Mean life expectancy of Old World screwworm fly,Chrysomya bezziana,inferred from the reproductive age-structure of native females caught on swormlure-baited sticky traps

Abstract. The reproductive status of native (wild) screwworm fly, Chrysomya bezziana, caught on swormlure-baited sticky traps in Papua New Guinea is described. A total of 1122 females and 25 males were trapped. Of these females 595 were scored for insemination status and stage of ovarian development (on a scale of 2–10) of which 20% were in suitable condition for assignment to first, second and third ovarian cycles. Of the nulliparous females, only 17% were inseminated at stage 3 of ovarian development, 70% at stage 4, 93-97% at stages 5 and 6, and all of stages 7–10 (gravids). All parous females were inseminated. More than half of the captured females were parous (58%) and only 7% of the total were gravid. Proportions of females in ovarian cycles 1, 2 and 3 were 41%, 50% and 9% respectively. Survival of female Ch. bezziana in the laboratory was adequately described by lognormal and Gompertz survival functions, for both of which the mortality rate is an increasing function of reproductive age. Analysis of the reproductive age distribution of native females estimated their mean life-expectancy at 9 days under the prevailing mean field temperature of 26.5^oC. This equates to completion of 1.7 ovarian cycles and an estimated mean lifetime fecundity of 146 female progeny. The survival models, which also allowed responsiveness of females to swormlure-baited traps (female trappability) to vary according to their stage of ovarian development, indicated significant age-dependent trapping bias. These findings are compared with similar data for the New World screwworm fly, Cochliomyia hominivorax.     

Endocrine and morphological correlates of reproduction in the draughtboard shark Cephaloscyllium laticeps (Elasmobranchii: Scyliorhinidae)

This study examined the endocrine and reproductive correlates of reproduction in 636 female and 468 male draughtboard sharks (Cephaloscyllium laticeps) captured from southeastern Australia. Females were oviparous and displayed a single external-type ovary with a maximum follicle diameter of 35 mm. Vitellogenesis commenced at a follicle diameter of 10 mm. Females showed a constant overlap between follicular recruitment, ovarian growth, and egg laying. The male reproductive tract consisted of paired testes with spermatocysts undergoing diametric development. Plasma levels of the presumptive gonadal steroids, testosterone (T), 17beta-estradiol (E2), progesterone (P4), and 11-ketotestosterone (11-KT; males only) were correlated with morphological developmental stages of the gonads. In females, E2 increased as the follicle developed before declining as the follicle reached maturity. T remained low during the first stages of ovarian growth and increased as the follicle reached maturity. P4 showed a peak just before ovulation. In males, T was the only hormone that varied with maturity, increasing in adults; E2 and P4 were present at low plasma concentrations in males and did not change with stage of gonadal development. 11-KT was undetectable at all times. Endocrine changes in draughtboard sharks were consistent with hormonal correlates reported for other species and suggest roles for E2( in females) and T (in both sexes) in gametogenesis and P4 in maturational events in females.     

Phenology and field biology of black cutworm (Lepidoptera: Noctuidae) in Ontario no-till corn

Black cutworm, Agrotis ipsilon (Hufnagel), is an occasional corn, Zea mays L., pest that is attracted to no-till fields. Understanding the phenology of black cutworm in Ontario no-till corn, particularly the time of arrival of adults in relation to the onset of crop damage and the stages of larvae that coincide with vulnerable corn seedling leaf stages, is important for their effective control. Pheromone and blacklight trap captures of moths first occurred in early April, whereas significant influxes did not occur until mid- to late April. Males and females were often captured simultaneously, in contrast to findings in Iowa and Illinois where males were captured in pheromone traps on average 3 wk ahead of females or males in blacklight traps. This may be a reflection of a more mature source population for the influxes into Ontario because first captures also were later than in the United States. Females arrived mated and corn seedling cutting occurred within 137 degree-days (DD) (base 10.4 degrees C) of first capture in Ontario corn. Cutworms were present in cornfields before planting, and the mean age of larvae increased along with corn leaf stage, suggesting that no new recruitment took place after planting. The apparent synchrony between corn and cutworm phenology in the northern areas of corn production seems more related to the availability and quality of food for young larvae relative to the development of the crop then the time of arrival of moths.     

