Nieri R, Mazzoni V, Gordon SD, Krugner R. 2017. Mating behavior and vibrational mimicry in the glassy-winged sharpshooter, Homalodisca vitripennis. Journal of Pest Science. 90:887-889

by Shira | Feb 18, 2017 |

The glassy-winged sharpshooter (GWSS), Homalodisca vitripennis, is an important vector of Xylella fastidiosa, the causal agent of Pierce’s disease of grapevine. GWSS control relies mainly on insecticides; therefore, an alternative method, such as vibrational mating disruption, is required. However, knowledge of GWSS intraspecific communication is necessary to evaluate applicability of such methods. Mating behavior and associated vibrational signals were described in different social contexts: individuals, pairs, and one female with two competing males. Behavioral analysis showed that GWSS mating communication involved the emission of three male and two female signals, with specific roles in two distinct phases of mating behavior, identification and courtship. Mating success depended on vibrational duets between genders, which were temporarily interrupted in the presence of male rivalry. Male rivalry behavior involved the emission of three distinct rivalry signals. Two rivalry signals resemble female signals and were associated with replacement of the female in the duet by the rival male. The third rivalry signal was emitted by competing males. Data suggested that rival males used mimicry and hostile signals to interrupt the ongoing duet and gain access to a female. In the future, knowledge acquired from this study will be essential to develop a mechanical mating disruption method for GWSS control. Nieri R, Mazzoni V, Gordon SD, Krugner R. 2017. Mating behavior and vibrational mimicry in the glassy-winged sharpshooter, Homalodisca vitripennis. Journal of Pest Science....

Sitvarin M, Gordon SD, Uetz GW, Rypstra A. 2016. The wolf spider Pardosa milvina detects predator threat level using only vibratory cues. Behaviour. 153:159-173

by Shira | Oct 9, 2016 |

Predators may inadvertently signal their presence and threat level by way of signals in multiple modalities. We used a spider, Pardosa milvina, known to respond adaptively to chemotactile predator cues (i.e., silk, faeces and other excreta) to evaluate whether it could also discriminate predation risk from isolated vibratory cues. Vibrations from its prey, conspecifics, and predators (Tigrosa helluo and Scarites quadriceps) were recorded and played back to Pardosa. In addition, we recorded predator vibrations with and without access to chemotactile cues from Pardosa, indicating the presence of prey. Pardosa did not appear to discriminate between vibrations from prey or conspecifics, but the response to predators depended on the presence of cues from Pardosa. Vibrations from predators with access to chemotactile cues from prey induced reductions in Pardosa activity. Predator cues typically occur in multiple modalities, but prey are capable of imperfectly evaluating predation risk using a limited subset of information. Sitvarin M, Gordon SD, Uetz GW, Rypstra A.  2016.  The wolf spider Pardosa milvina detects predator threat level using only vibratory cues.  Behaviour. ...

Gordon SD, Windmill JFC. 2015. Hearing ability decreases in ageing locusts. J. of Experimental Biology. 218:1990-199

by Shira | Oct 9, 2016 |

Insects display signs of ageing, despite their short lifespan. However, the limited studies on senescence emphasize longevity or reproduction. We focused on the hearing ability of ageing adult locusts, Schistocerca gregaria. Our results indicate that the youngest adults (2 weeks post-maturity) have a greater overall neurophysiological response to sound, especially for low frequencies (<10 kHz), as well as a shorter latency to this neural response. Interestingly, when measuring displacement of the tympanal membrane that the receptor neurons directly attach to, we found movement is not directly correlated with neural response. Therefore, we suggest the enhanced response in younger animals is due to the condition of their tissues (e.g. elasticity). Secondly, we found the sexes do not have the same responses, particularly at 4 weeks post-adult moult. We propose female reproductive condition reduces their ability to receive sounds. Overall our results indicate older animals, especially females, are less sensitive to sounds. Gordon SD, Windmill JFC. 2015. Hearing ability decreases in ageing locusts. J. of Experimental Biology....

Gordon SD, Jackson JC, Rogers SM, Windmill JFC. 2014. Listening to the Environment: Hearing Differences from an Epigenetic Effect in Solitarious and Gregarious Locusts. Proceedings of the Royal Society B. 281 no. 1795 20141693

by Shira | Oct 1, 2014 |

Locusts display a striking form of phenotypic plasticity, developing into either a lone-living solitarious phase or a swarming gregarious phase depending on population density. The two phases differ extensively in appearance, behaviour, and physiology. We found that solitarious and gregarious locusts have clear differences in their hearing, both in their tympanal and neuronal responses. We identified significant differences in the shape of the tympana that may be responsible for the variations in hearing between locust phases. We measured the nanometre mechanical responses of the ear’s tympanal membrane to sound, finding that solitarious animals exhibit greater displacement. Finally, neural experiments signified that solitarious locusts have a relatively stronger response to high frequencies. The enhanced response to high frequency sounds in the nocturnally flying solitarious locusts suggests greater investment in detecting the ultrasonic echolocation calls of bats, to which they are more vulnerable than diurnally active gregarious locusts. This study highlights the importance of epigenetic effects set forth during development and begins to identify how animals are equipped to match their immediate environmental needs. Gordon SD, Jackson JC, Rogers SM, Windmill JFC.  2014.  Listening to the Environment:  Hearing Differences from an Epigenetic Effect in Solitarious and Gregarious Locusts.  Proceedings of the Royal Society B. 281 no. 1795...

Eberhard MJB*, Gordon SD*, Windmill JFC, Ronacher B. 2014. Temperature effects on the tympanal membrane and auditory receptor neurons in the locust. Journal of Comparative Physiology A. 200:837-847 * These authors contributed equally

by Shira | Jun 29, 2014 |

Poikilothermic animals are affected by variations in environmental temperature, as the basic properties of nerve cells and muscles are altered. Nevertheless, insect sensory systems, such as the auditory system, need to function effectively over a wide range of temperatures, as sudden changes of up to 10 °C or more are common. We investigated the performance of auditory receptor neurons and properties of the tympanal membrane of Locusta migratoria in response to temperature changes. Intracellular recordings of receptors at two temperatures (21 and 28 °C) revealed a moderate increase in spike rate with a mean Q10 of 1.4. With rising temperature, the spike rate–intensity–functions exhibited small decreases in thresholds and expansions of the dynamic range, while spike durations decreased. Tympanal membrane displacement, investigated using microscanning laser vibrometry, exhibited a small temperature effect, with a Q10 of 1.2. These findings suggest that locusts are affected by shifts in temperature at the periphery of the auditory pathway, but the effects on spike rate, sensitivity, and tympanal membrane displacement are small. Robust encoding of acoustic signals by only slightly temperature-dependent receptor neurons and almost temperature-independent tympanal membrane properties might enable locusts and grasshoppers to reliably identify sounds in spite of changes of their body temperature. Eberhard MJB*, Gordon SD*, Windmill JFC, Ronacher B.  2014. Temperature effects on the tympanal membrane and auditory receptor neurons in the locust. Journal of Comparative Physiology A.  200:837-847 * These authors contributed...