Evaluation of the honeybee exposome in European apiaries by combining passive samplers and liquid chromatography with Zeno trap-time-of-flight mass spectrometry

This study introduces an analytical methodology that combines passive sampling with ultra-high pressure liquid chromatography coupled with a high-end quadrupole-time-of-flight mass spectrometer (UHPLC-QTOF-MS) for monitoring the honeybee (Apis mellifera L.) exposome across various European regions and seasons. The sampling methodology employs the recently developed adsorb pesticide in-hive strips (APIStrip) passive samplers, which use TENAX® TA adsorbent, to collect a wide range of chemicals when placed inside beehives. Following acetonitrile-based desorption, extracts were analyzed by UHPLC-QTOF-MS, equipped with an advanced ion trap -the Zeno trap- that enhances tandem-mass spectrometry (MS/MS) signals and improves mass accuracy, facilitating efficient feature annotation. A non-targeted analysis (NTA) approach, combined with multivariate analysis, was used to simultaneously identify exposure analytes (e.g.natural products) and effect-related metabolites associated with honeybee health and condition (e.g. pheromones and other compounds emitted by bees). This methodology revealed geographical and seasonal variations in the chemical profiles of honeybee hives. In the evaluated Nordic countries, natural products from plants and pollen, along with bee-emitted substances such us neurotransmitters and pheromones, were prevalent. Seasonal analysis in Denmark revealed distinct chemical profiles associated with blooming flowers and peak brood rearing activity in April. This integrated, non-invasive methodology has proven highly effective in assessing the honeybee exposome, providing valuable insights into how environmental factors influence the chemical profiles emitted by bees.

The Asymmetric Total Synthesis of the Female-Produced Sex Pheromone of the Tea Tussock Moth

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.

Chemical Composition of Five Lamiaceae Essential Oils and Their Insecticidal and Phytotoxic Activity

The Lamiaceae family is widely distributed worldwide. In this study, we investigated the insecticidal activity of five Lamiaceae essential oils against Thrips flavus Schrank and the phytotoxic activity against Glycine max (L.) Merr., Zea mays L., Portulaca oleracea L., and Echinochloa oryzoides (Ard.) Fritsch. Then, the chemical composition of the five essential oils was analyzed by using gas chromatography-mass spectrometry (GC-MS). The five Lamiaceae essential oils were melissa, basil, rosemary, negundo chastetree, and salvia. The main constituents of the five Lamiaceae essential oils were preliminarily determined to be as follows: α-pinene and 1,8-cineole in the rosemary essential oil; β-pinene, γ-terpinene, and d-limonene in the negundo chastetree essential oil; β-cadinene and isolongifolen-5-one in the melissa essential oil; 5-allylguaiacol in the basil essential oil; and isopropyl myristate, linalyl acetate, and linalool in the salvia essential oil. Using a bioassay, it was found that, among the five essential oils, the melissa essential oil exhibited the lowest LC50 value, which was 0.18 mg/mL, and the salvia essential oil exhibited the highest LC50 value, which was 0.42 mg/mL. The control efficacy of the five essential oils significantly increased with time and concentration in pot experiments. The negundo chastetree, basil, rosemary, and salvia essential oils at 900.00 g a.i.·hm-2 showed high control efficacy against T. flavus, with values higher than 90%. Female thrips were attracted to the negundo chastetree essential oil. The five essential oils were also tested for their effects on the germination rate, germination potential, germination index, and shoot length of G. max, Z. mays, P. oleracea, and E. oryzoides. The basil essential oil significantly inhibited the germination of P. oleracea, with germination at a concentration of 1.0 mg/mL being only 11.11 ± 5.09%. This study provides a reference for the development of botanical pesticides to control T. flavus, crops, and weeds.

Ontogenetic change in effectiveness of chemical defence against different predators in Oxycarenus true bugs

Many prey species change their antipredator defence during ontogeny, which may be connected to different potential predators over the life cycle of the prey. To test this hypothesis, we compared reactions of two predator taxa - spiders and birds - to larvae and adults of two invasive true bug species, Oxycarenus hyalinipennis and Oxycarenus lavaterae (Heteroptera: Oxycarenidae) with life-stage-specific chemical defence mechanisms. The reactions to larvae and adults of both true bug species strikingly differed between the two predator taxa. The spiders were deterred by the defences of adult bugs, but the larval defences were ineffective against them. By contrast, birds attacked the larvae considerably less often than the adult bugs. The results indicate a predator-specific ontogenetic change in defence effectiveness of both Oxycarenus species. The change in defence is likely linked to the life-stage-specific composition of secretions in both species: whereas secretions of larvae are dominated by unsaturated aldehydes, secretions of adults are rich in terpenoids, which probably serve dual function of defensive chemicals and pheromones. Our results highlight the variation in defence between different life stages and the importance of testing responses of different types of predators.