Development of the ovary and the female reproductive cells of the lung fluke, Paragonimus ohirai (Trematoda: Troglotrematidae)

The ultrastructure of the ovary of Paragonimus ohirai was investigated in different developmental stages of experimental infection in rats, from the metacercarial stage to the adult stage. The female reproductive cells were observed in order to understand the development of the ovary. During its development in the definitive host, the ovarian primordium and the ovary increased in size and cell number and underwent morphological changes. The blind end of the female genitalia was an undifferentiated primordium at the metacercarial stage, but became the bud of an ovary on day 3. Germ cells and supporting cells were observed on day 5. Oogonia were identified in the 15-day-old ovary, followed by the appearance of young oocytes at 17 days. Large oocytes were found on day 19, but the 21-day-old ovary contained degenerated oocytes. Mature ovaries were observed in the 26-day-old worms and egg formation was seen to arise on day 28. The development of the ovary and female reproductive cells was discussed in relation to the physiology of P. ohirai.     

Quantifying the spatial dependence of Culicoides midge samples collected by Onderstepoort-type blacklight traps: an experimental approach to infer the range of attraction of light traps

The emergence of bluetongue disease in Europe has led several countries to rapidly establish large-scale entomological surveys of its vectors, which are midges belonging to the genus Culicoides Latreille, 1809 (Diptera: Ceratopogonidae). These surveys have largely been based on the use of Onderstepoort-type blacklight traps. However, the range of attraction of the traps and the spatial dependence of the samples they provide are unknown, which somewhat complicates subsequent analyses. This paper investigates spatial interaction between Onderstepoort-type blacklight traps based on catches at a central trap placed close to two traps set in consecutive on/off modes. The spatial interaction is inferred from the drop in the number of midges collected in the central trap when nearby traps positioned at 50 m, 100 m or 200 m are turned on. The results showed a significant spatial interaction between traps separated by 50 m for female Culicoides obsoletus/Culicoides scoticus and Culicoides dewulfi. No significant interaction was found for female Culicoides of other species, for male Culicoides, or for traps spaced at ≥100 m. Based on the experimental design geometry and on simple assumptions on the distribution of Culicoides midges in the neighbourhood of the traps, the paper also presents a method to infer the range of attraction of the traps.     

Reproductive cycle and sex inversion in razor fish, a protogynous labrid in the southern Mediterranean Sea

The reproductive biology of the Mediterranean razor fish Xyrichthys novacula was investigated by demographic data and histological analysis of the female, intersexual and male gonads. Specimens were collected by bottom trawl on a monthly basis between June 2000 and July 2001 in a sandy bay in southern Thyrrenian. Gonad histology confirmed that the Mediterranean razor fish is a monandric, protogynous hermaphrodite. Females reached first sexual maturity at 100 mm ( L _T) and the estimated mean L _T at first maturity ( L ₅₀) was 125 mm. Females exhibited asynchronous ovarian development and multiple ovulations occurred over the spawning period. Vitellogenesis started in early May and spawning occurred from late May until late September. Sexual transition involved a large‐scale atresia of all oocyte stages and a massive degeneration of ovarian tissue followed by primordial germ cells proliferation. Sex change began at spawning time (June) but transitional individuals tended to cluster at the end of the reproductive period (September). They accounted for 17·1% of the population sampled and were found in a broad size range (105–150 mm L _T).     

Mating attraction by Stenotus rubrovittatus (Heteroptera: Miridae) females and its relationship to ovarian development

Stenotus rubrovittatus (Matsumura) (Heteroptera: Miridae) causes brown or black marks on rice, Oryza sativa L., grains (pecky rice), and it is becoming of increasing importance in Japan. Attractiveness of adult females or males of S. rubrovittatus to conspecific individuals was examined in the field in 2003 and 2004. Unmated female-baited traps captured significantly more males than did the unmated male-baited traps. However, the numbers of females captured by female- or male-baited traps were low, and they were not significantly different from the numbers caught by the control traps. No nymphs were captured by any traps. In 2004, we examined the effects of age and mating experience on female attraction ability with the goal of understanding the role of reproductive development in the observed behavior. The daily number of males captured by young unmated female (3-d-old)-baited traps increased from the first day until the fourth day of experiments, and then capture started to decrease. The peak in the number of captured males corresponded to the preoviposition period. When we observed ovarian development of S. rubrovittatus females under 25 degrees C and a photoperiod of 16:8 (L:D) h, we found that vitellogenesis had already started in approximately 30-50% of 1-d-old individuals. By the fifth day after emergence, 50-70% of individuals had mature eggs. These results indicated that the attractiveness of females is the strongest when egg laying becomes possible. Therefore, S. rubrovittatus females attract males selectively for mating, and it is probable that females use a sex pheromone for the attraction.     

