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An innovative scanning harmonic radar has been recently developed for tracking insects in complex landscapes. This movable technology has been tested on an invasive hornet species (Vespa velutina) for detecting the position of their nests in the environment, in the framework of an early detection strategy. The new model of harmonic radar proved to be effective in tracking hornets either in open landscapes, hilly environments and areas characterised by the presence of more obstacles, such as woodlands and urban areas. Hornets were effectively tracked in complex landscapes for a mean tracking length of 96 ± 62 m with maximum values of ~ 300 m. The effectiveness of locating nests was 75% in new invasive outbreaks and 60% in highly density colonised areas. Furthermore, this technology could provide information on several aspects of insect's ecology and biology. In this case, new insights were obtained about the mean foraging range of V. velutina (395 ± 208 m with a maximum value of 786 m) and flying features (ground speed), which was 6.66 ± 2.31 m s−1 for foraging individuals (hornets that are not carrying prey's pellet) and 4.06 ± 1.34 m s−1 for homing individuals. [ABSTRACT FROM AUTHOR]

Abstract: Yellowjackets in the genera Vespula and Dolichovespula are prevalent eusocial insects of great ecological and economic significance, but the chemical signals of their sexual communication systems have defied structural elucidation. Herein, we report the identification of sex attractant pheromone components of virgin bald‐faced hornet queens (Dolichovespula maculata). We analyzed body surface extracts of queens by coupled gas chromatographic–electroantennographic detection (GC‐EAD), isolated the compounds that elicited responses from male antennae by high‐performance liquid chromatography (HPLC), and identified these components by GC mass spectrometry (MS), HPLC‐MS, and NMR spectroscopy. In laboratory olfactometer experiments, synthetic (2Z,7E)‐3,7‐dimethyldeca‐2,7‐diendioic acid (termed here maculatic acid A) and (2Z,7E)‐10‐methoxy‐3,7‐dimethyldeca‐10‐oxo‐deca‐2,7‐dienoic acid (termed here maculatic acid C) in binary combination significantly attracted bald‐faced hornet males. These are the first sex attractant pheromone components identified in yellowjackets. [ABSTRACT FROM AUTHOR]

Little is known about the roles of sex pheromones in mate-finding behavior of social wasps ( Vespidae). Working with the aerial yellowjacket, Dolichovespula arenaria ( Fabricius), baldfaced hornet, Dolichovespula maculata (L.), western yellowjacket, Vespula pensylvanica ( Saussure), southern yellowjacket, Vespula squamosa ( Drury), and Vespula alascensis Packard, we tested the hypotheses (1) that gynes produce an airborne sex pheromone attractive to males, and (2) that males are more strongly attracted to non-sibling gynes based on olfactory cues. A field experiment provided the first definitive evidence that D. arenaria gynes attract males. Surprisingly, we did not find such evidence in similar field experiments for sexual attractiveness of gynes of V. squamosa, V. pensylvanica, V. alascensis, or D. maculata. In Y-tube olfactometer experiments with three of these species ( D. arenaria, D. maculata, V. pensylvanica), only D. maculata gynes attracted males, provided they were non-siblings, implying an olfactory-based mechanism of nestmate recognition and inbreeding avoidance. Lack of sex attraction responses for V. pensylvanica, V. alascensis, and V. squamosa in this study does not rule out pheromone-mediated sexual communication. Instead, it highlights the possibility that pheromonal signaling may be dependent on the presence of appropriate contextual cues. [ABSTRACT FROM AUTHOR]

individual wasps from five species were plated, and 27 yeast-like colonies were identified to the species level. Yeasts in the genera Lachancea and Hanseniaspora each comprised ∼30% of the isolates; ∼25% were identified as Metschnikowia spp., with the remaining 10% belonging to Rhodotorula. Four bacterial isolates were identified as Escherichia coli, Enterococcus faecalis, and two isolates of Stenotrophomonas maltophilia. Yeasts were present at all life stages of the wasps except for two unfed gynes of Dolichovespula maculata (L.) that contained only bacteria. The presence of a particular yeast species was not correlated with any wasp species. Furthermore, S. cerevisiae was not found in any wasp species. This highlights an interesting difference in the life cycle of both S. cerevisiae and wasps in Europe and the Pacific Northwest, and prompts further studies on the interactions of these microbes with their host wasps. [ABSTRACT FROM AUTHOR]

