The post-embryonic development and life history of the millipede, Ommatoiulus moreletii (Diplopoda: Iulidae), introduced in south-eastern Australia

The life cycle of Ommatoiulus moreletii consists of an egg, pupoid and up to sixteen stadia. Sexes are differentiated at the sixth stadium. Males may mature at any moult from the eighth to the twelfth stadia, but most are mature by the tenth or eleventh. Maturation is more difficult to determine in females but seems similar to the males with respect to stadial age. O. moreletii is periodomorphic.
Field studies were made of O. moreletii in an open grassland and a dry sclerophyllous woodland in South Australia. Females matured their eggs in late summer-autumn. They mated and oviposited during autumn-winter. After one year, O. moreletii was in the seventh, eighth or ninth stadium. After two years, the tenth or eleventh stadia were reached and after three years the twelfth or thirteenth. The moulting of individuals older than about one year was confined to moults in (1) spring and (2) summer. Adult males were mature from summer to spring and intercalary from spring to summer.     

The life history and post-embryonic development of "Spirobolus" bivirgatus (Diplopoda: Spirobolida) on Aldabra, Western Indian Ocean

Spirobolus bivirgatus, recently known as Mystalides bivirgatus, passes through 15 stadia. These were differentiated by the ocular field method. Development is anamorphic from stadia I to VIII and epimorphic from stadia IX to XV. Maturity is reached in a few males in the eighth stadium but more normally it occurs in the ninth to twelfth stadium. Females are mature in the ninth to fifteenth stadium. Adult males possess fully developed gonopods as well as soft pads on the ventral surface of the tarsi. The pads are illustrated with scanning electron micrographs. Males die after breeding but females probably breed in three or more successive years. Eggs are laid during the wet season, December to April, and these reach maturity within the second or, possibly, the first year of growth. The density, distribution and food of S. bivirgatus is briefly described.     

Millipedes faced with drought: the life cycle of a Mediterranean population of Ommatoiulus sabulosus (Linnaeus) (Diplopoda,Julida, Julidae)

Growth, development and life-cycle duration of the millipede Ommatoiulus sabulosus (f. aimatopodus) were studied in a Mediterranean shrubland of southern France and compared with previous data from northwest Europe. Changes in the proportions of stadia during the course of the year were analysed in several generations. The results show that stadia VII and VIII are consistently reached after the first year of growth, and stadia IX and X after the second year. First reproduction may occur at the age of two years in males reaching maturity at stadium X, but not until the age of three in those reaching maturity at stadia XI and XII. Reproduction cannot occur until at least the age of three in females, which carry mature eggs from stadium XI onwards. In comparison with more northern populations, life-cycle duration is not shorter in the Mediterranean population but there are marked differences in its phenology: the breeding period is in autumn, so that juveniles of stadia II to VI are never faced with the summer drought, and larger individuals are mostly inactive in summer; moreover, all individuals moult once every winter. The results illustrate how julid millipedes of humid temperate regions could respond to higher temperatures and drier summer conditions in the context of climate change.     

Additional moults into 'elongatus' males in laboratory-reared Polydesmus angustus Latzel, 1884 (Diplopoda, Polydesmida, Polydesmidae) - implications for taxonomy

The number of stadia during post-embryonic development is supposed to be fixed in most species of the millipede order Polydesmida. For the first time since 1928, additional moults were observed in two males of Polydesmus angustus Latzel, 1884 reared in the laboratory. These 'elongatus' males sensu Verhoeff reached stadium IX instead of stadium VIII, with addition of a further podous ring (32 pairs of legs). One male had well-developed gonopods at stadium VIII, which regressed at stadium IX; the other had no gonopods at stadium VIII, which developed at stadium IX. The two cases correspond to the 'regressionis' and 'progressionis' forms described by Verhoeff in Polydesmus complanatus (Linnaeus, 1761), which confirms entirely his results. Additional moults appear to be associated with small body sizes and possible underlying mechanisms are discussed. Comparisons between millipede orders indicate that post-embryonic development is less strictly canalized in Polydesmida than in Chordeumatida. This implies that the adult number of body rings is of limited taxonomic value in Polydesmida and should not be viewed as a character of generic importance.     

