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Palms are the food source for a variety of herbivores worldwide. All palm organs can be affected by pests: foliage, roots, flowers, fruit bunches, developing spear, and stems. The herbivores include mainly insects and Acari from different feeding guilds and taxa, in particular: defoliators (Lepidoptera, Orthoptera, and Phasmida), stipe borers (Coleoptera: Scarabaeidae, and Curculionidae), and sap feeders (Hemiptera). Pest profiles differ among regions and palm species. However, today, many species are found on all continents and new, accidentally introduced insect species have become invasive and a serious threat to palms. There are polyphagous species that can feed on fronds as adults, whereas others spend their entire developmental cycle on palms, with some specialist species living only in these trees. This chapter focuses on major insect pests associated with ornamental and cultivated palms. Their relative importance and distribution by climate and host species will be addressed. (Resume d'auteur)

International audience; Laboratory and field investigations to identify and evaluate plant co-attractants of the aggregation pheromone of the date palm pest Oryctes agamemnon are reported. Volatiles emitted by freshly cut palm core and palm core with feeding males, were collected, analyzed by gas chromatography coupled to mass spectrometry and evaluated in olfactometers alone or combined with synthetic pheromone. A collection of palm odor without male effluvia was attractive alone and enhanced attraction to synthetic pheromone in an olfactometer similar to that to a collection of palm odor emitted with feeding males and containing natural pheromone. Behavioral responses to collections of palm volatiles were correlated to the amount of volatiles material in them. Enhancement of the attractiveness of the pheromone was not correlated to chemicals specific to beetle feeding. The chemicals common to the active collections extracts were benzoate esters, mostly ethyl benzoate, anisole derivatives and sesquiterpenes. Blends of the most abundant components of the extracts were evaluated for enhancement of the attractiveness of pheromone (1 mu g) in olfactometers at 1 or 10 mu g doses. The mixtures were further evaluated by field trapping in Tunisia at 3-10 mg/day using reference (6 mg/day) or experimental pheromone formulations. A mixture of ethyl benzoate, 4-methylanisole and farnesol (1:1:1 w/w at 6.5 mg/day) enhanced captures in pheromone baited traps in 2014 and 2015 and this mixture was as active as the natural palm bait. The practical prospect of the result for the management for O. agamemnon, and other palm beetles is discussed.

Red palm weevil (RPW) ecology is characterized by the adults' ability to aggregate on palms. The aggregation process has the functions of protection, feeding, and reproduction for the individuals. Semiochemicals and visual cues strongly influence this behavior at intraspecific and interspecific levels. Adults actively fly over long distances, following chemical cues, such as aggregation pheromone and host plant odor, or visual cues to colonize a new host. The aggregation pheromone of RPW is a male-produced mixture of 4-methyl-5-nonanol (major component) and the related ketone 4-methyl-5-nonanone (minor component). These compounds are largely used in the field to lure males and especially females to traps. Visual cues also play a role, as color vision in RPW is tuned to the detection and recognition of conspecifics and to the contrast created by vegetation on the sky's UV-rich background. The role of host plant odor, the so-called kairomone, in host plant-finding behavior has been evidenced in field studies. Ethyl acetate and ethyl alcohol, abundant in the odor emitted by wounded or infested palms and by other fermenting plant material, contribute to the attraction. It is likely that the RPW use particular mixtures of compounds rather than a "palm-specific" one to orient and recognize the host. In this process, visual cues are also likely to play a role, as it has been inferred that the RPW has well-developed color vision and may be attracted by the dark holes in the palm trunk for oviposition, or the red color of its cuticle. This chapter describes the RPW's intra- and interspecific behaviors. Flight capability and chemical and visual cues that influence mating, aggregation, and host finding are outlined.

The invasive red palm weevil, Rhynchophorus ferrugineus (Olivier) (Coleoptera: Dryophthoridae) has become the main pest of palms. Because of the cryptic habits of the adult, little is known about the precise movements on palms and the actual dispersal capability in a population. Such data would help to improve risk assessment and management. Miniature radio tags have been increasingly used to monitor movements of animals. In this study, we evaluated the resistance of passive radio frequency identification (RFID) and active radio-transmitters (comprising an antenna) to the burrowing behavior of the insect and their effects on the flight activity. Tagged weevils were placed in boxes filled with fibrous plant material. After 1 week, ca. 90% of insects kept the tag but 83% of the radio-transmitters had a broken antenna. In a screen cage, 100% of insects equipped with RFID flew normally, in contrast to the 17% of insects equipped with active tags. RFID-tagged insects inserted in palm tissue could be easily identified. RFID glued to the thorax affected neither mating behavior nor oviposition. In conclusion, RFID tags appear to be the most efficient tool for tracking the displacement of the weevil in young palms and present new opportunities for promoting studies about gregarious behavior of the red palm weevil on young infected palms.

