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.     

Notes on the life-history and ecology of Tachypodoiulus niger (Diplopoda, Iulidae) in Britain

In some iulids females can moult several times after first attaining maturity but males cannot. Males of Tachypodoiulus niger (Leach) are exceptional in that they can moult, but they lose their functional intromittent organs in the process, regaining them after a second moult. The process can be repeated, a series of functional males alternating with nonfunctional males. This extension of the life and the consequent increase in number of segments led Verhoeff (1928) to postulate that the ancestral millipede was short-bodied and that many-segmented forms were derived from it. We think that this extension of life is of ecological rather than phylogenetic significance–adapting the species to disperse widely to scattered habitats. In particular, the extension of life of males as well as of females may ensure a reasonable sex ratio in those areas where the species is least dense.
In Britain, Tachypodoiulus niger lays eggs in spring which reach the fourth and fifth stadia by their first winter and the seventh, eighth and ninth stadia by their second winter. Maturity is usually attained by males in the eighth stadium but occasional specimens mature at stadium seven and others defer maturity until the ninth. Both sexes can proceed to the fourteenth stadium but adults in Britain usually belong to two generations of two and three years old, divided mainly between the eighth, ninth and tenth stadia. Details are given of a large collection made by the late Dr Scott of animals taking refuge in his house at Henley-on-Thames. Animals in Britain appear to have a similar life history to those in Germany as described by Verhoeff, but effective comparison has depended on correcting and re-interpreting some of Verhoeff's data.     

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.     

Changes in desiccation resistance during development in the millipede Polydesmus angustus

Water loss at increasing temperature in dry air (< 5% r.h.) was measured for the eight stadia of Polydesmus angustus Latzel (Diplopoda, Polydesmida: Polydesmidae). Instantaneous rates of water loss, expressed as percentages of original body water, were calculated at 20, 25 and 30°C. At each temperature, the rate of water loss varied greatly among stadia, decreasing between 15‐ and 18‐fold from stadium I to stadium VII, and then significantly increasing from stadium VII to stadium VIII (adult). In all stadia, the rate of water loss increased with rising temperature, but the temperature effect was much more pronounced in juveniles than in larger stadia. The threshold temperature of heat stupor, which was measured from stadium IV onwards, increased significantly during development, from 35.6°C in stadium IV to 39.5°C in adults. Survival at 20°C and 76% r.h. varied as could be expected from the water loss rates in dry air, survival time increasing from stadium I to stadium VII and then decreasing from stadium VII to the adult stage. The maximum tolerable water loss, estimated for stadia V, VII and adults, did not change significantly among stadia (mean: 47% of the original water content), suggesting that survival times under desiccating conditions depended primarily on the rates of water loss. The relevance of the results in terms of summer survival under natural conditions is discussed, and it is concluded that juvenile mortality could be substantial in the field. This is important for understanding the adaptive value of cohort‐splitting in P. angustus.     

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.     

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.     

1-Phenyl-2-pentanone and methyl salicylate: new defense allomone components and their content shift during ontogenetic development of the millipede <Emphasis Type="Italic">Nedyopus tambanus mangaesinus</Emphasis> (Polydesmida: Paradoxosomatidae)

Twelve components were identified in hexane extracts of the polydesmid millipede Nedyopus tambanus mangaesinus (Attems, 1909) and their contents were examined at all stadia of ontogenetic development including two adult conditions (before and after hibernation). Two compounds, 1-phenyl-2-pentanone and methyl salicylate, were newly identified as components of the millipede together with six well-known polydesmoid compounds (benzaldehyde, benzyl alcohol, benzoic acid, benzoyl cyanide, mandelonitrile, and mandelonitrile benzoate) and four phenols (phenol, p-cresol, 2-methoxyphenol, and 2-methoxy-4-methylphenol). Benzaldehyde and benzoyl cyanide were distributed from nymphs at stadium I, and other components started to become detectable at more advanced stadia. The largest content (35.1%) of methyl salicylate was detected in nymphs at stadium I, together with benzaldehyde and benzoyl cyanide, implying the reinforcement of defensive functions during or after egg emergence. The content (18.8%) of 1-phenyl-2-pentanone reached a maximum in hibernated females among all stadia and conditions. Its female-biased distribution at the mating season (ca. 5.7-fold more than in males) implies its sexually related functions.     

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.     

