Trapping social wasps (Hymenoptera: Vespidae) with acetic acid and saturated short chain alcohols

Nineteen compounds were evaluated in combination with a solution of acetic acid as baits for trapping the German yellowjacket, Vespula germanica (F.), the western yellowjacket Vespula pensylvanica (Sausssure), and the golden paper wasp Polistes aurifer Saussure. Compounds with three to six carbon chains or branched chains and with a hydroxy functional group were selected for testing based on their similarity to isobutanol. They were compared with isobutanol with acetic acid, which is a known wasp attractant. None of the compounds tested were superior to isobutanol when presented with acetic acid as a lure for these species of wasps. However, traps baited with either the S-(-)- or the racemic mixture of 2-methyl-1-butanol in combination with acetic acid captured similar numbers of both species of yellowjackets, compared with isobutanol with acetic acid. Polistes aurifer responded strongly to the S-(-)-enantiomer and to the racemic mixture of 2-methyl-1-butanol with acetic acid and not to the R-(+)-enantiomer with acetic acid.     

Behavioural response of the woodwasp Sirex noctilio to volatile emissions of its fungal symbiont

The wood‐boring wasp, Sirex noctilio, is a global invasive pest that infects and kills pine trees by inoculating spores of a symbiotic fungus (Amylostereum areolatum) at oviposition. Wasp larvae depend on fungal growth to feed, while the fungus relies on female wasps to initially condition the pine tree by inoculating a phytotoxic venom and for dispersal. Wasp larvae use the fungus as an external gut for the digestion of lignocellulosic compounds resulting in a strong correlation between fungal growth inside the wood and wasp fitness. This study explores the hypothesis that female wasps will use fungal volatiles as a synomone in the process of locating suitable oviposition areas (i.e. trees). Using a Y‐tube olfactometer, adult female wasp behaviour was assessed towards fungal and pine tree volatiles (i.e. positive control). Our results are the first to demonstrate attraction of female S. noctilio towards volatiles of their fungal symbiont. Furthermore, the positive response towards these volatiles seems to be stronger than the response to a known attractant (i.e. pine volatiles). These results could be an important contribution to improving baits for monitoring and control purposes. Further work is needed, mainly oriented towards the identification of the volatiles that trigger the observed attraction response and their possible synergistic effects with tree volatiles.     

Responses of the ambrosia beetle <Emphasis Type="Italic">Xylosandrus compactus</Emphasis> (Coleoptera: Curculionidea: Scolytinae) to volatile constituents of its symbiotic fungus <Emphasis Type="Italic">Fusarium solani</Emphasis> (Hypocreales: Nectriaceae)

Xylosandrus compactus is a polyphagus pest that cultivates a symbiotic fungus Fusarium solani in tunnels of host plants for food and is a major threat to coffee production in East Africa. We hypothesized that the female X. compactus, which is the only sex capable of flying to attack its hosts, is attracted to volatiles from F. solani. We investigated responses of females to volatiles released by fungal cultures and bioactive components identified in the fungal volatiles. In Y-tube olfactometer assays, ~68% of females were attracted to volatiles emitted from F. solani over clean air. Bioactive compounds were identified in the fungal volatiles by coupled gas chromatography (GC)/electroantennographic detection (EAD) and GC/mass spectrometric analyses as methyl isovalerate and 2,3-butanediol. We also identified ethanol, a known attractant of X. compactus, using solid phase microextraction captured fungal volatiles analyzed by GC/MS. In field trapping trials, we compared captures of females in plastic bottle traps baited with a range of doses of methyl isovalerate, 2,3-butanediol, and blends of the two compounds, with similar traps baited with solvent only and ethanol. Females were caught by all the baited traps at all the concentrations tested except traps baited with solvent only. Trap captures were however 14–37-fold lower in traps baited with single components and the blends than those baited with ethanol. The possible use of these components as a tool for kairomonal monitoring of populations of X. compactus is discussed.     