European corn borer (ECB) neonate larvae are capable of orienting towards maize odours and of avoiding spinach odours. We previously reported that maize odours' attraction was dependent on the stimulus regime. This led us to propose that maize odours could have a repellent or attractive effect depending on their concentration. In this work, we tested this hypothesis by evaluating attraction or avoidance of neonate ECB larvae to four concentrations of each of six single green leaf volatiles (GLVs); these are commonly found in maize and other plants. We found a dose-dependent effect for all of these GLVs with the exception of 1-hexyl acetate, which did not elicit any orientation behaviour over the range of concentrations tested. These five GLVs were repellent at high concentrations, while two of them were attractive at a lower concentration. These observations indicate for the first time that plant odours induce different behaviours in ECB neonate larvae depending not only on their chemical identity but also their concentration.

Olfactory trapping of Scapanes australis is being studied to develop it to complement existing control methods. Components required were traps, pheromone and pheromone synergist. The first two have been developed while field trials carried out to determine an efficient synergist co-attractant is reported. Synthetic synergist mixtures of compounds emitted from fermenting sugarcane were tested in comparison to split stalk of garden grown sugarcane and split bulb of nursery coconut. Some of the mixtures produced synergistic effect similar to sugarcane but lower than split bulb of coconut. Placing live Scapanes adult inside the stalk of sugarcane increased catches similar to the split bulb of coconut. This will enable the formulation of an efficient tool of beetle control.

The beetle pests Scapanes australis, Oryctes rhinocerous and Rhyncophorus bilineatus have been major constraints to coconut production in the Islands region of Papua New Guinea for the last 30 years. Efficient synthetic attractants able to lure and trap all three beetles have been developed. This paper describes several trap designs developed at the Cocoa and Coconut Research Institute and the results obtained for their trapping efficiency in the laboratory and the field. A modification of the "Titus Compound Bucket Trap" increased the number of R. bilineatus caught threefold and of female Scapanes twofold. PVC pipe traps caught more Scapanes than the modified "Titus Compound Bucket Trap". (Resume d'auteur)

Biology of Sphodroxia maroccana Ley and description of the female of this new forest pest (Coleoptera, Melolonthidae). In the Mamora forest (130,000 ha) which is extending along 70 km between Rabat and Kenitra, in Morocco, the endemic Melolonthid beetle Sphodroxia maroccana Ley can be considered as a local pest due to the development of its larvae (white grubs). The success of cork-oak artificial regeneration, by seedling acorns and by transplanting one-year old trees previously grown in nurseries, is locally reduced by very high mortality ranging between 24 and 43% during the first year, according to the plots. The larvae mostly damage seedlings under the collar level. The female of S. maroccana had never been observed previously and is described in this paper. The breeding period occurs in summer (July). The females, twice bigger than males, are unable to fly. During 3-4 hours in the afternoon till dusk, the females attract the males using a sex pheromone and mate at the entrance of tunnels dug in the sandy soil. Females oviposite 50-100 eggs in their life. The larval development is estimated to last 3 to 5 years. Anthropogenic degradation of the forest (mostly grazing) is likely partly at the origin of the recent record of S. maroccana as a forest pest in the Mamora forest., Dans la forêt de la Mamora (130000 ha), qui s'étend au Maroc entre Rabat et Kénitra, l'espèce endémique Sphodroxia maroccana Ley peut être considérée localement comme un nouveau ravageur. Ses larves (vers blancs) s'attaquent aux racines et au collet des plantules de chênes-lièges issus des glands et des jeunes plants (un an) repiqués de pépinière, compromettant les efforts de restauration de la forêt entrepris avec cette essence. Ainsi la mortalité enregistrée dès la première année du fait uniquement des attaques des vers blancs varie entre 24 et 43% selon les parcelles, à laquelle s'ajoutent d'autres facteurs de mortalité comme la sécheresse estivale. La femelle de S. maroccana, qui n'avait jamais été observée précédemment, est décrite ici. La période de reproduction a lieu en été, essentiellement en juillet. Les femelles, deux fois plus grosses que les mâles, sont incapables de voler. A partir du milieu de l'après-midi, avec un pic d'activité pendant les deux heures qui précèdent le crépuscule, les femelles attirent les mâles en utilisant une phéromone sexuelle. L'accouplement a lieu à l'entrée d'un terrier creusé dans le sol sablonneux de la forêt. Les femelles pondent entre 50 et 100 œufs. Le développement larvaire dure de 3 à 5 ans. La dégradation du milieu forestier due aux activités humaines (surpâturage notamment) paraît en grande partie responsable du passage récent de cette espèce du statut d'endémique discret à celui de ravageur de la forêt de la Mamora., Montreuil Olivier, Ghaioule Driss, Maatouf Noreddin, Rochat Didier, Lumaret Jean-Pierre. Biologie de Sphodroxia maroccana Ley et description de la femelle de ce nouveau ravageur forestier (Coleoptera, Melolonthidae). In: Bulletin de la Société entomologique de France, volume 109 (3), août 2004. pp. 317-321.

