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The blister beetle Epicauta atomaria (Germar) (Coleoptera: Meloidae) is a phytophagous pest of various agricultural crops, especially in Amaranthaceae, Solanaceae, and Fabaceae. Currently, this insect is managed through the spraying of synthetic insecticides that cause serious human health and environmental damage. To reduce the use of synthetic insecticides, the integrated pest management (IPM) programs for other crop pests rely on the use of semiochemical compounds, such as pheromones, kairomones, and allomones, to manipulate the insects' behavior to prevent crop damage. However, studies on semiochemical compounds related to E. atomaria have never been carried out. For this reason, the aim of this study was to explore the chemical communication of E. atomaria. This includes the existence of (i) a sex and/or an aggregation pheromone, (ii) attractant volatile kairomones from host plants, and (iii) repellent volatile allomones from non‐host plants. Tests were carried out using olfactometers and an experimental arena. First, olfactometer tests failed to show the existence of volatile sex and/or aggregation pheromones of these insects. Second, olfactometer and experimental arena tests failed to demonstrate attraction of E. atomaria via volatile kairomonal compounds from host plants (chard, bell pepper, and cock's‐eggs). However, olfactometer tests showed that non‐host plants of E. atomaria (thyme and lavender) emit allomonal volatile compounds with repellent activity. This work represents a first step toward the elucidation of the chemical ecology of E. atomaria and suggests that volatiles from non‐host plants help shape the host preferences of these insects. Those volatiles could be used as a "push" component in a "push–pull" strategy against this pest. [ABSTRACT FROM AUTHOR]

Although Drosophila suzukii Matsumura (Diptera: Drosophilidae) infests fresh and ripening fruits, it is attracted to fermented fruits as well. Because fermented fruits attract other flies too, if D. suzukii utilizes fermented fruits as oviposition substrates, competition can be more intense on them. To avoid such competition, D. suzukii may change oviposition preference when particular species of competitor flies are present, but the effect of odor cues associated with competitors on the oviposition preference of D. suzukii is still unknown. To examine such an effect, we investigated the oviposition preference of D. suzukii in the presence of four competitor fly species – Drosophila melanogaster Meigen, Drosophila lutescens Malloch, Drosophila rufa Kikkawa & Peng, and Drosophila auraria Peng – and D. suzukii itself. We prepared artificial substrates with yeast treatment (Y+: yeast supplementation, Y−: control) and competitor fly treatment (F+: pre‐inoculated with competitor fly odor, F−: control), and performed two‐choice experiments using the substrates with various Y and F treatments. Our results showed that D. suzukii oviposited more eggs on Y+ substrates than on Y− substrates when no competitor flies were present and the presence of competitor flies influenced D. suzukii's oviposition preference for yeast‐supplemented substrates and its effect changed depending on the competitor fly species. If the presence of competitors around fallen fruits on the ground suppresses D. suzukii's oviposition on the fallen fruits and facilitates the oviposition on non‐fermenting substrates in nature, it may drive D. suzukii to use ripening fruits on the tree. Such selective pressure may facilitate the evolution of morphological traits such as a serrated ovipositor in D. suzukii. [ABSTRACT FROM AUTHOR]

Predators can indirectly reduce herbivory by killing herbivores. In addition, predation risk can influence the feeding rate and feeding location of herbivores. Herbivores are expected to avoid plants currently occupied by a predator. Consequently, less herbivory is expected on plants bearing fresh predator cues. We examined whether wood crickets, Nemobius sylvestris Bosc (Orthoptera: Gryllidae), avoided plants bearing the chemical cues of nursery web spiders, Pisaura mirabilis Clerck ( Araneae: Pisauridae), or red wood ants, Formica rufa L. ( Hymenoptera: Formicidae). We conducted a series of behavioural experiments, in which crickets had the choice between a plant with spider or ant cues vs. a control plant, a plant with spider cues vs. a plant with ant cues, or two control plants. For all plants, we quantified leaf damage and the position and weight change in the crickets. Crickets avoided plants with spider cues. In contrast, ant cues did not significantly deter crickets. The herbivory pattern among the plants reflected the plant choice of the crickets. However, net herbivory was not affected by the presence of predator cues. Thus, our results suggest that spider cues affect feeding location rather than the total amount of herbivory. [ABSTRACT FROM AUTHOR]