Volatile Compound-Mediated Interactions between Barley and Pathogenic Fungi in the Soil

Plants are able to interact with their environment by emitting volatile organic compounds. We investigated the volatile interactions that take place below ground between barley roots and two pathogenic fungi, Cochliobolus sativus and Fusarium culmorum. The volatile molecules emitted by each fungus, by non-infected barley roots and by barley roots infected with one of the fungi or the two of them were extracted by head-space solid phase micro extraction and analyzed by gas chromatography mass spectrometry. The effect of fungal volatiles on barley growth and the effect of barley root volatiles on fungal growth were assessed by cultivating both organisms in a shared atmosphere without any physical contact. The results show that volatile organic compounds, especially terpenes, are newly emitted during the interaction between fungi and barley roots. The volatile molecules released by non-infected barley roots did not significantly affect fungal growth, whereas the volatile molecules released by pathogenic fungi decreased the length of barley roots by 19 to 21.5% and the surface of aerial parts by 15%. The spectrum of the volatiles released by infected barley roots had no significant effect on F. culmorum growth, but decreased C. sativus growth by 13 to 17%. This paper identifies the volatile organic compounds emitted by two pathogenic fungi and shows that pathogenic fungi can modify volatile emission by infected plants. Our results open promising perspectives concerning the biological control of edaphic diseases.     

Electrophysiological and behavioral responses of Asian and European honeybees to pear flower volatiles

Honeybee pollination behavior is influenced by flower volatiles, which honeybees sense via olfactory receptors. Honeybees are only weakly attracted to pear flowers. To investigate the potential reasons, we extracted and determined the floral volatile compounds from three pear cultivars (Su, Ya, and Xuehua) using headspace solid-phase micro-extraction (HS-SPME) and gas chromatography-mass spectrometry (GC–MS). The effects of pear flower volatiles on the Asian honeybee (Apis cerana cerana Fabricius) and the European honeybee (Apis mellifera ligustica Spinola) were determined by electroantennogram (EAG) assays and behavioral tests in a three-arm olfactometer. Among the 76 flower volatiles detected with GC–MS, 21 were found in all three pear cultivars, accounting for approximately 70% of the total volatile content. 3-Methyl-1-butanol and (+)-limonene volatiles had the highest relative content. Five compounds elicited strong EAG responses in both bee species: 2-methylbutyraldehyde, 1-nonanal, 6-methyl-5-hepten-2-one, 3-methyl-1-butanol, and (+)-limonene. Neither bee species showed positive taxis to these volatiles. In behavioral tests, A. mellifera ligustica showed a low preference for 6-methyl-5-hepten-2-one (20%, 400 µg/µL) and 2-phenethyl alcohol (16.7%, 400 µg/µL). Apis cerana cerana showed a low preference for 6-methyl-5-hepten-2-one (6.7%, 400 µg/µL) and 1-nonanal (10%, 400 µg/µL), whereas its preferences for 3-methyl-1-butanol (43.3%, 400 µg/µL) and α-farnesene (40%, 400 µg/µL) were similar to that for the control. Therefore, a lack of attractive volatile compounds could explain why honeybees are only weakly attracted to pear flowers. Therefore, to achieve acceptable pollination in pear orchards, we suggest using flower-scent sugar syrup feeding and a saturation pollination strategy.     

Variation in highbush blueberry floral volatile profiles as a function of pollination status, cultivar, time of day and flower part: implications for flower visitation by bees

Background and Aims

Studies of the effects of pollination on floral scent and bee visitation remain rare, particularly in agricultural crops. To fill this gap, the hypothesis that bee visitation to flowers decreases after pollination through reduced floral volatile emissions in highbush blueberries, Vaccinium corymbosum, was tested. Other sources of variation in floral emissions and the role of floral volatiles in bee attraction were also examined.

Methods

Pollinator visitation to blueberry flowers was manipulated by bagging all flowers within a bush (pollinator excluded) or leaving them unbagged (open pollinated), and then the effect on floral volatile emissions and future bee visitation were measured. Floral volatiles were also measured from different blueberry cultivars, times of the day and flower parts, and a study was conducted to test the attraction of bees to floral volatiles.

Key Results

Open-pollinated blueberry flowers had 32 % lower volatile emissions than pollinator-excluded flowers. In particular, cinnamyl alcohol, a major component of the floral blend that is emitted exclusively from petals, was emitted in lower quantities from open-pollinated flowers. Although, no differences in cinnamyl alcohol emissions were detected among three blueberry cultivars or at different times of day, some components of the blueberry floral blend were emitted in higher amounts from certain cultivars and at mid-day. Field observations showed that more bees visited bushes with pollinator-excluded flowers. Also, more honey bees were caught in traps baited with a synthetic blueberry floral blend than in unbaited traps.