Stage-specific effects of temperature and dietary protein on growth and survival of Manduca sexta caterpillars

The effects of temperature and dietary protein concentration on growth and survival of Manduca sexta L. (Lepidoptera: Sphingidae) caterpillars during different larval stages were examined. Sets of caterpillars were raised from hatching at one of five constant temperatures (18, 22, 26, 30 or 34°C) and on one of two artificial diets (low or high protein concentration). Mass gain, duration (development time) and mean growth rate were measured for each caterpillar for the 1st to 3rd stadia, the 4th stadium, and the 5th stadium. Temperature significantly affected mass gain during each larval stage, resulting in smaller mass gains at higher temperatures at each stage. This effect was strongest at high temperatures during the 5th stadium. Temperature significantly affected durations of each larval stage, but the effect varied among stages: for example, the duration of stadia 1–3 decreased continuously with increasing temperature, whereas the duration of the 5th stadium was shortest at 26–30°C and increased at lower and higher temperatures. The effect of temperature on mean growth rate changed dramatically across larval stages: maximal growth rate occurred at 34°C during the 1st to 3rd stadia, at 30°C during the 4th stadium and at 26°C during the 5th stadium. Higher dietary protein concentration significantly decreased the duration of stadia 1–3 and of the 4th stadium, but had no significant effect on the duration of the 5th stadium. Temperature and dietary protein had little effect on mortality rates during any larval stadium, with one exception: mortality during the 5th stadium increased dramatically at temperatures of 30 and 34°C. These results demonstrate that the effects of temperature and dietary protein concentration on growth, development and survival in M. sexta vary markedly in different larval stadia during development; 5th instar caterpillars are particularly sensitive to higher temperatures.     

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.     

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.     

Development,growth and metabolic rate of Hermetia illucens larvae

The larvae of Hermetia illucens are known to successfully bio‐convert a vast range of organic substrates into high protein and fat biomass, but little is known about the larval instars. During this research, larval head capsules and biomass growth were measured daily and the specific metabolic rate of larger instars were considered. The head capsule measurements revealed that H. illucens pass through 6 actively feeding larval stadia before entering the last nonfeeding but migrating 7th stadium. Larval growth follows a sigmoid curve with slowly accelerating growth in the earlier stadia and decelerating growth in the latest stadia. In contrast, development was fast until reaching stadium 6 and then slowed down. Accordingly, the specific metabolic rate was high in instars 3, 4 and 5 and reduced in instars 6 and 7.     

Developmental changes in the patterns of feeding in fourth- and fifth-instar Helicoverpa armigera caterpillars

Data are presented for developmental changes in feeding behaviour within and across the fourth and fifth stadium of Helicoverpa armigera (Lepidoptera, Noctuidae) caterpillars fed nutritionally homogeneous semi‐synthetic foods. We recorded the microstructure of feeding over continuous 12‐h periods on consecutive days throughout the two stadia, and in one experiment recorded continuously for 21 h. Larvae in the two stadia showed the same general pattern of macro‐events in feeding, including a similar duration of post‐ecdysis fast, which was usually broken by consumption of the exuviae, and then a sustained period in which discrete meals on the experimental food were taken regularly. There were, however, some distinct differences in the patterns of meal‐taking both between stadia and across different one‐third time segments within stadia. Considering between‐stadium differences, the proportion of time spent feeding differed significantly only in the last segment of the feeding period of the two stadia, with the value for the fourth‐instar larvae being substantially greater than for fifth‐instar larvae. As regards within stadium changes, the proportion of time feeding increased from the first to the second segment of both stadia. However, whereas the proportion of time feeding increased from the second to the final segment of the fourth stadium, it decreased across the same period in the fifth stadium. These patterns of changes in the proportion of time feeding within and between stadia, and their behavioural mechanisms (combination of meal durations and meal frequencies), can be explained only partially with reference to increasing food requirements with development. Three areas are identified where further study might help elucidate the reasons for the observed developmental changes in the microstructure of feeding: allometric constraint, the dynamic links between ingestion and post‐ingestive processing, and ecological factors such as predation.     

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.     

Effect of duration of larval development on sexual competence in young adult male Diploptera punctata

ABSTRACT. The duration of larval development was 27% longer, adult weight was 10% greater, and adult head capsule was 2% wider in Diploptera punctata (Eschscholtz) males with four larval stadia compared with those with three larval stadia. Four-instar males transferred significantly more sperm than three-instar males 8, 14 and 28 days after adult eclosion, but there was no difference in the length of sperma-tophore transferred by three- and four-instar males at these ages. Eight-day-old four-instar males were more successful than 8-day-old three-instar males in fertilizing complete batches of eggs. For both three- and four-instar males, males that mated when they were older (measured in days after adult eclosion) transferred more sperm and larger spermatophores than younger males. Body size did not have a significant effect on the number of sperm or size of spermatophore transferred by males.     