Chemical Signals Associated With Gender and Sexual Experience Affect Mating and the Attractiveness of the Poultry Pest, Alphitobius diaperinus (Coleoptera: Tenebrionidae)

Alphitobius diaperinus is one of the most significant pests in the poultry industry. Identifying the role of self-produced chemical signals can help control it. Here, we exposed adults to the olfactory signals of other adults of similar and different genders (either males or females) and sexual experiences (i.e., virgin and experienced) to assess their long-range attractiveness and, at short-range, their mating behavior responses (i.e., touching, mounting, and copulation). In olfactometric experiments, our results indicate that adults are attracted to the olfactory signals of other male adults, independently of gender, or sexual condition, indicating the presence of generalized long-range attractive signals, in contrast to female signals, can be both factor-dependent. However, in mating experiments, virgin males developed more robust mating responses (i.e., they mount and copulate longer with females) compared to sexually experienced males, even though they both have similar precopulatory behavioral responses (i.e., time of antennal and leg touching). These results address the importance of short-range chemical signals in eliciting copulation. Furthermore, when virgins of both genders were tested, their mating responses were significantly longer than any other pair combination, indicating that sexual experience also affects mating behavior. Chemical analyses of adult extracts showed that sexual experience, but not gender, is linked to differences in chemical profiles of adults, primarily involved in short-range signaling. These findings provide new insights into the attractiveness and mating responses of A. diaperinus and the role of sexual experience in shaping the behavior and chemical profile of insects that mate multiple times during their lifetime.

A New Essential Oil from the Leaves of the Endemic Andean Species Gynoxys miniphylla Cuatrec. (Asteraceae): Chemical and Enantioselective Analyses

A previously uninvestigated essential oil (EO) was distilled from Gynoxys miniphylla Cuatrec. (Asteraceae) and submitted to chemical and enantioselective analyses. The qualitative and quantitative analyses were conducted by GC-MS and GC-FID, over two orthogonal columns (5%-phenyl-methylpolysiloxane and polyethylene glycol stationary phases). Major constituents (≥2%) were, on both columns, respectively, as follows: α-phellandrene (16.1-17.2%), α-pinene (14.0-15.0%), germacrene D (13.3-14.8%), trans-myrtanol acetate (8.80%), δ-cadinene (4.2-4.6%), β-phellandrene (3.3-2.8%), (E)-β-caryophyllene (3.1-2.0%), o-cymene (2.4%), α-cadinol (2.3-2.6%), and α-humulene (1.7-2.0%). All the quantified compounds corresponded to 93.5-97.3% by weight of the whole essential oil, with monoterpenes counting for 53.8-55.6% of the total, and sesquiterpenes for 38.5-41.4%. For what concerns the enantioselective analyses, the chiral components were investigated through a β-cyclodextrin-based enantioselective column (2,3-diethyl-6-tert-butyldimethylsilyl-β-cyclodextrin). A total of six chiral metabolites were analysed and the respective enantiomeric excess calculated as follows: (1S,5S)-(-)-α-pinene (98.2%), (1S,5S)-(-)-β-pinene (11.9%), (1R,5R)-(+)-sabinene (14.0%), (R)-(-)-α-phellandrene (100.0%), (R)-(-)-β-phellandrene (100.0%), and (S)-(-)-germacrene D (95.5%). According to the chemical composition and enantiomeric distribution of major compounds, this EO can be considered promising as a cholinergic, antiviral and, probably, analgesic product.