Conclusions

Greater volatile emissions may help guide bees to unpollinated flowers, and thus increase plant fitness and bee energetic return when foraging in blueberries. Furthermore, the variation in volatile emissions from blueberry flowers depending on pollination status, plant cultivar and time of day suggests an adaptive role of floral signals in increasing pollination of flowers.     

Use of herbivore‐induced plant volatiles as search cues by Tiphia vernalis and Tiphia popilliavora to locate their below‐ground scarabaeid hosts

Japanese beetle, Popillia japonica Newman, and oriental beetle, Anomala orientalis (Waterhouse) (both Coleoptera: Scarabaeidae) are considered invasive species and have been reported as key pests of urban landscapes in the Northeastern USA. Tiphia vernalis Rohwer and Tiphia popilliavora Rohwer (Hymenoptera: Tiphiidae) were introduced as biocontrol agents against these beetles. These parasitic wasps burrow into the soil and search for grubs. When a host is found, the wasp attaches an egg in a location that is specific for the wasp species. It is unknown if these wasps can detect patches of concealed hosts from a distance above ground and what role, if any, herbivore‐induced plant volatiles play in their host location. This study evaluated the responses of female T. vernalis and T. popilliavora to grub‐infested and healthy plants in Y‐tube olfactometer bioassays. Also the effect of root herbivory on the composition of turfgrass (Poaceae) volatile profiles was investigated by collecting volatiles from healthy and grub‐infested grasses. Tiphia wasps were highly attracted to volatiles emitted by grub‐infested tall fescue (Festuca arundinacea Schreb.) and Kentucky bluegrass (Poa pratensis L.) over healthy grasses. In contrast, wasps did not exhibit a significant preference for grub‐infested perennial ryegrass (Lolium perenne L.) as compared with the control plants. The terpene levels emitted by grub‐infested Kentucky bluegrass and tall fescue were greater than that of control plants. Low levels of terpenes were observed for both test and control perennial ryegrass. The elevated levels of terpenes emitted by grub‐infested Kentucky bluegrass and tall fescue coincided with the attractiveness to the tiphiid wasps. Here, we provide evidence that plant exposure to root‐feeding insects P. japonica and A. orientalis resulted in an increase in terpenoid levels in turfgrasses, which strongly attracts their above‐ground parasitoids.     

Maize plants sprayed with either jasmonic acid or its precursor,methyl linolenate,attract armyworm parasitoids,but the composition of attractants differs

Treatment of both uninfested and armyworm‐infested maize plants with jasmonic acid (JA) is known to attract the parasitic wasp, Cotesia kariyai Watanabe (Hymenoptera: Braconidae). Here, we show that treatment with a methyl ester of a JA precursor, methyl linolenate (MeLin), also causes maize plants to attract this wasp, yet does not cause elevated levels of endogenous JA. The volatile chemicals emitted from either infested or uninfested maize plants treated with MeLin were qualitatively and quantitatively different from those emitted from JA‐treated plants. Among compounds emitted from MeLin‐treated plants, α‐pinene and menthol attracted wasps in pure form in a two‐choice test using a choice chamber. A mixture of methyl salicylate, α‐copaene, and β‐myrcene also attracted wasps. In contrast, (Z)‐3‐hexenyl acetate was among the main attractants for C. kariyai in JA‐treated plants. These data show that in addition to JA, MeLin also has the potential to increase the host‐finding ability of C. kariyai, but that the composition of attractants they induce differs.     

