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(2S,7S)-2,7-Nonanediyl dibutyrate is the sex pheromone of Sitodiplosis mosellana (Géhin). In this study, this sex pheromone and its three stereoisomers were prepared. Central to this strategy was the ring opening of chiral epoxide with an alkynyllithium and the hydrogenation of the triple bond. Moreover, this approach consisted of six steps, and the total yields were 59–64%. [ABSTRACT FROM AUTHOR]

Periplaneta cockroaches use periplanone analogs as female sex pheromones to attract males. We previously identified two periplanone receptor genes, PameOR1 and PameOR2, in the American cockroach Periplaneta americana. Here, we report the identification of PameOR1-like, an additional olfactory receptor resembling PameOR1 in P. americana. PameOR1-like showed high-level sequence similarity to PameOR1, and is preferentially expressed in the male antennae. Quantitative expression analysis revealed that, in the adult male antennae, the expression level of PameOR1 is 2.4-fold higher than that of PameOR1-like. Fluorescent in situ hybridization revealed that PameOR1 and PameOR1-like are co-expressed in the periplanone-A-responsive sensory neurons within the single walled-B sensilla on the male adult antennae. These data support the idea that PameOR1 and PameOR1-like are generated by a recent gene duplication event and play a redundant function in sex pheromone reception in P. americana. [ABSTRACT FROM AUTHOR]

Simple Summary: Tomato leaf miner Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) has emerged as a significant pest worldwide, necessitating effective pest management strategies. This study, conducted in Khyber Pakhtunkhwa, Pakistan, over two consecutive years (2020–2021), aimed to evaluate the efficacy of various pheromone-based traps and sticky pads in capturing male T. absoluta adults. The results demonstrated that Delta traps equipped with rubber septum pheromone lures were significantly more attractive, with mean captures of 76.0 and 86.17 adults in 2020 and 2021, compared to polymer wax (32.83 and 28.2) and polymer vial (10.37 and 11.77) lures. Additionally, among sticky traps without pheromone lures, black-colored pads proved most effective, capturing an average of 17.93 and 21.73 adults per year, while yellow pads were least effective, with captures of 1.33 and 1.47 adults. Significant differences were observed in both pheromone lure types and sticky pad colors. The findings suggest that Delta traps with rubber septum pheromones and black sticky pads offer a more effective approach for integrated management of T. absoluta. Tomato leaf miner Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) has gained the status of major pest globally. Integrated pest management (IPM) consists of different control methods. This field study was conducted to evaluate the influence of different pheromone-based traps to attract the male population and the potential of sticky pads of four different colors in capturing the adults in the absence of pheromone lures. The trials were conducted in Khyber Pakhtunkhwa (Pakistan) for two consecutive years, 2020 and 2021. The Delta trap with rubber septum type lure was significantly more attractive in both years, with mean number of capturing 76.0 and 86.17, as compared to polymer wax (32.83 and 28.2) and polymer vial (10.37 and 11.77), lures. The highest mean number of capturing of T. absoluta adults were noted as 17.93 and 21.73 with black color sticky trap without pheromone, whereas the lowest number of adults, i.e., 1.33 and 1.47, were captured during the first and second year of the study, respectively, with yellow color sticky traps. However, a significant difference was found in pheromone lures and among black, red, green, and yellow color sticky pads. Hence, Delta traps equipped with rubber septum pheromones lures and black colored sticky pads were more useful for the control of T. absoluta than any other colored sticky pads and pheromone lures alone. These findings could be helpful for the integrated management of T. absoluta. [ABSTRACT FROM AUTHOR]

Simple Summary: The role of pheromones in crane flies (family Tipulidae) has never been studied before. This family contains over 15,000 species, including two recognized as pests. Pheromones are an important tool for controlling insect behavior. Therefore, the aim of this study was to determine whether crane flies produce pheromones, and if so, to identify the chemical compounds involved. To achieve this, we selected a model species with features that would make pheromone detection easier. Tipula autumnalis was chosen because males have well-developed antennae, which are essential for detecting smells, and females are wingless, requiring them to attract males. Using advanced techniques, we identified nine key chemical compounds, all classified as cuticular hydrocarbons, which triggered a response in males. In behavioral tests, three compounds—n-pentacosane, (Z)-9-pentacosene, and (Z, E)-6,9-pentacosadiene—attracted males, suggesting that these are components of the female sex pheromone. Some evidence also suggests that a few of these compounds may play a role in male–male interactions. Chemical communication in T. autumnalis is therefore quite complex. The pheromones of crane flies (Tipulidae), one of the largest families within the order Diptera (over 15,000 species), are unknown. The aim of our study was to identify the chemical compounds involved in communication in Tipula autumnalis, a representative species of the family. Female cuticular washes were found to be attractive to males in a bioassay. GC-EAD analysis revealed nine EAG-active compounds, which were identified as cuticular hydrocarbons (CHCs). Both males and females contained these CHCs, though in different ratios. The strongest antennal responses in male T. autumnalis were evoked by n-pentacosane, (Z)-9-pentacosene, and (Z, E)-6,9-pentacosadiene, which were the predominant components in females. Each of these compounds were attractive to males in the behavioral assay and are therefore attributed to the female sex pheromone of T. autumnalis. (Z)-9-tricosene and (R)-3-methylheneicosane elicited both EAG and behavioral responses in males and were abundant in washes from same-sex individuals. In addition to the compounds involved in female–male interactions, it is evident that T. autumnalis also employs CHCs in male–male interactions. The exact roles of some compounds remain undetermined. Among the semiochemicals, the established stereostructure of (Z, E)-6,9-pentacosadiene and the olfactory/behavioral effects of (R)- and (S)-3-methylheneicosane were novel findings in insects. [ABSTRACT FROM AUTHOR]

Simple Summary: This study investigates the inhibitory effect of sex pheromone components of the plum fruit moth (PFM), Grapholita funebrana, loaded with different doses of (Z)-8-tetradecenyl acetate (Z8-14:Ac) or (Z)-10-tetradecenyl acetate (Z10-14:Ac) on the trapping of the closely related species, the male oriental fruit moth (OFM), G. molesta. Field tests showed that adding 5–30% of Z8-14:Ac to a mixture of Z8-12:Ac and E8-12:Ac did not significantly affect the trapping of PFM males but reduced OFM male trapping by more than 86%. In contrast, adding over 10% of Z10-14:Ac to a mixture of Z8-12:Ac and E8-12:Ac inhibited the trapping of both OFM and PFM males. GmolPBP2 from OFMs exhibited the strongest binding affinity for Z8-14:Ac compared to the other GmolPBP/GmolGOBP and was considered the most likely OBP for recognizing and transporting Z8-14:Ac. Mutating the Phe12 residue of GmolPBP2 to Ala12 resulted in a loss of affinity for Z8-14:Ac, suggesting that Phe12 was the key amino acid and that π–alkyl was the primary weak interaction maintaining the binding affinity for GmolPBP2. These findings enhance our understanding of the molecular mechanisms through which insects recognize the sex pheromones of closely related species and thereby contribute to the development of species-specific sex attractants for PFMs using secondary sex pheromones. The plum fruit moth (PFM), Grapholita funebrana, and the oriental fruit moth (OFM), G. molesta, are closely related fruit moth species that severely damage fruit trees in Rosaceae. Both species share common primary sex pheromone components Z8-12:Ac and E8-12:Ac. The secondary sex pheromone components of PFMs consist of Z8-12:OH, Z8-14:Ac, and Z10-14:Ac, while those of OFMs include Z8-12:OH and 12:OH. Previous researchers have proved that the inclusion of Z8-14:Ac and Z10-14:Ac did not augment PFM catches but inhibited OFM catches in orchards in Europe, thereby maintaining the species-specificity of the PFM sex attractant. However, which of these components, Z8-14:Ac or Z10-14:Ac, plays the major role in inhibiting OFM attraction remains unclear. In the current study, electroantennogram (EAG) assays indicated that both OFM and PFM males exhibited a moderate EAG response to Z8-14:Ac and Z10-14:Ac. Rubber septa loaded with varying ratios of Z8-14:Ac (1% to 30%) or Z10-14:Ac (5% to 110%) combined with a constant dose of Z8-12:Ac and E8-12:Ac produced diverse trapping effects. Sex attractants containing Z8-14:Ac did not significantly affect the trapping of PFM males but drastically reduced the capture of OFM males, with the reduction reaching up to 96.54%. Attractants containing more than 10% of Z10-14:Ac simultaneously reduced the number of OFM and PFM males captured. Z8-14:Ac was indispensable for maintaining the specificity of sex pheromones. Fluorescence competitive binding assays of recombinant GmolPBP2 showed the lowest Ki value (0.66 ± 0.02 μM) among the PBPs/GOBPs from OFMs, suggesting that it is the most likely target for Z8-14:Ac. Molecular dynamic simulation and site-directed mutagenesis assays confirmed that the Phe12 residue, which forms a π–alkyl interaction with Z8-14:Ac, was crucial for GmolPBP2 binding to Z8-14:Ac. In conclusion, Z8-14:Ac is vital to the specificity of PFM sex pheromones inhibiting OFM attractants when added to Z8-12:Ac and E8-12:Ac. This could be potentially used to develop species-specific sex attractants for the PFM. [ABSTRACT FROM AUTHOR]

The pine caterpillar, Dendrolimus punctatus (Walker), is a notorious forest pest. An efficient and convenient synthesis of the sex pheromones of this pest has been achieved. In our synthetic approach, a Wittig coupling of an aldehyde with an ester-bearing phosphonium salt was used to construct the Z-alkene, whereas the E-alkene was prepared via a stereoselective reduction of an alkyne with LiAlH4. The synthetic sex pheromones would be useful for integrated pest management of the pine caterpillar.

