Gordon and Krugner 2021. Copulatory Signaling and Polygamy of Glassy-Winged Sharpshooters (Hemiptera: Cicadellidae)

by Shira | May 26, 2021 |

Finding a partner to mate with may be only part of ensuring successful siring of offspring. Females often exhibit cryptic female choice (CFC) during or after copulation, which can influence whose sperm from her multiple partners is chosen for egg fertilization. Known behavioral mechanisms for CFC include assessment of males by their nuptial gifts, duration of copulation, and seminal fluid contents. In this study, the glassy-winged sharpshooter, Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), behaviors during the course of copulation were investigated. Glassy-winged sharpshooter (GWSS) use vibrational communication before copulation occurs. However, little is known about behaviors that occur during and after copulation. Results from this study determined that vibrational signaling also occurs during copulation. Vibrational signals similar to those emitted during precopulatory communication were identified during copulation alongside a new, ‘hum-like’ signal that typically occurred within 10 s after the pair joined in copulation. In addition, results determined the duration of copulation was on average of 15 h, though with a 10-h range (8.5–18.5 h) among observed male–female pairs. Finally, both males and females mated more than once. Collectively, results identified key reproductive parameters required for CFC to occur in GWSS. The study expands on the known animals that use CFC and emphasizes the role that copulatory vibrational communication may play setting the foundations for future more in-depth studies. Understanding of insect behaviors necessary for successful production of offspring is important from an ecological perspective and for development of pest control methods.   Gordon SD, Krugner R. 2021. Copulatory Signaling and Polygamy of Glassy-Winged Sharpshooters (Hemiptera: Cicadellidae). Annals of the Entomological Society of America....

Gordon et al (2019) Transmission of the frequency components of the vibrational signal of the glassy‑winged sharpshooter, Homalodisca vitripennis,within and between grapevines

by Shira | Aug 23, 2019 |

The agricultural pest, Homalodisca vitripennis, relies on vibrational communication through plants for species identification, location, and courtship. Their vibrational signal exhibits a dominant frequency between 80 and 120 Hz, with higher frequency, lower intensity harmonics occurring approximately every 100 Hz. However, previous research revealed that not all harmonics are recorded in every signal. Therefore, how the female H. vitripennis vibrational signal changes as it travels through the plant was investigated. Results confirmed that transmission was a bending wave, with decreased signal intensity for increasing distance from the source; moreover, at distances of 50 cm, higher frequencies traveled faster than lower frequencies, suggesting that dispersion of H. vitripennis signal components may enable signaling partners to encode distance. Finally, H. vitripennis generates no detectable airborne signal (pressure wave), yet their low vibrational frequency components are detectable in neighboring plants as a result of leaf-to-air-to-leaf propagation. For instance, with isolated key female signal frequencies, 100 Hz was detected at a 10 cm gap between leaves, whereas 600 Hz was detectable only with a 0.1 cm gap. Together, these results highlight the complexity of vibration propagation in plants and suggest the possibility of the animals using the harmonic content to determine distance to the signaling H. vitripennis source.   Gordon, S.D., Tiller, B., Windmill, J.F.C. et al. J Comp Physiol A (2019)....

Gordon SD, Klenschi E, Windmill JFC. 2017. Hearing on the fly: the effects of wing position on noctuid moth hearing. Journal of Experimental Biology. 220:1952-1955

by Shira | Mar 21, 2017 |

The ear of the noctuid moth has only two auditory neurons, A1 and A2, which function in detecting predatory bats. However, the noctuid’s ears are located on the thorax behind the wings. Therefore, since these moths need to hear during flight, it was hypothesized that wing position may affect their hearing. The wing was fixed in three different positions: up, flat, and down. An additional subset of animals was measured with freely moving wings. In order to negate any possible acoustic shadowing or diffractive effects, all wings were snipped, leaving the proximal most portion and the wing hinge intact. Results revealed that wing position plays a factor in threshold sensitivity of the less sensitive auditory neuron A2, but not in the more sensitive neuron A1. Furthermore, when the wing was set in the down position, fewer A1 action potentials were generated prior to the initiation of A2 activity. Analyzing the motion of the tympanal membrane did not reveal differences in movement due to wing position. Therefore, these neural differences due to wing position are proposed to be due to other factors within the animal such as different muscle tensions.   Gordon SD, Klenschi E, Windmill JFC. 2017. Hearing on the fly: the effects of wing position on noctuid moth hearing. Journal of Experimental Biology....

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....