Laboratory and field investigations were carried out to investigate the nature and role of the male pheromone emitted by the Dynast beetle Scapanes australis and to develop a mass trapping technique against this major coconut pest in Papua New Guinea. We report the biological data obtained from natural and synthetic pheromone, previously described as an 84:12:4 (w/w) mixture of 2-butanol (1), 3-hydoxy-2-butanone (2), and 2,3-butanediol (3). EAG recordings from natural and synthetic pheromone and a pitfall olfactometer were poorly informative. In contrast, extensive field trapping trials with various synthetic pheromone mixtures and doses showed that 1 and 2 (formulated in polyethylene sachets in 90:5 v:v ratio) were necessary and sufficient for optimum long-range attraction. Beetles were captured in traps baited with racemic 1 plus 2, with or without a stereoisomer mixture of 3 (2.5- to 2500-mg/day doses). Plant pieces, either sugarcane or coconut, enhanced captures by the synthetic pheromone, which was active alone. Traps with the pheromone caught both sexes in a 3:2 female–male ratio. A pheromone-based mass trapping led to the capture of 2173 beetles in 14 traps surrounding 40 ha of a cocoa-coconut plantation. The captures followed a log-linear decrease during the 125-week trapping program. The role of the male pheromone and its potential for crop protection are discussed.

International audience; Laboratory and field investigations aimed to characterize the chemical communication system of the date palm pest Oryctes agamemnon. Live males or extracts of male effluvia attracted conspecifics in an olfactometer, whereas female effluvia attracted only males. Volatile emissions from adults feeding on sugarcane were sampled and analysed by gas chromatography (GC) and GC/mass spectrometry (GC/MS). Males emitted a blend of 1) ethyl 4-methyloctanoate, 2) 4-methyloctanoic acid, 3) 4-methyloctanyl acetate, and 4) 4-methyloctanol in variable ratio. Single sensillum recordings demonstrated that compounds 1, 2, and 3 are detected by specific olfactory receptor neurons. Olfactometric experiments showed that compounds 1 and 3 attract both sexes of O. agamemnon, but females are more attracted by compound 1 and males by compound 3. Compound 2 was more attractive for females, especially virgin ones. Field experiments confirmed that compound 1 and compound 2 attracted O. agamemnon of both sexes and showed synergy with palm odors. No clear activity of compound 3 was observed. A mix of compounds 1 and 2 with date palm core odor was significantly the most attractive, and captured more females than males. The male aggregation pheromone of O. agamemnon appears therefore to be based on a mixture in contrast to previously identified Oryctes pheromones. Our results provide the basis for developing mass trapping to control this pest.

Solid-phase microextraction (SPME) samplings from live insects or natural secretion allowed one to identify the aggregation pheromones of the pest beetles Scapanes australis and Strategus aloeus by efficient and rapid isolation of their highly volatile (72

Scapanes australis is a major coconut pest, endemic in Papua New Guinea. Early in the night, males placed singly into artificial galleries made in young coconut palms exhibited a sex specific calling behaviour for 0 to 1.5 h. Coming to the gallery entrance, they raised the abdomen and the hind legs, the head lowered inside the gallery, and emitted a liquid secretion, rhythmically smeared by crossing the legs. Females, which did not behave so, were very mobile. The adult flying period coincided with the male calling behaviour. In field assays with caged insects on coconut palms, attraction of both sexes to males was evidenced when they were calling. Males fought for gallery possession at a male arrival. No aggression but mating was observed with arriving females, which proved not to have developed oocytes. The strong male attraction was confirmed using automatic traps, baited with one live male in a sugarcane piece. Males were assumed to release an aggregation pheromone. Further studies are underway to identify the putative pheromone.

Thirteen host-plant kairomone blends, including 28 compounds, were tested and showed moderate to high synergy with rhynchophorol. The blends plus rhynchophorol also attracted the related Dynamis borassi. Ethanol–ethyl acetate blends in various ratios showed moderate synergy. Two blends, including "characteristic coconut" odor molecules, were as efficient as sugarcane in synergizing rhynchophorol and field luring American Palm weevils (APWs). Preliminary olfactometer tests of natural host-plant volatiles demonstrated the role of fermentation in primary APW attraction. The synergists were chosen from a comparative study of the odors emitted by four plant materials attractive to the APW: sugarcane, coconut, Jacaratia digitata tree and Elaeis guineensis (Oil palm). The volatiles were isolated during 6 days of sequential trappings onto Supelpak-2 adsorbent. The highly volatile fraction of sugarcane volatiles was sampled by solid-phase microextraction (SPME). Odors were analyzed and identified by gas chromatography and mass spectrometry. Electroantennogram responses to the plant odors were recorded to help in screening for bioactivity. The odor compositions between plants prior to and during fermentation were compared using a principal component analysis (PCA) to determine common odor features of the plants and to design simplified blends for field activity screening. About 100 components were identified in the >4-carbon fraction of the odors, among which 65% were fermentation volatiles. Fermentation generated a strong increase in the amount and variety of the volatiles emitted. The palm materials emitted two- to threefold greater odor amounts than the other plants. The odors from each plant were distinct according to PCA, with few common abundant components: isopentanol, 2-methylbutanol, their acetates, acetoin, isobutyl acetate, 2,3-butanediol, and 2-phenylethanol. Ethanol and ethyl acetate accounted for 80–90% in the highly volatile fraction of sugarcane odors. Coconut odor was mainly characterized by phenol, guaiacol, 1,2-dimethoxybenzene, ethyl esters of tiglic and 3,3-dimethylacrylic acids, 2-hexanone, 2-nonanone; and, to a lesser extent, by 2-heptanone, menthone, β-phellandrene, ethyl octanoate and decanoate, which were also present in other plants.