二化螟绒茧蜂对二化螟及其寄主植物挥发物的趋性反应

利用Y-型嗅觉仪研究了二化螟绒茧蜂Cotesia chilonis对寄主植物（水稻或茭白）、二化螟Chilo suppressalis幼虫、虫粪及虫害苗挥发物的行为反应。健康植株、二化螟幼虫和虫粪的挥发物对二化螟绒茧蜂具有显著引诱作用。在虫害苗与健康苗挥发物之间,二化螟绒茧蜂显著地偏好虫害苗,但当去除虫害苗中的幼虫和虫粪后,寄生蜂对去虫苗与机械损伤苗的选择无显著差异;在虫害苗与有虫健康苗之间,寄生蜂显著趋向虫害苗,表明虫害苗本身释放的挥发物对二化螟绒茧蜂引诱作用与机械损伤苗无显著差异,但与二化螟幼虫或虫粪挥发物之间可能具有协同增效作用。水稻苗经机械损伤或损伤后以二化螟幼虫唾液处理,其挥发物对二化螟绒茧蜂的引诱作用无显著改变。二化螟绒茧蜂对不同为害程度水稻挥发物的选择无显著差异。二化螟绒茧蜂对两种寄主植物的健康苗、虫害苗、取食两种植物的幼虫及虫粪的挥发物的选择无显著差异。结果表明,二化螟绒茧蜂栖境定位和寄主选择过程中所利用的挥发物主要来自寄主植物、二化螟幼虫和虫粪以及虫害苗与幼虫和虫粪的协同作用。     

A nocturnal Provespa wasp species as the probable pollinator of epiphytic orchid Coelogyne fimbriata

Many vespid wasps visit flowers to forage nectar. These hymenopterans sometimes contribute to flower pollination. However, none of the nocturnal wasp species is a known pollinator. We collected individuals of light‐attracted Provespa nocturna workers in a montane rainforest on Peninsular Malaysia: some wasps collected bore orchid pollinia on their thoraxes. Among 114 trapped individuals, four bore pollinaria and nine bore only viscidia, suggesting that pollinia had been successfully transported. Molecular barcoding of the pollinia (based on their ITS sequences) assigned the orchid to a species in Coelogyne fimbriata complex. These findings and our other analyses suggest that this nocturnal wasp contributes to pollination of an epiphytic nectarless orchid that probably releases olfactory attractants. This discovery sheds light on the importance of mutualistic relationships between the nocturnal social wasps and epiphytic orchids in Southeast Asian tropical rainforest canopies.     

Behavioral and electrophysiological responses of the parasitic wasp Psyttalia concolor (Szépligeti) (Hymenoptera: Braconidae) to Ceratitis capitata-induced fruit volatiles

Psyttalia concolor (Szépligeti) is a koinobiont larval-pupal endoparasitoid of many Tephritidae of great economic importance, such as the medfly, Ceratitis capitata (Wiedemann). In several species of parasitoids it has been demonstrated that the mated females are strongly attracted by specific volatiles from insect-damaged plants. Yet the role of olfactory cues deriving from C. capitata-infested fruits on the female’s decision during the P. concolor host location was poorly investigated. In the present study, the responses of P. concolor females to either healthy or C. capitata-infested fruits was studied through behavioral assays. Volatiles emitted by healthy and infested fruits were SPME-sampled and analyzed by gas chromatography–mass spectrometry (GC–MS). The attractiveness of the identified volatiles was assessed and their electrophysiological activity was analyzed through gas-chromatography coupled with electroantennography (GC-EAD). P. concolor preferred infested peaches and apples over healthy ones, either when visual and olfactory or only olfactory cues were given. Nine compounds were found as exclusive of infested peaches, with respect to healthy ones, and seven of them evoked electrophysiological responses. In apples only quantitative changes in volatile emissions were observed after the medfly infestation. The emissions of 1-butyl butylate, 1-hexyl acetate and 1-butyl esanoate increased in infested apples, whereas 1-hexyl (E)-2-methyl butenoate decreased significantly. Among apple volatiles, 1-butyl butylate, 2-methyl-1-butyl acetate, 1-hexyl acetate, 2-methyl-1-butyl 2-methylbutanoate, 1-butyl hexanoate and 1-hexyl (E)-2-methyl butenoate elicited responses in female antennae. Synthetic blends reproducing the odors emitted by infested peaches and apples elicited strong attraction towards P. concolor females. For both fruits, the blend attractiveness was mainly due to some specific electrophysiological active chemicals: ethyl octanoate, decanal and 4-decanolide for peach, and 1-butyl butylate and 1-butyl hexanoate for apple. The responses induced by the identified fruit volatiles to P. concolor females allow us to suppose that they play a role as short-range attractants during host location.     