The millipedes of a Cheshire wood

The density and surface activity of the millipedes in a quarter of an acre of a sycamore ash wood are described. Seven species were extracted by Tullgren funnels from samples of soil and litter over five years and were also caught in pitfall traps during a further two years; four other species occurred occasionally in the traps. Each square metre of the site supported 100 individuals over the winter, rising to 300 in the summer. Of these, 85 % belonged to three species, Iulus scandinavius, Polydesmus angustus and P. denticulatus .
Male I. scandinavius become adult in either the ninth, tenth or eleventh stadium; females in the tenth and eleventh. Eggs are laid in spring and these take three years to become adults which breed and then die. The majority of Polydesmus spp. in the samples are young belonging to the first six of the eight free-living stadia. The adults fell into the traps in the summer and newly emerged young appear in the samples at this time. They overwinter in their first year mainly as fifth stadia; some might reach maturity (eighth stadia) in the summer following, but it is not certain that they could breed at this time.
The pattern of dispersion of lulus is fairly even and is correlated with the distribution of leaf litter but the Polydesmus spp. are highly aggregated. All stadia of lulus fall into the traps but only the last two of Polydesmus . The aggregation of Polydesmus spp. appears to be correlated with the relative inactivity of the younger stadia. The estimates of density of Polydesmus spp. are unreliable because of their aggregation but those of lulus have determinable limits and it is possible to derive rough though meaningful standing crop, production and life-table data. The overwintering standing crop of lulus consists of the survivors of three generations of 5, 2.2 and 1.4% of the original eggs laid; it has a fresh weight of about 1.25 g and a production in the order of 1.5–2.5 g/m².     

Timing and duration of moult in three populations of Purple Sandpipers Calidris maritima with different moult/migration patterns

Timing and duration of primary moult in three populations of Purple Sandpipers Calidris maritima were described and discussed in relation to the birds’ need to complete moult before the onset of winter, when resources are required for survival. We predicted that moult would be completed earlier by birds wintering at higher latitudes. The south Norwegian breeding population, which moults and winters along the coast of east Britain (54–57°N) had a mean starting date of 21 July for primary moult (16 July for females and 24 July for males), a mean duration of 61 days, and completed on 20 September. Resident Icelandic (64–65°N) birds had a mean starting date of 22 July for primary moult (17 July for females and 25 July for males), a mean duration of 51 days, and completed on 11 September. Birds moulting in north Norway (70°N) arrived in north Norway in suspended primary moult or without having started moult, and completed it there. They had a mean completion date of 2 November for primary moult (31 October for females and 3 November for males). Starting date and duration could not be estimated because some suspended moult for an undetermined period, but it was thought that they started in late August. It is likely that most originated from Russia. The onset of moult appears to be set by the end of breeding and there is little overlap in these two events. The earlier start of moult by females in all three populations may be because they abandon the males when the chicks hatch, leaving the males to attend the chicks. Although the duration of primary moult followed the expected trend, being fastest in north Norway and slowest in Britain, the onset of moult was so late in north Norway that they had an unexpectedly late completion date, despite their rapid moult. The late completion of primary moult in north Norway suggests that wintering in the far north may not pose the energetic constraints on Purple Sandpipers that had previously been supposed.     

Social influences on nymphal development in the cockroach, Diploptera punctata

Solitary male nymphs of the cockroach Diploptera punctata (Eschscholtz) (Blattaria: Blaberidae) took significantly longer to reach adulthood than males paired with either a male or female nymph or grouped with four other male nymphs since birth. When isolated throughout nymphal development, 15.8% of males passed through 3 stadia before adult eclosion, and the remainder went through 4 stadia. In contrast, 61.3% of paired males became adults in 3 stadia. Males need not, however, be isolated or paired for the entire nymphal period to express isolated or paired patterns of development. About 60% of males paired in just the first stadium or its initial 9 days became adults in 3 stadia, and only 20.4% of males isolated in the first stadium and the first 3 days of the second reached adulthood within 3 stadia. Although the first stadium was a critical period in which social condition determined the course of future development, analyses of covariance showed that isolated males gained less weight than paired ones, not only in the first stadium, but in the second as well. Moreover, the degree of growth of a male in the second stadium, measured as either weight gain or relative growth rate, did not depend on the male's social condition in the first stadium, because isolated second-instar males grew less than paired ones, even when both sets of insects had been paired in the first stadium. Female nymphal development, unlike that of males, was not greatly affected by social factors.     