Many animals rely on chemical cues to recognize and locate a resource, and they must extract the relevant information from a complex and changing odor environment. For example, in moths, finding a mate is mediated by a sex pheromone, which is detected in a rich environment of volatile plant compounds. Here, we investigated the effects of a volatile plant background on the walking response of male Spodoptera littoralis to the female pheromone. Males were stimulated by combining pheromone with one of three plant compounds, and their walking paths were recorded with a locomotion compensator and analyzed. We found that the addition of certain volatile plant compounds disturbed the orientation toward the sex pheromone. The effect on locomotion was correlated with the capacity of the plant compound to antagonize pheromone detection by olfactory receptor neurons, suggesting a masking effect of the background over the pheromone signal. Moths were more sensitive to changes in background compared to a constant background, suggesting that a background odor also acts as a distracting stimulus. Our experiments show that the effects of odorant background on insect responses to chemical signals are complex and cannot be explained by a single mechanism.

The diastereoselective synthesis of (1S∗, 3R∗, 5R∗, 7S∗) 2,8-dioxa 1-ethyl 3,5,7-trimethyl bicylo [3,2,1] octane 1d has been achieved using as key-step the regioselective Baeyer-Villiger reaction of 2,6-disubstituted cyclohexanone. It confirms the identification of a new male pheromone emitted by the banana weevil, Cosmopolites sordidus. The trivial name sordidin is proposed.

Sex pheromones are released by adults of a species to elicit a sexual interaction with the other sex of the same species. Here we report an unexpected effect of a moth sex pheromone on the caterpillars of the same species. We demonstrate that larvae of the cotton leafworm Spodoptera littoralis are attracted by the moth sex pheromone and that this phenomenon is independent of sex determination. In addition, we show that the olfactory sensilla carried by the caterpillar antennae are sensitive to the pheromone and that the caterpillar sensilla express pheromone-binding proteins that are used by adult antennae to bind pheromone components. Finally, we demonstrate that the larvae are preferentially attracted to a food source when it contains the sex pheromone main component. A possible interpretation of these results is that the sex pheromone is used to promote food search in caterpillars, opening potential new routes for insect pest management.

Background Many behavioral responses to odors are synergistic, particularly in insects. In beetles, synergy often involves a pheromone and a plant odor, and pest management relies on them for the use of combined lures. To investigate olfactory synergy mechanisms, we need to distinguish synergistic effects from additive ones, when all components of the mixture are active. Results As versatile tools and procedures were not available, we developed a bioassay, and a mathematical model to evaluate synergy between aggregation pheromone (P) and host plant odors (kairomone: K) in the American palm weevil, a pest insect showing enhanced responses to P+K mixtures. Responses to synthetic P and natural K were obtained using a 4-arm olfactometer coupled to a controlled volatile delivery system. We showed that: (1) Response thresholds were ca. 10 and 100 pg/s respectively for P and K. (2) Both stimuli induced similar maximum response. (3) Increasing the dose decreased the response for P to the point of repellence and maintained a maximum response for K. (4) P and K were synergistic over a 100-fold range of doses with experimental responses to P+K mixtures greater than the ones predicted assuming additive effects. Responses close to maximum were associated with the mixture amounts below the response threshold for both P and K. Conclusion These results confirm the role of olfactory synergy in optimizing active host-plant localization by phytophagous insects. Our evaluation procedure can be generalized to test synergistic or inhibitory integrated responses of various odor mixtures for various insects.

The enantioselective synthesis of both (4R,5R)- and (4S,5S)-4-methyl-5-nonanol (1) was achieved by starting from an optically active epoxide 5. A GC comparison on a chiral stationary phase of the synthetic enantiomers of 1 with the naturally occurring 1 was executed, and (4S,5S)-1 was shown to be identical with the natural 1 isolated as the male-produced pheromone compound of the weevils Rhynchophorus vulneratus and Metamasius hemipterus.

The relative configuration of the naturally occurring 3-methyl-4-octanol (1), the male-produced aggregation pheromone of Rhynchophorus phoenicis, was determined as syn by a GC comparison of the synthetic (±)-syn- and (±)-anti-1 with the natural product. Enantioselective synthesis of both (3R,4R)-and (3S,4S)-1 was achieved by starting from the optically active epoxide 9, and the natural product was shown to be (3S,4S)-1 by a GC comparison on a chiral stationary phase.

The diastereoselective synthesis of (1S∗, 3R∗, 5R∗, 7S∗) 2,8-dioxa 1-ethyl 3,5,7-trimethyl bicylo [3,2,1] octane 1d has been achieved using as key-step the regioselective Baeyer-Villiger reaction of 2,6-disubstituted cyclohexanone. It confirms the identification of a new male pheromone emitted by the banana weevil, Cosmopolites sordidus. The trivial name sordidin is proposed.

