphellandrene was identified as a pheromone component of Piezodorus hybneri. 6 More recently, two stereoisomeric 1,10-bisaboladien-3-ols 7 were identified as part of the male-produced pheromone of the rice stalk stink bug, Tibraca limbativentris, 8 and 10,11-epoxy-1-bisabolen-3-ol (called "murgantiol") has been reported as an aggregation pheromone of the harlequin bug, Murgantia histrionica. 9,10 As with murgantiol, the relative and absolute configurations of the 1,10-bisaboladien-3-ols from T. limbativentris have not been determined. Reliable assignment of relative configurations across the cyclohexene ring of the murgantiol structure was problematic, and 1 H and 13 C NMR recordings of murgantiol failed to provide a conclusive answer. 9 Several related compounds were isolated from the oil of ginger, Zingiber off icinale, among them a 1,10-bisaboladien-3-ol, called "zingiberenol". 11 The latter was assigned a trans-configuration based on similarities of its IR spectrum with that of trans-p-menth-2-en-1-ol, 12 but the structure was presented as the cis-isomer 11 and the absolute configuration has not been disclosed. A sex pheromone of the rice stink bug, Oebalus poecilus, has recently been also identified as zingiberenol and, more specifically, (1R,4R,1′S)-(1′,5′-dimethylhex-4′-enyl)-1-methyl-cyclohex-2-en-1-ol. 13 The absolute configuration has been assigned based on the correlation to natural zingiberene and similarities of 13 C NMR spectra of a synthetic mixture containing the pheromone and (R,R)-quercivorol. However, the pher-omone of O. poecilus has not been synthesized in pure form and
... Synthesis of the vittatalactone mixture intended to contain 8 diastereomers with 2R,3R configuration was performed by the method of Chauhan and Paraselli (2017) by the contract of USDA ARS with Chemveda Life Sciences, San Diego, California. The content of natural vittatalactone (2R,3R,4S,6S,8S-2-methyl-3-(2,4,6,8tetramethyloctyl)oxetan-3-one) in the mixture was determined as approximately 9%, by comparison with volatiles emitted by hostfeeding A. vittatum males (Weber et al. 2023). Gray rubber septa (1-F SS 1888 GRY, (18 mm × 9 mm max ∅, West Pharmaceutical Services, Lititz, Pennsylvania) were washed with hexane in a Soxhlet apparatus, and dried in an exhaust hood overnight. ...
... This provided adequate material for field trials in the eastern USA, in which the mixture proved attractive in the field to A. vittatum (Weber 2018). It was attractive to other species as well, including the squash bug, Anasa tristis (De Geer) (Hemiptera: Coreidae) (Brzozowski et al. 2022), the horned squash bug, Anasa armigera (F.) , and the spotted cucumber beetle, Diabrotica undecimpunctata howardi Barber (Haber et al. 2023). In addition to trapping A. vittatum in the eastern USA, we deployed traps in California, where we noted a strong response of A. trivittatum adults to the mixed vittatalactone lures. ...
... Currently, control methods such as exclusion nets [17][18][19] and biological control programs [20][21][22] are being examined but are still at a preliminary stage and require elaboration. The availability of the BMSB two-component aggregation pheromone [23] and pheromone synergist [24] has led research into developing management strategies centered around behavioral manipulation that could prevent or lessen crop losses [25,26]. These pheromones have been refined and optimized [27] and are commercially available and globally used in BMSB monitoring programs [28][29][30]. ...
... During our ongoing investigation toward chemistry diversity of marine-derived A. taichungensis 299, one new bisabolane sesquiterpene, 2-bisabolen-1,10,11,12-tetraol (1), along with three known ones, (3R, 6R, 7S, 10S)-1-bisabolen-3,10,11-triol (2) [11], (3R, 6S, 7R)-1,10-bisaboladien-3-ol (3) [12], and nor-bisabolan-1,11-diol (4) [13], were isolated and identified from A. taichungensis 299. Herein, the details of isolation, structure elucidation, and antibacterial activity evaluation of compound 1 are described. ...
... For example, n-tridecane has been identified as kairomone used by T. japonicus females for host location (Zhong et al., 2017;Malek et al., 2021). This compound is not only present in H. halys adults, nymphs and eggs (Karimi and Gross, 2024), but it is also a major component of the metathoracic scent glands of D. baccarum males and females, as well as of many other stink bugs (Millar, 2005;Durak, 2008;Harris et al., 2015;Nixon et al., 2018). Moreover, tridecane is also a common volatile compound emitted by plants (Schiestl, 2010) and is the most abundant volatile emitted by Phaseolus vulgaris L. (Fabales: Fabaceae) plants damaged by 2-3 d H. halys feeding (Fraga et al., 2017). ...
