Gryllotalpa Major Research Articles

Competition decreases with relatedness and lek size in mole crickets: a role for kin selection?

Are “leks,” where males advertise in groups for females to gain mating opportunities, the result of competition, or cooperation? In the prairie mole cricket Gryllotalpa major, we present evidence that 1) males display near relatives and 2) males on smaller, more highly related leks experience lower levels of competition. These data suggest that kin selection may be operating within kin clusters on leks and males likely gain a reproductive benefit by displaying nearby relatives.

Making high-stakes decisions in complex acoustic environments: Revisiting the Cocktail Party problem in a multimodal sensory context

Ambient noise in its many forms represents an ecological reality and evolutionary driver that influences numerous expressions of animal behavior, especially those associated with communication. Noise often extends across sensory modalities, resulting in channel-specific effects that can range from non-additive to synergistic. Here, we describe how noise modality influences female preference for a preferred signal trait (low dominant frequency) in the lek-mating prairie mole cricket, Gryllotalpa major, a species whose mating system has evolved in the ecological context of both biotic and abiotic noise. We conducted two-choice playback experiments with females presented with male signals of the preferred vs. non-preferred trait in the context of isomodal (male chorus), cross-modal (substrate-borne vibration) and multimodal noise (both) conditions. We found that female preference for lower DF signals was robust to isomodal noise, but preference was weakened in treatments with a cross-modal stimulus only. Female performance in multimodal noise was comparable to control and isomodal treatments, suggesting that while cues obtained via the subgenual organs can mask salient airborne information, biotic noise may act as a releaser from this interference.

The kin selection hypothesis in a lekking mole cricket: assessing nested patterns of relatedness

Loosely defined, a lek is a male mating aggregation visited by females primarily for the purpose of fertilization. No consensus has been forged that successfully explains how and why leks have evolved across the full breadth of lekking taxa. The two major conceptual explanations (cooperation and competition) are both intricately intertwined in any given system and exhibit varying levels of plasticity based on an organism's environment and life history. The kin selection hypothesis suggests that if females prefer larger leks (as is often the case), unattractive males may aggregate with their attractive relatives in order to boost the latter's reproductive success, while effectively sacrificing any opportunities of their own. Here we develop microsatellite markers to genetically evaluate the kin selection hypothesis by measuring relatedness and precise spatial locations of males in a population of the lekking prairie mole cricket (Gryllotalpa major Saussure). Results indicate that neighbouring males are often highly related, suggesting that kin selection may play some role in this system. However, because leks are comprised of multiple kin groups, if kin selection is operating it is likely doing so at a smaller scale than predicted by the kin selection hypothesis of lek formation. The high levels of subgroup relatedness within this species likely occurs as a passive process due to male viscosity, but the functional implications of this interesting genetic organization remain unknown.

Are Centrally Displaying Males Always the Centre of Female Attention? Acoustic Display Position and Female Choice in a Lek Mating Subterranean Insect

Several conceptual models seek to explain patterns of male display and factors that influence female mate choice in lek mating systems. The central advantage model predicts that males displaying at or near the lek centre should be more attractive to females than are males positioned along the lek periphery. Females may exhibit biases toward these centrally displaying males based on either spatial or display-related cues. We tested the prediction of the central advantage model in investigating the importance of male display position in the subterranean and lek mating prairie mole cricket (Gryllotalpa major). Gryllotalpa major males form mating aggregations in the early spring and produce an acoustic advertisement signal from a constructed calling chamber at the soil surface. Pair formation occurs in the calling chamber, and males typically maintain these structures for the duration of the reproductive season. To assess whether G. major females exhibit a preference for males calling from centrally located acoustic burrows, we documented the spatial position and number of female attractions for all advertising males across the focal lek. Six spatial attributes related to display position were reduced using principal component analysis and examined for an association with male attractiveness. We found that in general, female attractions were distributed randomly across the lek; male attractiveness was not related to proximity to the lek centre nor to any factor associated with display position. The most highly attractive males, however, were located further from the lek centre and from nearest calling neighbours than other attractive males. Advertising males that segregate themselves within the aggregation and locate nearer the lek margin may gain a geometric advantage resulting in the increased probability of attracting a searching female.