International audience; In moths, the components of the female pheromone blend are detected in the male antennae by pheromone olfactory receptor neurons (Ph-ORNs) expressing narrowly tuned olfactory receptors. Responses to sex pheromones have generally been thought to be independent from the odorant background. However, interactions between pheromone components and plant volatiles have been reported at behavioral and detection levels. To document the mechanisms of such interactions, we analyzed Ph-ORN responses of Spodoptera littoralis to the main pheromone component, Z9E11-14:Ac, in the presence of 4 monoterpenes. To mimic natural contexts in which plant odors and pheromone emanate from different sources, the 2 stimuli were presented with different temporal patterns and from independent sources. Linalool reversibly reduced the firing response to Z9E11-14:Ac and produced an off effect. Geraniol and geranyl and linalyl acetates reduced the responses to Z9E11-14:Ac with a longer time course. Pulses of linalool over prolonged pheromone stimulation resulted in a discontinuous firing activity. Pulses of pheromone were better separated over a background of linalool, compared with odorless air. The data confirm that plant compounds may modulate the intensity and the temporal coding by Ph-ORNs of pheromone information. This modulation might positively affect mate location at high pheromone density especially nearby a pheromone source.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; Lepidoptera larvae are capable of orienting towards or away from plants by using odors as cues but whether this attraction is innate or secondarily acquired remains unknown. We tested the hypothesis that European corn borer (ECB) neonate larvae express an innate attraction towards odors released from maize, and avoidance towards odors from spinach. Neonate larvae were placed on a locomotion compensator within a constant stream of humidified air that was loaded intermittently with airborne odors drawn from potted plants. The odor stream was delivered continuously or pulsed (1 to 10 sec pulses) at 40 ml/min. ECB larvae oriented toward maize odors pulsed at 2 to 6 sec but walked away from maize odors delivered at lower frequencies (9 and 10 sec pulses or to continuous ones). They consistently walked away from spinach odors, irrespective of the pulsing regime except at 1 sec pulses that did not elicit orientation. We further explored odor intensity on orientation towards maize odors by adjusting the odor stream intensity. At higher intensity (60 ml/min), the direction reversal started at the 6 sec half period, while at lower intensity (20 ml/min), it showed up only for the continuous stimulus. ECB larvae exhibit a striking ability to lock on to a direction, which they maintained despite gaps of up to 10 sec in the odor stream. Our results demonstrate that ECB neonate larvae express innate orientation preferences towards natural odors from plants. These reactions correlate well with the biological value of these plants for ECB: maize generally is accepted by ECB larvae and adults, while spinach represents a poor host because it produces (nonvolatile)

International audience; Field trapping of the American palm weevil (APW),Rhynchophorus palmarum, showed that the combination of caged male APWs and palm stem was much more attractive to APWs of both sexes than palm stem alone. Caged female APWs did not enhance the attractiveness of the palm. Caged APWs without palm stem were not attractive. Virgin laboratory-bred males were highly attractive to APWs of both sexes in a two-choice pitfall olfactometer, whereas virgin laboratory-bred females were not. Adsorbenttrapped volatiles from virgin laboratory-bred males reproduced the effect of living males, giving evidence for a male-produced aggregation pheromone in this species. Wild-mated APWs of both sexes were as responsive to the aggregation pheromone as virgin laboratory-bred APWs. This is the first record of chemical communication in this species. These results have prompted investigations into the chemical identification of the aggregation pheromone.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; Oryctes monoceros is a serious coconut pest, causing LIP to 40% damage in tropical Africa. Synthetic aggregation pheromone, ethyl 4-methyloctanoate, has been used to lure adults to traps. Traps with pheromone Plus decaying palm material captured a high proportion of males. This raises the question whether individuals, which damage palms are receptive to the pheromone. We studied the sex ratio of the insects feeding on coconuts and those attracted to pheromone traps. Sixty two percent of adults from feeding galleries on living coconut palms were females. Pheromone with rotting palm material lured 43% females. To investigate the reasons for this difference, we compared the reproductive system of females lured to the odour traps or feeding in coconut galleries, or present in old rotting stems. Ninety six percent of the females trapped by pheromone had mated, and were sexually mature. In the galleries on living palms, 46% of females were immature, and 24% had not mated. In old rotting stems where eggs are laid and larvae develop, a mixture of 52% mated and 48% virgin females was found. Therefore, the pheromone together with the odour of rotting coconut stems signals a reproduction site to beetles, particularly mature females. In practice, the pheromone-baited traps will help in reducing the dissemination of gravid females, but will not affect directly the numbers Of immature ones attacking palms. Our results Show that when using pheromones for monitoring or controlling insects, the physiological status of the insects may have unexpected effects on the outcome.

Circadian rhythms are observed in mating behaviors in moths: females emit sex pheromones and males are attracted by these pheromones in rhythmic fashions. In the moth Spodoptera littoralis, we demonstrated the occurrence of a circadian oscillator in the antenna, the peripheral olfactory organ. We identified different clock genes, period ( per), cryptochrome1 ( cry1) and cryptochrome2 ( cry2), in this organ. Using quantitative real-time PCR (qPCR), we found that their corresponding transcripts cycled circadianly in the antenna as well as in the brain. Electroantennogram (EAG) recordings over 24 h demonstrated for the first time a circadian rhythm in antennal responses of a moth to sex pheromone. qPCR showed that out of one pheromone-binding protein (PBP), one olfactory receptor (OR), and one odorant-degrading enzyme (ODE), all putatively involved in the pheromone reception, only the ODE transcript presented a circadian rhythm that may be related to rhythms in olfactory signal resolution. Peripheral or central circadian clock control of olfaction is then discussed in light of recent data.