Reproductive biology of the Alaska skate Bathyraja parmifera,with comments on an intersexual individual

A total of 1357 specimens of Alaska skate Bathyraja parmifera were collected in the eastern Bering Sea by fisheries observers and during scientific groundfish surveys from 2003 to 2005. Male and female gonads were examined for maturity stage and seasonal reproductive timing. Based on seasonal reproductive data, including the occurrence of egg cases, ovum size, ovum number, shell‐gland width and gonado‐somatic index, this species appears to reproduce continually throughout the year. Potential effects of maternal size upon the size and number of mature oocytes were also investigated, with total length having a significant, although weak, influence on both. Morphology of a single intersexual individual encountered during the collection period is also described.     

Euschistus conspersus female morphology and attraction to methyl (2E,4Z)-decadienoate pheromone–baited traps in processing tomatoes

Previous work documented seasonal field response dynamics of Euschistus conspersus Uhler (Heteroptera: Pentatomidae) to Euschistus spp. pheromone [methyl (2E,4Z)‐decadienoate]‐baited traps in California processing tomatoes, Lycopersicon esculentum (Miller) (Solanaceae). A laboratory phenology model has been reported for E. conspersus egg incubation to adult emergence. In the present work, reproductive and thoracic dissections were performed on female E. conspersus collected year‐round from seasonal habitats in California's Central Valley. We used these dissection data to establish relationships between the morphology of E. conspersus and time of year, habitat, sample recovery method, and female attraction to pheromone traps in commercial tomato fields. All ovariole categories, sexually immature through postreproductive, were recorded for females collected from tomatoes by plant‐beating sample throughout the growing season. Conversely, pheromone trap captures in tomatoes over the same period revealed that females entering the traps were exclusively reproductively active with matured eggs. We conclude that early season female‐biased E. conspersus pheromone trap catch can be used to establish a ‘biofix’ from which to accumulate degree days and forecast nymphal development in the field. Focusing control efforts on the more susceptible nymph stages may improve efficacy of reduced‐risk insecticides such as the neonicotinoids. Thoracic dissection results, with no significant difference in flight muscle size or color by ovariole condition, failed to support our hypothesis of a life history trade‐off between female reproductive activity and flight capability to explain a decline in female pheromone trap response during the mid‐summer tomato‐fruiting stages. The adaptive value of the observed retention of E. conspersus flight capability over the calendar year, and across reproductive stages, is discussed.     

Selective attractiveness of rodent-baited traps for female blowflies

Five species of Calliphoridae, mostly females, were collected using fly-traps baited with freshly killed rodent carcasses. Female blowflies were examined to determine the stages of ovarian development. The traps were selective for certain ovarian stages which varied according to the species. Phaenicia eximia (Wiedemann) was attracted to the traps mainly to oviposit, whereas females of Chrysomya albiceps (Wiedemann), C. putoria (Wiedemann) and C. megacephala (Fabricius) were captured in intermediate stages of oogenesis but seldom with eggs mature for oviposition. It is concluded that this kind of baited trap is unsuitable for the collection of male blowflies and that samples of female blowflies are specifically biased in favour of certain ovarian conditions.     

Ovarian maturity,egg development,and offspring generation of the deep-water shrimp Plesionika edwardsii (Decapoda,Pandalidae) from three isolated populations in the eastern North Atlantic