The invasive emerald ash borer, Agrilus planipennis Fairmaire ( Coleoptera: Buprestidae), is a major pest of ash trees, Fraxinus spp., in its introduced range in North America. Field studies were conducted to quantify the efficacy of traps baited with kairomone and pheromone lures for early detection of A. planipennis infestation. A trapping experiment demonstrated that green traps baited with the kairomone (3 Z)-hexenol detected at least one adult A. planipennis in 55.3% of plots with 'nil to low'-density infestations and in 100% of plots with 'moderate to high'-density A. planipennis infestations. Mean trap captures increased significantly with increasing infestation density. In terms of the optimal number of traps per plot, when one (3 Z)-hexenol-baited trap was placed per plot, the trap detected populations in 62% of the plots with 'low to moderate'-density infestations through branch sampling. Detectability was increased to 82% when two traps were placed per plot. Finally, addition of female-produced (3 Z)-lactone pheromone to traps significantly increased detection rates at both the trap and plot level, as compared with traps baited with the host volatile, (3 Z)-hexenol, alone (88 vs. 60%, respectively). Our results are the first to demonstrate the efficacy of baited green sticky traps for detecting low-density A. planipennis infestations, particularly when the (3 Z)-lactone pheromone is used. This combination is therefore recommended for development of early-detection protocols against A. planipennis. [ABSTRACT FROM AUTHOR]

Timely detection of western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is important to help prevent economic damage to crops. Coloured traps are commonly used for thrips monitoring and their efficacy can be markedly improved with the addition of semiochemicals such as methyl isonicotinate (MI). However, the behavioural response of thrips to these compounds is poorly understood. In leaf/petal disc laboratory experiments the effect of MI on adult female WFT was examined with respect to walking and take-off behaviour. Clean air or air with MI was blown over the leaf/petal discs at an angle of 30° via a glass pipette connected to a wash bottle containing a cotton dental roll with or without a defined amount of MI. At airspeeds of 0.6-1.2 m s−1 and at doses of 1, 10, 50, 100, and 1000 μl (equivalent to indicative concentrations of 1.7, 4.5, 7.3, 8.8, and 14.9 ng MI l−1 air blown over the leaf discs), WFT spent a greater proportion of time walking on chrysanthemum leaf discs in the presence of MI than the non-attractive thrips compound β-caryophyllene or clean air. Western flower thrips showed a dose-dependent take-off response to the thrips attractant MI, but not to β-caryophyllene (virtually no take-off). At 100 μl of MI (8.8 ng l−1 air), WFT spent a greater proportion of time walking on host plant tissue than in clean air, depending on plant disc substrates. Furthermore, WFT took off more often from plant discs exposed to an air current containing MI than from those exposed to clean air. Western flower thrips exposed to MI took off at a similar rate from chrysanthemum leaves, chrysanthemum flower petals, and sweet pepper leaves, but much less readily from bean leaves. The results show that MI stimulates walking and take-off behaviour for adult female WFT under these experimental conditions and these responses are dose-dependent and mediated by the host plant. These results are placed in the context of previous research on the behavioural response of thrips to semiochemicals and their implications for thrips pest management are discussed. [ABSTRACT FROM AUTHOR]

Responses of macropterous females of the ectoparasitoid Melittobia digitata Dahms (Hymenoptera: Eulophidae) to direct and indirect cues emitted by its natural hosts as well as laboratory hosts were investigated using a Y-tube olfactometer. To locate the nest of mud dauber wasps, Trypoxylon politum Say (Hymenoptera: Crabronidae), and one of their inquilines, Anthrax spec., parasitoids exploit volatiles from the freshly built nest mud and the empty cocoon constructed by the wasps, as well as their meconium. However, the parasitoids did not respond to odors emitted by older nest mud or by the host stages that are attacked ( T. politum prepupae and Anthrax spec. larvae). Melittobia digitata was not attracted to direct volatiles released by the dipteran hosts Anastrepha ludens Loew (Diptera: Tephritidae) (a natural host) and Sarcophaga bullata (Parker) (Diptera: Sarcophagidae) (a laboratory host). Based on our results, we suggest that M. digitata adopts a ‘sit and wait’ strategy to locate mud dauber wasps, relying mainly on indirect host-related cues: females search for nests that are under construction and once found, they wait inside the cell until the host completes its cocoon and releases meconium, an indicator that is associated with host suitability. No attraction was found to dipteran hosts, suggesting that parasitization of these hosts may be incidental, due to the broad host plasticity of Melittobia wasps. [ABSTRACT FROM AUTHOR]