Sexual dimorphism is a crucial aspect of mating and reproduction in many animals, yet the molecular mechanisms remain unclear. In Bactrocera dorsalis, sex pheromones trimethylpyrazine (TMP) and tetramethylpyrazine (TTMP) are specifically synthesized by Bacillus strains in the male rectum. In the female rectum, Bacillus strains are found, but TMP and TTMP are not, indicating sexually dimorphic differences in sex pheromone synthesis. Our anatomical observations and precursor measurements revealed significant differences in rectal structure and ammonium levels between sexes. In vitro and in vivo experiments reveal that ammonium is vital for sex pheromone synthesis in rectal Bacillus strains. Comparative transcriptome analysis identified ammonium‐producing genes (carboxypeptidase B and peptide transporter) in the protein digestion pathway that show much higher expression in the male rectum than in the female rectum. Knocking down the expression of either carboxypeptidase B (or inhibiting enzyme activity) or peptide transporter decreases rectal ammonium levels significantly, resulting in the failure of sex pheromone synthesis in the male rectum. This study provides insights into the presence of sexual dimorphism in internal organs and their functionalities in male‐specific sex pheromone synthesis and has significant implications for understanding the molecular mechanisms underlying sex pheromone synthesis by symbionts in insects. [ABSTRACT FROM AUTHOR]

Simple Summary: The navel orangeworm is an important pest of high-value crops including almonds, pistachios, and walnuts. Monitoring and mating disruption are important tools for control of this moth, and improved understanding of its response to pheromone composition and concentration has the potential to improve monitoring and mating disruption. Experiments with high-release rate passive diffusion pheromone dispensers revealed that capture of males in pheromone traps was suppressed more successfully at an intermediate rate of dispensers per acre when a second pheromone component was included. Traps baited with part or all of the single compound dispensers as bait were minimally attractive in the absence of mating disruption, thereby confirming earlier research on the mechanism of mating disruption for navel orangeworm. Traps baited with the two-compound dispensers captured similar numbers of navel orangeworm in either the presence or absence of mating disruption, indicating that this dispenser could also be used to improve monitoring. This study provides scientists and extension personnel with further insight into the mechanism of the current widely used mating disruption products for navel orangeworm and indicates that the two-compound dispensers could provide improvements in monitoring for navel orangeworm compared with the presently-used products. Mating disruption is used to manage Amyelois transitella (Walker) (Lepidoptera: Pyralidae). Current mating disruption uses a single compound, but at least one other is necessary for source contact in laboratory assays and efficient capture in traps in the field. We conducted experiments to examine disruption of sexual communication and attraction of males to these high-rate dispensers with either one or both compounds. Trap suppression experiments compared males captured in pheromone traps in orchard blocks treated at a low, medium, or high number of dispensers per ha, and a trapping study used the dispensers as attractants in sticky traps to compare their relative attractiveness. The 2-compound dispensers suppressed male capture in pheromone traps more effectively than the 1-compound dispensers at the intermediate density. The trapping study found that both dispensers captured fewer males than a monitoring lure in the absence of mating disruption but more males in the presence of mating disruption. These data provide additional support for a hybrid mechanism of mating disruption for this species and indicate that the use of the more attractive 2-compound dispensers could make mating disruption more effective at the lowest dispenser density currently used. Alternatively, a lure base on the 2-compound dispenser could provide equally effective monitoring in the presence of mating disruption. [ABSTRACT FROM AUTHOR]

Simple Summary: The number of invasive pests has increased worldwide, mainly due to international trade. This problem is further exacerbated by climate change and the continued restrictions on the quantity and number of pesticides imposed by international authorities. Delottococcus aberiae, a mealybug native to South Africa, was first detected in Europe in 2009, specifically in the Valencia Community (Spain). The identification of its sex pheromone allowed the development of a monitoring network for this pest a decade later. This network facilitated the mapping of the affected citrus area and its subsequent expansion over time. The monitoring network has revealed that from 2019 until 2023, the citrus area affected by the pest has considerably increased. This network, in conjunction with fruit damage assessments conducted at the end of the crop cycle, has also allowed us to know that the damage to the fruit is independent of the maximum annual population level of the pest. The male catches obtained during the months of March to June, when fruit setting occurs, seem to be related to economic losses due to fruit damage. The invasive mealybug Delottococcus aberiae De Lotto (Hemiptera: Pseudococcidae) has rapidly spread in the Mediterranean basin since its detection in 2009 in the Valencia Community in eastern Spain. The use of sticky traps baited with its sex pheromone, (4,5,5-trimethyl-3-methylenecyclopent-1-en-1-yl)methyl acetate, has allowed to determine the geographical distribution of D. aberiae by means of the surveillance network described in the present work. The population monitoring of the pest over a five-year period (2019–2023) has revealed an increase from 31% to 70% of the affected citrus-growing area. The monitoring network has also allowed a better understanding of the pests' biological cycle throughout the year. The populations start growing from March to June and reach their maximum in July–August. During autumn, there is a gradual decline in the population. Although the highest annual populations were detected in 2022 and 2023, the greatest crop losses were recorded in 2020 and 2021, with mean values near 18%. Data suggest that the damage responsible for fruit deformation, and thus the economic losses, are related to the population levels in spring (April–May) rather than those in summer (July–August). The findings of this study can be valuable for future research and development of effective pest control strategies. [ABSTRACT FROM AUTHOR]

Simple Summary: The rice leaf-roller Cnaphalocrocis medinalis is a migratory pest of rice. Monitoring its population is important in integrated pest management systems. Trapping them with a sex pheromone or plant odor has been used in population monitoring. We studied the physiological status of adults trapped by sex pheromones and floral odors. In the immigrant group, the number of males caught in the floral trap was greater than those caught by the sex pheromone trap. The volumes of testes in adults caught using the above two trapping methods were similar. In the local breeding group, the number of males caught by sex pheromone trapping was greater than that by floral trapping. The volume of testes was smaller in males caught in the floral odor trap compared to the pheromone trap. In the emigrant group, the adult olfactory response to the sex pheromone and floral odor was low. The number of eggs laid by the females in the local breeding group was greater in those caught in the sweep net in comparison with those caught in the floral odor trap. The rice leaf-roller Cnaphalocrocis medinalis is an important migratory pest of rice. We conducted a study to determine the physiological status of adults trapped by a sex pheromone and floral odor. In the immigrant group, the number of males trapped by the floral odor was greater than the number caught by sex pheromone trapping. The volume of testes was similar in the above two trapping methods but was smaller than in the sweep net method. The ovary developmental grade, mating rate, and number of matings of females caught in floral odor trap were higher than in those caught in the sweep net. In the local breeding group, the number of males trapped by sex pheromones was greater than the number trapped by the floral odor. The volume of testes was smaller in the floral odor trap compared to the pheromone trap group, with the largest in the sweep net group. The ovarian developmental grade, mating rate, and number of matings of females were significantly higher in the floral odor trap group than in the sweep net group. In the emigrant group, the adult olfactory response to the sex pheromone and floral odor was low. The volume of testes was larger in the sweep net group compared to the moths caught by floral odor trapping. The number of eggs laid by female immigrants trapped by the floral odor and sweep net was similar, while the number in the local breeding group was greater in moths caught with the sweep net in comparison with those caught by the floral odor trap. The difference in egg hatchability between the two trapping methods in both immigrants and local breedings was not significant. [ABSTRACT FROM AUTHOR]

