Low Mating Research Articles

Mating Suppression of Caged Spruce Budworm (Lepidoptera: Tortricidae) Moths in Different Pheromone Atmospheres and High Population Densities

High densities of laboratory-reared Choristoneura fumiferana (Clemens) were placed in cages, surrounded by synthetic pheromone emitters, in a temperate conifer forest. Compared to controls, mating was suppressed for 3, 6, 12 pairs, and 12 males and 6 females per cage for release rates of 20 to 80 mg/h per ha. For the two highest population densities, mating suppression increased linearly with increase in pheromone concentration. As population density increased, at low pheromone concentration mating suppression decreased, but at high concentration, mating suppression was unchanged. Changes in olfactory sensitivity and random encounters may explain part of these results. Also. female activity may explain some of the mating disruption at high pheromone concentrations.

Modified zirconia abradable seal coating for high temperature gas turbine applications

The results and development of a new full ceramic abradable turbine seal coating material prepared by thermal spraying are presented. The main objective was to achieve high temperature abradability and low mating part wear using an erosion-resistant coating with high temperature stability and thermal shock resistance. The new coating was successfully laboratory tested at temperatures of at least 1100°C (2012°F). Commercial metal-based abradable coatings which are currently available are limited to lower operating temperatures. Typical plasma- sprayed ceramic coatings, because of inherent high particle velocities, are normally to dense to permit abrading without experiencing high turbine blade tip wear damage. In contrast, lower velocity combustion-sprayed ceramic coatings frequently have lower toughness and cohesive particle strength for resistance to abrasive erosion. The new coating material is designed to react exothermically, during combustion spraying, to produce a coating both with high interparticle cohesive strength for resistance to abrasive particle erosion and with controlled porosity for low turbine blade tip wear and effective abradability. Adjustment of spraying conditions gives flexibility to alter the coating hardness and porosity and permits the tailoring of abradability and erosion resistance properties for specific operating requirements. Based on specially developed test methods for high temperature abradability, high temperature particle erosion and thermal cycling, the modified zirconia coating showed superior performance to high performance baseline materials tested in the program. Industrial evaluation of this coating is presently being conducted.

Environmental Temperatures and Activities in Wild Spotted Turtles, Clemmys guttata

Cloacal and environmental temperatures of 512 wild spotted turtles, Clemmys gut- tata, from southeastern Pennsylvania were recorded during various phases of their normal activities: basking, feeding, moving in water or on land, dormant in water of both high and low temperatures, and courtship, mating and nesting. The mean cloacal temperature for activity was calculated as approximately 20.16?C and the normal activity range 3-32?C. Cloacal temperatures were closely correlated to those of the environment during all activities. Males fed and were otherwise more active than females in waters of cooler temperatures (P < 0.05), but this was probably due to females remaining active longer into the warmer parts of the annual cycle. Clemmys guttata are often active at water temperatures of about 5?C in early spring. They become dormant when water temperatures reach about 30?C in June, and also shift their diel activity cycle from afternoon to morning as summer approaches. Feeding begins when water temperatures reach 14?C. Reproductive activity may occur at cloacal temperatures as low as 8?C in water of 8.5?C. Clemmys guttata behaviorally thermoregulate by basking in cooler weather, and by burrowing into the soft bottom of a waterway or entering muskrat burrows and lodges to avoid extreme hot and cold conditions.

Fertility of Chickens from Lines Divergently Selected for Mating Frequency

Fertility comparisons of males under natural and artificial mating situations were made among lines of chickens selected for high and low mating frequency and the randombred population from which the selected lines originated. Although highly significant differences existed among lines for the frequency of sexual behaviors, there were no significant differences in fertility among lines either when males were with females for extended periods of time or when hens were artificially inseminated. Significant differences were found between mating systems for days to peak and duration of fertility.

The Effects of Exogenous Steroidal Hormones on the Testes of Quail from Selected High and Low Mating Lines

Several steroid hormones were tested for their effects on the testes of lines of Japanese quail selected for high and low mating frequency. Estradiol benzoate and testosterone propionate caused a complete and partial regression of the testes, respectively, while dihydrotestosterone did not affect testicular weight. Spermatogenesis was adversely affected by both estradiol benzoate and testosterone propionate but not by dihydrotestosterone. Dihydrotestosterone caused a significant increase in the diameter of the seminiferous tubles while estradiol benzoate and testosterone propionate caused a significant decrease in tubular diameter. Significant line differences were found; the high mating line exceeded the low mating line for each of the treatments except extradiol benzoate. Extradiol benzoate caused testicular regression in both lines.