Anamorphosis and life-history of the millipede Nopoiulus kochii (Gervais, 1847), new for Egypt

Abstract

Monthly samples were taken to determine the anamorphosis and the life-history of the millipede Nopoiulus kochii, new to Egypt. Stadial determination was possible from counting the podous and apodous rings, rows of ocelli, and serial additions of defence glands. Sexual dimorphism occurred at stadium IV. Maturity is achieved at stadium VII. Few males, however, attained maturity at stadium VI. Further moultings of adult stadia occur so that additional adults are found from stadia VII to XIV. N. kochii breeds at the age of six months.     

Circadian locomotory rhythm and the influence of moulting in Australian field cricket nymphs

ABSTRACT. Evidence is presented for a circadian control of locomotory activity in the larval stadia of the cricket, Teleogryllus commodus Walker. Under light—dark cycles (LD), maximal activity occurs around the L/D transition and/or in the hours preceding it. Free-running rhythm patterns longer than 24 h are observed in constant light. Re-entrainment to phase advances in the LD cycle is also accompanied by several transient cycles. However, free-running rhythms under constant darkness or transients when exposed to LD cycle delays were not found. LD cycles during the eighth stadium set the phase of a free-running rhythm in the adult, even if the nymph does not show a rhythm. Nymphal activity is often erratic and is disrupted periodically by the moulting cycle, but moulting does not interrupt the operation of the circadian system. The daily timing of the moult itself is not under circadian control.     

Behavioural and morphological correlates of variation in the extent of postjuvenile moult in the Siskin Carduelis spinus

Siskins Carduelis spinus show great variation in the acquisition of adult plumage, so that yearling birds can be classified as either "delayed" (i.e. still showing yearling plumage) or "advanced" (i.e. with an adult plumaged appearance). The extent of moult in males is related to the size of their black bib, which in turn is highly correlated with their social dominance rank. Autumn male body mass is higher in advanced than in delayed moult birds, but by winter the relationship is reversed, suggesting a trade-off between investment in moult and subsequent body condition. Results were similar in Spain and Britain. A possible cost of advancing moult is suggested by an analysis of aggressive interactions at bird feeding tables which showed that adult males discriminate between delayed and advanced birds, directing most aggression towards adult-looking yearling males. The results suggest that the variation in the extent of postjuvenile moult is not only related to energetic constraints but has other important behavioural and ecological implications.     

The life-history of the julid millipede Cylindroiulus nitidus in a Derbyshire wood

A population of C. nitidus in a deciduous wood at Milldale, Derbyshire included adult males with 36 to 54 podous segments but the highest number of segments possessed by immature males was 38. The occcurrence of males in successive stadia is contrasted with the alternation of copulatory and intercalary males in some other juliform millipedes.
Samples were taken to determine the course of post-embryonic development and life-history in the field. Stadial determination by counting rows of ocelli was not possible but a separation was made by analysis of dimensions. These dimensions and segmental formulae are compared with those of German examples. No intercalary or other modified post-imaginal male stages were present.
From a comparison of the distribution of stadia in five samples it appears that males mature in three and females in four years. Males survive a further four to five, females a further three years after first achieving maturity. The significance of the special and general life-history characters of the species are discussed.     

Effects of infection with a granulosis virus on larval growth, development and ecdysteroid production in the cabbage looper, Trichoplusia ni

ABSTRACT. Granulosis virus-infected Trichoplusia ni (Hûbner) larvae exhibited an increased larval life span with no supernumerary moult and no pupation. Weight gain was not affected. Insects infected shortly after hatching were slower in reaching the fourth and fifth stadia than were control insects. Haemolymph ecdysteroid titres were lower in virus-infected insects than control insects, but these differences were only significant ( P <0.05) in the fifth stadium. Electron microscopic examination of the pro thoracic glands revealed extensive granulosis virus infection, and glands from virus-infected insects produced no RIA-detectable ecdysteroids in vitro. Injection of 20-OII-ecdysone into virus-infected larvae at various concentrations and times did not induce pupation.     