National audience; Au cours des dernières décennies, les essais de régénération du chêne-liège en forêt de la Mamora se sont heurtés à des attaques massives de vers blancs sur les racines des jeunes plants, avec un taux de réussite des plantations ne dépassant guère 12% dans la majorité des parcelles de régénération. La biologie de Sphodroxia maroccana Ley (Coleoptera : Melolonthidae), le ravageur principal, a été en partie élucidée, avec encore des lacunes concernant la période exacte d’émergence des mâles par rapport aux femelles, la longévité des imagos et la sex-ratio. La sècheresse estivale est parmi les autres causes de dépérissement des jeunes plants. Lors de la première année suivant la plantation dans des parcelles expérimentales, la mortalité cumulée due aux attaques larvaires et à la sécheresse a varié entre 41% et 68% selon les blocs considérés dans les parcelles. La mortalité liée aux attaques des larves de S. maroccana était comprise entre 24 et 43%, avec une distribution en taches des dégâts, plus ou moins importantes selon la densité initiale des plants. L’isolement par micro-extraction en phase solide des effl uves femelles de S. maroccana a permis d’identifier le résorcinol (1,3-benzènediol) comme composé phéromonal présumé. La fonction de cette molécule comme phéromone reste toutefois à démontrer.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; Oryctes monoceros is the most serious pest in coconut plantations, causing up to 40% damage in tropical Africa, especially in Ivory Coast. With a view to reducing pest populations by olfactory trapping, field trials were carried out to assess the efficiency of a synthetic aggregation pheromone: ethyl 4-methyloctanoate (1), 4-methyloctanoic acid (2), a related volatile produced by males, and decaying palm material, either oil palm empty fruit bunches (EFB) or pieces of coconut wood (CW) of various ages. Vertical polyvinyl chloride tube traps (2 x 0.16 m with two openings in the upper half), embedded in the soil, were more efficient than 30-L pail traps 1.5 m above ground. EFB, which were inactive alone, synergized captures with synthetic pheromone. CW was more effective than EFB in comparative trials. Compound 2 did not catch any beetles when assessed with EFB, and reduced catches by 1 + EFB when tested at > 10% with the pheromone. Trapping over 6 mo in 2002 and 2003 in a 19-ha coconut plot inside a 4,000-ha oil palm estate reduced damage from 3.8% in 2001 to 0.5% in 2002, then to 0.2% in 2003. Damage was 0.0% in 2004 with routine trapping using 32 traps, which caught 3369 beetles in 9 mo. The results are discussed in relation to other Dynastid palm pests and coconut protection in Ivory Coast.

International audience; We adapted a four-arm olfactometer (55 x 55 x 5.5 cm) for bioassays of large insects and its usefulness was evaluated by testing the responses of three beetles, the palm weevil Rhynchophorus palmarum (L.) (Coleoptera: Curculionidea) and two Dynast scarabs Strategus aloeus (L.) and Oryctes rhinoceros (L.) (Coleoptera: Scarabaeidae) to plant odours and aggregation pheromones. This olfactometer was coupled to a volatile delivery system dispensing highly volatile semiochemicals at constant concentrations. We materialized airflows in the olfactometer by discolouring sensitive papers with acid vapours under various conditions (air straighten by stainless steel grids in inputs and output, 500 ml/min per arm) to visualize air turbulence and to test air-tightness. The volatile delivery system can be used to mix and dispense a broad range of concentrations of semiochemicals in air from diluted aqueous solutions. It was calibrated by measuring the release of the pheromone using solid phase-microextraction (SPME). Dose-response curves to synthetic pheromone were obtained for O. rhinoceros of both sexes. Coupling the volatile delivery system to the fourarm olfactometer provided a system with which the responses of R. palmarum and S. aloeus to their synthetic aggregation pheromones and to natural plant volatiles could be readily observed and studied.

Aggregation of Rhynchophorus palmarum weevils on host plants is mediated by a male pheromone (rhynchophorol: R) and host-plant volatiles (PVs) acting in synergy. Synthetic PV blends synergizing pheromone contain acetoin (A) and ethyl acetate (EtAc). R, A, and EtAc are detected by specialized olfactory receptor neurons (ORNs). In addition, particular types of ORNs are tuned to both A and R. To specify the role played by acetoin in pheromone perception, we recorded the responses of ORNs to 100 ng of A or R presented either separately or mixed. Behavioral responses to R, A, and EtAc were studied in a four-armed olfactometer and by field trapping. We screened 59 R-, A-, and AR-tuned ORNs by recording specific responses to odors presented either separately or mixed. Stimulations by blends elicited complex response profiles from the three ORN types: some gave synergistic responses, others were inhibited, and the remainder responded as though both odors were detected independently. Several gave either a weak or no response to a first stimulation by R, but responded clearly to a second stimulation after an intercalary stimulation by A. In the olfactometer, both sexes were more attracted to a blend of A + R (1 + 0.01 ng/sec) than to pure compounds, whereas EtAc did not enhance response to R. Pheromone-baited traps (1 mg/day) containing PV blends (650 mg/day) based on an ethanol/EtAc blend (1:1), plus either 5 or 10% A, or a more complex reference blend, or sugarcane (natural pheromone synergist), caught similar numbers of weevils and about twice as many insects as a control ethanol/EtAc blend. Traps with only pheromone caught about 10 times fewer insects. Behavioral results support the role of acetoin as a pheromone synergist for R. palmarum, and electrophysiological data provide evidence of modulation of peripheral sensory responses to pheromone by acetoin. Sexual dimorphism was observed neither at the ORN nor at the behavioral levels.