The Indian meal moth, Plodia interpunctella, poses a significant threat to global agricultural products. Although pheromone-based technologies show promise for P. interpunctella management, limitations such as single-sex targeting necessitate exploring complementary strategies. Vegetable-based oils represent a potential alternative but their efficacy, sex-specificity, and interaction with sex pheromones remain unclear. To address these questions, we first examined the attraction of P. interpunctella female and male adults to 10 commercially available vegetable oils in semi-field conditions. Sesame, olive, and blended oils were the most attractive, capturing significantly more adults compared to other oils. We then evaluated the effectiveness of these three attractive oils and their combinations with P. interpunctella sex pheromones in a grain warehouse. Traps baited with these oils captured significantly more females and males compared to control traps without attractants; however, the addition of sex pheromones did not improve male capture and significantly reduced female capture, suggesting an inhibitory effect. Finally, we demonstrated that female mating status (mated vs. virgin) did not influence the attractiveness of traps baited with these effective oils. Our findings highlight the potential of standalone traps baited with blended, olive, or sesame oil as a practical, economic, and effective management strategy for P. interpunctella in storage facilities. [ABSTRACT FROM AUTHOR]

Conogethes punctiferalis is a crop and fruit pest that has caused serious economic losses to agricultural production. This pest relies heavily on its sex pheromone to ensure sexual encounters and subsequent mating success. However, the molecular mechanism underlying sex pheromone biosynthesis in this species remains elusive. The present study investigated the detailed mechanism underlying PBAN-regulated sex pheromone biosynthesis in C. punctiferalis by transcriptome sequencing of the C. punctiferalis pheromone glands (PGs) and subsequent functional identification of the target genes. The results showed that female mating started from the first scotophase, and peaked at the second to fifth scotophases in accordance with the release of sex pheromones. PBAN regulated sex pheromone biosynthesis by employing Ca2+ and cAMP as secondary messengers, as demonstrated by RNA interference (RNAi), pharmacological inhibitors, and behavioral assays. Further investigation revealed that calcineurin (CaN) and acetyl-CoA carboxylase (ACC) were activated by PBAN/Ca2+ signaling, and the RNAi-mediated knockdown of CaN and ACC transcripts significantly reduced sex pheromone production, ultimately leading to a significantly reduced ability of females to attract males. Importantly, hexokinase (HK) was found to regulate sex pheromone biosynthesis in response to the PBAN/cAMP/PKA signaling pathway, as demonstrated by RNAi, enzyme activity, and pharmacological inhibitor assays. Furthermore, Far2 and Desaturase1 were found to participate in PBAN-regulated sex pheromone biosynthesis. Altogether, our findings revealed that PBAN regulates sex pheromone biosynthesis through the PBANR/Ca2+/CaN/ACC and PBANR/cAMP/PKA/HK pathways in C. punctiferalis, which enriches our comprehension of the details of sex pheromone biosynthesis in moths.

Firefly flashes are well-known visual signals used by these insects to find, identify, and choose mates. However, many firefly species have lost the ability to produce light as adults. These "unlighted" species generally lack developed adult light organs, are diurnal rather than nocturnal, and are believed to use volatile pheromones acting over a distance to locate mates. While cuticular hydrocarbons, which may function in mate recognition at close range, have been examined for a handful of the over 2000 extant firefly species, no volatile pheromone has ever been identified. In this study, using coupled gas chromatography - electroantennographic detection, we detected a single female-emitted compound that elicited antennal responses from wild-caught male winter fireflies, Photinus corruscus. The compound was identified as (1S)-exo-3-hydroxycamphor (hydroxycamphor). In field trials at two sites across the species' eastern North American range, large numbers of male P. corruscus were attracted to synthesized hydroxycamphor, verifying its function as a volatile sex attractant pheromone. Males spent more time in contact with lures treated with synthesized hydroxycamphor than those treated with solvent only in laboratory two-choice assays. Further, using single sensillum recordings, we characterized a pheromone-sensitive odorant receptor neuron in a specific olfactory sensillum on male P. corruscus antennae and demonstrated its sensitivity to hydroxycamphor. Thus, this study has identified the first volatile pheromone and its corresponding sensory neuron for any firefly species, and provides a tool for monitoring P. corruscus populations for conservation and further inquiry into the chemical and cellular bases for sexual communication among fireflies.

The tea tussock moth is a pest that damages tea leaves, affecting the quality and yield of tea and causing huge economic losses. The efficient asymmetric total synthesis of the sex pheromone of the tea tussock moth was achieved using commercially available starting materials with a 25% overall yield in 11 steps. Moreover, the chiral moiety was introduced by Evans' template and the key C-C bond construction was accomplished through Julia–Kocienski olefination coupling. The synthetic sex pheromone of the tea tussock moth will facilitate the subsequent assessment and implementation of pheromones as environmentally friendly tools for pest management. [ABSTRACT FROM AUTHOR]

Sex pheromones play a crucial role in mate location and reproductive success. Insects face challenges in finding mates in low-density environments. The population dynamics of locusts vary greatly, ranging from solitary individuals to high-density swarms, leading to multiple-trait divergence between solitary and gregarious phases. However, differences in sexual communication between solitary and gregarious locusts have not been sufficiently explored. Herein, we found that solitary locusts but not gregarious ones heavily rely on a single compound, dibutyl phthalate (DBP), for sexual communication. DBP is abundantly released by solitary female locusts and elicits strong attraction of male solitary and gregarious locusts. Solitary adult males display much higher electrophysiological responses to DBP than adult females. Additionally, LmigOr13 was identified as the DBP-specific odorant receptor expressed in neurons housed in basiconic sensilla. Male LmigOr13-/- mutants generated by CRISPR/Cas9 have low electrophysiological responses and behavioral attraction to DBP in both laboratory and field cage experiments. Notably, the attractiveness of DBP to male locusts becomes more evident at lower population densities imposed by controlling the cage size. This finding sheds light on the utilization of a sex pheromone to promote reproductive success in extremely low-density conditions and provides important insights into alternative approaches for population monitoring of locusts. [ABSTRACT FROM AUTHOR]

Volatile sex pheromones are vital for sexual communication between males and females. Females of the American cockroach, Periplaneta americana, produce and emit two sex pheromone components, periplanone-A (PA) and periplanone-B (PB). Although PB is the major sex attractant and can attract males, how it interacts with PA in regulating sexual behaviors is still unknown. In this study, we found that in male cockroaches, PA counteracted PB attraction. We identified two odorant receptors (ORs), OR53 and OR100, as PB/PA and PA receptors, respectively. OR53 and OR100 were predominantly expressed in the antennae of sexually mature males, and their expression levels were regulated by the sex differentiation pathway and nutrition-responsive signals. Cellular localization of OR53 and OR100 in male antennae further revealed that two types of sensilla coordinate a complex two-pheromone-two-receptor pathway in regulating cockroach sexual behaviors. These findings indicate distinct functions of the two sex pheromone components, identify their receptors and possible regulatory mechanisms underlying the male-specific and age-dependent sexual behaviors, and can guide novel strategies for pest management. [ABSTRACT FROM AUTHOR]

The Lichen moth, Lyclene dharma dharma (Arctiidae, Lithosiinae), plays a significant role in forest ecosystem dynamics. A concise and novel method to synthesize the active sex pheromone components, (S)-14-methyloctadecan-2-one ((S)-1), (S)-6-methyloctadecan-2-one ((S)-2), and their enantiomers has been developed. Key steps in the synthesis include the use of Evans' chiral auxiliaries, Grignard cross-coupling reactions, hydroboration–oxidation, and Wacker oxidation. The synthesized sex pheromone components hold potential value for studies on communication mechanisms, species identification, and ecological management. [ABSTRACT FROM AUTHOR]