α-Terpineol: An Aggregation Pheromone in Optatus palmaris (Coleoptera: Curculionidae) (Pascoe, 1889) Enhanced by Its Host-Plant Volatiles

The Annonaceae fruits weevil (Optatus palmaris) causes high losses to the soursop production in Mexico. Damage occurs when larvae and adults feed on the fruits; however, there is limited research about control strategies against this pest. However, pheromones provide a high potential management scheme for this curculio. Thus, this research characterized the behavior and volatile production of O. palmaris in response to their feeding habits. Olfactometry assays established preference by weevils to volatiles produced by feeding males and soursop. The behavior observed suggests the presence of an aggregation pheromone and a kairomone. Subsequently, insect volatiles sampled by solid-phase microextraction and dynamic headspace detected a unique compound on feeding males increased especially when feeding. Feeding-starvation experiments showed an averaged fifteen-fold increase in the concentration of a monoterpenoid on males feeding on soursop, and a decrease of the release of this compound males stop feeding. GC-MS analysis of volatiles identified this compound as α-terpineol. Further olfactometry assays using α-terpineol and soursop, demonstrated that this combination is double attractive to Annonaceae weevils than only soursop volatiles. The results showed a complementation effect between α-terpineol and soursop volatiles. Thus, α-terpineol is the aggregation pheromone of O. palmaris, and its concentration is enhanced by host-plant volatiles.

Tephritid Fruit Fly Semiochemicals: Current Knowledge and Future Perspectives

The Dipteran family Tephritidae (true fruit flies) comprises more than 5000 species classified in 500 genera distributed worldwide. Tephritidae include devastating agricultural pests and highly invasive species whose spread is currently facilitated by globalization, international trade and human mobility. The ability to identify and exploit a wide range of host plants for oviposition, as well as effective and diversified reproductive strategies, are among the key features supporting tephritid biological success. Intraspecific communication involves the exchange of a complex set of sensory cues that are species- and sex-specific. Chemical signals, which are standing out in tephritid communication, comprise long-distance pheromones emitted by one or both sexes, cuticular hydrocarbons with limited volatility deposited on the surrounding substrate or on the insect body regulating medium- to short-distance communication, and host-marking compounds deposited on the fruit after oviposition. In this review, the current knowledge on tephritid chemical communication was analysed with a special emphasis on fruit fly pest species belonging to the Anastrepha, Bactrocera, Ceratitis, and Rhagoletis genera. The multidisciplinary approaches adopted for characterising tephritid semiochemicals, and the real-world applications and challenges for Integrated Pest Management (IPM) and biological control strategies are critically discussed. Future perspectives for targeted research on fruit fly chemical communication are highlighted.

Host Plant and Antibiotic Effects on Scent Bouquet Composition of Anastrepha ludens and Anastrepha obliqua Calling Males, Two Polyphagous Tephritid Pests

In insects, the quality of sex pheromones plays a critical role in mating success and can be determined by the ability of larvae/adults to accrue chemical precursors. We tested the host-quality-effect hypothesis by analyzing the chemical composition of scent bouquets emitted by calling males of two polyphagous tephritid species (Anastrephaludens and A. obliqua) that originated from 13 fruit species representing diverse plant families. In A. ludens, we worked with an ancestral host (Rutaceae), nine exotic ones (Rutaceae, Anacardiaceae, Rosaceae, Solanaceae, Lythraceae), and two species never attacked in nature but that represent candidates for host-range expansion (Solanaceae, Myrtaceae). In A. obliqua, we tested an ancestral, a native, and an exotic host (Anacardiaceae), one occasional (Myrtaceae), and one fruit never attacked in nature (Solanaceae). We identified a core scent bouquet and significant variation in the bouquet’s composition depending on the fruit the larvae developed in. We also tested the possible microbial role on the scent bouquet by treating adults with antibiotics, finding a significant effect on quantity but not composition. We dwell on plasticity to partially explain our results and discuss the influence hosts could have on male competitiveness driven by variations in scent bouquet composition and how this could impact insect sterile technique programs.

Loading, release profile and accelerated stability assessment of monoterpenes-loaded solid lipid nanoparticles (SLN)

Glycerol monostearate solid lipid nanoparticles (SLN) were produced by hot high-pressure homogenization technique to load alpha-pinene, citral, geraniol or limonene. SLN were composed of 1 wt.% monoterpene, 4 wt.% of Imwitor^® 900K as a solid lipid and 2.5 wt.% of Poloxamer188 as a surfactant. Empty SLN consisted of 5 wt.% of Imwitor^® 900K and 2.5 wt.% of Poloxamer188. The mean particles size (Z-Ave) and polydispersity index (PDI) of SLN were analyzed by dynamic light scattering (DLS), while the zeta potential (ZP) of each formulation were measured by electrophoretic light scattering. LUMiSizer^® was applied to calculate the velocity distribution in the centrifugal field and instability index. Drug release profile from SLN was analyzed using Franz cell diffusion cells assayed by UV-Vis spectrophotometry, whereas the gas chromatography technique was applied to determine the encapsulation parameters of volatile monoterpenes. The matrix state, polymorphism and phase behavior of SLN were studied by X-ray diffraction (XRD, low and wide angles) and differential scanning calorimetry (DSC). Selected monoterpenes were successfully loaded in glycerol monostearate SLN. A burst release profile within the first 15 min was observed for all formulations, being the modified release profile dependent on the type of monoterpene and on the encapsulation efficiency.

