Journal of Chemical Ecology

Clavijo McCormick, Andrea; Kah-Wei Hee, Alvin; Zhu, Junwei Jerry

doi: 10.1007/s10886-024-01549-zpmid: 39739223

Sugawara, Yuma; Inoue, Hiromitsu; Toda, Satoshi; Tabata, Jun

doi: 10.1007/s10886-024-01473-2pmid: 38308747

The sex pheromone of the azalea mealybug, Crisicoccus azaleae (Tinsley, 1898) (Hemiptera: Pseudococcidae), includes esters of a methyl-branched medium-chain fatty acid, ethyl and isopropyl (E)-7-methyl-4-nonenoate. These compounds are exceptional among mealybug pheromones, which are commonly monoterpenes. Determination of the absolute configuration is challenging, because both chromatographic and spectrometric separations of stereoisomers of fatty acids with a methyl group distant from the carboxyl group are difficult. To solve this problem, we synthesized the enantiomers via the Johnson–Claisen rearrangement to build (E)-4-alkenoic acid by using (R)- and (S)-3-methylpentanal as chiral blocks, which were readily available from the amino acids L-(+)-alloisoleucine and L-(+)-isoleucine, respectively. Each pure enantiomer, as well as the natural pheromone, was subsequently derivatized with a highly potent chiral labeling reagent used in the Ohrui–Akasaka method. Through NMR spectral comparisons of these derivatives, the absolute configuration of the natural pheromone was determined to be S. Field-trap bioassays showed that male mealybugs were attracted more to (S)-enantiomers and preferred the natural stereochemistry. Moreover, the synthetic pheromones attracted Anagyrus wasps, indicating that the azalea mealybug pheromone has kairomonal activity.

Abubaker, Tareq A. S.; Matsui, Yuki; Naka, Hideshi

doi: 10.1007/s10886-024-01531-9pmid: 39075205

The female sex pheromone of Grammodes geometrica (Lepidoptera: Erebidae: Erebinae) was identified as a 2:100:4 mixture of (3Z,6Z,9Z)-3,6,9-icosatriene (T20), (3Z,6Z,9Z)-3,6,9-henicosatriene (T21), and (3Z,6Z,9Z)-3,6,9-tricosatriene (T23) through chemical and electrophysiological analyses of female gland extracts. T23 is a novel sex pheromone component in Erebinae species. Field trapping tests demonstrated optimal male captures in attractant-baited traps when using a 2:100:4 blend of T20, T21 and T23, with a significant decrease in captures observed when T20 or T23 were removed from the full blend. Traps were set in early August, but males began to be captured in early September. The seasonal prevalence showed a bimodal peak, occurring on September 11 and October 9. These findings provide valuable insights into the chemical communication and ecological dynamics of this species within the subfamily Erebinae.

El-Sayed, Ashraf M.; Bunn, Barry

doi: 10.1007/s10886-023-01446-xpmid: 37477755

The broom twig miner, Leucoptera spartifoliella (Hübner) is a highly specific biological control agent for the Scotch broom, Cytisus scoparius (L.). Cytisus scoparius has become a major invasive weed spreading in North America, South America, Australia and both the South and North Island of New Zealand, causing a major disturbance to the ecology of the area where it has been established. Currently, there is no tool available to monitor the population density, dispersal, and establishment of L. spartifoliella. This work was undertaken to identify the sex pheromone of L. spartifoliella and develop a monitoring tool for this biological control agent. Analysis of the extract of the female sex pheromone gland by gas chromatography/mass spectrometry and chemical ionization identified a single compound in the extract. Using the mass spectral data and synthesis of candidate compounds, this compound was identified as 5-methylheptadecane. In a field trapping trial, testing various doses (0.01, 0.1 and 1 mg) of 5-methylheptadecane and virgin females as a positive control, the highest male catch obtained was in traps baited with the 1 mg dose. When testing two releasing substrates for the pheromone (i.e. a glass vial containing a cotton ball and another containing white septum), the male catch in a trap baited with a glass vial with the cotton ball was significantly higher than in a trap baited with a white septum. The identification of the sex pheromone of L. spartifoliella will help to detect and determine population densities, distribution, and dispersal of L. spartifoliella.