Grassland Botanical Structure Influences Lek Spatial Organization in Gryllotalpa major S. (Orthoptera: Gryllotalpidae)

The prairie mole cricket (Gryllotalpa major Saussure) is a rare endemic of the tallgrass prairie ecosystem of the south central United States. Males advertise for females using a low frequency acoustic signal from surface burrows aggregated in leks, but much of the spatial variation observed within the lek remains unexplained. This study reports on the relationship between male spacing and grassland habitat structure within the display arena. The data suggest that as grass heights increase within the lek arena, advertising males increase the distance between their burrows and increase the angle of the surface opening of the burrow. The positive correlation between biomass and spacing was not also seen between biomass and angle of the burrow opening. Prairie mole cricket males, thus, exhibit a form of behavioral plasticity that may have evolved in response to the dynamic disturbance regimes that form and maintain the tallgrass prairie ecosystem.

Burrow Aggregation of Prairie Mole Cricket, Gryllotalpa major Saussure (Orthoptera: Gryllotalpidae) Males is Not Based on Soil Microhabitat Constraints at Lek Sites in Oklahoma

Gryllotalpa major Saussure is a rare burrowing insect native to the tallgrass prairie in the south-central United States. Males construct aggregated burrows in lek arenas from which they produce sexual advertisement calls in a landscape that superficially appears to be rather homogeneous. To test the hypothesis that male calling burrows are aggregated due to habitat limitations linked to fine scale differences in soil characteristics, we analyzed ten soil samples per site taken along a transect from each of three lek sites in Osage and Craig Counties in northeastern Oklahoma for mineral content, moisture content, pH, texture and color. Transects ran across a lek, and thus samples were taken from empty areas on either side of the aggregation, as well as from near burrows. Although there were differences in these soil attributes within and among lek sites, this analysis showed no correlation between number of G. major burrows within 10 m of a soil sample site and any of these attributes for the three lek sites sampled.

Hearing and spatial behavior in Gryllotalpa major Saussure(Orthoptera: Gryllotalpidae)

The prairie mole cricket (Gryllotalpa major Saussure) is a rare orthopteran insect of the tallgrass prairie ecosystem of the south central USA. Populations are known to currently occupy fragmented prairie sites in Oklahoma, Arkansas, Kansas and Missouri, including The Nature Conservancy's Tallgrass Prairie Preserve in north central Oklahoma. Prairie mole cricket populations were surveyed at this site and at another site in Craig County, OK during the spring of 2005 and 2006, using the male cricket's acoustic call to locate advertising aggregations of males. Five males from one large aggregation were removed in a study to describe (1) the hearing thresholds across the call's range of frequencies, (2) the distances over which the higher harmonic components of the male's calls are potentially detectable, (3) the species' sensitivity to ultrasound and (4) the spatio-auditory dynamics of the prairie mole cricket lek. Results indicate that G. major has a bimodal pattern of frequency tuning, with hearing sensitivities greatest at the 2 kHz carrier frequency (41 dB SPL) and declining through the call's frequency range (84 dB at 10 kHz). A second sensitivity peak is evident in the ultrasound range at 25 kHz (62 dB SPL). Spatial analysis of G. major lek sites indicates that approximately 73% of males within the lek are spaced in such a way as to allow acoustic interaction at the species' carrier frequency, while any information in higher harmonic overtones in the call appears to be available only to nearest neighbors.

The Effect of Fire on Spatial Distributions of Male Mating Aggregations in Gryllotalpa Major Saussure (Orthoptera: Gryllotalpidae) at The Nature Conservancy's Tallgrass Prairie Preserve in Oklahoma: Evidence of a Fire-dependent Species

Abstract The prairie mole cricket (Gryllotalpa major Saussure) is a native of the tallgrass prairie ecosystem of the south central United States. Its populations have dwindled with the reduced availability of suitable grassland habitat. Populations are known to occupy relict prairie sites in Oklahoma, Kansas, Arkansas and Missouri. The Nature Conservancy's Tallgrass Prairie Preserve in north central Oklahoma is the largest continuous tract of tallgrass prairie remaining (about 16,100 ha). The long-term management plan for this property includes the utilization of prescribed burns, bison grazing, cattle grazing and limited mowing to restore a functional tallgrass prairie landscape. Prairie mole cricket populations were surveyed at the site during the years 1993, 1994, 1998, and by our research team in 2005, using the male cricket's acoustic call as a discrete presence indicator. Records from these surveys were integrated with prescribed burn maps to identify spatial distribution patterns of the calling agg...