International audience; Laboratory and field investigations were carried out to characterize the chemical communication system of the date palm fruit stalk borer, Oryctes elegans, and to develop pheromone-based trapping in Eastern Iran. Adults of both sexes feeding on date palm pieces attracted conspecifics, whereas date palm alone was minimally attractive. Males were twice as attractive as females. More beetles were captured at the palm crown than at ground level. Odors from adults feeding on sugarcane were sampled and analyzed by gas chromatography and mass spectrometry. Whereas females did not emit sex specific volatiles, males emitted a blend of 4-methyloctanoic acid (1: major component) and ethyl 4–methyloctanoate (2), occasionally mixed with minor components: 4-methyloctanyl acetate (3), methyl 4-methyloctanoate (4), 4-methyloctanol (5), and nonanyl acetate (6). Electroantennography and field trapping experiments demonstrated that compound 1 is an essential component of the male aggregation pheromone of O. elegans. It was barely attractive by itself but synergistic with fresh date palm odor. It attracted many more beetles than any of compounds 2–6. The addition of one or several of compounds 2–6 to 1 did not improve trap captures. During the course of 2 years, we captured 4000 beetles, with a weekly average of 6.3 beetles/trap, and were able to monitor the seasonal flight of O. elegans. Our results provide the basis for developing mass trapping for control of this pest.

The distribution, fine structure and function of the sensilla present on the antennal club of Rhynchophorus palmarum were studied. No sex dimorphism was observed. Scanning and transmission electron microscopy showed five types of hair-like structures, four of which were evenly distributed on the antennal club. Two types of hair (IV and V) showed wall pores, a characteristic of olfactory sensilla. The antenna numbers 11,190 ± 3040 type IV and 7360 ± 1500 type V hairs. Using single sensillum recording, we identified 17 types of olfactory receptor neurons (ORNs) on the basis of their responses to pheromone and host plant odors, triggering synergic behavioral responses. We characterized highly specific and sensitive ORNs tuned to the aggregation pheromone (18% ORNs; 0.01–1 ng response threshold) and to host plant odors such as ethyl acetate, ethanol, acetoin and guaiacol (10% ORNs; 1–10 ng response threshold). Eleven percent of the ORNs were more generalist, responding to several odors with low sensitivity. Nine percent of the ORNs showed a complex pattern of responses, being co-activated by the pheromone and plant odors. This suggests an interaction at the sensory neuron level between pheromone and plant odors, triggering synergic behavioral responses.

Laboratory and field investigations were carried out to investigate the nature and role of the male pheromone emitted by the Dynast beetle Scapanes australis and to develop a mass trapping technique against this major coconut pest in Papua New Guinea. We report the biological data obtained from natural and synthetic pheromone, previously described as an 84:12:4 (w/w) mixture of 2-butanol (1), 3-hydoxy-2-butanone (2), and 2,3-butanediol (3). EAG recordings from natural and synthetic pheromone and a pitfall olfactometer were poorly informative. In contrast, extensive field trapping trials with various synthetic pheromone mixtures and doses showed that 1 and 2 (formulated in polyethylene sachets in 90:5 v/v ratio) were necessary and sufficient for optimum long-range attraction. Beetles were captured in traps baited with racemic 1 plus 2, with or without a stereoisomer mixture of 3 (2.5- to 2500-mg/day doses). Plant pieces, either sugarcane or coconut, enhanced captures by the synthetic pheromone, which was active alone. Traps with the pheromone caught both sexes in a 3:2 female-male ratio. A pheromone-based mass trapping led to the capture of 2173 beetles in 14 traps surrounding 40 ha of a cocoa-coconut plantation. The captures followed a log-linear decrease during the 125-week trapping program. The role of the male pheromone and its potential for crop protection are discussed.

Oryctes rhinoceros (Scarabaeidae, Dynastinae) trapping is possible with the pheromone (ethyl 4-methyloctanoate) as the attractant. This article describes a new type of trap that functions without insecticides or water, and can remain in place for several months without any particular maintenance so long as the attractant does not run out. As it is 2 m tall, it offers the advantage of having the silhouette of a palm stem, which is visually attractive to this insect. (Resume d'auteur)

The five synthetic pheromone components of the West Indian sugarcane borer (WISB), Metamasius hemipterus (L.) (Coleoptera, Curculionidae) were tested in the field. The combination of sugarcane (SC) and the major pheromone compound, 4-methyl-5-nonanol (1) was attractive. However, the addition of 2-methyl-4-heptanol (2) or 2-methyl-4-octanol (3) was required to reach high catch levels while 5-nonanol (4) or 3-hydroxy-4-methyl-5-nonanone (5) did not enhance WISB attraction. The redundancy phenomenon, here reported for the first time in rhynchophorinous species, was observed between compounds 2 and 3. SC + 1 + 3 was more attractive than living male baits, however, the sex-ratio of the catches was equivalent between both treatments. The sex-ratio of catches was affected by the qualitative composition of the pheromone formulation. Compound 3 had a sexual role, attracting more females while 5 seemed to play an aggregation role, luring both sexes in the same proportion.