Habe, Shunya; Matsuyama, Shigeru; Kanzaki, Natsumi; Hamaguchi, Keiko; Ozaki, Mamiko; Akino, Toshiharu

doi: 10.1007/s10886-024-01548-0pmid: 39305440

The nuptial flight of ants usually occurs during certain periods of the year. Alate females and males fly out of their nests to mate simultaneously. In the genus Camponotus, sex-specific chemicals are deposited in the male head; however, their roles in nuptial flight have not yet been clarified. This study aimed to elucidate the functions of male-specific chemicals in the Japanese carpenter ant Camponotus japonicus. First, we identified three chemicals characteristic to the male - methyl salicylate (MS), methyl 6-methylsalicylate (MMS), and methyl anthranilate (MA) - all of which triggered electroantennogram (EAG) responses in both alate males and females. As the relative content of MS was insufficient for GC comparison, we investigated the quantitative changes of MMS and MA in the male head capsules before and after flight under laboratory conditions. The amounts of both compounds were significantly reduced after flight, which suggested that males secrete them during flight. Thereafter, a field trap experiment was conducted in three fields of the Kyoto Prefecture, Japan, during the nuptial flight season in 2021 using MMS and MA as baits. The number of captured alate males was significantly higher than that of the females, suggesting that these compounds primarily attracted males rather than females. Considering the field conditions, if the local concentration of these chemicals is increased by male aggregation, females may be attracted as they also showed EAG responses. Our findings represent a first step toward understanding chemically mediated male lek formation during the process of male aggregation syndrome in this species.

Li, Xiaowei; Cheng, Jianghui; Han, Haibin; Kirk, William D.J.; O’Brien, Matthew; Wang, Likun; Chen, Limin; Zhang, Haixia; Zhang, Zhijun; Ullah, Farman; Desneux, Nicolas; Lu, Yaobin

doi: 10.1007/s10886-024-01532-8pmid: 39133432

Odontothrips loti (Haliday) (Thysanoptera: Thripidae) is one of the most serious pests on alfalfa, causing direct damage by feeding and indirect damage by transmitting plant viruses. This damage causes significant loss in alfalfa production. Semiochemicals offer opportunities to develop new approaches to thrips management. In this study, behavioral responses of female and male adults of O. loti to headspace volatiles from live female and male conspecifics were tested in a Y-tube olfactometer. The results showed that both male and female adults of O. loti were attracted to the odors released by conspecific males but not those released by females. Headspace volatiles released by female and male adults were collected using headspace solid-phase microextraction (HS-SPME). The active compound in the volatiles was identified by gas chromatography-mass spectrometry (GC-MS). The analysis showed that there was one major compound, (R)-lavandulyl (R)-2-methylbutanoate. The attractive activity of the synthetic aggregation pheromone compound was tested under laboratory and field conditions. In an olfactometer, both male and female adults showed significant preference for synthetic (R)-lavandulyl (R)-2-methylbutanoate at certain doses. Lures with synthetic (R)-lavandulyl (R)-2-methylbutanoate significantly increased the trap catches of sticky white traps at doses of 40–80 µg in the field. This study confirmed the production of aggregation pheromone by O. loti male adults and identified its active compound as (R)-lavandulyl (R)-2-methylbutanoate, providing a basis for population monitoring and mass trapping of this pest.