Resource choice of social wasps: influence of presence, size and species of resident wasps

Summary: The role of visual cues provided by resident wasps on resource choice by yellowjacket and paper wasp foragers was investigated. Large spring queen yellowjackets and small early season yellowjacket foragers (Vespula germanica, Vespula maculifrons, and Vespula vidua) were extracted in hexane to remove odors and posed as though feeding at petri dish feeders bearing daisy-like flower models, equipped with microcapillary feeding tubes, and containing 1:3 honey:water solution. An array of five feeders was presented to foragers at a suburban and a woodland site in Saratoga Springs, New York. The visual cues provided by resident wasps influenced resource choice by approaching social wasp foragers. Vespula germanica, an introduced yellowjacket species that tends to dominate at rich resources, was the only wasp visiting the suburban feeders. Foragers of this species preferentially fed on feeders and flowers with posed wasps and fed most often next to large wasps. Polistes fuscatus foragers at the woodland site similarly preferred to feed on occupied feeders and flowers. Vespula maculifrons and V. consobrina preferentially visited unoccupied feeders. Individual V. maculifrons, V. consobrina and V. vidua foragers that landed on occupied feeders all preferentially visited unoccupied flowers on those feeders. Vespula vidua and V. flavopilosa foragers did not demonstrate a feeder preference based on the presence/absence of posed wasps. Vespula consobrina foragers that visited occupied feeders preferred those occupied by extracted V. maculifrons queens and workers; no other wasps showed species based landing preferences.     

Fig volatiles: Their role in attracting pollinators and maintaining pollinator specificity

Each fig tree species (Ficus) is totally dependent on a specific species of wasp for pollination and the larvae of these wasps only develop in the ovules of their specificFicus host. Because the fig crop on any particular tree is generally highly synchronized, the shortlived female wasps must leave their natal tree in order to find figs which are suitable for oviposition. Chemical volatiles produced by figs when they are ready for pollination are thought to be the means by which the wasps detect a suitable host. Gas chromatograms of the fig volatiles of 7 species ofFicus showed them to be species specific. Age related changes in the volatile profiles were noted as extra volatiles are produced when the figs were ready for pollination.     

榕果挥发物对传粉榕小蜂的吸引作用

榕树 /榕小蜂专一性共生系统的维持 ,与榕树开花期释放的特殊的挥发性化合物以及榕小蜂对其寄主榕树的化学识别和定位紧密相关。研究选取了西双版纳地区常见的 3种榕树 ,即对叶榕 Ficus hispida、木瓜榕 F.auriculata和鸡嗉子榕F.semicordata的榕果作为实验材料 ,利用野外诱捕实验、室内生物检测实验检测传粉榕小蜂 Hymenoptera:ChalcidoidaeAgaonidae对 12种信息化合物及榕果的二氯甲烷浸提物的趋向性反应 ,研究不同榕属植物的传粉榕小蜂对相同的信息化合物的反应差异 ,以及传粉榕小蜂受不同发育时期榕果浸提物吸引的显著性程度。诱捕实验中对叶榕小蜂 Ceratosolen solmsimarchali对香叶醇的趋向性反应显著 ,大果榕小蜂 C.emarginatus对接受期榕果浸提物和芳樟醇都有明显的趋向性反应 ,而对间花期榕果浸提物则无显著反应。嗅觉仪生物检测实验中 ,鸡嗉果榕小蜂 C.gravelyi对香叶醇和松油醇都表现出显著的趋向性反应。结果表明 ,对叶榕、鸡嗉子榕传粉榕小蜂对 12种信息化合物的反应存在一定的差异 ,木瓜榕传粉榕小蜂对香叶醇和木瓜榕接受期榕果浸提物的趋向性反应比间花期榕果强得多     

A double-edged sword: Amylostereum areolatum odors attract both Sirex noctilio (Hymenoptera: Siricidae) and its parasitoid,Ibalia leucospoides

The Eurasian woodwasp, Sirex noctilio, is an invasive pest of pines in temperate regions of the Southern Hemisphere, and has been introduced to North America. A parasitoid, Ibalia leucospoides, has been broadly employed for biological control of this pest. Volatiles emitted from the fungal symbiont of S. noctilio, Amylostereum areolatum, are reliable cues for S. noctilio and I. leucospoides females to optimize their foraging behavior (host location and host habitat finding) in a chemically complex environment. The headspace volatiles of A. areolatum, were analyzed using coupled gas chromatography-mass spectrometry (GC-MS) and GC-electroantennographic detection (GC-EAD) for both S. noctilio and I. leucospoides females. Analyses revealed that both species could detect several fungal volatiles. In olfactometer bioassays, S. noctilio females were attracted to a 4-component blend of 6-methyl-5-hepten-2-one, trans-3-hexenyl acetate, linalool, and geraniol, while the addition of ρ-anisaldehyde to the blend was necessary for attraction of I. leucospoides females. The results of trap catches in field experiments confirmed that these fungal volatiles in combination with host tree volatiles are attractive to both species, although the release rate of the fungal volatiles is important. These volatiles can serve as a basis for the development of improved lures for both species.     

