Guerin, Patrick

2012, Gurba, A., Harraca, V., Perret, J. L., Casera, S., Donnet, S., Guerin, Patrick

Tsetse flies Glossina spp. (Diptera; Glossinidae) are blood-feeding vectors of disease that are attracted to vertebrate hosts by odours and visual cues. Studies on how tsetse flies approach visual devices are of fundamental interest because they can help in the development of more efficient control tools. The responses of a forest tsetse fly species Glossina brevipalpis (Newstead) to human breath are tested in a wind tunnel in the presence or absence of a blue sphere as a visual target. The flight responses are video recorded with two motion-sensitive cameras and characterized in three dimensions. Although flies make meandering upwind flights predominantly in the horizontal plane in the plume of breath alone, upwind flights are highly directed at the visual target presented in the plume of breath. Flies responding to the visual target fly from take-off within stricter flight limits at lower ground speeds and with a significantly lower variance in flight trajectories in the horizontal plane. Once at the target, flies fly in loops principally in the horizontal plane within 40 cm of the blue sphere before descending in spirals beneath it. Successful field traps designed for G. brevipalpis take into account the strong horizontal component in local search behaviour by this species at objects. The results suggest that trapping devices should also take into account the propensity of G. brevipalpis to descend to the lower parts of visual targets.

2004, Otalora-Luna, F., Perret, J. L., Guerin, Patrick

A combination of 1,000 ppm CO2 plus 30-40 ppb NH3 in an air stream induced Rhodnius prolixus nymphs walking on a servosphere to perform a series of appetence behaviours. Shortly after the onset of stimulation the nymphs turned sharply upwind towards the source of the chemostimuli (within 13 +/- 9 s) from mostly downwind and crosswind walks in the air stream alone. The mean vector angles of these upwind tracks were concentrated in a cone 60degrees either side of due upwind. The upwind walking bugs stopped more frequently but for a shorter duration and walked at a higher speed than before stimulation. During stops in the presence of the chemostimuli the bugs frequently corrected their course angles and extended their forelegs to reach higher with their antennae in the air. In the air stream alone R. prolixus nymphs frequently sampled the sphere surface with the antennae and cleaned their antennae with the foreleg tarsi. However, the nymphs only briefly tapped the left or right antennal flagellum on the corresponding first leg tarsus and never touched the servosphere surface in the presence of the chemostimuli. After chemostimulus removal from the air stream the bugs continued to respond with the same appetence responses as during stimulation, but walked more tortuously in a crosswind direction in an effort to regain contact with the chemostimuli.

2000, McMahon, Conor, Guerin, Patrick

Male Amblyomma variegatum ticks feeding on a host release a mixture of o-nitrophenol and methyl salicylate which serves to attract conspecifics. The behavioural responses of A. variegatum on a servosphere to these volatiles presented in an air stream are detailed hers. In still air, ticks walked on all eight legs, but with long halts. In contrast, the air stream caused continuous walking and induced a reaching response where the forelegs actively sampled the air. Such reaching increased the angular velocity and reduced walking speed, effects that were amplified in the presence of vapours from o-nitrophenol and methyl salicylate in the air flowing over the ticks. Vapour from a 1:1 mixture of o-nitrophenol and methyl salicylate was attractive over a 10(4)-fold concentration range providing an increase in upwind displacement of 20-40%, significantly higher than the natural ratio where o-nitrophenol vapour predominates. Although the responses to o-nitrophenol vapour were variable when presented alone, this chemical was consistently attractive when delivered with steer hair odour - unattractive on its own. Moreover, the upwind walk to this combination did not cause a change in speed or angular velocity. This supports the hypothesis that the response to the pheromone is enhanced by host odour.

1999, Thomas Kröber, Guerin, Patrick

Larvae of the cattle tick Boophilus microplus and all life stages of the European sheep tick Ixodes ricinus avoid walking on a wet membrane surface surrounding a dry patch. Of 170 reactions made at a border with liquid water by 22 B. microplus larvae, 40% consisted of immediate turns to the opposite side to bring all the legs back onto a dry patch, 41% were walks along the border, during which the ticks maintained contact with both the dry and wet zones, and 19% were returns to the dry patch after a short excursion onto the wet surround. Since contact with one front leg tip was sufficient to cause return reactions from the wet surface in most of the border contacts, the water receptor(s) that enable ticks to perceive the wet surface are probably located in terminal pore sensilla on the first-leg tarsi. Observations on the return reactions of ticks with different groups of chemosensilla masked confirmed this. Ticks have an ambiguous relationship with water: they appear to avoid direct contact with it, but they need a high humidity to compensate for any deficit in body water.