In eusocial insects like Bald-faced hornets, Dolichovespula maculata, nest defense is essential because nests contain a large number of protein-rich larvae and pupae, and thus are attractive to nest predators. Our objectives were to investigate whether D. maculata exhibit pheromone-mediated nest defense , and to identify and field test any pheromone components. We tested for pheromone-mediated nest defense behavior of D. maculata by placing a paired box-apparatus near the entrance of D. maculata nests, and treating both boxes with a solvent control, or one of the two boxes with a solvent control and the other with either venom sac extract, the putative source of nest defense pheromone, or synthetic pheromone. The sound impulses caused by nest mates attempting to sting or strike the boxes were recorded for 3 min. Compared to the double-control treatment, the number of strikes increased 27-fold when one of the two boxes was treated with venom sac extract, providing evidence for an alarm response. The box treated with venom sac extract also induced a significantly greater proportion of strikes than the corresponding control box, providing evidence for a target-oriented response. Analyzing venom sac extract by gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometry resulted in the identification of seven candidate pheromone components: (a) dimethylaminoethanol, (b) dimethylamino ethyl acetate, (c) 2,5-dimethylpyrazine, (d) N-3-methylbutylacetamide, (e) 2-heptadecanone, (f) ( Z)-8-heptadecen-2-one, and (g) ( Z)-10-nonadecen-2-one. Testing in paired-box bioassays blends of the nitrogen-containing volatile components a-d, the less volatile ketones e-g, or both (a-g), indicated that a-d primarily have an alarm function. The ketones e-g, in contrast, induced target-oriented responses, possibly marking the box, or potential nest predators, for guided and concerted attacks, or enhancing the alarm-inducing effect of the volatile pheromone components, as shown in honey bees. Comparing the behavioral effects of venom sac extract, blends a-d, e-g, and a-g, venom sac extract was most effective in triggering the full complement of alarm and target-oriented responses. These comparisons further suggested that a component is missing in the group of components that triggers the alarm rather than the target-oriented response. [ABSTRACT FROM AUTHOR]

The species of paper wasps in the tribe Vespini, family Vespidae from America North of Mexico are reviewed, including a new identification key to the genera and species, complete synonymy, distribution and biology. This fauna includes six species of Dolichovespula Rohwer, three species of Vespa Linnaeus and 13 species of Vespula Thomson. No Holarctic species are recognized, with the result that Dolichovespula arctica (Rohwer) and Vespula intermedia (du Buysson) are again recognized as species, while Vespula infernalis (de Saussure) is given new status as a species. [ABSTRACT FROM AUTHOR]

The difficulty of directly observing predatory events hinders a complete understanding of how predation structures food webs. Indirect approaches such as PCR-based and isotopic analyses clarify patterns of resource consumption but fail to distinguish predation from scavenging. Given that facultative scavenging is a ubiquitous and phylogenetically widespread foraging strategy, an improved ability to discriminate prey from carrion is needed to enhance an understanding of the demographic effects of consumption and the true nature of trophic interactions. Using physiological properties of muscle tissue - specifically pH and rate of water loss - we develop a novel method to discriminate prey from carrion collected by scavenging hymenopteran predators. Our focal system is the western yellowjacket ( Vespula pensylvanica), a common scavenging predator in Hawaii and western North America. Prior to consumption, the physical properties of hymenopteran muscle tissue change in a quantifiable and deterministic manner post mortem and can be used to estimate the time and putative cause of death of diet items. Applying this method in laboratory and field situations resulted in the correct identification of prey and carrion in 49 out of 56 cases (88%). Although further investigation is needed to determine how post-mortem physiology of diet items changes in the guts of consumers, the approaches developed in this study can be used to distinguish predation from scavenging by central-place foragers (particularly arthropods). Such information will provide a more definitive characterization of species interactions and food webs. [ABSTRACT FROM AUTHOR]

1. Intact caterpillars (Barathra brassicae) react to the airborne vibrations of an approaching wasp (Dolichovespula media) by cessation of movement or by squirming. These reactions are no longer observed after removal of the eight filiform hairs on the caterpillars' thorax. When directly attacked, both intact and operated caterpillars squirm and often regurgitate gut-contents. 2. The selective advantage of detecting a wasp's approach with the vibration sensitive hairs was quantitatively determined. A cage contained a wasp colony and intact or operated caterpillars as the only prey: it was found that intact caterpillars which react to the wasp's approach are attacked about 30% less frequently than operated animals. Of all caterpillars that are attacked, about 20% are killed. Of all caterpillars killed 30% were intact, while 70% lacked their filiform hairs (P < 0.001). 3. Air vibration generated in the near field of a tethered wasp in flight was measured at different distances and directions. The dominant frequency in the spectral energy distribution of flight-generated vibration was about 150 Hz. Maximal medium displacements were below and behind the wasp (Figs. 2 and 3). This vibration amplitude was above threshold for the filiform hairs (at 150 Hz) up to a distance of 70 cm from the wasp. 4. The influence of the caterpillars' response on the hunting strategies of wasps predating or parasitizing on them is discussed. [ABSTRACT FROM AUTHOR]

Two citrus-based sodas and a known wasp attractant were compared in a field trial to assess their attractiveness to local nuisance wasp species. The wasps captured included Vespula germanica (F.), Vespula maculifrons (Buysson), Vespula vulgaris (L.), Vespula flavopilosa Jacobson, Vespula squamosa (Drury), Dolichovespula maculata (L.), Polistes fuscatus (L), Polistes metricus Say, and Polistes dominulus (Christ). Wasps in the genus Vespula were present in significantly higher numbers in traps than Dolichovespula and Polistes. Both citrus soda products were superior to the isobutanol-acetic acid mixture as attractants for almost all of the wasp species. [ABSTRACT FROM AUTHOR]