A sexual conflict in collared flycatchers,Ficedula albicollis: early male moult reduces female fitness

A sexual conflict over levels of parental care occurs in most animals with biparental care, and studies of sexual differences in levels of parental care have usually focused on its intra-annual fitness consequences. We investigated inter-annual fitness consequences of a sexual difference in timing of feather replacement (moult) in collared flycatchers (Ficedula albicollis). In this study, males overlapped reproduction and moult more often than females, they also initiated their moult at an earlier stage of breeding than females. Females mated to males with a moult-breeding overlap had significantly lowered survival chances than females mated with males initiating moult after breeding. Furthermore, females mated with moulting males risked a lowered future fecundity in terms of a delayed start to breeding in the following season. However, early moulting males achieved a similar reproductive success as males initiating moult after breeding. Likewise, male survival probability to the following breeding season did not differ between early and late moulting individuals, nor was there any evidence that males gained or lost in future mating advantages by moulting early. These results show not only that a sexual conflict over timing of moult may operate, but also that it can impose severe fitness consequences, in terms of reduced future fecundity and survival probability, upon the ''losing'' sex.     

Der Fortpflanzungszyklus vonCyathura carinata (Isopoda,Anthuridea) im Nord-Ostsee-Kanal

The life cycle ofC. carinata (Krøyer) from the Kiel Canal and the seasonal change of its population structure have been studied.C. carinata is a protogynic hermaphrodite which may attain an age of 3 years. The young are born in summer and only very few reach sexual maturity during the following year. Some of them become functional small males without passing through a female stage. At the end of the breeding season, some individuals of the same generation become functional females. They moult into pre-males during winter and are functional males in the following summer, when they are 2 years old. The remaining two-year-old animals are breeding females. Mature females can be recognized by the presence of antennules with four jointed flagella and 3 pairs of oostegites. In September they moult to pre-males which have antennules equipped with six jointed flagella. In June of the following (third) year they become functional males which die at the end of the breeding season. It is supposed that this cycle also applies for population from the Gdansk Gulf studied by Jadewski (1969) despite a different interpretation given by this author.     

Nutrient self-selection by the omnivorous cockroach Supella longipalpa

Larvae of the brown-banded cockroach, Supella longipalpa, grown from the beginning of the third instar to the adult moult, self-selected a 15.5:85.5 casein:glucose ratio when given a choice between two diet cubes that were nutritionally complete except that one lacked protein (casein) and the other lacked carbohydrate (glucose). The self-selectors were superior in all utilization parameters to control larvae placed in similar arenas and fed on two nutritionally complete diet cubes, each containing equal amounts of casein and glucose. However, when forced to feed throughout their entire larval life on a diet containing a 20:80 casein:glucose ratio (approximating the self-selected ratio) incorporated into a single cube, larvae grew very poorly compared to others offered a 50:50 cube or an opportunity to self-select. Measurements of casein and glucose consumption throughout the entire first- and last-larval stadia showed that in each case carbohydrate intake was high at first, but decreased through the stadium, finally equalling the level of protein intake, which remained low and constant throughout the stadium. Thus, a 20:80 diet may be nutritionally unsuitable because it does not match closely enough the varying needs of the insect throughout the stadium.     

The growth and maturation of the "tarantula", Avicularia avicularia L.

The growth of the theraphosid spider, Avicularia avicularia L. was studied principally by taking measurements of the fang length of exuviae and dead specimens. The relatic ships between fang length and increment at ecdysis and fang length and instar duration were investigated and used to construct a projected growth curve for the species. This suggests that males reach sexual maturity in approximately 13 instars and at a minimum age of about two and a half years. In males the adult instar is terminal and rarely lasts more than three months. Reproductive maturity in females is probably not reached earlier than the XIVth instar or three years from birth. The females continue to moult annually after maturity and have a longevity in excess of seven years. The pattern of colouration shows characteristic changes in early immature life and develops a slight sexual dimorphism in adults. Type II urticating hairs are present throughout life and occur in light and dark forms in the IInd instar. The mean length of the urticating hairs increases during the life cycle and a sexual dimorphism develops in the XIIth or XIIth instar. In adult males the urticating hairs are uniformly barbed whereas in the adult females the barbs are restricted to the proximal end.     

Developmental changes in fatty acid biosynthesis and composition in the house cricket,Acheta domesticus

