Male behaviour over the season in a wild population of the field cricket Gryllus campestris L.

Abstract

1. Cricket model systems have greatly enhanced our knowledge about mate choice and sexual selection. However, no studies exist that take seasonal dynamics into account and that follow individual males over the complete adult stage in the wild. In the present study, all adult field crickets (Gryllus campestris L.) were individually marked and measured in a population in central Germany and their behaviour was followed over their life from May to July 2000.2. The population reached a maximum of 108 males within 10 days and continuously declined thereafter. Daily mortality was positively correlated with burrow‐changing activity, which was highest at high mean temperatures. Median burrow occupation time was short at 1 day but males stayed up to 34 days in one burrow. Heavy males stayed longer in burrows and achieved a higher age.3. Male displacement was on average 2.8 m per day and up to 284 m during their life. Displacement and lifespan were negatively correlated.4. Burrows were highly aggregated at the meadow in areas of vegetation cover <85%. Aggregation of males increased with advancing season and declining population size. Consequently, nearest‐neighbour distances remained stable at 5 m until the 50th day of the study.5. About half of the 159 detected matings occurred 4–6 h after sunrise. An increased mating frequency was observed between the 30th and 50th day after adult moult.

Natural and sexual selection on male behaviour and morphology, and female choice in a wild field cricket population: spatial, temporal and analytical components

“…Simmons (1992Simmons ( , 1995 showed in cross-sectional studies that mated males of G. campestris were older, larger and more symmetrical than unmated males. In an accompanying paper we have shown that large males eclose to adults earlier and therefore, age and body size are correlated in the beginning of the season (Ritz and Köhler 2007).…”

“…The two fitness variables lifespan and number of mates were transformed into relative fitness measures by dividing them by their population mean. Pronotum width and body mass of male crickets were highly correlated (r = 0.81, Ritz and Köhler 2007) and therefore, body condition (residual body mass) was used instead of body mass. Body condition was calculated by regressing body mass over pronotum width and saving residual body mass as ratio of the predicted mass.…”

“…We decided to show the dependent variable over normalized and standardized traits. Although, using the normalized and standardized values for the traits under selection masks the range and distribution of the original data (which can be seen in our accompanying paper, Ritz and Köhler 2007) the resulting graph has a more equally distribution of supporting data points and the modes of selection can be easily seen because the population mean of a trait is centred at zero.…”

Playing to an audience: the social environment influences aggression and victory displays

“…Whether such displays serve to reinforce winner dominance (browbeating) or to communicate victory to mates or rivals (advertising; [5,19]) is unknown. Given that cricket densities can be high [12,20], and mate attraction and contests occur in close proximity [21], contests are likely to occur with female and male audiences nearby. We therefore investigated whether winners' behaviour during and after contests is influenced by the presence and sex of an audience.…”

The dispersal ability of wood cricket (Nemobius sylvestris) (Orthoptera: Gryllidae) in a wooded landscape

“…In this case the 510 daily rate was calculated over the first 24 h using distances observed for all the 511 individuals in the released population, recording mean rates of 1.7-3.8 m day -1 for 512 juveniles and 3.0-6.3 m day -1 for adults (Diekötter et al, 2005). For field crickets 513 (Gryllus campestris L.) living in herb-rich meadows, rates were obtained for all males, 514 which moved a mean distance of 2.8 m day -1 (Ritz & Kohler, 2007). Considered 515 together these results suggest that, compared to other cricket species for which data 516 are available, dispersal within wood cricket populations is limited, and the species can 517 be considered as relatively sedentary.…”