Ovarian maturity, egg development and brood size were analysed for three isolated populations (Madeira, the Canary Islands and Cape Verde Islands) of Plesionika edwardsii (Decapoda, Pandalidae) in the eastern Atlantic. Multiple colour patterns were observed at the same ovarian maturity stage, which was verified histologically, invalidating the extensive use of ovarian colour as a maturity stage criterion. The physiological size at sexual maturity, based on the maturity of the ovaries, was higher in Madeira (carapace length of 19.73?mm) and decreased to the Cape Verdes (16.39?mm). Synchronic ovarian maturation was observed during the embryo incubation process, and ovigerous females bearing embryos at the final stage of development were found throughout the year. Females are multiple spawners during the reproductive season, after which the reproductive process ends and a rest period begins. The absence of females larger than the size at sexual maturity with ovaries in Stage 1, the incubation of embryos in the final developmental stages, suggests that the resting period begins with a process that reabsorbs the energy located in the ovaries and that the resting period occurs asynchronously in females in each of the studied populations. Embryo size was independent of female body size in the three populations studied, but increased with the developmental stage. A power equation was used to describe the relationship between brood size and female body size in the three areas studied. The mean number of external Stage I embryos carried by females decreased from Madeira (n?=?7868) to the Cape Verdes (n?=?3781), where less energy, in terms of the number of embryos and the size of the eggs, was invested in reproduction. Although female size decreases from north to south, the egg number was higher in Madeira than in the Cape Verdes for the same size range.     

Effect of Microwave Exposure on the Ovarian Development of Drosophila melanogaster

In the present experiments the effect of GSM radiation on ovarian development of virgin Drosophila melanogaster female insects was studied. Newly emerged adult female flies were collected and divided into separate identical groups. After the a lapse of certain number of hours-different for each group-the insects (exposed and sham-exposed) were dissected and their intact ovaries were collected and photographed under an optical microscope with the same magnification. The size of the ovaries was compared between exposed and sham-exposed virgin female insects, during the time needed for the completion of oogenesis and maturation of the first eggs in the ovarioles. Immediately after the intact ovaries were photographed, they were further dissected into individual ovarioles and treated for TUNEL and acridine-orange assays to determine the degree of DNA damage in the egg chamber cells. The study showed that the ovarian size of the exposed insects is significantly smaller than that of the corresponding sham-exposed insects, due to destruction of egg chambers by the GSM radiation, after DNA damage and consequent cell death induction in the egg chamber cells of the virgin females as shown in previous experiments on inseminated females. The difference in ovarian size between sham-exposed and exposed virgin female flies becomes most evident 39-45 h after eclosion when the first eggs within the ovaries are at the late vitellogenic and post-vitellogenic stages (mid-late oogenesis). More than 45 h after eclosion, the difference in ovarian size decreases, as the first mature eggs of the sham-exposed insects are leaving the ovaries and are laid.     

Characteristics of the reproductive cycles and development times of Copidodiaptomus numidicus (Copepoda: Calanoida) and Acanthocyclops robustus (Copepoda: Cyclopoida)

The female reproductive cycles of the calanoid copepod Copidodiaptomus numidicus and the cyclopoid Acanthocyclops robustus were characterized by periodic changes in the oviducts. Females oscillated between a gravid and a non-gravid condition, and the whole cycle was strongly dependent on temperature. In both species, the maturation of new oocytes took place when the old egg sacs were still being carried, thus ensuring a rapid clutch succession. The embryonic and post-embryonic development duration of C.numidicus and A.robustus was investigated at five and four different temperatures, respectively. Embryonic development time was related to oviductal cycle duration at each temperature to estimate the minimum amount of non-ovigerous females expected under non-limiting mate and food conditions. Copidodiaptomus numidicus females spent 35-19% of the cycle without carrying eggs at 7-20C. Acanthocyclops robustus females spent 31-33% of the cycle without carrying eggs at the same temperature interval. Both naupliar and copepodid durations were inverse functions of temperature with nauplii developing at a faster rate than copepodids. In general, A.robustus showed reproductive advantage over C.numidicus due to a faster oviductal cycle and shorter embryonic and post-embryonic development times. However, the influence of food quality may be crucial. Acanthocyclops robustus copepodid development may lengthen well beyond the corresponding development stages of C.numidicus when growing only on algae. This retardation of development affects especially the later development stages of the cyclopoid.      