Enantiospecific Synthesis of Nepetalactones by One-Step Oxidative NHC Catalysis

An efficient oxidative NHC-catalyzed one-step transformation of (S)- or (R)-8-oxocitronellal to nepetalactone (NL) in enantio- and diastereomerically pure form has been developed. Several new and "easy to make" N-Mes- or N-Dipp-substituted 1,2,4-triazolium salts carrying nitroaromatic groups on N1 were synthesized and evaluated as precatalysts in combination with base and stoichiometric organic oxidant. Under optimized conditions, NLs are accessible in very good yields and diastereomerically pure under mild conditions. The oxidant used could be recovered and recycled under operationally simple conditions.

Chemical convergence between plants and insects: biosynthetic origins and functions of common secondary metabolites

Despite the phylogenetic distance between plants and insects, these two groups of organisms produce some secondary metabolites in common. Identical structures belonging to chemical classes such as the simple monoterpenes and sesquiterpenes, iridoid monoterpenes, cyanogenic glycosides, benzoic acid derivatives, benzoquinones and naphthoquinones are sometimes found in both plants and insects. In addition, very similar glucohydrolases involved in activating two-component defenses, such as glucosinolates and cyanogenic glycosides, occur in both plants and insects. Although this trend was first noted many years ago, researchers have long struggled to find convincing explanations for such co-occurrence. In some cases, identical compounds may be produced by plants to interfere with their function in insects. In others, plant and insect compounds may simply have parallel functions, probably in defense or attraction, and their co-occurrence is a coincidence. The biosynthetic origin of such co-occurring metabolites may be very different in insects as compared to plants. Plants and insects may have different pathways to the same metabolite, or similar sequences of intermediates, but different enzymes. Further knowledge of the ecological roles and biosynthetic pathways of secondary metabolites may shed more light on why plants and insects produce identical substances.

Eucalyptol Detected by Aeration from the Eggs of the Common Bed Bug (Hemiptera: Cimicidae)

To determine whether volatiles from bed bug eggs were similar to the defensive secretions from nymphs and adults, headspace volatiles from eggs of the common bed bug (Cimex lectularius L.) were collected by aeration, daily until hatch, and subsequently analyzed by gas chromatography-mass spectrometry. We now report that eucalyptol (1,8-epoxy-p-menthane) was identified from all egg samples. Blank control samples containing no eggs had no evidence of eucalyptol. Positive controls, containing nymphs, adults, and fecal deposits, showed the presence of the defensive secretions (E)-2-hexenal and (E)-2-octenal, but no eucalyptol. The lack of detectable (E)-2-hexenal and (E)-2-octenal in viable egg samples and the detection of eucalyptol are discussed in relation to canine detection of bed bugs.

Qualitative analysis of Schizonepeta annua (Pall.) Schischk essential oil by gas chromatography-quadrupole time-of-flight mass spectrometry

In this study, a method for the qualitative analysis of small molecular compounds in Schizonepeta annua (Pall.) Schischk essential oil was established based on gas chromatography-quadrupole time-of-flight mass spectrometry. In addition to an automated search of the NIST library, the identification of oxygenated monoterpenes, phenolic esters, and phenolic compounds was achieved by two additional strategies. One strategy involved comparing the relative errors of accurate masses measured for ions in the experimental spectra with those calculated for fragments identified from the NIST database of candidate matches. The second strategy involved combination of the product ion scans and positive chemical ionisation spectra for structural elucidation. Overall, 95.45% of the total essential oil volatile chemical content of Schizonepeta annua (Pall.) Schischk was identified, with phenolic monoterpenes dominating.