Incorporation of [1-¹⁴C] acetate into various phospholipid and triacylglycerol fatty acids showed cyclic fluctuations in fatty acid biosynthesis that were similar for all of the major fatty acids in both male and female house crickets, Acheta domesticus, during development. All three stadia showed low levels of biosynthesis near ecdysis followed by increased synthesis to a peak at midstadium. In the phospholipid fraction, the incorporation of newly synthesized saturated fatty acids, 16:0 and 18:0, predominated near ecdysis, while at midstadium linoleic acid was the most actively synthesized fatty acid. In the triacylglycerol fraction, 18:0 and 18:1 predominated throughout the entire stadium. In contrast to the large fluctuations in fatty acid biosynthesis, the fatty acid compositions of the phospholipid and triacylglycerol fractions did not change within a stadium. However, significant differences were demonstrated between the stages and were associated primarily with differences between nymphal and adult stadia. Males and females differed in the proportions of 16:0 and 18:2 incorporated into phospholipids with females showing a greater proportion of 18:2 and a corresponding smaller proportion of 16:0 than males. The greater proportion of linoleic acid in females and in adults in general compared to nymphs and the predominance of the incorporation of newly synthesized linoleic acid into the phospholipid fraction of all stadia are consistent with the importance of this fatty acid in a number of biological roles.     

Sensitive periods for wing development and precocious metamorphosis after precocene treatment of the brown planthopper,Nilaparvata lugens

The critical periods for juvenile hormone suppression of wing development and metamorphosis were examined in a pure brachypterous line of Nilaparvata lugens following topical application of Precocene II (PII) to various stages of the third and fourth nymphal stadia. When PII, in doses ranging from 10 pg to 100 ng, was applied to 12-h-old third or 6-h-old fourth stadium nymphs, long-wing formation (macroptery) was induced. Macropter induction ranged from 5 to 50% in females and from 30 to 50% in males, the effect being more prominent in males. The sensitive period for macropter induction lasted from the early second stadium through to day one of the fourth (penultimate) stadium. Beyond that period nymphs required sensitivity to PII and the numbers of macropters increased towards the final nymphal molt, again males were more sensitive. On the other hand, periods sensitive to PII for precocious metamorphosis induction appeared from early second stadium to 18 h after molting to the third nymphal stadium. Overlapping application of JH-III with PII at early third stadium could totally inhibit the occurrence of precocious metamorphosis and significantly rescue the macropter induction. From the data described, a scheme is presented for the control of wing development and metamorphosis by juvenile hormone, assuming two types of threshold value determining wing form and metamorphosis.     

Sex‐specific patterns of fuelling and pre‐breeding body moult of Little Stints Calidris minuta in South Africa

The timing and duration of each stage of the life of a long‐distance migrant bird are constrained by time and resources. If the parental roles of males and females differ, the timing of other life stages, such as moult or pre‐migratory fuelling, may also differ between the sexes. Little is known about sexual differences for species with weak sexual dimorphism, but DNA‐sexing enables fresh insights. The Little Stint Calidris minuta is a monomorphic long‐distance migrant wader breeding in the Arctic tundra. Males compete for territories and perform elaborate aerial displays. Females produce two clutches a season. Each sex may be a bigamist and incubate one nest a season, each with a different partner. We expect that these differences in breeding behaviour entail different preparations for breeding by males and females, so we aimed to determine whether Little Stints showed any sex differences in their strategies for pre‐breeding moult and pre‐migratory fuelling at their non‐breeding grounds in South Africa. We used body moult records, wing length and body mass of 241 DNA‐sexed Little Stints that we caught and ringed between 27 January and 29 April in 2008–2018 at two neighbouring wetlands in North West Province, South Africa. For each individual we assessed the percentage of breeding plumage on its upperparts and took blood samples for DNA‐sexing. We calculated an adjusted Body Moult Index and an adjusted Wing Coverts Moult Index, then used the Underhill–Zucchini moult model to estimate the start dates and the rate of body moult in males and females. We estimated the changes in the sex ratio of the local population during their stay in South Africa, and also estimated the timing and rate of pre‐migratory fuelling and the potential flight ranges for males and females. The males started body moult on average on 7 February and the females on 12 February, but the sexes did not differ in their timing of wing covert moult, which started on average on 10 February. In January to mid‐February, males constituted c. 57% of the population, but their proportion declined afterwards, indicating an earlier departure than females. We estimated that both sexes began pre‐migratory fuelling on average on 15 March. The sexes did not differ in fuelling rate, but most females stayed at the non‐breeding site longer than the males, and thus accumulated more fuel and had longer potential flight ranges. These patterns of moult and fuelling suggest sex differences in preparations for breeding. We suggest that the males depart from South Africa earlier but with smaller fuel loads than the females to establish breeding territories before the females arrive. We conclude that for each sex the observed trade‐offs between fuelling and moult at the non‐breeding grounds are precursors to different migration strategies, which in turn are adaptations for their different roles in reproductive behaviour.