Simple Summary: Mass outbreaks of the pine sawfly Diprion pini can cause severe damage to pine forests. The larvae of this herbivorous insect feed selectively on the needles of pine trees, notably Pinus sylvestris. During mass outbreak periods, the females release large amounts of sex pheromones. A prior study revealed that the survival rate of sawfly eggs laid on pheromone-exposed pine needles was lower than that of eggs on unexposed pine. In our study, we found that D. pini females avoided oviposition on pheromone-exposed pine, possibly as a counter-adaptation to the enhanced defenses of previously pheromone-exposed trees against sawfly eggs. The females only discriminated between pheromone-exposed and unexposed trees when they had the chance to touch the needles, but not when exposed to the odor of these types of trees. However, the performance of larvae did not significantly differ on pheromone-exposed and unexposed trees. These results underscore the complexity of the chemical ecology of sawfly–pine interactions and highlight the nuanced roles that pheromones play in shaping the relationships between herbivores and their host plants. Insect pheromones have been intensively studied with respect to their role in insect communication. However, scarce knowledge is available on the impact of pheromones on plant responses, and how these in turn affect herbivorous insects. A previous study showed that exposure of pine (Pinus sylvestris) to the sex pheromones of the pine sawfly Diprion pini results in enhanced defenses against the eggs of this sawfly; the egg survival rate on pheromone-exposed pine needles was lower than that on unexposed pine. The long-lasting common evolutionary history of D. pini and P. sylvestris suggests that D. pini has developed counter-adaptations to these pine responses. Here, we investigated by behavioral assays how D. pini copes with the defenses of pheromone-exposed pine. The sawfly females did not discriminate between the odor of pheromone-exposed and unexposed pine. However, when they had the chance to contact the trees, more unexposed than pheromone-exposed trees received eggs. The exposure of pine to the pheromones did not affect the performance of larvae and their pupation success. Our findings indicate that the effects that responses of pine to D. pini sex pheromones exert on the sawfly eggs and sawfly oviposition behavior do not extend to effects on the larvae. [ABSTRACT FROM AUTHOR]

A concise synthesis of the sex pheromones of elm spanworm as well as painted apple moth has been achieved. The key steps were the alkylation of acetylide ion, Sharpless asymmetric epoxidation and Brown's P2-Ni reduction. This approach provided the sex pheromone of the elm spanworm (1) in 31% total yield and those of the painted apple moth (2, 3) in 26% and 32% total yields. The ee values of three final products were up to 99%. The synthesized pheromones hold promising potential for use in the management and control of these pests. [ABSTRACT FROM AUTHOR]

The paulownia bagworm, Clania variegata Snell, is an economically important pest of agriculture and forests. The sex pheromone of this pest and its stereoisomers were synthesized, and two of the stereoisomers were prepared for the first time. Our strategy was efficient and mainly included the ring-opening reaction of (S)-2-methyloxirane, the coupling of chiral sulfonate, the oxidative cleavage of olefin, and Yamaguchi esterification. Moreover, the overall yields of our synthesis were 23–29%, with eight steps in the longest route. [ABSTRACT FROM AUTHOR]

Bactrocera tryoni (Froggatt) and Bactrocera neohumeralis (Hardy) are sibling fruit fly species that are sympatric over much of their ranges. Premating isolation of these close relatives is thought to be maintained in part by allochrony—mating activity in B. tryoni peaks at dusk, whereas in B. neohumeralis , it peaks earlier in the day. To ascertain whether differences in pheromone composition may also contribute to premating isolation between them, this study used solid-phase microextraction and gas chromatography-mass spectrometry to characterize the rectal gland volatiles of a recently collected and a more domesticated strain of each species. These glands are typical production sites and reservoirs of pheromones in bactrocerans. A total of 120 peaks were detected and 50 were identified. Differences were found in the composition of the rectal gland emissions between the sexes, species, and recently collected versus domesticated strains of each species. The compositional variation included several presence/absence and many quantitative differences. Species and strain differences in males included several relatively small alcohols, esters, and aliphatic amides. Species and strain differences in females also included some of the amides but additionally involved many fatty acid esters and 3 spiroacetals. While the strain differences indicate there is also heritable variation in rectal gland emissions within each species, the species differences imply that compositional differences in pheromones emitted from rectal glands could contribute to the premating isolation between B. tryoni and B. neohumeralis. The changes during domestication could also have significant implications for the efficacy of Sterile Insect Technique control programs. [ABSTRACT FROM AUTHOR]

Simple Summary: The tea geometrid (Ectropis obliqua (Prout)) is a major defoliator of tea plants and seriously affects the tea quality and yield in China. The females release three Type-II sex pheromone components for mate communication, but knowledge about the biosynthesis of these compounds is still limited. In this study, we screened for the candidate genes in the sex pheromone biosynthetic pathway with a combination of comparative RNAseq, phylogenetic relationship, and tissue expression pattern analyses. A total of seven tentative biosynthetic enzymes were identified, including two ELOs (ELO3 and ELO5), two FARs (FAR2 and FAR9), one DEC (CYP4G173), one LIP (LIP1), and one epoxidase (CYP340BD1). Overall, our results provide a foundation for further functional elucidation of the vital genes involved in E. obliqua sex pheromone biosynthesis. Ectropis obliqua, a notorious tea pest, produces a Type-II sex pheromone blend for mate communication. This blend contains (Z,Z,Z)-3,6,9-octadecatriene, (Z,Z)-3,9-cis-6,7-epoxy-octadecadiene, and (Z,Z)-3,9-cis-6,7-epoxy-nonadecadiene. To elucidate the genes related to the biosynthesis of these sex pheromone components, transcriptome sequencing of the female E. obliqua pheromone gland and the abdomen without pheromone gland was performed. Comparative RNAseq analyses identified 52 putative genes, including 7 fatty acyl-CoA elongases (ELOs), 9 fatty acyl-CoA reductases (FARs), 1 decarbonylase (DEC), 3 lipophorins (LIPs), and 32 cytochrome P450 enzymes (CYPs). Tissue expression profiles revealed that two ELOs (ELO3 and ELO5), two FARs (FAR2 and FAR9), one DEC (CYP4G173), and one LIP (LIP1) displayed either abdomen-centric or -specific expression, suggesting potential roles in sex pheromone biosynthesis within the oenocytes of E. obliqua. Furthermore, the tissue expression patterns, combined with phylogenetic analysis, showed that CYP340BD1, which was expressed specifically and predominantly only in the pheromone gland, was clustered with the previously reported epoxidases, highlighting its potential role in the epoxidation of the unsaturated polytriene sex pheromone components. Collectively, our research provides valuable insights into the genes linked to sex pheromone biosynthesis. [ABSTRACT FROM AUTHOR]

The Indian meal moth, Plodia interpunctella, poses a significant threat to global agricultural products. Although pheromone-based technologies show promise for P. interpunctella management, limitations such as single-sex targeting necessitate exploring complementary strategies. Vegetable-based oils represent a potential alternative but their efficacy, sex-specificity, and interaction with sex pheromones remain unclear. To address these questions, we first examined the attraction of P. interpunctella female and male adults to 10 commercially available vegetable oils in semi-field conditions. Sesame, olive, and blended oils were the most attractive, capturing significantly more adults compared to other oils. We then evaluated the effectiveness of these three attractive oils and their combinations with P. interpunctella sex pheromones in a grain warehouse. Traps baited with these oils captured significantly more females and males compared to control traps without attractants; however, the addition of sex pheromones did not improve male capture and significantly reduced female capture, suggesting an inhibitory effect. Finally, we demonstrated that female mating status (mated vs. virgin) did not influence the attractiveness of traps baited with these effective oils. Our findings highlight the potential of standalone traps baited with blended, olive, or sesame oil as a practical, economic, and effective management strategy for P. interpunctella in storage facilities.

The mealybug, Planococcus ficus (Signoret), is a primary vineyard pest in California and other grape-growing regions throughout the World. Mating disruption programs are commercially available to manage Pl. ficus, but widespread adoption has been limited, in part, by high costs compared with insecticide programs. To improve mating disruption economic effectiveness, different deployment technologies (passive, aerosol, and microencapsulated formulations) were individually examined. Adult male Pl. ficus captures in pheromone traps and categorical ratings of vine infestation or crop damage suggest that all deployment strategies lowered mealybug densities or damage. Using passive dispensers, deployment rates of 310 and 465 per ha lowered Pl. ficus crop damage similar to 615 per ha, a rate commonly used in commercial operations; reduced rates would lower product and deployment costs. Meso dispensers, containing more a.i., deployed at 35 per ha did not have a treatment impact, but a microencapsulated formulation and aerosol canisters lowered male flight captures and/or crop damage. Male mealybug flight activity was greatest from 0500-1100 hr, which coincided with temperatures >16° and

The vine mealybug, Planococcus ficus, is a significant pest of vineyards in all major grape growing regions of the world. This pest causes significant aesthetic damage to berry clusters through its feeding behavior and secretion of ''honeydew'', which leads to significant decreases in crop marketability. More importantly, the vine mealybug is a vector of several grapevine viruses which are the causal agent of grapevine leafroll disease, one of the most destructive and economically devastating diseases of the grape industry worldwide. As there is no cure for grapevine leafroll disease, the only control measures available to reduce its spread are to remove infected vines whilst simultaneously controlling mealybug populations. Using transcriptomic libraries prepared from male and female mealybugs and a draft genome, we identified and evaluated expression levels of members of the odorant receptor gene family. Interestingly, of the 50 odorant receptors identified from these P. ficus genetic resources, only 23 were found to be expressed in females, suggesting this flightless life stage has a decreased reliance on the olfactory system. In contrast, 46 odorant receptors were found to be expressed in the alate male life stage. Heterologous expression of eight of these receptors, along with the obligate co-receptor, Orco, in HEK293 cells allowed for the identification of two receptors that respond to lavandulyl senecioate, the sole constituent of the sex pheromone used by this species. Interestingly, one of these receptors, PficOR8, also responded to the sex pheromone used by the Japanese mealybug, Planococcus kraunhiae. The data presented here represent the first report of odorant receptor gene family expression levels, as well as the identification of the first sex pheromone receptor, in soft-scale insects. The identification of a receptor for the vine mealybug sex pheromone will allow for the development of novel, species-specific pest control tools and monitoring devices.

