Home About us Contact
|
Home About us Contact | ||
|
|
||
EAG Responses (eag + response)
Selected AbstractsThe role of volatile semiochemicals in mediating host location and selection by nuisance and disease-transmitting cattle fliesMEDICAL AND VETERINARY ENTOMOLOGY, Issue 4 2004M. A. Birkett Abstract., The role of volatile semiochemicals in mediating the location and selection within herds of Holstein-Friesian heifers by nuisance and disease-transmitting cattle flies was investigated using coupled gas chromatography,electrophysiology (GC,EAG), coupled gas chromatography,mass spectrometry (GC,MS), electrophysiology (EAG), laboratory behaviour and field studies. Using volatile extracts collected by air entrainment from heifers in the Netherlands, a number of active peaks were located by coupled GC,EAG for Musca autumnalis (de Geer) (Diptera: Muscidae) and Haematobia irritans (L.) (Diptera: Muscidae). Volatile samples were also collected from two heifers in Denmark shown in previous counting experiments to differ significantly in their fly loads. Coupled GC,EAG using Ha. irritans antennae revealed differences in the EAG response to the samples, with additional EAG activity in the sample collected from the heifer with the lower fly load. To identify more EAG active compounds, volatiles were also collected from 48-h-old urine by air entrainment. In total, 23 compounds were located and identified by coupled GC,EAG and GC,MS. Further electrophysiological testing of these compounds with five fly species [M. autumnalis, Ha. irritans, Hydrotaea irritans (L.) (Diptera: Muscidae), Stomoxys calcitrans (L.) (Diptera: Musicidae) and Wohlfahrtia magnifica (Schiner) (Diptera: Sarcophagidae)] showed that only some of the compounds were physiologically active across the range of flies tested. These included 1-octen-3-ol, 6-methyl-5-hepten-2-one, (Z)-3-hexen-1-ol, naphthalene, and all EAG active compounds identified from urine. Compounds showing significant EAG activity were tested for behavioural activity using a wind-tunnel designed for measuring upwind flight behaviour. At certain concentrations, 1-octen-3-ol, 6-methyl-5-hepten-2-one and 3-octanol increased upwind flight, whereas naphthalene, propyl butanoate and linalool reduced upwind flight. In field studies using small herds of heifers ranked according to their fly load, individual slow-release formulations of 1-octen-3-ol and 6-methyl-5-hepten-2-one, when applied to low and high fly loading heifers, reduced fly loads on these individuals. This study provides evidence for the hypothesis that the natural differential attractiveness within herds of Holstein-Freisian heifers, i.e. a single host species, for cattle flies is partly due to differences in volatile semiochemicals emitted from the host. It is suggested that this phenomenon applies to other vertebrate host species and their associated insect pests. [source] Quantitative method for pheromone delivery in studies of sensory adaptation of moth antennaePHYSIOLOGICAL ENTOMOLOGY, Issue 4 2007R. M. TRIMBLE Abstract A pheromone sprayer and an electroantennogram (EAG) are used to study sensory adaptation in the antennae of male obliquebanded leafrollers, Choristoneura rosaceana and oriental fruit moths, Grapholita molesta, to the main pheromone compounds (Z)-11-tetradecen-1-yl acetate (Z11-14:Ac) and (Z)-8-dodecen-1-yl acetate (Z8-12:Ac), respectively. The atomization of 0.125, 0.25, 0.5 or 1 ,L ethanol min,1 into the EAG air delivery tube at an airflow rate of 2 L min,1, with resultant concentrations of 6.25, 12.5, 25 or 50 × 10,5,L ethanol mL air,1, respectively, does not affect the EAG response of C. rosaceana or C. molesta after a 30-min exposure period. The atomization of 0.125 ,L min,1 of a solution of 8 mg Z11-14:Ac mL,1 ethanol into the EAG air delivery tube at an airflow rate of 2 L min,1, with a resultant concentration of 0.5 ng pheromone mL,1 air, reduces the EAG response of C. rosaceana by approximately 70% after a 15-min exposure period. An additional 15 min of exposure to pheromone does not result in increased sensory adaptation. Antennae recover 32% of the lost responsiveness when exposed to pheromone-free air for 15 min. The atomization of 0.125 ,L min,1 of a solution of 8 mg Z8-12:Ac mL,1 ethanol into the EAG air delivery tube at an airflow rate of 2 L min,1, with a resultant concentration of 0.5 ng pheromone mL,1 air, reduces the EAG response of C. molesta antenna by approximately 80% after a 15- or 30-min exposure period. The antennae of this species do not recover responsiveness when exposed to pheromone-free air for 15 min. [source] Olfactory responses of two species of grasshoppers to plant odoursENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2000H.H. Chen Abstract Electroantennogram (EAG) responses were recorded from two species of oedipodine grasshoppers, Oedaleus decorus asiaticus L. (graminivorous) and Angaracris barabensis Pall. (forbivorous), to volatiles emitted by chopped leaves of ten plant species. Male O. d. asiaticus showed much stronger EAG responses than conspecific females and both sexes of A. barabensis. Sexual differences in EAG responses correspond to different numbers of antennal sensilla of both sexes and to certain behavioural and morphological factors as well. The overall EAG response profiles of the two grasshopper species to the ten plant odours were similar. However, adaptation to host odour might have occurred because of differences in their feeding habits. Females of the graminivorous O. d. asiaticus possess a significantly higher olfactory sensitivity for poaceous plant species than A. barabensis, while the forbivorous A. barabensis showed significantly higher EAG responses to Allium senescens (Liliaceae), and a tendency of high responses to composite plant species in comparison with O. d. asiaticus. [source] Identification of feeding attractants in oak sap for adults of two nymphalid butterflies, Kaniska canace and Vanessa indicaPHYSIOLOGICAL ENTOMOLOGY, Issue 3 2000Hisashi Ômura Abstract The active compounds of oak-sap odour in attracting adults of two butterflies, Kaniska canace (L.) and Vanessa indica (Herbst) (Lepidoptera: Nymphalidae), were identified by chemical analyses, electroantennogram (EAG) and two behavioural assays: proboscis extension reflex (PER) and attraction to artificial tree models. Fourteen compounds were identified from two sap samples collected in 1997 and 1998, of which the major volatiles were ethanol and acetic acid (, 900 p.p.m. and 500 p.p.m. in sap, respectively). However, the chemical composition of the minor volatiles varied considerably between the two samples. Among 13 chemicals tested, V. indica showed strong PER to five aliphatic acids (acetic, propionic, butyric, isobutyric and isovaleric), 2-methylpropan-1-ol and 3-hydroxybutan-2-one, whereas the PER-active compounds for K. canace were these seven compounds and also ethanol, 3-methylbutan-1-ol and 1-hydroxypropan-2-one. In two-choice behavioural bioassays, the model scented with a sap-odour mimic, which was an aqueous mixture of the PER-active compounds, was more attractive to the two butterflies than an unscented control. These results demonstrated that the sap odour stimulates foraging behaviour of the butterfly. Although EAG responses of both butterflies to 3-methylbutan-1-ol and that of V. indica to 2-methylpropan-1-ol were positively dose-dependent, responses to other compounds were not strong and not dose-dependent at 1,100 ,g doses. These EAG responsiveness suggests that the olfactory receptors for these compounds might be few in the antenna and that the butterflies have enough olfactory sensitivity to the dose of 1 ,g. [source] | ||||||||||