An IDS-Type Sesquiterpene Synthase Produces the Pheromone Precursor (Z)-α-Bisabolene in Nezara viridula

Insects use a wide range of structurally diverse pheromones for intra-specific communication. Compounds in the class of terpenes are emitted as sex, aggregation, alarm, or trail pheromones. Despite the common occurrence of terpene pheromones in different insect lineages, their origin from dietary host plant precursors or de novo biosynthetic pathways often remains unknown. Several stink bugs (Hemiptera: Pentatomidae) release bisabolene-type sesquiterpenes for aggregation and mating. Here we provide evidence for de novo biosynthesis of the sex pheromone trans-/cis-(Z)-α-bisabolene epoxide of the Southern green stink bug, Nezara viridula. We show that an enzyme (NvTPS) related to isoprenyl diphosphate synthases (IDSs) of the core terpene metabolic pathway functions as a terpene synthase (TPS), which converts the general intermediate (E,E)-farnesyl diphosphate (FPP) to the putative pheromone precursor (+)-(S,Z)-α-bisabolene in vitro and in protein lysates. A second identified IDS-type protein (NvFPPS) makes the TPS substrate (E,E)-FPP and functions as a bona fide FPP synthase. NvTPS is highly expressed in male epidermal tissue associated with the cuticle of ventral sternites, which is in agreement with the male specific release of the pheromone from glandular cells in this tissue. Our study supports findings of the function of similar TPS enzymes in the biosynthesis of aggregation pheromones from the pine engraver beetle Ips pini, the striped flea beetle Phyllotreta striolata, and the harlequin bug Murgantia histrionica, and hence provides growing evidence for the evolution of terpene de novo biosynthesis by IDS-type TPS families in insects.

De novo formation of an aggregation pheromone precursor by an isoprenyl diphosphate synthase-related terpene synthase in the harlequin bug

Many insects release volatile terpenes for chemical communication. However, the biosynthetic origin and evolution of these infochemicals are mostly unknown. We show that the harlequin bug, Murgantia histrionica, a stink bug pest (Hemiptera) of crucifer crops, produces a terpene aggregation pheromone by an enzyme that is unrelated to microbial and plant terpene synthases. M. histrionica terpene synthase activity is highly sex- and tissue-specific and makes a sesquiterpene alcohol, so far unknown in animals, as pheromone precursor. The enzyme evolved from ancestral isoprenyl diphosphate synthases and provides new evidence for de novo biosynthesis of terpenes in hemipteran insects. Knowledge of pheromone biosynthesis in stink bugs may lead to the development of new controls of these pests.

Insects use a diverse array of specialized terpene metabolites as pheromones in intraspecific interactions. In contrast to plants and microbes, which employ enzymes called terpene synthases (TPSs) to synthesize terpene metabolites, limited information from few species is available about the enzymatic mechanisms underlying terpene pheromone biosynthesis in insects. Several stink bugs (Hemiptera: Pentatomidae), among them severe agricultural pests, release 15-carbon sesquiterpenes with a bisabolene skeleton as sex or aggregation pheromones. The harlequin bug, Murgantia histrionica, a specialist pest of crucifers, uses two stereoisomers of 10,11-epoxy-1-bisabolen-3-ol as a male-released aggregation pheromone called murgantiol. We show that MhTPS (MhIDS-1), an enzyme unrelated to plant and microbial TPSs but with similarity to trans-isoprenyl diphosphate synthases (IDS) of the core terpene biosynthetic pathway, catalyzes the formation of (1S,6S,7R)-1,10-bisaboladien-1-ol (sesquipiperitol) as a terpene intermediate in murgantiol biosynthesis. Sesquipiperitol, a so-far-unknown compound in animals, also occurs in plants, indicating convergent evolution in the biosynthesis of this sesquiterpene. RNAi-mediated knockdown of MhTPS mRNA confirmed the role of MhTPS in murgantiol biosynthesis. MhTPS expression is highly specific to tissues lining the cuticle of the abdominal sternites of mature males. Phylogenetic analysis suggests that MhTPS is derived from a trans-IDS progenitor and diverged from bona fide trans-IDS proteins including MhIDS-2, which functions as an (E,E)-farnesyl diphosphate (FPP) synthase. Structure-guided mutagenesis revealed several residues critical to MhTPS and MhFPPS activity. The emergence of an IDS-like protein with TPS activity in M. histrionica demonstrates that de novo terpene biosynthesis evolved in the Hemiptera in an adaptation for intraspecific communication.