Release-recapture estimates of the population density of Ephestia cautella (Walker) in a commercial peanut warehouse

Seasonal trends in adult Ephestia (= Cadra) cautella (Walker) population density in an in-shell peanut storage facility were estimated from suction trap catches adjusted for recapture rates. Recapture rates the 1st day after release were 7% of females and 20% of males in an unstocked warehouse and 31% of males in a stocked warehouse; total recoveries were 11, 32 and 50%, respectively. Mating frequencies were generally between 46 and 75%. However, low mating frequencies (21–35%) during periods of low population density could have been partially due to the trapping of males. Every 4 weeks the E. cautella population increased roughly two-fold in the unstocked ware-house (scattered peanuts remaining) and 37-fold in the stocked warehouse. Since breeding was continuous, generations overlapped.

The reproductive physiology of the screwworm, Cochliomyia hominivorax (Diptera: Calliphoridae). III. Mating.

Male screwworm flies demonstrated maximal mating vigor from 4 to 16 days postemergence, but females had low mating levels until 5 days postemergence. Mating occurred when the females had eggs at stages 4 to 10 of development, but the greatest proportion of females were inseminated when they had stage 7 through 10 eggs. Removal of the ring gland from females at 4 or 24 h postemergence reduced mating by 50%, but ovariectomy had no effect on mating. Therefore, the correlation of ovarian development with mating was secondary to neuroendocrine events. Screwworm holding temperatures 15.6° to 43.3°C had no effect on the adjusted percentage inseminated females nor on the rate of increase of the percentage of insemination vs the stage of egg development. However, temperature did influence the time postemergence which mating occurred. Females died before mating at 10°C, but at 12.8°C, mating was observed at 480 h, and this decreased to 96 h at 43°C.

The reproductive physiology of the screwworm, Cochliomyia hominivorax (Diptera: Calliphoridae). I. Oogenesis.

Male screwworm flies demonstrated maximal mating vigor from 4 to 16 days postemergence, but females had low mating levels until 5 days postemergence. Mating occurred when the females had eggs at stages 4 to 10 of development, but the greatest proportion of females were inseminated when they had stage 7 through 10 eggs. Removal of the ring gland from females at 4 or 24 h postemergence reduced mating by 50%, but ovariectomy had no effect on mating. Therefore, the correlation of ovarian development with mating was secondary to neuroendocrine events. Screwworm holding temperatures 15.6° to 43.3°C had no effect on the adjusted percentage inseminated females nor on the rate of increase of the percentage of insemination vs the stage of egg development. However, temperature did influence the time postemergence which mating occurred. Females died before mating at 10°C, but at 12.8°C, mating was observed at 480 h, and this decreased to 96 h at 43°C.

Testosterone-induced precocious sexual behavior in chickens differing in adult mating frequency

Precocious adult sexual behavior was determined for chicks from two lines of chickens selected bidirectionally for adult mating frequency. Three-day-old chicks were injected with either 0 or 12.5 mg testosterone cypionate (TC) in sesame oil, and their sexual responses to a hand thrust test (HTT) measured at 10, 12, 14, 16 and 18 days of age. TC stimulated copulation in both the high and low mating line, while birds receiving injections of the vehicle only, failed to copulate. There were differences in precocious sexual behavior between lines at this young age, although further differential maturation of neural tissues mediating mating behavior may occur. Courts, mounts, treads and matings were determined for these same birds at 7 weeks of age, following treatment with 25 mg TC. Differences were found between the lines, with high mating line birds scoring higher than low mating line birds for all behaviors measured. Early treatment with TC, however, had no direct effect on sexual behaviors at this age. Correlations between 7-week behaviors and HTT scores were determined and their possible meanings discussed.

Testosterone determinations in lines of chickens selected for differential mating frequency

This study was designed to evaluate the relationship between plasma testosterone titers and mating behavior in lines of chickens that had undergone bidirectional selection for high and low mating frequency and in the unselected population from which the selected lines originated. Plasma testosterone (T) concentrations were determined by radioimmunoassay procedures. Also measured were packed blood cell volumes (PCV) and two behaviors, courtship and completed matings. Significant differences were found among lines for all measures with the high mating line ranking above the low mating line and the unselected control line being intermediate to the selected lines for all measures. Also found was a positive correlated response of plasma T titers to selection for the cumulative number of completed matings.