Reproductive plasticity, ovarian dynamics and maternal effects in response to temperature and flight in Pararge aegeria

In nature, ovipositing females may be subjected to multiple extrinsic and intrinsic environmental factors simultaneously. To adequately assess a species response to environmental conditions during oviposition it may therefore be necessary to consider the interaction between multiple intrinsic and extrinsic factors simultaneously. Using the butterfly, Pararge aegeria, this study examined the combined effects of extrinsic (temperature and flight) and intrinsic (body mass and age) factors on ovarian dynamics, egg provisioning and reproductive output, and explored how these effects subsequently influenced offspring fitness when egg-stage development occurred in a low humidity environment. Both temperature- and flight-mediated plasticity in female reproductive output was observed, and there were strong temperature by flight interaction effects for the traits oocyte size and egg mass. As females aged, mean daily fecundity differed across temperature treatments, but not across flight treatments. Overall, temperature had more pronounced effects on ovarian dynamics than flight. Flight mainly influenced egg mass via changes in relative water content. A mismatch between the physiological response of females to high temperature and the requirements of their offspring had a negative impact on offspring fitness via effects on egg hatching success.     

Ultrasonography of the female reproductive organs in farmed ostriches (Struthio camelus spp.)

The main objective of this study was to determine whether transcutaneous ultrasonography could be used as a diagnostic tool to monitor the reproductive organs of female breeding ostriches. An additional aim was to investigate whether the use of this technique could facilitate prediction of the start or end of the egg production season. A technique for on-farm ultrasound scanning is described and examples of ultrasonographic images of different ovarian structures, developing ova and eggs within the genital tract are presented. These data were obtained by scanning mature female breeding ostriches (n=8). In vivo scanning took place a day prior to slaughter, and immediately after slaughter the reproductive organs were scanned in vitro in a water bath. By comparing ultrasonographic images with post mortem ovarian morphology, it appeared that the following morphological structures can be identified using ultrasonography: ovarian follicles of different sizes (diameter (phi) 1-9 cm), atretic follicles, post-ovulatory follicles (POFs), ova at different stages of development and eggs within the genital tract. Of the number of follicles counted during post mortem investigation, 58% (95% confidence interval 0.41-0.79) had been detected during previous in vivo examination. In the second part of our study, ultrasonographic scans were made at weekly intervals in two farmed female ostriches (n=2) during the breeding season in order to determine the predictive value of the technique. By comparing the images of ovarian activity with individual egg production of these hens, preliminary evidence was obtained that scanning might be of value in predicting egg production, especially at the start and the end of the breeding season. It is concluded that transcutaneous ultrasound scanning in mature female breeding ostriches is an easy, noninvasive technique for the monitoring of ovarian (in)activity, for visualization of different functional ovarian structures, for following the development of individual ova and for visualization of an egg with calciferous shell within the oviduct, and that this technique will be a valuable tool in future research on reproductive physiology and pathology, and the development of more advanced reproductive technologies, such as artificial insemination.     

Reproductive biology of female big‐bellied seahorses

In this study, ovarian morphology, reproductive condition and sex steroid levels were investigated in the big‐bellied seahorse Hippocampus abdominalis , collected by snorkel and SCUBA diving in Wellington Harbour, New Zealand. Within the ovary, oocytes were contained between an outer muscular wall and an inner layer of luminal epithelium. Two germinal ridges ran along the entire length of the ovary. In cross‐section, oocytes were arranged in sequential order of development beginning at the germinal ridges and ending at the mature edge. Ovarian lamellae were absent. Vitellogenic and advanced cortical alveoli oocytes were elongated in shape, whereas maturing oocytes were distinctively pear‐shaped. Mature oocytes were large (2·6 – 4·4 mm in length) and aligned with the animal pole towards the muscular wall. Reproductively mature females were found throughout the year indicating a protracted reproductive season. The gonado‐somatic index was significantly different between all ovarian stages, but the hepato‐somatic index was not. Females with previtellogenic ovaries had significantly higher plasma concentrations of testosterone than females with vitellogenic or maturing ovaries. There was no significant difference in plasma concentrations of testosterone between females with vitellogenic or maturing ovaries, or in plasma concentrations of 17β‐oestradiol between females in all ovarian stages. This study contributes to the knowledge on the reproductive biology of female syngnathids.     