The occurrence of a kairomonal response of the parasitoid Anagyrus spec. nov. near pseudococci (Hymenoptera: Encyrtidae) to (+)-(1 R,3 R)- cis-2,2-dimethyl-3-isopropenyl-cyclobutanemethanol acetate (PcA, namely, planococcyl acetate) and ( S)-(+)-lavandulyl senecioate (LS), the respective female sex pheromones of its hosts, the citrus mealybug, Planococcus citri (Risso) and the vine mealybug, Planococcus ficus (Signoret) (Homoptera: Pseudococcidae) was investigated. Attraction to the pheromones was tested by employing pheromone traps in field trials and by static air olfactometer bioassays in the laboratory. Female wasps showed a significant response to LS, in both field and olfactometer experiments. No significant response was registered to the sex pheromone of P. citri. Despite the similarity between the structures of LS and its analogue ( S) -(+)-lavandulyl isovalerate (LI), no significant response to the latter compound was observed. It seems that differences between the structures of the carboxylate moiety of the respective molecules (LS and LI) markedly affect the kairomonal attractiveness to the parasitoid. The kairomonal response of Anagyrus spec. nov. near pseudococci was neither influenced by the host habitat nor by the host species on which it developed. This suggested innate behaviour of Anagyrus spec. nov. near pseudococci, possibly derived from evolutionary relationships between the parasitoid and P. ficus. The practical implications of the results are discussed. [ABSTRACT FROM AUTHOR]

MaleMelolonthacockchafers are known to use green leaf volatiles induced by female feeding on host plants for their mate location. Earlier studies of the response of the European cockchafer,Melolontha melolonthaL. (Coleoptera: Scarabaeidae), to different green leaf aldehydes, alcohols, and acetates revealed that only green leaf alcohols were attractive to males in the field. Females were not attracted at all by these volatiles. Here, we present a study that aimed to elucidate the structure–activity relationships of aliphatic alcohols. Both behavioural and physiological responses were studied in male and femaleM. melolonthaby field tests and electroantennography. The compounds tested were saturated aliphatic alcohols with chain lengths between five and eight carbon atoms. Furthermore, the cockchafer's response to six-carbon alcohols with (E)-2-, (E)-3-, (Z)-2-, (Z)-3-, and (Z)-4-configurated double bonds was tested. All compounds elicited dose-dependent responses on the antennae of both sexes. In general, males showed a stronger normalized EAG response to the stimuli than females. However, only the naturally occurring six-carbon alcohols, i.e., 1-hexanol (E)-2-, (Z)-3, and (E)-3-hexen-1-ol were attractive toM. melolonthamales in the field. Females were not attracted to any of the tested compounds, confirming previous results on the olfactory orientation ofMelolonthacockchafers. [ABSTRACT FROM AUTHOR]

We investigated by olfactometry and feeding- and oviposition-choice-tests how the highly specialised elm leaf beetle,Xanthogaleruca luteolaMüller (Coleoptera: Chrysomelidae),responds to conspecifically induced defences in the field elmUlmus minorMiller (Ulmaceae). While egg deposition of the beetle induced elms to release volatiles attractive to the egg parasitoidOomyzus gallerucaeFonscolombe (Hymenoptera: Eulophidae), feeding alone did not. In the present study, females of the elm leaf beetle showed preferences for the odours of twigs induced by low egg deposition and feeding over odours from uninfested twigs. In contrast, heavy infestation rendered elm odours less attractive to the beetles. Feeding and oviposition bioassays revealed an oviposition preference for leaves from uninfested twigs when compared to locally infested leaves. However, beetles preferred to feed upon systemically induced leaves compared to uninfested ones. The different preferences of the elm leaf beetle during host plant approach might be explained by a strategy that accounts for both gaining access to high quality nutrition and avoiding competition or parasitism. [ABSTRACT FROM AUTHOR]

In studies of foraging behaviour in a multitrophic context, the fourth trophic level has generally been ignored. We used four aphid hyperparasitoid species:Dendrocerus carpenteri(Curtis) (Hymenoptera: Megaspilidae),Asaphes suspensusWalker (Hymenoptera: Pteromalidae),Alloxysta victrix(Westwood) (Hymenoptera: Alloxystidae) andSyrphophagus aphidivorus(Mayr) (Hymenoptera: Encyrtidae), to correlate their response to different cues with their ecological attributes such as host range and host stage. In addition, we compared our results with studies of primary parasitoids on the same plant–herbivore system. First, the olfactory response of females was tested in a Y-tube olfactometer (single choice: plant, aphid, honeydew, parasitised aphid, aphid mummy, or virgin female parasitoid; dual choice: clean plant, plant with aphids, or plant–host complex). Second, their foraging behaviour was described on plants with different stimuli (honeydew, aphids, parasitised aphids, and aphid mummies). The results indicated that olfactory cues are probably not essential cues for hyperparasitoid females. In foraging behaviour on the plant, all species prolonged their total visit time and search time as compared to the control treatment (clean plant). OnlyA. victrixdid not react to the honeydew. Oviposition in mummies prolonged the total visit time because of the long handling time, but the effect of this behaviour on search time could not be determined. No clear correlation between foraging behaviour and host stage or host range was found. In contrast to specialised primary aphid parasitoids that have strong fixed responses to specific kairomones and herbivore-induced synomones, more generalist aphid hyperparasitoids seem to depend less on volatile olfactory stimuli, but show similarities with primary parasitoids in their use of contact cues while searching on a plant. [ABSTRACT FROM AUTHOR]