2012, Schmera, D., Guerin, Patrick

BACKGROUND: The codling moth is the most serious pest of deciduous tree fruit (apples, pears, crabapples, walnuts, quince) worldwide. The high frequency of insecticide treatments per season has resulted in breakdown of codling moth control owing to insecticide resistance. As an alternative, integrated pest management includes mating disruption to achieve population suppression in orchards. Under this scheme, the sex pheromone of the codling moth, (E, E)-8,10-dodecadien-1-ol (codlemone), is released from dispensers in crops to hinder mating by luring males. Increasing the attractiveness of codlemone formulations to codling moth males can be regarded as a key to increasing the efficacy of mating disruption. With this aim, the effects of adding plant volatiles on the behavioural responses of codling moth males to codlemone were tested. RESULTS: Adding R(+)-limonene, linalool, (E)-beta-farnesene or ethyl (E, Z)-2,4-decadienoate to codlemone significantly increases the proportion of males flying to the pheromone source in a wind tunnel. The response level is equivalent to that of males responding to females releasing codlemone. Using real-time recordings, it is shown how these four plant products also shorten the response time of males to codlemone under the behavioural criteria time to activation, time till upwind flight is induced and time to pheromone source contact. CONCLUSION: Shortening the response time and increasing source location by males of dispensers releasing codlemone with R(+)-limonene, linalool, (E)-beta-farnesene or ethyl (E, Z)-2,4-decadienoate added would enhance mating disruption through better engagement ofmales with dispensers, to the detriment of females. (C) 2011 Society of Chemical Industry

2003, Perret, Jean-Luc, Guerin, Patrick, Diehl, Peter-Allan, Vlimant, Michèle, Gern, Lise

The behaviour of Ixodes ricinus nymphs was recorded in 10-day experiments using computer-assisted video-tracking, in the absence of any host stimuli. These ticks switch spontaneously from questing in a desiccating atmosphere to quiescence in a water-saturated atmosphere after dark. Quantification of both questing and quiescence duration demonstrates that questing duration is inversely related to saturation deficit whereas quiescence duration is not. Distance walked after quiescence increased with desiccating conditions, while the distance walked after questing remained unchanged. Almost all locomotor activities of I. ricinus occurred during darkness under either a 14 h:10 h L:D or a 8 h:4 h L:D cycle. We established that all life stages of I. ricinus are equipped to sense shifts in light intensity with bilaterally placed strings of photoreceptors. This permits I. ricinus to use onset of darkness to trigger mobility when desiccation risk is reduced in nature.

2000, McMahon, Conor, Guerin, Patrick

The responses of A. variegatum adults to constituents ot 'their aggregation-attraction pheromone presented in an air stream were studied using a locomotion compensator. The responses to vapours from two mixtures were compared, the first a 1:1 mixture of o-nitrophenol and methyl salicylale, the second a four component mixture ® containing o-nitrophenol, methyl salicylale, 2,6 dichlorophenol and phenyl acetaldehyde in the ratio 10:10:2:1, respectively. No difference was found between the kineses responses of A. variegatum adults for either mixture: both elicited an increase in angular velocity and a reduction in speed. Moreover, attraction to vapours of either mixture was reduced significantly as the source dose was increased: both mixtures were good attractants at a source dose of 10 μg of the main components, but were not attractive at source doses 100 times higher. As with many other arthropods, A. variegatum adults arc responsive to the ratio, as well as to the dose, of constituents in an attractant mix. We suggest that the quantity and ratios of compounds in attractive mixtures released from commercial dispensers should be measured before use in any control programme.

