Field Cricket Gryllus Integer Research Articles

Sperm Competition in the Field Cricket Gryllus integer (Orthoptera: Gryllidae)

Sperm competition was studied in the field cricket Gryllus integer. Control females mated with a normal, fertile male, and then with a second fertile male (NN females). Experimental females mated with a fertile male and then with a male sterilized with gamma radiation (NR females), or with a sterile male and then with a fertile male (RN females). Females oviposited in individual dishes for 8 days, and 3 successive dishes were used for each female for eight days each. Nymphs and unhatched eggs were counted for each female for each dish. There were generally no differences in the percentage of eggs hatching when different dishes were compared. Considering all egg dishes, NN and RN females produced significantly more offspring than NR, but there were no differences between NN and RN females. Mean $P

Sterilization of Adult Male Field Crickets Gryllus integer (Orthoptera: Gryllidae) by Gamma Radiation

In this paper I report a dose of gamma radiation that will induce sterility in adult male field crickets. This work was undertaken as part of a larger study on sperm competition in the field cricket Gryllus integer (Backus, 1985). The methods used in this study are outlined in Backus (1985). Fifteen virgin adult female G. integer were each mated twice to 1 of 15 adult male crickets within 24 hr of the male's exposure to 7,000 roentgens of gamma radiation (R males). Following mating females were allowed 11 days for oviposition in a container filled with 250 ml moist vermiculite. Oviposition dishes were examined daily for the presence of nymphs; any nymphs found were mouth-aspirated and counted. A control group consisted of 5 females mated with unirradiated (N) males and were treated similarly to females mated with R males. Following 8 weeks, the soil in each oviposition dish was dried and examined under a dissecting microscope for the presence of unhatched eggs. All unhatched eggs were counted; any nymphs that had hatched and were remaining in the soil were counted and added to the number of emerged nymphs. Productivity, the total number of eggs laid by a female, was determined by summing the number of nymphs emerged with the number of unhatched eggs. Mean productivity for females mated with R males was 337.5 (SD 201.4, Range 65-733), whereas mean productivity for females mated with N males was 291.2 (SD 128.3, Range 153-500). A Mann-Whitney U test revealed no significant difference in mean productivity between the 2 groups (U = 35.5, p > 0.05). The mean proportion of eggs hatched for females mated with R males was 0.01 (SD 0.02, Range 0-0.04); for females mated with N males was 0.67 (SD 0.27, Range 0.190.86). There was a significant difference between these values (U = 0, p < 0.05; onetailed). The mean age of death for males in the R group was 22.8 days (SD 30, Range 16-28); for males in the N group was 59.2 days (SD 19.0, Range 27-77). There was a significant difference between the 2 groups of males for age of death (U = 1, p < 0.05, two-tailed). The proportion of eggs hatched for females mated with N males was much greater than for females mated with males exposed to 7,000 roentgens of gamma radiation. The proportion of eggs hatched by females in the R group was so low that 7,000 roentgens was apparently sufficient to sterilize adult male G. integer. A second effect of this dosage appears to be a significantly shortened lifespan in R group males. The dosage of radiation used did not appear to affect male courtship or mating behavior (Backus, 1985). This was the only dosage of radiation tested and may be considered as a minimum as 1% of the eggs laid by females mated with R group males hatched. Support for this work was provided by a Natural Sciences and Engineering Council of Canada grant to Dr. W. H. Cade.

Some factors influencing male-male aggression in the field cricket Gryllus integer (time of day, age, weight and sexual maturity)

Male field crickets ( Gryllus integer; Orthoptera: Gryllidae) stridulate aggressively and fight vigorously in competition for females. We studied the degrees to which male-male aggression is influenced by time of night or day, sexual maturity, age and weight. Trials were observed between males matched for age and/or weight that had not previously been exposed to each other. Data were gathered on attack latency, aggressive stridulation, time spent in aggressive interactions and the winner of a trial. Aggression was equally likely to occur at any time of the day or night. Sexually mature males were more aggressive than adult males which had not yet produced a spermatophore. Age past sexual maturity did not greatly influence aggression, and heavy males were more aggressive than lighter ones. In repeated trials between the same males, one male in each pair won significantly more contests.

A guide to the literature on aggressive behavior

A guide to the literature on aggressive behavior

Factors Affecting Calling Behaviour in Field Crickets, Teleogryllus and Gryllus (Age, Weight, Density, and Parasites)

The duration of calling by male acoustical insects should reflect the selective forces of mating success and longevity. Nightly calling durations were studied in the field crickets Gryllus integer, G. pennsylvanicus, G. veletis, and Teleogryllus africanus. Immediately after the final molt, males were placed in individual jars in the laboratory. Jars were monitored electronically for the production of calling song. Males started calling at 4 to 7 days on average in each species, and there were no significant changes in duration of calling with increasing age. G. integer was also studied in a large outdoor arena. Arena males first called at approximately the same age as males in the laboratory, and the duration of calling did not change with age. Onset of first calling followed initial production of the spermatophore by a few days in separate samples of each species. Absence of ontogenetic changes in the amount of calling demonstrates that calling and satellite males in field populations of G. integer do not result from age differences. Mean calling duration per night was determined for each male, and there was no difference in mean calling duration with male weight in any species in the laboratory, or G. integer in the arena. G. integer called significantly less on average than the other species. Individual calling durations in G. integer were highly skewed, whereas distributions of the other species were normal in shape. Reduced calling in G. integer may result from the attraction of acoustically orienting parasitic flies, Euphasiopteryx ochraces, to the calling song of this cricket species. Coefficients of variation demonstrated that G. integer is more variable in acoustical behaviour than the remaining species, an observation confirmed by previous field studies.

Field Cricket Spacing, and the Phonotaxis of Crickets and Parasitoid Flies to Clumped and Isolated Cricket Songs

AbstractNearest neighbor analyses of the field crickets Gryllus integer, G. veletis, and Teleogryllus oceanicus demonstrated that calling ♂♂ were aggregated. Broadcasts of conspecific song to calling ♂♂ indicated that attraction of neighboring ♂♂ maintained inter‐male distances. Broadcasts of G. integer song through aggregated and isolated loudspeakers showed that the total number of crickets and parasitoid flies, Euphasiopteryx ochracea, attracted to aggregated loudspeakers was greater than that to an isolate. The average number of attracted crickets and flies in an aggregation was comparable to the isolated total.