Morphology and calling song characteristics in Gryllotalpa major Saussure (Orthoptera: Gryllotalpidae)

Abstract The prairie mole cricket (Gryllotalpa major Saussure) is a native of the tallgrass prairie ecosystem of the south central United States. The largest of North American crickets, its populations have declined with the reduced availability of suitable grassland habitat. Prairie mole cricket populations were surveyed at The Nature Conservancy's Tallgrass Prairie Preserve in Oklahoma in the spring of 2005. We located 95 acoustic burrows occupied by calling males and recorded the calling songs of 55. We measured 3 morphological characters for 8 of these field-recorded males and characterized each male's calling song for 7 key acoustic variables. Statistically significant relationships were discovered between male body length and 2 song parameters: syllables chirp−1 and dominant frequency.

Talking Back: Sending Soil Vibration Signals to Lekking Prairie Mole Cricket Males

Talking Back: Sending Soil Vibration Signals to Lekking Prairie Mole Cricket Males

Talking Back: Sending Soil Vibration Signals to Lekking Prairie Mole Cricket Males1

SYNOPSIS. The male prairie mole cricket, Gryllotalpa major, native of the tallgrass prairie of the south central U.S., constructs a specialized acoustical burrow in the spring in the prairie soil from which he generates an airborne calling song that attracts flying females for mating. Males do not phonorespond to manipulations involving playbacks of airborne sounds. At the same time, vibrations with the same temporal scale and pattern as the airborne signal are produced in the substrate through an unknown mechanism. These ground vibrations can be distinguished from background vibrations in the soil at distances up to 3 m depending on soil conditions and conditions that control the background vibration environment (e.g., wind, highway traffic). We hypothesize that males use the vibration component of the call as information for spacing as they form display arenas, or leks. We used modified field recordings of soil vibrations from singing males with an electromechanical vibration exciter to simulate the vibration component of a calling song in playback experiments. Airborne sounds of males were monitored for two minutes before and two minutes after the introduction of the ground vibration stimulus with a tape recorder microphone placed 20 cm from the burrow opening. Males did respond to the manipulation experiment; although, we observed individual variation in the level of response.

Lekking in Gryllotalpa major, the Prairie Mole Cricket (Insecta: Gryllotalpidae)

Gryllotalpa major is a rare, burrowing insect native to the tallgrass prairie of the south‐central United States and is known to exhibit ‘lek‐like’ behavior during mating. Here I report on a study carried out in the field that demonstrates that the prairie mole cricket meets all criteria defining a classical lekking species. Males construct specialized acoustic burrows from which they call to attract females for mating. I show that these burrows, which seem to serve no purpose other than for sexual advertisement and mating, are aggregated spatially on at least three scalar levels. Females fly through the aggregation of burrows and drop to the ground in the vicinity of calling males, and are, thus, not constrained in choosing a mate. Females enter the males’ acoustic burrows, but I argue that the burrows are not used as oviposition sites, and that the males do not otherwise sequester resources important to females. Although the term ‘lek’ is useful for the discussion of mating systems, its definition remains ambiguous. I discuss the current usage of the term and suggest extensions.

Environmental and social influences on calling effort in the prairie mole cricket (Gryllotalpa major)

Sexual advertisement in the form of acoustic display is energetically expensive. Calling effort, or metabolic energy expended specifically for advertisement, is adjusted in some species in response to competition from other males or to changes in climatic conditions. The prairie mole cricket (GrjUotatpa -major) is a rare insect of die south-central United States that produces its calling song, or advertisement rail, from a specially constructed burrow in taDgrass prairie soiL I found that prairie mole cricket males do not adjust their call amplitude with competition or female availability, nor do they vary amplitude with soil temperature or moisture within their established range of calling conditions. Chirp rate adjustments were made with social interactions and changes in soil temperature, but group size did not influence calling effort Males produced more complex calls in response to closer calling neighbors, but prairie mole cricket males may selectively respond to only the nearest one to two neighbors. Kty words: acoustic signaling, calling effort, Gryllotalpa major, prairie mole cricket, sexual advertisement. {Bthav Ecol 9:101108 (1998)]

Characterization of Prairie Mole Cricket Chorusing Sites in Oklahoma

-Prairie mole crickets Gryllotalpa major were known historically from the southern tallgrass prairie region of North America, but have declined substantially and are now restricted to prairie fragments in Missouri, Kansas, Arkansas and Oklahoma. Surveys of calling males in Oklahoma from 1987 through 1991 located sixty distinct chorusing sites, 70% of which were located within the historical tallgrass prairie biome. Chorusing sites were characterized by higher silt content and higher plant diversity than sites where crickets did not call. Adequate silt content of the soil may be critical to proper burrow construction. Higher plant species diversity on chorusing sites is probably the result of past land management practices such as mowing for hay. Although presently secure in Oklahoma, prairie mole cricket populations may be threatened in the future by land use changes and continued habitat fragmentation.