2009, Becher, P. G., Guerin, Patrick

Larvae of the grapevine moth Lobesia botrana (Lepidoptera: Tortricidae) are a major pest of vine, Vitis vinifera. As larvae have limited energy reserves and are in danger of desiccation and predation an efficient response to plant volatiles that would guide them to food and shelter could be expected. The responses of starved 2nd or 3rd instar larvae to volatile emissions from their artificial diet and to single host plant volatiles were recorded on a locomotion compensator. Test products were added to an air stream passing over the 30 cm diameter servosphere. The larvae showed non-directed walks of low rectitude in the air stream alone but changed to goal-oriented upwind displacement characterised by relatively straight tracks when the odour of the artificial diet and vapours of methyl salicylate, 1-hexanol, (Z)-3-hexen-1-ol, terpinen-4-ol, 1-octen-3-ol, (E)-4,8-dimethyl-1,3,7-nonatriene and (Z)-3-hexenyl acetate were added to the air stream. This chemoanemotactic targeted displacement illustrates appetence for certain volatile cues from food by starved Lobesia larvae. Analysis of the larval behaviour indicates dose dependent responses to some of the host plant volatiles tested with a response to methyl salicylate already visible at 1 ng, the lowest source dose tested. These behavioural responses show that Lobesia larvae can efficiently locate mixtures of volatile products released by food sources as well as single volatile constituents of their host plants. Such goal-oriented responses with shorter travel time and reduced energy loss are probably of importance for larval survival as it decreases the time they are exposed to biotic and abiotic hazards. (C) 2009 Elsevier Ltd. All rights reserved.

2001, Guerenstein, Pablo G., Guerin, Patrick

Olfactory receptors in basiconic and grooved-peg sensilla on the antenna of fifth-instar Triatoma infestans nymphs respond to host odours. Gas chromatography analyses of host odour extracts coupled to electrophysiological recordings from basiconic sensillum receptors indicate that nonanal is a constituent of sheep wool and chicken feather odour that stimulates one of the receptors in this type of sensillum. Similar analyses revealed isobutyric acid in rabbit odour to be a chemostimulant for one of the receptors in grooved-peg sensilla. The response of the aldehyde receptor was higher to heptanal, octanal and nonanal than to other aliphatic aldehydes, and the response of the acid receptor was higher to isobutyric acid than to other short-chain branched and unbranched acids. The behavioural responses of fifth-instar T. infestans nymphs to nonanal and isobutyric acid in an air-stream on a servosphere indicate that, whereas nonanal causes activation of the bugs, isobutyric acid induces an increase in upwind displacement, i.e. odour-conditioned anemotaxis. Binary mixtures of these compounds did not improve the attraction obtained with isobutyric acid alone. A comparison of the behavioural and electrophysiological responses of the bugs to different amounts of isobutyric acid in air suggests that attraction is obtained at concentrations that causes low-to-moderate increases in the firing rate of the acid-excited receptor in the grooved-peg sensilla, whereas at a dose that evokes relatively high firing rates (>40 Hz) no attraction is obtained.

1999, Dougherty, M. J., Guerin, Patrick, Ward, R.D., Hamiltion, J.G.C.

Compounds from the odour-producing glands of the fox Vulpes vulpes were collected. This complex mixture of compounds was used to stimulate the 'ascoid' olfactory organs of female sandflies in single sensillum and gas chromatography-linked single sensillum recordings. Sixteen of these compounds were identified using gas chromatography-linked mass spectrometry and amounts present were determined. The compounds fell into four organic classes: ketones, carboxylic acids, alcohols and aldehydes. Specific neurones present in the ascoid sensillum that responded to each of these classes of compound were characterized.
A bioassay chamber was developed that gave female sandflies the choice of two odour sources. Female sandflies were attracted upwind by fox odour and were trapped in closer proximity to the fox odour port than the control port. Synthetic compounds were recombined in appropriate quantities to mimic the fox odour. In this bioassay, the synthetic blend attracted sandflies upwind, and again they were caught closer to the test port than the control port. Furthermore, the synthetic fox odour induced an electrophysiological response from neurones in the ascoid sensillum that was very similar to that induced by natural fox odour. No synthetic compound alone induced the same behavioural response from sandflies as did whole fox odour. However, benzaldehyde, 4-hydroxy-4-methyl-2-pentanone and 4-methyl-2-pentanone alone did cause sandflies to fly upwind and to be caught closer to the test port than the control.