Male and female Trybliographa rapae (Hymenoptera: Figitidae) behavioural responses to food plant, infested host plant and combined volatiles

Many parasitoids use volatiles produced by plants as important cues during their food and host search process. We investigated the attraction of the parasitic wasp Trybliographa rapae Westwood (Hymenoptera: Figitidae) to volatiles emitted from plants infested by the cabbage root fly Delia radicum L. (Diptera: Anthomyiidae), as well as to volatiles from a nectar food plant. Behavioural choice tests showed that male parasitoids were not attracted to any volatiles from plants infested by D. radicum or from nectar plants, while females showed clear attraction to both volatile sources. Young females were more attracted to combined volatiles of host and food plants over those from only the host plant, whereas older females showed no differences in attraction to the two odour sources. This suggests that intercropping attractive flowers with host plants could potentially be used to recruit newly emerged parasitoids from surrounding fields while older parasitoids invest more energy in host location than in additional food search. Volatiles from a whole infested plant were chosen over those emitted from separated above- and below-ground parts from infested plants. It is important to consider the availability of both energy and host resources for parasitoids when designing an eco-compatible management of a vegetable crop system.     

Colonization of a Submersed Aquatic Plant, Eurasian Water Milfoil (Myriophyllum spicatum), by Fungi under Controlled Conditions

A laboratory assay to assess colonization of a submersed aquatic plant, Eurasian water milfoil (Myriophyllum spicatum), by fungi was developed and used to evaluate the colonization potential of Colletotrichum gloeosporioides, Acremonium curvulum, Cladosporium herbarum, Aureobasidium pullulans, a Paecilomyces sp., and an unidentified sterile, septate fungus. Stem segments of plants were first immersed in suspensions of fungal propagules for 24 h and then washed to remove all but the tightly attached component of the population. Inoculation was followed by two growth cycles of 3 days each. At the start of each cycle, washed plants were transferred to a mineral salts medium to provide an opportunity for the attached fungal populations to grow. After each growth period, plants were again washed, and fungal populations in the medium (nonattached), loosely attached and tightly attached to the plant, and within the plant (endophytic) were assayed by dilution plating. The fungi differed in the extent to which they attached to water milfoil and in their ability to grow in association with it. There were relatively few significant differences among the tightly attached fungal populations after 24 h, but growth of the better colonizers led to a greater number of significant differences after 4 and 7 days. In addition, the better colonizers showed sustained regrowth of loosely and nonattached fungal propagules in the face of intermittent removal by washing. A milfoil pathogen, C. gloeosporioides, was the only endophytic colonizer; it was also among the best epiphytic colonizers but was not demonstrably better than A. curvulum, a fungus commonly found as an epiphyte on watermilfoil. The yeastlike hyphomycete Aureobasidium pullulans was the only fungus that consistently failed to establish an increasing population on the plant.     

Herbivore-induced Blueberry Volatiles and Intra-plant Signaling

Herbivore-induced plant volatiles (HIPVs) are commonly emitted from plants after herbivore attack^1,2. These HIPVs are mainly regulated by the defensive plant hormone jasmonic acid (JA) and its volatile derivative methyl jasmonate (MeJA)^3,4,5. Over the past 3 decades researchers have documented that HIPVs can repel or attract herbivores, attract the natural enemies of herbivores, and in some cases they can induce or prime plant defenses prior to herbivore attack. In a recent paper⁶, I reported that feeding by gypsy moth caterpillars, exogenous MeJA application, and mechanical damage induce the emissions of volatiles from blueberry plants, albeit differently. In addition, blueberry branches respond to HIPVs emitted from neighboring branches of the same plant by increasing the levels of JA and resistance to herbivores (i.e., direct plant defenses), and by priming volatile emissions (i.e., indirect plant defenses). Similar findings have been reported recently for sagebrush⁷, poplar⁸, and lima beans⁹..Here, I describe a push-pull method for collecting blueberry volatiles induced by herbivore (gypsy moth) feeding, exogenous MeJA application, and mechanical damage. The volatile collection unit consists of a 4 L volatile collection chamber, a 2-piece guillotine, an air delivery system that purifies incoming air, and a vacuum system connected to a trap filled with Super-Q adsorbent to collect volatiles^5,6,10. Volatiles collected in Super-Q traps are eluted with dichloromethane and then separated and quantified using Gas Chromatography (GC). This volatile collection method was used n my study⁶ to investigate the volatile response of undamaged branches to exposure to volatiles from herbivore-damaged branches within blueberry plants. These methods are described here. Briefly, undamaged blueberry branches are exposed to HIPVs from neighboring branches within the same plant. Using the same techniques described above, volatiles emitted from branches after exposure to HIPVs are collected and analyzed.     