Cette etude rapporte l'utilisation d'une technique de microextraction en phase solide (SPME) pour collecter la pheromone d'un insecte, le charancon de la canne a sucre (Metamasius hemipterus), ainsi que pour etudier du rythme quotidien d'emission de pheromones par cette espece. Comparee aux approches classiques d'echantillonnage de pheromones, la SPME est une technique qui n'utilise pas de solvants. L'utilisation de cette technique d'extraction permet de reduire la duree d'une analyse en chromatographie gazeuse (elution des 5 composants de la pheromone en 10 minutes). Cette technique plus rapide, moins chere, reproductible et facile d'utilisation est une alternative puissante et appropriee pour l'analyse de composes volatiles emis par des insectes vivants

Male American palm weevils (APWs),Rhynchophorus palmarum (L.) produced two sex-specific compounds, which were disclosed by volatile collections on Supelpak-2 and gas chromatography. One was a minor compound, not always detected. The major male-produced volatile was identified as (2E)-6-methyl-2-hepten-4-ol through coupled gas chromatography-mass spectrometry and gas chromatography-Fourier transform infrared spectrometry, proton nuclear magnetic resonance spectrometry, and rational synthesis. We propose the trivial name rhynchophorol for this new molecule, which proved to be the essential component of the APW aggregation pheromone by electroantennography, coupled gas chromatography-electroantennography and behavioral bioassays.

Scapanes australis# is a major insect pest of coconut palms in Papua New Guinea. Field observations showed that on host plants like coconuts, male #Scapanes# always attracted females and other male members. Bucket traps were developed to lure #Scapanes# beetles using live males as attractant (bait). Live males feeding on sugarcane were placed singly in an inner bucket within a 10 litres bucket container with rectangular holes at the side for insect entry and soapy water inside for drowning the insects. #Scapanes# populations were continuously monitored by traps and results indicated a gradual decline in the #Scapanes# population over time. Traps were also placed in the field to see if losses to coconuts used by #Scapanes# can be reduced. Results indicated that the reduction in trap catches was not consistent. Further studies are required to study the physiological behavior of male #Scapanes# and to improve the technique of trapping of #Scapanes# with male member alone. The role of trapping #Scapanes# in pest management is discussed. (Resume d'auteur)

The upwind flight and landing responses of male Mamestra suasa (Den. & Schiff.) (Lepidoptera; Noctuidae) to various synthetic chemicals were studied in a wind tunnel. Amixture of (Z)-11-hexadecenyl acetate (Z11–16:Ac) and (Z)-11-hexadecenal (Z11–16:Ald) elicited upwind flight responses past the midpoint of the wind tunnel, and both components were necessary for landing of the males to occur at the pheromone source point. The best response to the mixtures tested was to a ratio 100:1 (ng) of Z11–16:Ac and Z11–16:Ald (blend B). The addition of (Z)-9-tetradecenyl acetate (Z9–14:Ac) (10 ng) to blend B resulted in a significant decrease of upwind flight and landing responses. The inhibitory effect of this chemical when it is mixed with blend B, and the presence of a specific receptor for this compound in sensilla trichodea of male M. suasa, suggest that Z9–14: Ac is involved in the chemical communication between M. suasa and other sympatric species. The addition of (Z)-11-hexadecenol (Z11–16: OH) (1 or 10 ng) to blend B had no effect on male upwind flight and landing responses. This compound does not seem to be involved in the chemical communication of this species. Resume Etude en tunnel de vol des reponses des mâles de Mamestra suasa a des composes pheromonaux de synthese. L'observation et la comptabilisation des vols orientes et des atterrissages des mâles de Mamestra suasa (Den. & Schiff.) (Lepidoptera; Noctuidae) sur une source de pheromone de synthese ont mis en evidence un melange attractif appele melange B et constitue par 100 ng de Z11–16: Ac et 1 ng de Z11–16: Ald. L'attraction et l'atterrissage sont sous la dependance du melange de ces 2 composes. Les variations de leurs proportions relatives affectent les differentes phases du comportement de vol des mâles. L'addition de 10 ng d'acetoxy-1 tetradecene-9 Z (Z9–14: Ac) diminue significativement les proportions de vols orientes et d'atterrissages par rapport aux reponses obtenues avec le melange B seul. L'effet inhibiteur de cette molecule sur l'attractivite du melange B et la presence chez M. suasa d'un recepteur specialise dans la perception de ce compose suggerent que le Z9–14: Ac est implique dans la communication chimique entre M. suasa et d'autres especes sympatriques. L'addition d'hexadecenol-11 Z (Z11–16:OH) au melange B a la dose de 1 ou 10 ng ne modifie pas les reponses des mâles. Ce compose ne semble pas implique dans la communication chimique chez M. suasa.