Identifying the sex pheromone systems of local pest populations facilitates their management, especially for moth species that show significant geographic variation in sex pheromone communication. We investigated the pheromone production and behavioral responses of the Asian corn borer (Ostrinia furnacalis Guenée; ACB) in Xinjiang, China. The ACB produces three compounds: (Z)-12-tetradecenyl acetate (Z12-14:Ac) and (E)-12-tetradecenyl acetate (E12-14:Ac) which are two sex pheromone compounds, and n-tetradecyl acetate (14:Ac) which has variable roles in mediating behavioral responses. The ratios of these three compounds produced in female gland are geographically distinct among different populations. Quantitative analysis of pheromone production showed that the proportions of Z12-14:Ac in the E/Z isomers (i.e., Z and E12-14:Ac) and the proportions of 14:Ac in the ternary blend respectively averaged 60.46% (SD=5.26) and 25.00% (SD=7.37), with their probabilities normally or near-normally distributed. Trapping experiments in a cornfield indicated that deploying the E/Z isomers and the three compounds in rubber septa close to their gland ratios yielded the most captured males, while other ratios that deviated from the gland ratios showed reduced field captures. The ternary blend was significantly more attractive to males than the E/Z isomers in the field, indicating a functional role of 14:Ac as the third pheromone component used by the local population. Additionally, the dose-response test demonstrated that the application of the three compounds at dosages between 200 and 350 μg attracted significantly more males compared to other dosages. Therefore, the characterization of this local ACB pheromone system provides additional information about its geographic variation and serves as a basis for optimizing the pheromone-mediated control of this pest in Xinjiang.

Introduction: The parasitoid wasp Microplitis mediator is an important natural enemy of the turnip moth Agrotis segetum and other Noctuidae pests. In our field observation, it was fortuitously discovered that sex pheromone traps used for A. segetum also attract female wasps, verified by a simulated field condition dual-choice laboratory assay. Therefore, it was hypothesized that olfactory recognition could be crucial in this process. In this regard, a female-biased odorant receptor of the wasp, MmedOR49, attracted our attention. Objectives: To unravel the significance of the female-biased MmedOR49 regulating host pheromone recognition. Methods: Expression analysis (fluorescence in situ hybridization; quantitative realtime PCR), in vitro (two-electrode voltage-clamp recordings) and in vivo (RNAi combined with behavioral assessments) functional studies, and bioinformatics (structural modeling and molecular docking) were carried out to investigate the characteristics of MmedOR49. Results: MmedOR49 expression was detected in the antennae of females by FISH. Quantification indicated that the expression level of MmedOR49 increased significantly after adult emergence. In vitro functional study revealed that MmedOR49 was specifically tuned to cis-5-decenyl acetate (Z5-10:Ac), the major sex pheromone component of A. segetum. Molecular docking showed that Z5-10:Ac strongly bound to the key amino acid residues His 80, Ile 81, and Arg 84 of MmedOR49 through hydrogen bonding. Behavioral assays indicated that female wasps were significantly attracted by Z5-10:Ac in a three-cage olfactometer. RNAi targeting further confirmed that MmedOR49 was necessary to recognize Z5-10:Ac, as female wasps lost their original behavioral responses to Z5-10:Ac after down-regulation of the MmedOR49 transcript. Conclusion: Although M. mediator is a larval endoparasitoid, female wasps have a behavioral preference for a sex pheromone component of lepidopteran hosts. In this behavior, for female M. mediator, MmedOR49 plays an important role in guiding the habitat of host insects. These data provide a potential target for enhancing natural enemy utilization and pest control.

The tea tussock moth (Euproctis pseudoconspersa) is one of the most destructive chewing pests in tea plantations and causes a serious allergic reaction on the skin of tea plantation workers. The sex pheromone components of its Japanese population were first identified as 10,14-dimethylpentadecyl isobutyrate (10Me14Me-15:iBu) and 14-methylpentadecyl isobutyrate (14Me-15:iBu), with a stereogenic center. Only 10Me14Me-15:iBu has been identified in the Chinese E. pseudoconspersa population. However, field tests have shown that 10Me14Me-15:iBu cannot meet the demand of effective pest control in China. To develop a high-efficiency E. pseudoconspersa sex pheromone formula, electroantennogram (EAG) recordings of (S)- and (R)-enantiomers of 10Me14Me-15:iBu and 14Me-15:iBu were obtained in the present study. The results demonstrated that the EAG responses of male antennae to (R)-enantiomers were significantly higher than responses to the (S)-enantiomers, and 14Me-15:iBu also elicited EAG activity. Field tests showed that the catch numbers of male moths by (R)-enantiomers were significantly higher (P

Background. Diamondback moth (Plutella xylostella L.) has now acquired the status of the most dangerous pest of plants from the Brassicaceae family in the world, including Russia. In order to identify genotypes resistant to the pest, cabbage accessions from the VIR global collection were assessed in the field according to plant infestation and damage by diamondback moth in the vicinity of St. Petersburg.Materials and methods. The infestation of plants by diamondback moth was assessed on model accessions when examining all plants in the plot by (1) the number of larvae and pupae, and (2) leaf damage, assessed using a standard scoring scale. The number of adults was monitored using sticky Delta traps of two designs: (1) cardboard traps equipped with commercial dispensers with synthetic sex pheromone, and (2) plastic LED traps designed at VIZR.Results. The results of field surveys attested to very high variation among cabbage accessions in the rates of infestation and damage to plants caused by diamondback moth. The data on the abundance of adults caught by pheromone traps correlated well with the estimates of larval and pupal density of the pest on plants. The capture rate of diamondback moths with LED traps varied greatly during the season. In June/early July, i.e., during the period of the so called “white” nights, LED traps caught diamondback moths much worse than pheromone ones, but during the second half of July and August their capture rate significantly exceeded that of pheromone traps. As a result, the relationship between numbers of diamondback moth larvae on plants and adults in LED traps turned out to be negative. Conclusion. The resulting materials indicate obvious prospects of studying the VIR global collection in order to identify sources of host plant resistance to diamondback moth. The abundance of this pest in northern regions of its spreading is recommended to be controlled with pheromone traps.

The study of insect reproduction is important from both basic and applied perspectives, particularly in mealybugs (Hemiptera: Pseudococcidae), because of the diversity of reproduction modes and also because they are important agricultural pests. Sex pheromone control strategies are currently being developed for many species. Pseudococcus calceolariae (Maskell) and Pseudococcus longispinus (Targioni Tozzetti) are closely related species that often coexist in the same host plant. In this study, mating behavior, the possible occurrence of asexual reproduction, and hybridization between them were investigated. We confirmed that both species did not show asexual reproduction and required the presence of a male to reproduce. When couples of the same species were put together, males had a highly stereotyped mating behavior, and females showed an active role in mating success by accepting or rejecting males with abdominal movements. In hybridization trials, no progeny was obtained for any of the interspecific combinations. Moreover, in interspecific pairs, males mainly moved randomly in the arena without direct contact with females and females showed no willingness to mate, escape, or not move in the presence of the male. Therefore, courtship and copulation success in both species were directly related to the specificity of the mating pair and, there was no evidence of hybridization. This information is useful for the understanding of reproduction in this family and supports the development of management techniques based on sex pheromones to disrupt reproduction or to monitor these mealybug species populations. [ABSTRACT FROM AUTHOR]