Infochemicals are the most important cues used by parasitoids for host location. The attractiveness of infochemicals in a tritrophic context is expected to be determined by the degree of specialization of the parasitoid and its host(s). Microctonus hyperodae Loan (Hymenoptera: Braconidae) is an oligophagous parasitoid that attacks adult Curculionidae of the Brachycerinae subfamily, especially Listronotus bonariensis Kuschel, on Gramineae. In 1996, a new host–parasitoid association between the carrot weevil Listronotus oregonensis LeConte and M. hyperodae was created in the laboratory. In this study, the infochemicals used by M. hyperodae when searching for its adult weevil hosts were determined using a Y-shaped olfactometer. Three curculionid species ( L. oregonensis, Listronotus sparsus Say, and Neydus flavicaudis Boheman) and one bruchid species [ Callosobruchus maculatus (Fabricius)], and their feces, were tested. It was expected that hosts phylogenetically and ecologically close to L. bonariensis would be more attractive than species less related but in fact, M. hyperodae responded only to L. oregonensis and its feces. When feces and host insects were tested separately, M. hyperodae responded to the odors emitted by L. oregonensis adults but not to their feces, suggesting that most of the kairomones came from the host itself. Host plants were also tested, but M. hyperodae responded neither to Lolium multiflorum Lamark (Gramineae) nor to Daucus carota L. (Umbelliferae) leaves. [ABSTRACT FROM AUTHOR]

The vine weevil Otiorhynchus sulcatus is a parthenogenetic reproducing species which forages for suitable host plants at night, but is found congregated in dark places during the day. Frass of this weevil species is suspected to contain attractive compounds that are host-plant related. Using a still-air olfactometer, we tested adult vine weevils at night for their behavioural response to odours from conspecifics, feeding on a mixture of spindle tree ( Euonymus fortunei) and yew ( Taxus baccata), and to a sexually reproducing related species ( Otiorhynchus salicicola), feeding on a mixture of ivy ( Hedera helix) and cherry laurel ( Prunus laurocerasus). Their attraction to conspecifics and O. salicicola appeared to be related to frass production. Freshly collected frass from O. sulcatus and from O. salicicola males and females was attractive. Prunus laurocerasus and H. helix have not been observed to be hosts of the vine weevil in the field. However, our tests showed that the vine weevil was attracted to mechanically damaged leaves of both plant species, whereas undamaged leaves were not attractive. Only undamaged young unfolding leaves of H. helix were also attractive. The attraction to odours from mechanically damaged host and non-host plants suggested the involvement of compounds that are commonly found in many plant species. The involvement of plant compounds and/or aggregation pheromones in attraction to frass of the vine weevil and frass of the related weevil species O. salicicola is discussed. [ABSTRACT FROM AUTHOR]

Abstract For the location of hosts and prey, insect carnivores (i.e., parasitoids or predators) often use infochemical cues that may originate from the host/prey itself but also from the food of the host/prey, a food plant, or another feeding substrate. These cues can be either specific for certain host/prey complexes or generally present in various complexes, and the reaction of the carnivores to these cues is either innate or learned. According to the concept on dietary specialization and infochemical use in natural enemies, the origin and specificity of the infochemical cues used and the innateness of the behavioural response are dependent on the degree of dietary specialization of the carnivore and its host/prey species. This concept has been widely adopted and has been frequently cited since its publication. Only few studies, however, have been explicitly designed to test predictions of the concept. Thus, more than 10 years after publication and despite of its broad acceptance, the general validity of the concept is still unclear. Using data from about 140 research papers on 95 species of parasitoids and predators, the present literature study comparatively scrutinises predictions from the concept. In accordance with the concept, learning to react to infochemicals and the use of general host and host plant cues was more often found in generalists than in specialists. In addition, more specialists were using specific infochemicals than generalists. In contrast to the concept, however, there was no significant difference between specialists and generalists in the proportion of carnivore species that use infochemicals during foraging and also extreme generalists are using infochemical cues for foraging. Likewise, an innate reaction to infochemicals was found in both specialists and generalists. Several reasons why infochemical use, including an innate reaction to infochemicals, is adaptive in generalist carnivores are discussed . We conclude that the concept has been a useful paradigm in advancing the chemical ecology of arthropod carnivores, but needs to be modified: the use of infochemicals is expected in all arthropod carnivores, regardless of dietary specialization. [ABSTRACT FROM AUTHOR]