... Individual SSRS and RSRS isomers were prepared in the Invasive Insect Biocontrol and Behavior Laboratory according to the synthetic methods of Shirali et al. (2017). Chemical purities of tested stereoisomers were ≥95% and diastereomeric ratios were ~9:1 for both SSRS and RSRS. ...
... ,[93][94][95][96][97] This similarity in compounds with sometimes identical structures found in both insects and plants was first discovered over 50 years ago, such as cis-zingiberenol identified in both Zingiber officinale (or ginger plant) and Oebalus poecilus (or rice stink bug), actinidine (iridoid) identified in honeysuckle and valerian as well as in the stick insect, and the cyanogenic glycoside linamarin found in cassava and Zygaena filipendulae (or burnet moth).58,[98][99][100][101][102][103][104] There are several theories for how this phenomenon came about, for example through convergent evolution to adapt to similar needs such as for defense and pollination/mating purposes, or through the sequestration of phytocompounds by insects through ingestion.58 ...
... During our ongoing investigation toward chemistry diversity of marine-derived A. taichungensis 299, one new bisabolane sesquiterpene, 2-bisabolen-1,10,11,12-tetraol (1), along with three known ones, (3R, 6R, 7S, 10S)-1-bisabolen-3,10,11-triol (2) [11], (3R, 6S, 7R)-1,10-bisaboladien-3-ol (3) [12], and nor-bisabolan-1,11-diol (4) [13], were isolated and identified from A. taichungensis 299. Herein, the details of isolation, structure elucidation, and antibacterial activity evaluation of compound 1 are described. ...
... Male N. viridula produce a pheromone that attracts conspecific females, males, and late instars (Mitchell andMau 1971, Harris andTodd 1980). For H. halys, the dual pheromone lures which include the aggregation pheromones of H. halys and Plautia stali (Scott) also attract conspecific females and males in the field (Khrimian et al. 2014. Trichopoda pennipes uses the N. viridula pheromone as a kairomone to find its host in the field (Harris andTodd 1980, Aldrich et al. 1987). ...
... Sex pheromones produced in rectal gland extracts through their metabolic attractive signal stimuli have been noted in banana fruit fly B. musae (Perkins et al., 1990;Levi-Zada et al., 2012;Benelli, 2014;Noushini et al., 2020). VOCs manage insects through the banana-spotting bug A. lutescens (Khrimian et al., 2012). Active gland extraction and some volatile production may have insecticidal or repellent activities confirmed by GC-EAD against P. nigronervosa (Berhal et al., 2017;Murhububa et al., 2021). ...
![Scheme 1. Syntheses of Bisaboladienol Stereoisomers 5−12 by the Reaction of ∼1:1 Diastereomeric Mixtures of (6S,7R)-1 and (6R,7R)-1 (Left) and (6S,7S)-2 and (6R,7S)-2 (Right) with Trimethylaluminum (2 equiv) in the Presence of [Rh(cod)Cl] 2 (0.05 equiv) and(R)-or (S)-BINAP (0.12 equiv)](https://www.researchgate.net/profile/Ashot-Khrimian/publication/263476623/figure/fig5/AS:667191804428293@1536082330363/Scheme-1-Syntheses-of-Bisaboladienol-Stereoisomers-5-12-by-the-Reaction-of-11_Q320.jpg)
![Scheme 1. Syntheses of Bisaboladienol Stereoisomers 5−12 by the Reaction of ∼1:1 Diastereomeric Mixtures of (6S,7R)-1 and (6R,7R)-1 (Left) and (6S,7S)-2 and (6R,7S)-2 (Right) with Trimethylaluminum (2 equiv) in the Presence of [Rh(cod)Cl] 2 (0.05 equiv) and(R)-or (S)-BINAP (0.12 equiv)](https://www.researchgate.net/profile/Aijun-Zhang-7/publication/349121256/figure/fig1/AS:989054128635904@1612820288081/Scheme-1-Syntheses-of-Bisaboladienol-Stereoisomers-5-12-by-the-Reaction-of-11_Q320.jpg)