The pine sawfly Diprion jingyuanensis Xiao and Zhang (Hymenoptera: Diprionidae) is a serious pest of Pinus tabulaeformis Carr. in the Shanxi, Gansu, and Inner Mongolia provinces in P. R. China. The sex pheromone of D. jingyuanensis was shown to be the propionate ester of 3,7-dimethyl-2-tridecanol. Virgin females contained an approximate 1:3 blend of the pheromone precursors erythro-(2S,3S,7R/S and 2R,3R,7R/S)-3,7-dimethyl-2-tridecanol and threo-(2S,3R,7R/S and 2R,3S,7R/S)-3,7-dimethyl-2-tridecanol, but the exact stereoisomers were not determined. Males responded the strongest to the propionate ester of the two threo-isomers, (2S,3R,7R) and (2S,3R,7S), in electroantennogram (EAG) recordings, followed by a significant EAG response to the (2S,3R,7R) propionate of diprionol (pheromone component of D. similis), whereas the remaining two isomers (2S,3S,7S and 2S,3S,7R) of the propionate ester of 3,7-dimethyl-2-tridecanol and the acetate of the (2S,3R,7R) isomer (one of the two pheromone components of D. pini) did not elicit any significant increase in antennal response. In the field, the strongly EAG-active (2S,3R,7R)-isomer alone was only weakly (but significantly) attractive to D. jingyuanensis males at 100 µg, while the equally EAG- active (2S,3R,7S)-isomer alone at the same loading was 8–14 times more attractive than was the (2S,3R,7R)-isomer alone. Traps baited with the same amounts of the two threo-isomers ((2S,3R,7R) and (2S,3R,7S), 100 µg + 100 µg) caught significantly more males than did traps baited with other isomers, either of the two isomers alone or other proportions of the two isomers. Thus, the (2S,3R,7S)-isomer is considered as a strong and essential sex-attractant component for D. jingyuanensis males, whereas the (2S,3R,7R)-isomer is a weak but synergistic sex-attractant. This is one of the few examples of a pine sawfly responding significantly stronger to a binary blend of stereoisomers in a synergistic fashion than to a single stereoisomer alone. [ABSTRACT FROM AUTHOR]

As a typical solitary animal, adult giant pandas rely on chemical signals (sex pheromones) to transmit reproductive information during oestrous. Although researchers have confirmed that the gut microbiota is related to the emission and reception of sex pheromones, there is no clear correlation between the gut microbes and the synthesis of sex pheromone of giant pandas, that is, which gut microbes and microbial metabolites are participate in the synthesis of giant panda’s sex pheromone. As a mirror of gut microbiota, fecal microbiota can reflect the composition of gut microbiota and its interaction with host to some extent. The purpose of this study is to explore how the gut microbes affect the synthesis of sex pheromones in captive giant pandas by combining analysis of the fecal microbiome and metabolomics. The results of correlation and microbial function analysis show that intestinal microorganisms such as Veillonellaceae and Lactobacillilaceae are associated with the synthesis of short chain fatty acid (acetic acid) and volatile ester metabolites, such as 1-butanol, 3-methyl, acetate, acetic acid, hexyl ester and 3-hexen-1-ol, acetate, (Z). In summary, based on this study, we believe that volatile metabolites such as fecal acetate participate in the process of mate preference of captive giant pandas and affect their expression of natural mating behavior. The possible mechanism is that the gut microbes can promote the synthesis of key chemical signaling substances in perianal glands through mediated intermediate fecal metabolites, thus affecting the normal information exchange between giant pandas individuals. The results of this study have greatly enriched our understanding of gut microbes regulating the synthesis of sex pheromones in giant pandas.

Insect sex pheromones are volatile chemicals that induce mating behavior between conspecific individuals. In moths, sex pheromone biosynthesis is initiated when pheromone biosynthesis-activating neuropeptide (PBAN) synthesized in the suboesophageal ganglion binds to its receptor on the epithelial cell membrane of the pheromone gland. To investigate the function of PBAN receptor (PBANR), we identified two PBANR isoforms, MviPBANR-B and MviPBANR-C, in the pheromone glands of Maruca vitrata. These two genes belong to G protein-coupled receptors (GPCRs) and have differences in the C-terminus but share a 7-transmembrane region and GPCR family 1 signature. These isoforms were expressed in all developmental stages and adult tissues. MviPBANR-C had the highest expression level in pheromone glands among the examined tissues. Through in vitro heterologous expression in HeLa cell lines, only MviPBANR-C-transfected cells responded to MviPBAN (≥5 µM MviPBAN), inducing Ca2+ influx. Sex pheromone production and mating behavior were investigated using gas chromatography and a bioassay after MviPBANR-C suppression by RNA interference, which resulted in the major sex pheromone component, E10E12-16:Ald, being quantitatively reduced compared to the control, thereby decreasing the mating rate. Our findings indicate that MviPBANR-C is involved in the signal transduction of sex pheromone biosynthesis in M. vitrata and that the C-terminal tail plays an important role in its function. [ABSTRACT FROM AUTHOR]

Traditional traps for Spodoptera frugiperda (J. E. Smith) monitoring require manual counting, which is time-consuming and laborious. Automatic monitoring devices based on machine vision for pests captured by sex pheromone lures have the problems of large size, high power consumption, and high cost. In this study, we developed a micro- and low-power pest monitoring device based on machine vision, in which the pest image was acquired timely and processed using the MATLAB algorithm. The minimum and maximum power consumption of an image was 6.68 mWh and 78.93 mWh, respectively. The minimum and maximum days of monitoring device captured image at different resolutions were 7 and 1486, respectively. The optimal image resolutions and capture periods could be determined according to field application requirements, and a micro-solar panel for battery charging was added to further extend the field life of the device. The results of the automatic counting showed that the counting accuracy of S. frugiperda was 94.10%. The automatic monitoring device had the advantages of low-power consumption and high recognition accuracy, and real-time information on S. frugiperda could be obtained. It is suitable for large-scale and long-term pest monitoring and provides an important reference for pest control. [ABSTRACT FROM AUTHOR]

The total synthesis of multifidene, a sex pheromone found in brown algae, is described. The synthesis features the highly enantioselective and diastereoselective addition reaction of an aldehyde to a nitroolefin in the presence of a Hayashi–Jørgensen catalyst and a Nef reaction initiated by visible light irradiation. These key reactions enabled the 11-step synthesis from commercially available compounds. The synthetic pheromones are examined with gametes.

Cacao is a promising high-value crop in the Philippines and is considered one of the key players globally in providing the raw materials for chocolate making. However, before the Philippines can take this market opportunity, production constraints from various pests should be addressed. The cacao pod borer (CPB), Conopomorpha cramerella, is one of the major insect pests of cacao in the Philippines, which can cause up to 50% annual loss or even higher if proper management is not employed. Management of CPB heavily relies on chemical control but is becoming unpopular because of its high cost and health risk to people and the environment. A number of efforts have been made to develop sex pheromones to monitor and control CPB. A field bioassay of the new blend of CPB sex pheromones was conducted in southern Philippines to determine its efficiency and identify the appropriate trap height placement in a cacao field, which is important in maximizing the efficiency of the sex pheromone traps for inclusion in the integrated pest management (IPM) program of CPB. Pheromone lures at four different trap heights (1.0 m, 0.5 m above the canopy, 0.0 m or along the canopy, and 0.5 m below the canopy) and a blank lure (control) placed 1.0 m above the canopy were evaluated in terms of male CPB trap catches. Results showed significantly higher male CPB trap catches when installed at least 0.5 m above the canopy while minimal to zero male CPB catches were obtained from the control traps with blank lures, confirming the attractiveness of the new blend of the CPB sex pheromone in the field. This suggests the reliability of the pheromone-based method to monitor and control CPB and as a major component of the IPM program.