A case of flying insects visiting an anatomy and embalming laboratory in Medellín, Colombia

From July to September of 2012, the fauna of flying insects visiting the anatomy and embalming laboratory of the Tecnológico de Antioquia, Faculty of Forensic Sciences, located in the city of Medellin, Colombia, were recorded. The first checklist in the literature of incidental flying insects occurring in this type of locale is provided, and a brief discussion is given of their behavioral habits related to this uncommon case.

New oxygenated himachalenes in male-specific odor of the Chinese windmill butterfly, Byasa alcinous alcinous

Male adults of the Chinese windmill Byasa alcinous alcinous (Papilionidae) are well known to have a strong musk-like odor, in which two oxygenated himachalene compounds, together with six sesquiterpene hydrocarbons, were newly discovered. γ-Himachalen-4-yl acetate (1) was the predominant compound isolated from the solvent extract of the males. The structure of 1 was determined using MS and NMR, and its relative configuration was established as 1S*,4R*,6R* by NOE analysis with the help of quantum mechanical computation. Interestingly, the amount of 1 in males increased until 7 days after eclosion, suggesting that this compound is involved in sexual maturation for mating. Another new compound was identified as γ-himachalen-4-ol (2) by comparison with the retention time and mass spectrum of the hydrolysate of 1. Since males of other papilionid species have general volatiles omnipresent in plants and insects, the presence of species-specific volatiles in males is characteristic of B. alcinous alcinous.

Aromatized to find mates: α-pinene aroma boosts the mating success of adult olive fruit flies

BACKGROUND

Contrary to other Tephritidae, female but also male olive flies, Bactrocera oleae release pheromones during their sexual communication. Alpha-pinene, a common plant volatile found in high amounts in unripe olive fruit and leaves has been detected as one of the major components of the female pheromone. However, possible effects of α-pinene and that of other host volatiles on the mating behavior of the olive fly have not been investigated.

METHODOLOGY

Using wild olive flies, reared on olive fruit for 3 generations in the laboratory, we explored whether exposure of male and female olive flies to α-pinene affects their sexual performance.

RESULTS

Exposure of sexually mature adult olive flies to the aroma of α-pinene significantly increases the mating performance over non-exposed individuals. Interestingly, exposure to α-pinene boosts the mating success of both males and female olive flies.

CONCLUSIONS

This is the first report of such an effect on the olive fly, and the first time that a single plant volatile has been reported to induce such a phenomenon on both sexes of a single species. We discuss the possible associated mechanism and provide some practical implications.

Terpenes and polyacetylenes from cultivated Artemisia granatensis boiss (Royal chamomile) and their defensive properties

Artemisia granatensis, an endemic endangered plant species from Sierra Nevada (Spain) has been successfully cultivated in artificial systems (plants in artificial soil and transformed in vitro roots) to generate enough plant biomass (aerial and root) to allow for its chemical and biological study and at the same time to provide with methods for the sustainable production of the plant and its metabolites. A eudesmanolide (17) along with six sesquiterpenes (11-16), nine monoterpenes (2-10), one nor-monoterpene (1), three acetylenic spiroacetal enoleters (18-20) and one coumarin (21) have been identified from the aerial plant ethanolic extract. Acetylenic spiroacetal enoleters 18-19 and coumarins 21-23 have been isolated from the transformed root ethanolic extract. These extracts and some isolated compounds or mixtures of them have been tested for their insect antifeedant effects against Spodoptera littoralis, Myzus persicae and Rhopalosiphum padi. Significant antifeedant properties were determined for the aerial plant extract, spiroacetals 19-20 and secoguaianolides 13+14 and 16.

Essential oils composition of two Sicilian cultivars of Opuntia ficus-indica (L.) Mill. (Cactaceae) fruits (prickly pear)

The essential oils composition of the skin, pulp and seeds from fruits of two Sicilian cultivars of Opuntia ficus-indica (cv. Sanguigna and cv. Surfarina) has been obtained by hydrodistillation and the possible antioxidant, antimicrobial and semiochemical roles have been investigated comparing the data with those reported in the literature. The presence of antioxidants and antimicrobials found in this study increases the spectrum of compounds that have beneficial properties in O. ficus-indica. In addition, several compounds identified in this study have been reported to influence the behaviour of Ceratitis capitata, a phytophagous pest which causes severe damages to several crops including O. ficus-indica and the kairomonal activity of the odour of the fruits seems provided by a blend of compounds found in the various matrices analysed.