Kerr, Jessica L.; Romo, Cecilia M.; O’Connor, Brooke; Dickson, Georgia; Novoselov, Max; Aguilar-Arguello, Samuel; Todoroki, Christine; Najar-Rodriguez, Adriana; Manning, Lee-Anne; Twidle, Andrew; Barrington, Anne; Leclair, Gaetan; Mayo, Peter; Sweeney, Jon

doi: 10.1007/s10886-024-01508-8pmid: 38842637

Minegishi, Hiroyuki; Ohashi, Akihiro; Nakamuta, Kiyoshi

doi: 10.1007/s10886-024-01526-6pmid: 38951422

Mating disruption of a flighted spongy moth, Lymantria dispar japonica (Motchulsky)(Lepidoptera: Lymantridae), with a synthetic version of its sex pheromone, (+)-disparlure ([7R,8S] -cis-7,8-epoxy-2- methyloctadecane), was tested in the forests in Japan. Pheromone trap catches and the percentage mating of tethered females were measured in the pheromone-treated and untreated control forests. The attraction of male moths to pheromone traps placed at a height of 1.5 m was significantly disrupted when the pheromone dispensers were placed at 1.5 m height, but many moths were captured in control plots. Mating of tethered females placed at 1.5 m was inhibited entirely, while 44% of females were mated in an untreated control forest. We report the first trial of mating disruption against a flighted spongy moth, and these results suggest that mating disruption with the synthetic sex pheromone appears promising for reducing damage caused by L. dispar japonica.

Tan, Keng Hong; Nishida, Ritsuo

doi: 10.1007/s10886-024-01499-6pmid: 38644437

The natural occurrence, distribution (within a plant) and roles of four phenylbutanoid compounds (anisyl acetone, cue-lure, raspberry ketone and zingerone) are elucidated for the Asia-Pacific and Oceania regions. These phenylbutanoids may act individually or in combination to attract true fruit fly males belonging to a tribe Dacini of subfamily Dacinae (Diptera: Tepritidae). Of special interest are the mutualistic interactions between the Dacini fruit fly males and the tropical daciniphilous (attracting exclusively Dacini fruit flies) orchids – leading to cross pollination for the orchids and enchanced mating success for the flies. When offered to male flies, anisyl acetone and cue-lure are generally converted to raspberry ketone. Upon consumption, raspberry ketone and zingerone are individually sequestered in the male rectal (pheromonal) gland unchanged. Attracted male flies readily imbibe the phenylbutanoid(s) in the floral synomone to compliment the endogenously synthesized male sex pheromonal components – to enhance attraction of conspecific females during courtship as well as attract conspecific males to form ‘leks’. The phenylbutanoid(s) may also act as an allomone to deter vertebrate predators, especially geckos, besides possessing antimicrobial and antioxidant activities. Cue-lure, raspberry ketone and zingerone are important attractants/lures used in pest surveillance and mass trapping under the integrated pest management (IPM) program against quarantine Dacini fruit fly pest species, particularly Bactrocera tryoni and Zeugodacus cucurbitae.

Shamshir, Rabiatul Addawiyah; Wee, Suk-Ling

doi: 10.1007/s10886-024-01507-9pmid: 38722477

Zeugodacus cucurbitae and Z. tau are two major fruit fly pests of cucurbitaceous plants in the tropical and subtropical regions. The former species has a broader host range and wider world distribution than the latter. With global climate change, Z. tau shows great potential for geographical expansion with several invasion records in recent years. Males of both species are attracted to cue lure (CL) (and raspberry ketone (RK), a deacetyl derivative of CL), a common male lure used in fruit fly population detection, monitoring and control programs. Males of both species are also known to respond to zingerone (ZN), which are produced by some rainforest orchids. Previous studies have shown that fruit fly-male lure interactions are unique to species and lure types, and significantly impact the success of a lure-based fruit fly control program. We seek to compare the attraction of Z. cucurbitae and Z. tau males to CL, RK and ZN via Probit behavioral assays. Our results showed that CL is more attractive to Z. cucurbitae and Z. tau males than RK, while ZN is a poor lure for both species. Attraction Z. tau to CL is slightly lower than Z. cucurbitae, but the former is at least 1.71 times less attractive to RK than the latter. Together with published information on species’ sexual development, our current study indicates a lure-based control program via male annihilation technique for Z. tau will be more challenging than Z. cucurbitae and should incorporate other integrated pest management strategies for a desirable outcome.