[Display omitted] • Female parasitoid wasps (Microplitis mediator) are attracted by the sex pheromone of the turnip moth (Agrotis segetum). • The female-biased odorant receptor MmedOR49 tuned to the Z 5-10:Ac (the main sex pheromone component of the turnip moth) in vitro. • Z 5-10: Ac strongly binds to MmedOR49 by the formation of hydrogen bonds with the key residues (His 80, Ile 81, and Arg 84). • The behavioral response of female M. mediator to Z 5-10:Ac was strongly diminished when MmedOR49 was downregulated by RNAi. • MmedOR49 is involved in the locating of parasitic wasp host habitats using the perception of host sex pheromone. The parasitoid wasp Microplitis mediator is an important natural enemy of the turnip moth Agrotis segetum and other Noctuidae pests. In our field observation, it was fortuitously discovered that sex pheromone traps used for A. segetum also attract female wasps, verified by a simulated field condition dual-choice laboratory assay. Therefore, it was hypothesized that olfactory recognition could be crucial in this process. In this regard, a female-biased odorant receptor of the wasp, MmedOR49, attracted our attention. To unravel the significance of the female-biased MmedOR49 regulating host pheromone recognition. Expression analysis (fluorescence in situ hybridization; quantitative realtime PCR), in vitro (two-electrode voltage-clamp recordings) and in vivo (RNAi combined with behavioral assessments) functional studies, and bioinformatics (structural modeling and molecular docking) were carried out to investigate the characteristics of MmedOR49. MmedOR49 expression was detected in the antennae of females by FISH. Quantification indicated that the expression level of MmedOR49 increased significantly after adult emergence. In vitro functional study revealed that MmedOR49 was specifically tuned to cis -5-decenyl acetate (Z5-10:Ac), the major sex pheromone component of A. segetum. Molecular docking showed that Z5-10:Ac strongly bound to the key amino acid residues His 80, Ile 81, and Arg 84 of MmedOR49 through hydrogen bonding. Behavioral assays indicated that female wasps were significantly attracted by Z5-10:Ac in a three-cage olfactometer. RNAi targeting further confirmed that MmedOR49 was necessary to recognize Z5-10:Ac, as female wasps lost their original behavioral responses to Z5-10:Ac after down-regulation of the MmedOR49 transcript. Although M. mediator is a larval endoparasitoid, female wasps have a behavioral preference for a sex pheromone component of lepidopteran hosts. In this behavior, for female M. mediator , MmedOR49 plays an important role in guiding the habitat of host insects. These data provide a potential target for enhancing natural enemy utilization and pest control. [ABSTRACT FROM AUTHOR]

Sex pheromones are pivotal for insect reproduction. However, the mechanism of sex pheromone communication remains enigmatic in hymenopteran parasitoids. Here we have identified the sex pheromone and elucidated the olfactory basis of sex pheromone communication in Campoletis chlorideae (Ichneumonidae), a solitary larval endoparasitoid of over 30 lepidopteran pests. Using coupled gas chromatography-electroantennogram detection, we identified two female-derived pheromone components, tetradecanal (14:Ald) and 2-heptadecanone (2-Hep) (1:4.6), eliciting strong antennal responses from males but weak responses from females. We observed that males but not females were attracted to both single components and the blend. The hexane-washed female cadavers failed to arouse males, and replenishing 14:Ald and 2-Hep could partially restore the sexual attraction of males. We further expressed six C. chlorideae male-biased odorant receptors in Drosophila T1 neurons and found that CchlOR18 and CchlOR47 were selectively tuned to 14:Ald and 2-Hep, respectively. To verify the biological significance of this data, we knocked down CchlOR18 and CchlOR47 individually or together in vivo and show that the attraction of C. chlorideae to their respective ligands was abolished. Moreover, the parasitoids defective in either of the receptors were less likely to court and copulate. Finally, we show that the sex pheromone and (Z)-jasmone, a potent female attractant, can synergistically affect behaviors of virgin males and virgin females and ultimately increase the parasitic efficiency of C. chlorideae. Our study provides new insights into the molecular mechanism of sex pheromone communication in C. chlorideae that may permit manipulation of parasitoid behavior for pest control. [ABSTRACT FROM AUTHOR]

For insects, olfaction is an important signal input source for their behavioral perception. There are many kinds of proteins involved in the process of odor recognition, and they play a leading role in regulating feeding, swarming, mating, oviposition and other behaviors of insects. These proteins include Odorant-binding Proteins (OBPs), Chemosensory Proteins (CSPs), Odorant Receptors (ORs), Ionotropic Receptors (IRs), Sensory Neuron Membrane Proteins (SNMPs) and Odorant Degrading Enzyme (ODE). Among them, ORs play a critical role in identifying odor molecules and transmitting olfactory signals downstream. The specific combination of odorant molecule and dendrites of olfactory sensory neurons (OSNs) mediated by odorant receptors is an important basis for olfactory recognition. Odorant receptors involves two types: conventional odorant receptors (ORs), and odorant receptor coreceptor (ORCO). ORs, a highly divergent family of receptors, have the ability to recognize odor molecule, and the homology is lower between different insects. ORCO, a receptor without odor sensitivity, co-expresses with ORs to recognize odor molecule, and its sequence is remarkably conserved among insect species. Cell line culture, voltage clamp technique and drosophila"empty neuron"method were used to verify the function of odor receptors. Research about odor receptors'function can lay a theoretical foundation for looking for odor ligands, development of food attractants and repellents against pests, sex attractants and aggregation pheromones and so on. This article reviews the research progress in identification and classification, structure, expression profile, phylogenetic relationships and function of odorant receptors in the domestic and overseas, which provides reference for the research of insect olfactory mechanism as well as the prevention and control of pests.

Protein feeding is critical for male reproductive success in many insect species. However, how protein affects the reproduction remains largely unknown. Using Bactrocera dorsalis as the study model, we investigated how protein feeding regulated sex pheromone synthesis. We show that protein ingestion is essential for sex pheromone synthesis in male. While protein feeding or deprivation did not affect Bacillus abundance, transcriptome analysis revealed that sarcosine dehydrogenase (Sardh) in protein-fed males regulates the biosynthesis of sex pheromones by increasing glycine and threonine (sex pheromone precursors) contents. RNAi-mediated loss-of-function of Sardh decreases glycine, threonine, and sex pheromone contents and results in decreased mating ability in males. The study links male feeding behavior with discrete patterns of gene expression that plays role in sex pheromone synthesis, which in turn translates to successful copulatory behavior of the males.

Iridoid monoterpenes, widely distributed in plants and insects, have many ecological functions. While the biosynthesis of iridoids has been extensively studied in plants, little is known about how insects synthesize these natural products. Here, we elucidated the biosynthesis of the iridoids cis-trans-nepetalactol and cis-trans-nepetalactone in the pea aphid Acyrthosiphon pisum (Harris), where they act as sex pheromones. The exclusive production of iridoids in hind legs of sexual female aphids allowed us to identify iridoid genes by searching for genes specifically expressed in this tissue. Biochemical characterization of candidate enzymes revealed that the iridoid pathway in aphids proceeds through the same sequence of intermediates as described for plants. The six identified aphid enzymes are unrelated to their counterparts in plants, conclusively demonstrating an independent evolution of the entire iridoid pathway in plants and insects. In contrast to the plant pathway, at least three of the aphid iridoid enzymes are likely membrane bound. We demonstrated that a lipid environment facilitates the cyclization of a reactive enol intermediate to the iridoid cyclopentanoid-pyran scaffold in vitro, suggesting that membranes are an essential component of the aphid iridoid pathway. Altogether, our discovery of this complex insect metabolic pathway establishes the genetic and biochemical basis for the formation of iridoid sex pheromones in aphids, and this discovery also serves as a foundation for understanding the convergent evolution of complex metabolic pathways between kingdoms. [ABSTRACT FROM AUTHOR]

Simple Summary: Spodoptera litura (Fabr.) is a serious Lepidopteran pest that can be controlled using the eco-friendly radio-genetic Inherited (F1) Sterility (IS) technique. In contrast with the conventional male-only release applied in IS techniques, this study was conducted to determine a suitable dose at which females can be fully radio-sterilized while leaving the more radio-resistant males partially sterile, meaning that both sexes could be irradiated together and released simultaneously in pest infested fields. Behavioral and molecular investigations ascertained 130 Gy to be a suitable dose for female sterilization, at which point their reproductive fitness in terms of calling ability and mating competence will not be significantly compromised. These irradiated females would be sufficiently viable to compete with wild females for mating with wild males, ultimately suppressing the pest population. The simultaneous release of sub-sterile male and sterile female moths using the IS technique might improve its efficacy, leading to more effective pest suppression. Radiobiological investigations on the reproductive behavior of female Spodoptera litura (Fabr.) were conducted with the aim of determining the suitable radio-sterilizing dose for females in order to release them along with sub-sterile males for effective implementation of the Inherited Sterility technique against this pest. Calling and copulation duration significantly increased, while mating success, oviposition, fertility and longevity significantly decreased with increasing radiation dose (100–200 Gy) compared to control. In view of the effect of irradiation on mating behavior and reproductive viability of female S. litura, 130 Gy was identified as a suitable radio-sterilization dose. Further molecular studies were conducted to corroborate this dose for female sterilization, along with a higher dose of 200 Gy in order to validate the gradational response of ionizing radiation. GC-MS analysis indicated decreased sex pheromone titer at 130 Gy, which was more pronounced at 200 Gy. Pheromone-associated genes, PBAN and PBAN-R showed decreased expression at 130 Gy, and were drastically reduced at 200 Gy. The fertility-related Vg gene also showed a negative correlation with radiation exposure. Based on these radiation responses of female S. litura, 130 Gy might be considered a suitable dose for complete female sterility and its inclusion in sterile insect programs against S. litura. [ABSTRACT FROM AUTHOR]