The effects of dietary nitrogen on reproductive development in the female boll weevil, Anthonomus grandis

ABSTRACT. The role of dietary nitrogen in reproductive development was investigated in the female boll weevil, Anthonomus grandis (Boh.)(Coleoptera: Curculionidae). Artificial diets were employed containing 1.7%, 2.6% and 4.0% N. Each diet was labelled with a ¹⁴C-amino acid mixture and standardized relative to cpm and N per mg of diet dry weight. Egg production, diet consumption, nitrogen consumption and nitrogen utilization were measured by recovering the cpm in the faeces, ovaries plus eggs and the carcass.
Females given the 4% N diet initiated oviposition on day 4 with maximum egg production of 11 eggs/day/female occurring on day 6. Females on the 2.6% N diet also initiated oviposition on day 4, but the time necessary to reach maximum egg production was extended. Egg production by these females eventually equalled the total production of the group on the 4% N diet. This was achieved by consuming more diet per female and dedicating a higher percentage of the absorbed diet to egg formation. With the 1.7% N diet, females showed both a delay and a decrease in total egg production because of reduced feeding and a reduced commitment of consumed nutrients to oöcyte maturation.
Switching dietary nitrogen concentrations after the initiation of oviposition resulted in changes in consumption and reproductive allocation within 48 h.     

中华真地鳖的生殖系统

通过解剖分析中华真地鳖EupolyphagasinensisWalker雌雄内生殖系统和外生殖器的构造,比较不同生长期雌虫的内生殖系统变化,并依据雌虫外生殖器和最后一腹节的构造叙述了地鳖虫卵鞘的形成过程。结果表明:中华真地鳖雌性附腺和雄性附腺发达;雄性外生殖器的阳体结构较为复杂;雌虫外生殖器、腹末构造与卵鞘表面形态的形成有必然的关系。     

Histomorphological and endocrine assessment of female Arabian carpetshark,Chiloscyllium arabicum (Elasmobranchii: Hemiscylliidae) from the Persian Gulf during annual reproductive cycle

The present study aimed at assessing the annual reproductive cycle of female Arabian carpetshark, Chiloscyllium arabicum from the Persian Gulf by a macroscopic and microscopic evaluation of the reproductive tract. The annual cycle of gonadal steroids [17β-estradiol (E2), progesterone (P4) and testosterone (T)] was also assessed in this shark. In total, 130 female C. arabicum were collected from the Bahrakan Creek (located northwest of the Persian Gulf) between January 2018 and March 2019. Females were oviparous with an external-type ovary and only one functional ovary. Five sexual maturity stages were recognized based on macroscopic and microscopic evaluation: Immature I (August–October), Immature II (November–January), Mature (February–March), Pregnant (April–May) and Spent (June–July). The structural changes in the oviducts, oviducal glands and uterus throughout the annual reproductive cycle were consistent with their roles in the egg movement, the egg capsule production and sperm storage. The plasma levels of the gonadal steroids were associated with morphological changes in the reproductive tract. E2 showed two detectable peaks during March (close to ovulation) and June (just before mating). P4 and T displayed a peak just before ovulation.     

Polymorphism in the couch potato gene clines in eastern Australia but is not associated with ovarian dormancy in Drosophila melanogaster

Natural selection can generate parallel latitudinal clines in traits and gene frequencies across continents, but these have rarely been linked. An amino acid (isoleucine to lysine, or I462K) polymorphism of the couch potato (cpo) gene in Drosophila melanogaster is thought to control female reproductive diapause cline in North America (Schmidt et al. 2008, Proc Natl Acad Sci USA, 105, 16207-16211). Here, we show that under standard diapause-inducing conditions (12 °C and short photoperiod) (Saunders et al. 1989, Proc Natl Acad Sci USA, 86, 3748-3752), egg maturation in Australian flies is delayed, but not arrested at previtellogenic stages. At 12 °C, the phenotypic distribution in egg development was bimodal at stages 8 and 14 and showed a strong nonlinear pattern on the east coast of Australia, with incidence of egg maturation delay (ovarian dormancy) increasing both toward tropical and temperate climates. Furthermore, we found no evidence for an association between the cpo I462K polymorphism and ovarian dormancy at either 12 or 10 °C (when egg maturation was often delayed at stage 7). Owing to strong linkage disequilibrium, the latitudinal cline in cpo allele frequencies was no longer evident once variation in the In(3R)P inversion polymorphism was taken into account. Our results suggest that the standard diapause-inducing conditions (12 °C and short photoperiod) were not sufficient to cause the typical previtellogenic developmental arrest in Australian flies and that the cpo I462K polymorphism does not explain the observed delay in egg development. In conclusion, ovarian dormancy does not show a simple latitudinal cline, and the lack of cpo-dormancy association suggests a different genetic basis to reproductive dormancy in North America and Australia.