Mating competency of rams and flock fertility

The mating performances of four rams with low mating competency (ratio of mounts to serves approx. 12:1) were compared with those of four rams with high mating competency (ratio approx. 2:1) when they were mated for 8 days in single-sire flocks at a ram: ewe ratio of 1:90. The two groups of rams had achieved similar number of serves in an earlier series of mating tests. The rams with high and low mating competency did not differ in percentage of oestrous ewes marked, percentage of oestrous ewes inseminated or percentage of ewes which became pregnant. The rams failed to inseminate 10% of the ewes which were marked, but this was not related to mating competency.

Crowing and mating behaviors in lines of chickens selected for mating frequency

The frequency and relationship of crowing to several mating behaviors were determined in lines selected for high and low cumulative number of completed matings, and in the unselected random-bred population from which the selected lines originated. A diurnal rhythm in crowing frequency was observed, with birds crowing more at 09.00 h than at 13.00 and 16.00 h. The frequency of crowing increased from 24 to 68 weeks of age in the high mating line which was in contrast to decreases in the low mating and unselected control lines. Significant positive correlations were obtained between crowing at the various ages and between crowing and courting at 68 weeks of age. Implications of these findings to the backyard flocking situation are discussed.

Fitness of the “Apricot Eye” Mutant of the Mediterranean Fruit Fly, Ceratitis capitata1

The recessive mutant “apricot eye” was found inferior to the wild-type in mixed population cages. The apparent inferiority was due to a lower mating propensity of the “Apricot eye” males and a lowered survival of the “apricot eye” larvae under competition with wild-type larvae on artificial diet. Attraction to host fruit (such as various citrus varieties) was not affected by the eye color. The use of the genetically-marked strain of the Mediterranean fruit fly in ecological field studies should take into consideration the sexual inferiority of the “apricot eye” males.

Androgen influence on mating behavior in selected lines of Japanese quail

Bidirectional selection for high and low mating behavior has resulted in lines of Japanese quail that differ significantly in mating frequency. To evaluate the effects of this selection on the endocrine aspects of mating behavior, exogenous testosterone cypionate (TC) was administered to caponized and intact males from selected and control lines. Dosages of TC, administered as a single injection, were 0, 5.0, and 10.0 mg for the caponized and 1.25, 2.5, and 5.0 mg for the intact males. Mating performance was measured by testing each male individually with a series of female tester-flocks for eight 8-min periods. Capons mated within 3 to 4 days postinjection, with the period of peak activity occurring between the eighth and twelfth days. Hypertrophy of the cloacal gland followed a similar pattern. At no TC level was the mating frequency of caponized males from the low mating line equal to that of males from the high mating line. Furthermore, exogenous TC at these dosages failed to stimulate capons from the high and low mating lines to mate as frequently as the intact males of their respective lines. Exogenous TC had a depressing effect upon the mating frequency of intact males from the high mating and control lines but had no influence on those from the low mating line.

The Mating System of Caenorhabditis elegans: Evolutionary Equilibrium between Self- and Cross-Fertilization in a Facultative Hermaphrodite

A model accounts for the low mating efficiency of Caenorhabditis elegans males when raised with hermaphrodites in laboratory cultures and for the relative behavioral indifference of hermaphrodites to mating. It is suggested that the mating system of C. elegans may provide a test case for distinguishing among the several theories which attribute an evolutionary advantage to sexual reproduction.

Influence of mating pressure and season on the semen characteristics of rams

SUMMARYTwo groups of 4 Suffolk rams were each subjected to mating pressures of 90 ejaculates (High) and 45 ejaculates (Low) over a 3-day period during summer and autumn. Every sixth (High) or every third (Low) ejaculate was collected into an artificial vagina and assessed for volume, sperm density, total sperm per ejaculate, motility and percentage of live and abnormal sperm.There was a general lowering of semen quantity and quality with successive ejaculations. Rate of change of the various measures was greater on the High than on the Low mating pressure. Volume and percentage of live sperm showed a greater decline, and percentage of abnormal sperm a greater increase, during the autumn than during the summer. Density showed a greater decline in summer than in autumn.The significance of the changes in semen characteristics observed is considered in relation to requirements for high fertility after pro-gestagen treatment.

