Factors Affecting Phonotaxis in Male House Crickets, Acheta domesticus

This research addresses some of the possible factors that affect male Acheta domesticus phonotactic responses to calls of males of the same species. The study examines cricket age and social interaction with females as possible factors affecting this behavior. Through Friedman rank test analysis, the study attempts to demonstrate a link between these factors and the responsiveness of the male crickets in the study. As the crickets aged, they responded to a wider ranges of syllable periods, which may imply that they follow a similar pattern of decreasing selectivity in their response with age as their female counterparts. A Friedman\u27s rank test was done on the data to determine whether there was a statistically significant difference within any of the syllable period as the crickets aged. This test showed slight significance in the syllable periods 50ms and 90 ms. Socializaion with females had minimal effects on male phonotactic behavior

P-27 Factors Affecting Phonotactic Responses in Male Acheta domesticus

This research addresses some of the possible factors that affect male Acheta domesticus phonotactic responses to calls of males of the same species. The study examines cricket age and social interaction with females as possible factors affecting this behavior. Through logistic regression analysis, the study attempts to demonstrate a link between these factors and the responsiveness of the male crickets in the study. As the crickets aged, they responded to a wider range of syllable periods, which may imply that they follow a similar pattern of decreasing selectivity in their response with age as their female counterparts. The socialization aspect of the research is still underway. However, if it follows a similar trend as other cricket species, we expect to see socialization with females decrease responsiveness to conspecific calls

P-22 Phonotaxis in Male House Crickets, Acheta domesticus

Calls of male crickets convey both reproductive and territorial intentions of the caller. Reproductively mature conspecific females use these calls to judge the quality of the caller and walk toward the source of the call (positive phonotaxis). Males of a few cricket groups also exhibit positive phonotaxis though for different proximate reasons than those hypothesized for females. We placed male house crickets, Acheta domesticus, in a circular arena and presented them with electronically synthesized model calls that differed from each other only in syllable periods. Seven syllable periods that ranged from 30msec to 90msec were used in this setup. Our Results revealed that male responses to calls with a syllable period of 50 msec had an earlier commencement and were more consistent than those of any other syllable period. However, age led to a progressive change in male responses and eventually resulted in those that were more than a month old responding to different syllable periods indiscriminately. The tuning of male and female auditory systems to calls of similar temporal structure indicates a common underlying genetic basis

Volcanic plume height correlated with magma-pressure change at Grímsvötn Volcano, Iceland

International audienceMagma flow during volcanic eruptions causes surface deformation that can be used to constrain the location, geometry and internal pressure evolution of the underlying magmatic source(1). The height of the volcanic plumes during explosive eruptions also varies with magma flow rate, in a nonlinear way(2,3). In May 2011, an explosive eruption at Grimsvotn Volcano, Iceland, erupted about 0.27 km(3) dense-rock equivalent of basaltic magma in an eruption plume that was about 20 km high. Here we use Global Positioning System (GPS) and tilt data, measured before and during the eruption at Grimsvotn Volcano, to show that the rate of pressure change in an underlying magma chamber correlates with the height of the volcanic plume over the course of the eruption. We interpret ground deformation of the volcano, measured by geodesy, to result from a pressure drop within a magma chamber at about 1.7 km depth. We estimate the rate of magma discharge and the associated evolution of the plume height by differentiating the co-eruptive pressure drop with time. The time from the initiation of the pressure drop to the onset of the eruption was about 60 min, with about 25% of the total pressure change preceding the eruption. Near-real-time geodetic observations can thus be useful for both timely eruption warnings and for constraining the evolution of volcanic plumes

Seismic and geodetic insights into magma accumulation at Katla subglacial volcano, Iceland: 1999 to 2005

International audienceKatla is one of Iceland's most active volcanoes with at least 20 eruptions in the last 1100 years. The volcano is covered mostly by the Mýrdalsjökull ice cap; consequently, Katla eruptions are phreato-magmatic and are capable of producing jökulhlaups. A jökulhlaup in July 1999, preceded by an episode of continuous seismic tremor, was the first sign of renewed magma movement under the volcano since 1955. Using seismic and geodetic observations, and insights into geothermal activity from ice-surface observations, we analyze this period of unrest and assess the present state of Katla volcano. From 1999 to 2004, GPS measurements on nunataks exposed on the caldera edge revealed steady inflation of the volcano. Our measurements show uplift and horizontal displacement of the nuntatak benchmarks at a rate of up to 2 cm a−1, together with horizontal displacement of far-field stations (>11 km) at about 0.5 cm a−1 away from the caldera centre. Using a point-source model, these data place the center of the magma chamber at 4.9 km depth beneath the northern part of the caldera. However, this depth may be overestimated because of a progressive decrease in the mass of the overlying ice cap. The depth may be only 2–3 km. About 0.01 km3 of magma has accumulated between 1999 and 2004; this value is considerably less than the estimated 1 km3 of material erupted during the last eruption of Katla in 1918. Presently, rates of crustal deformation and earthquake activity are considerably less than observed between 1999 and 2004; nonetheless, the volcano remains in an agitated state