House Fly (Musca domestica L.) Attraction to Insect Honeydew

House flies are of major concern as vectors of food-borne pathogens to food crops. House flies are common pests on cattle feedlots and dairies, where they develop in and feed on animal waste. By contacting animal waste, house flies can acquire human pathogenic bacteria such as Escherichia coli and Salmonella spp., in addition to other bacteria, viruses, or parasites that may infect humans and animals. The subsequent dispersal of house flies from animal facilities to nearby agricultural fields containing food crops may lead to pre-harvest food contamination with these pathogens. We hypothesized that odors from honeydew, the sugary excreta produced by sucking insects feeding on crops, or molds and fungi growing on honeydew, may attract house flies, thereby increasing the risk of food crop contamination. House fly attraction to honeydew-contaminated plant material was evaluated using a laboratory bioassay. House flies were attracted to the following plant-pest-honeydew combinations: citrus mealybug on squash fruit, pea aphid on faba bean plants, whitefly on navel orange and grapefruit leaves, and combined citrus mealybug and cottony cushion scale on mandarin orange leaves. House flies were not attracted to field-collected samples of lerp psyllids on eucalyptus plants or aphids on crepe myrtle leaves. Fungi associated with field-collected honeydews were isolated and identified for further study as possible emitters of volatiles attractive to house flies. Two fungal species, Aureobasidium pullulans and Cladosporium cladosporioides, were repeatedly isolated from field-collected honeydew samples. Both fungal species were grown in potato dextrose enrichment broth and house fly attraction to volatiles from these fungal cultures was evaluated. House flies were attracted to odors from A. pullulans cultures but not to those of C. cladosporioides. Identification of specific honeydew odors that are attractive to house flies could be valuable for the development of improved house fly baits for management of this pest species.     

Antimicrobial volatile organic compounds affect morphogenesis-related enzymes in Guignardia citricarpa,causal agent of citrus black spot

Although non-volatile substances toxic to plant pathogenic microorganisms have been extensively studied over the years, few studies have focused on microbial volatile organic compounds (VOCs). The VOCs produced by the yeast Saccharomyces cerevisiae strain CR-1, used in fermentative processes for fuel ethanol production, are able to inhibit the vegetative development of the fungus Guignardia citricarpa, causal agent of the disease citrus black spot. How microbial VOCs affect the development of fungi is not known. Thus, the objective of the present work was to study the effect of the artificial mixture of VOCs identified from S. cerevisiae on intracellular enzymes involved in the mycelial morphogenesis in G. citricarpa. The phytopathogenic fungus was exposed to artificial mixture of VOCs constituted by alcohols (ethanol, 3-methyl-1-butanol, 2-methyl-1-butanol and phenylethyl alcohol) and esters (ethyl acetate and ethyl octanoate) in the proportions naturally found in the atmosphere produced by the yeast. The VOCs inhibited considerably the mycelial development and interfered negatively with the production of the morphogenesis-related enzymes. After 72 h of exposure to the VOCs the laccase and tyrosinase activities decreased 46 and 32%, respectively, however, the effect on the chitinase and β-1,3-glucanase activities was lower, 17 and 13% of inhibition, respectively. Therefore, the exposure of the fungus to the antimicrobial volatiles can influence both fungal mycelial growth rate and activity of enzymes implicated in morphogenesis. This knowledge is important to understand the microbial interactions mediated by VOCs in nature and to develop new strategies to control plant pathogens as G. citricarpa in postharvest.