Genetic analysis of tonic immobility in young Japanese quail (Coturnix coturnix japonica).

Data were obtained on tonic immobility from 10th-generation matings of replicated lines of Japanese quail. These lines had been selected for high and low mating ability and included the random-bred control population from which the selected lines originated. At 6, and again at 12 days of age, each bird was subjected to uniform procedures of immobilization and was given two scores, one indicating the number of trials required to induce immobility, another the duration of induced immobility. Although there were no differences between sexes, lines were significantly different for duration and percentage incidence to the immobility response at both ages. Individuals that responded faster also exhibited longer durations of immobility, suggesting a high degree of susceptibility. Heritability estimates indicate that the additive genetic variation effecting tonic immobility is low to moderate in magnitude. These results, when taken in an evolutionary context, suggest prior natural selection for tonic immobility and indicate that this trait is associated with fitness.

Relative mating activity of the sexes in homokaryotypes of Drosophila persimilis from a Redwoods population.

Previous tests for mating activity of Drosophila persimilis homokaryotype KL (Klamath) and MD (Mendocino) chromosomal arrangements (northern California population: Redwoods) had shown KL to mate faster on the average than MD in homogamic tests. A strain (double-cross hybrid of four KL lines from the same population) with reliable high mating activity was developed for testing the sexes separately. Five pairs of KL-MD homokaryotype strains were chosen to be tested by the criterion that each pair had been derived from a separate wild KL/MD progenitor. Strains were crossed within arrangements in a diallelic design (20 inter- and five intrastrain crosses tested in 16 replicates per cross) to provide mating activity indices of four sets: KL females, KL males, MD females, MD males. Mating tests employed ten virgin experimental flies with ten tester (double-cross hybrid) flies of the opposite sex in 30-min observation periods. All flies were matured for 5 days at 25 degrees C before testing. Among parental strains, females were consistently higher in mating activity than males for both KL and MD arrangements. Most interstrain hybrids were heterotic, with KL and MD females not significantly different. However, hybrid MD males displayed greatest variation and had lowest mating activity, while KL males were the least variable and highest in mating activity. With heterosis in the hybrids, there was no predictability (additivity) from performance of parental strains to hybrid offspring. Mating activities of the two sexes were uncorrelated, indicating either that the sexes have independent genetic systems controlling mating activity or that the expression of the same genetic system is influenced by sex. Since the hybrid males of the two karyotypes displayed different courtship activity while the females were at about an equal level of receptivity, intrasexual selection among males is likely to be important in nature.

Effects of mating behaviour and ram libido on the fertility of young ewes

Two groups of 92 and 93, 2 1/2-year-old maiden Merino ewes were each mated to a team of two, 13-year-old Corriedale rams. Both rams of each ram team were either of high or low libido and mating dexterity as determined by a series of pen libido tests. Continuous observations of mating behaviour were carried out on each group for 9.5 days and at 4-5 weeks post coitum (p.c.) the pregnancy rate was determined by laparotomy and hysterotomy. Although the ram pairs differed in libido in the pen tests, under the conditions of paddock mating there was found to be no significant difference between the two mating groups in the total number of mounts and services, the proportion of ewes detected in oestrus, the proportion of ewes pregnant, or the mean duration of oestrus. The duration of oestrus was shown to be dependent on the time of day at which the ewe was first detected in oestrus. Some ewes, although probably in oestrus, were not detected by the ram during periods of little mating activity and therefore their subsequent duration of oestrus was significantly shorter. The pregnancy rate of ewes with a duration of oestrus of less than one hour was significantly lower than that of ewes with a longer duration of oestrus.

Social variables and divergent selection for mating behaviour of male chickens ( Gallus domesticus)

Heterosexual or unisexual contact of juvenile males from two lines divergently selected for male mating frequency, and a control line had little, if any influence on their subsequent mating behaviour. The interaction of lines x social environments for mating behaviour was not significant, showing that lines responded in a similar manner to the environments. It is hypothetized that selection for low cumulative number of completed matings (CNCM) was primarily for higher neural thresholds, whereas selection for high CNCM affected loci operative after neural thresholds are attained. The magnitude of the sexual component of a court was found to be dependent on the genetic background of the population, being less in the low mating than in the high mating line.