The total synthesis of multifidene, a sex pheromone found in brown algae, is described. The synthesis features the highly enantioselective and diastereoselective addition reaction of an aldehyde to a nitroolefin in the presence of a Hayashi–Jørgensen catalyst and a Nef reaction initiated by visible light irradiation. These key reactions enabled the 11-step synthesis from commercially available compounds. The synthetic pheromones are examined with gametes. [ABSTRACT FROM AUTHOR]

Despite the identification of the potato tuber moth Phthorimaea operculella (Zeller) sex pheromone, no effective application based on this pheromone has yet been developed and evaluated. This study investigated the effect of pheromone lures, trap densities, heights of trap deployment, and pheromone doses in Yunnan, China, for the purpose of increasing the control efficiency of P. operculella and improving the application of pheromone technology in the field. The results showed that lures made of corn oil and red PVC pipes attracted the highest number of moths (11.73±1.90 per trap per day). Sex pheromone loading of 100 µg was optimal for trapping moths, but higher doses of pheromone inhibited attraction. The density of traps did not affect capture rates; therefore, the optimum trap density was 30–40 traps ha–1. The optimum height of trap deployment was not above the height of the plant canopy. This study provides technical details necessary for the monitoring and control of potato tuber moth using sex pheromones.

In moths, mate finding relies on female-emitted sex pheromones that the males have to decipher within a complex environmental odorant background. Previous studies have shown that interactions of both sex pheromones and plant volatiles can occur in the peripheral olfactory system, and that some plant volatiles can activate the pheromone-specific detection pathway. In the noctuid moth Agrotis ipsilon, plant volatiles such as heptanal activate the receptor neurons tuned to the pheromone component (Z)7-12:OAc. However, the underlying mechanisms remain totally unknown. Following the general rule that states that one olfactory receptor neuron usually expresses only one type of receptor protein, a logic explanation would be that the receptor protein expressed in (Z)7-12:OAc-sensitive neurons recognizes both pheromone and plant volatiles. To test this hypothesis, we first annotated odorant receptor genes in the genome of A. ipsilon and we identified a candidate receptor putatively tuned to (Z)7-12:OAc, named AipsOR3. Then, we expressed it in Drosophila olfactory neurons and determined its response spectrum to a large panel of pheromone compounds and plant volatiles. Unexpectedly, the receptor protein AipsOR3 appeared to be very specific to (Z)7-12:OAc and was not activated by any of the plant volatiles tested, including heptanal. We also found that (Z)7-12:OAc responses of Drosophila neurons expressing AipsOR3 were not affected by a background of heptanal. As the Drosophila olfactory sensilla that house neurons in which AipsOR3 was expressed contain other olfactory proteins – such as odorant-binding proteins – that may influence its selectivity, we also expressed AipsOR3 in Xenopus oocytes and confirmed its specificity and the lack of activation by plant volatiles. Altogether, our results suggest that a still unknown second odorant receptor protein tuned to heptanal and other plant volatiles is expressed in the (Z)7-12:OAc-sensitive neurons of A. ipsilon.

Leopard moth, Zeuzera pyrina L., is a dangerous wood borer pest of the walnut trees in different parts of the world. The larvae bore deep into twigs, branches and trunks, and its chemical, biological and mechanical control is difficult, therefore use of mass trapping is an efficient method to reduce the pest population. The purpose of this study was to increase the efficiency of mass trapping by combining the light and pheromone baited traps in walnut orchards. The study was conducted based on the randomized complete block design with three treatments (pheromone trap, solar-powered insect light trap and combined pheromone trap and light) and six replicates during 2014-2015. Pheromone traps were installed one meter below the apical point of tree canopy before the starting of the adult emergence (May 10th). Observation was done weekly during the moth flight period and the number of captured moth was counted and compared in different treatments. Based on the results, in all sampling dates, the highest number of captured males (65.6±4.38 and 79.2±1.25 in 2014 and 2015, respectively) observed in combined pheromone trap and light, whereas the lowest (27.6±1.28 and 27.6±3.78 in 2014 and 2015, respectively) observed in the light trap treatment. Combining of light with pheromone trap significantly increased the efficiency of Z. pyrina mass trapping in the walnut orchards.

The sex pheromones emitted by Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) females attract males for copulation, but no studies to date have investigated if conspecific females also are attracted. Here, the attraction of females of S. frugiperda to their sex pheromone in flight tunnel laboratory bioassays and field trapping is reported. Genitalia of females and males captured in the field were dissected for taxonomic identification and studied with an environmental scanning electron microscope to know the mating status of the females. In wind tunnel attraction bioassays, virgin females flew upwind and landed on the stimulus, likewise the males, whereas mated females, although they headed for the stimulus, showed fewer landings. The sex ratio of captured insects in the field was 1 female to 4 males. The presence of spermatophores allowed the separation of mated and virgin females using the genitalia; both were found in the traps throughout the sampling period. This study demonstrated that S. frugiperda females autodetect their sex pheromone, and its implications on the management strategy for these moths are discussed. Las feromonas sexuales emitidas por las hembras de Spodoptera frugiperda J. E. Smith (Lepidoptera: Noctuidae) atraen a los machos para la cópula, pero no hay estudios que investiguen si las hembras conespecíficas son atraídas. En este estudio, se informa de la atracción de las hembras de S. frugiperda a su feromona sexual en bioensayos de laboratorio en túnel de vuelo, y trampas de campo. Se disectaron las genitalias de las hembras y los machos capturados en el campo para su identificación taxonómica y también se estudiaron con el microscopio electrónico de barrido ambiental para conocer el estado de apareamiento de las hembras. En los bioensayos de atracción en el túnel de viento, las hembras vírgenes volaron contra el viento y se posaron en el estímulo, al igual que los machos, mientras que las hembras apareadas, aunque se dirigieron al estímulo, mostraron menos aterrizajes. En el campo, la proporción sexual de los insectos capturados fue de una hembra por cada cuatro machos. Las genitalias de las hembras apareadas y vírgenes se distinguieron por la presencia del espermatóforo. Este estudio demuestra que las hembras de S. frugiperda autodetectan su feromona sexual y se discuten sus implicaciones en la estrategia de manejo de estas palomillas. [ABSTRACT FROM AUTHOR]

Darwin argued a role for sexual selection in the evolution of male sensory structures, including insect antennae, the strength of which will depend upon the importance of early arrival at receptive females. There is remarkable variation in the nature and degree of sexual dimorphism in moth antennae, with males of some species having spectacular, feathery antennae. Although it is widely assumed that these elaborate structures provide greater sensitivity to chemical signals (sex pheromones), the factors underlying the interspecific diversity in male antennal structure and size are poorly understood. Because male antennal morphology may be affected by several female life–history traits, including flight ability, we conducted a phylogenetic comparative analysis to test how these traits are linked, using data from 93 species of moths across 11 superfamilies. Our results reveal that elaborate antennae in males have evolved more frequently in species where females are monandrous. Further, female loss of flight ability evolved more frequently in species where males have elaborate antennae. These results suggest that elaborate antennae have evolved in response to more intense male competition, arising from female monandry, and that the evolution of elaborate antennae in males has, in turn, shaped the evolution of female flightlessness.

Simple Summary: We demonstrate that male potato aphids respond more to a combination of volatiles from the host plant on which the species overwinters and the female sex pheromone than to the host plant alone. In both cases, the level of response declines as wind speed increases, but the higher attraction to the combined odour sources is maintained. These findings are discussed within the context of mate location by male aphids, which are insects that have little control over flight direction. In fall, alate males of the potato aphid, Macrosiphum euphorbiae (Thomas), migrate from their summer (secondary) host plants, such as potatoes, to primary host plants, such as roses, where they mate with wingless oviparae who produce the overwintering egg stage. Males are weak fliers and generally walk towards a pheromone source under windy conditions, so we tested the hypothesis that upwind walking behaviour in response to wind velocity would be affected by the volatile cues present. We compared male responses to the odour of a rugosa rose cutting alone and to the combination of host plant volatiles and the female sex pheromone under a range of wind speeds in a laboratory walking bioassay. The proportion of males responding decreased as the wind speed increased, but at all wind velocities, the responses to the combined odours were higher than to the host plant alone. However, at any given wind velocity, the speed at which responding aphids moved was not influenced by the odour source. These findings support the idea that host plant volatiles serve as long-distance cues for males and that the female sex pheromone is used once on the host plant. [ABSTRACT FROM AUTHOR]