Ecology of an Indian grassland millipede Streptogonopus phipsoni (Diplopoda: Polydesmoidea)

Each of stadia II-VII and adults (stadia VIII) of Streptogonopus phipsoni (Pocock) can be distinguished by segment numbers, length, breadth and paired legs. Sexes are separate from stadium IV and sex ratios in immature stages were more or less 50% throughout the year, but high proportions of adult females are noted from June to September. High ratios of immature to adult were related to the breeding periods, from May to October, and in other months adults increased in proportion as a result of heavy mortality of immatures.
Adults were aggregated in distribution from April to October while solitary individuals were common in other months of the year.
Population density of S. phipsoni varied from 0.25 to 98 m^-2 on the soil surface and 1 to 11.75 m^-2 in the lower layer (0–7 cm deep). Biomass ranged from 12.25 to 2253 mg^-2 on the surface and 50.75 to 424.75 mg^-2 in the lower layer (0–7 cm deep).
A positive and significant correlation was found between mean monthly population density and mean monthly rainfall.
Streptogonopus phipsoni appears to complete its life cycle in one or two years     

The juvenile hormone titer of Trichoplusia ni and its potential role in embryogenesis of the polyembryonic wasp CopidosomaFloridanum

The hemolymph juvenile hormone (JH) titer of third through fifth stadia Trichoplusia ni parasitized by the polyembryonic parasitoid, Copidosoma floridanum, was measured by radioimmunoassay and compared to the titers of unparasitized larvae. The JH titer of parasitized larvae fluctuated from 28 pg/μl to undetectable levels. Maximum levels of hormone were present at ecdysis to the fourth and fifth stadium, and at the prepupal stage. Qualitatively, similar fluctuations were observed in unparasitized larvae. However, the titers in unparasitized larvae were much lower than those of parasitized larvae in the third and early fourth stadia, and the titer fell to undetectable levels in the fifth stadium 24 h earlier (48 h) than in parasitized larvae (72 h). Preventing the JH titer from falling during the fourth and fifth stadia by topical application of (RS)-methoprene or JH II had a juvenilizing effect on parasitized T. ni, and inhibited C. floridanum embryo morphogenesis. The effect of exogenous methoprene and JH on C. floridanum development depended on timing of application and dosage. Application of 100 pmol per day of methoprene beginning at 2 h of the host fourth stadium, prior to the large drop in the endogenous JH titer, inhibited morphogenesis in the majority of C. floridanum embryos. Application of methoprene at later times of host development did not inhibit morphogenesis although other developmental alterations were observed. The potential significance of host JH and ecdysteroid titers on polyembryonic development are discussed.     

Changes in the titer of the female-predominant storage protein (81K) during larval and pupal development of the waxmoth,galleria mellonella

The levels of an 81K storage protein in the waxmoth, Galleria mellonella, were monitored during the course of development using rocket immunoelectrophoresis. During the fifth and sixth larval stadia, 81K protein levels increased during feeding and growth but sharply declined at each larval molt. During the fifth and sixth stadia hemolymph levels of the 81K protein increased to about 1 and 2.5 mg/ml, respectively, with no discernible differences between levels in males and females. Neither the fat body nor the remainder of the carcass contained the 81K protein, indicating that the accumulation of this protein during the intermolt period was exclusively in the hemolymph and redistribution of the 81K protein into other tissues does not occur at the final two larval molts. During the seventh (final) larval stadium the absolute quantities of the 81K protein increased from 23 μg per insect to over 1,600 μg in females and to 300 μg in males. The hemolymph concentration of the 81K protein reached 28 mg/ml in females and 6 mg/ml in males with only low levels found in the remaining tissues. Shortly after pupal apolysis, marked by eyespot retraction, the fat body in both sexes rapidly and quantitatively sequestered the 81K protein from the hemolymph. The 81K protein in the hemolymph of both males and females rapidly dropped to nearly zero concentration by pupation. The 81K storage protein remained localized in the fat body cells after uptake occurred, even though the fat body cells disaggregate and reaggregate during metamorphosis. During pharate adult development the 81K storage protein disappeared from the fat body without entering the hemolymph. At adult eclosion 81K was virtually absent from the tissues of both males and females.     

Juvenile hormone esterase is a biochemical anti-juvenile hormone agent

Juvenile hormone esterase, purified by affinity chromatography from the larval hemolymph of Manduca sexta in the fifth stadium, was injected into larvae of the same species in the earlier stadia resulting in a blackening of the cuticle following ecdysis to the next larval stadium. This anti-juvenile hormone response was dose-dependent for an injection in the second, third or fourth stadium. Cuticular blackening was prevented by treating larvae with the juvenoid epofenonane. Larval response to injected juvenile hormone esterase also varied with the time of injection within a single stadium, having a maximum effect for injections at the time of head capsule slippage. Juvenile hormone esterase activity measured from the hemolymph after injection of larvae in the second stadium decreased over an 11 h time-course. Because the anti-juvenile hormone effects resulting from a single injection of juvenile hormone esterase were dependent on the time of injection, it appears that when juvenile hormone biosynthesis is active in the insect, the duration of enzyme activity limits the anti-juvenile effects that can be induced.