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.     

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.     

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.     

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.     

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.     

Changes in life-cycle strategies of Carabus problematicus over a range of altitudes in Northern England

ABSTRACT.

• 1 Mandible tip length has been used to estimate the age of individual C.problematicus Herbst caught over an altitude range of more than 700 m in northern England.
• 2 At 100 m the great majority of females laid eggs in the summer of their emergence as adults. The female life-cycle is predominantly annual and 24% only of the egg-bearing individuals were in their second year.
• 3 Above 250 m, most females did not reproduce until the summer of the year following emergence, giving a biennial life-cycle. 96% of egg-bearing females caught above 830 m were in their second year.
• 4 All the males caught during the breeding season at 100 m had emerged within that calendar year and it is concluded that the male life-cycle is annual at this altitude.
• 5 Above 250 m, 83% of the males caught during the breeding season were in their first calendar year, suggesting that recently emerged males may inseminate second year females and also that the male life-cycle is predominantly annual over the whole altitude range studied.
• 6 At the higher temperatures of the lowland site females not only produce eggs in the year of emergence, they also produce more eggs per individual than at the higher sites. Egg production depends on food intake which involves mandible wear and individuals at the lowland site have significantly higher rate of mandible wear than at the sites above 250 m.

     

Daily and seasonal changes in heat exposure and the Hsp70 level of individuals from a field population of Xeropicta derbentina (Krynicki 1836) (Pulmonata, Hygromiidae) in Southern France

The Mediterranean land snail Xeropicta derbentina forms huge populations in Southern France. In order to characterize heat exposure and the induction of the 70-kD heat shock protein (Hsp70) response system during the life cycle of this snail, a selected population from the Vaucluse area, Provence, was investigated encompassing the issues of morphological life cycle parameters (shell size and colouration), the daily courses of heat exposure at different heights above the ground, of shell temperature, and that of the individual Hsp70 levels. The study covered all four seasons of the year 2011. Snails were found to be annual, reaching their final size in August. The shell colouration pattern showed high variation in juveniles (spring) with a strong tendency towards becoming uniformly white at old age in autumn. In all seasons, ambient air temperature decreased with increasing distance from the ground surface during daytime while remaining constantly low in the night. Overall, the Hsp70 level of individuals followed the ambient temperature during diurnal and seasonal variations. Correlation analysis revealed a positive association of individual shell temperature and Hsp70 level for the most part of the life cycle of the snails until late summer, whereas a negative correlation was found for aged animals indicating senescence effects on the capacity of the stress response system.     

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.     

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.     

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.     

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.     

Hydrocarbon accumulation and lipid biosynthesis during larval development in the cabbage looper,Trichoplusia ni

Larvae of the cabbage looper, Trichoplusia ni, were analyzed for the accumulation and biosynthesis of cuticular and internal hydrocarbon at closely spaced and accurately timed intervals during the fourth and fifth stadia. Large differences in the incorporation of [1-¹⁴C]acetate into hydrocarbon were observed at different times during larval development. Much higher incorporation was observed during feeding stages as compared to wandering stages, while lowest rates of biosynthesis occurred just prior to ecdysis. Fourth stadia wanderers accumulated increased amounts of internal hydrocarbon, which is apparently used to cover the newly forming cuticle. During the fourth to fifth stadium moult insects lost all cuticular hydrocarbon that was present on the old cuticle (about 8 μg/insect) and had about 8 μg/insect on the surface of the newly exposed cuticle. During the fourth stadium incorporation of [1-¹⁴C]acetate into total lipid declined between feeding and wandering stages from 24% of injected radiolabel to 7%. Similar decreases in lipid biosynthesis were observed between feeders and wanderers in fifth stadium larvae with the greatest decrease found in the triacylglycerol fraction. These results document dramatic changes in the accumulation and biosynthesis of hydrocarbon and other lipids during larval development.     

Biomass variation and reproductive phenology of Gracilaria gracilis in a Patagonian natural bed (Chubut, Argentina)

The biomass variation and the reproduction of the natural Gracilaria gracilis bed in Bahía Bustamante (Patagonia, Argentina) were analyzed for 2 years, with the aim of determining the present situation of the population for an updated status overview; establishing the relevant features of the temporal variation in both biomass and reproductive states in relation to environmental factors, epiphytes and associated algae; and assessing carpospore availability for future spore-culture development. Field measurements and sampling were performed monthly between March 2006 and February 2008. In both years, G. gracilis biomass presented marked seasonal variations, with a minimum in winter and a maximum in late spring and in summer. During both years, coexistence of the three life-cycle phases was found, with dominance of tetrasporophytes. Two data sets from individuals originated from sexual reproduction (tetraspores and carpospores) and from asexual reproduction by thallus fragmentation were analyzed separately. In the fragmentation fraction, tetrasporophyte frequencies remained higher than those for gametophytes. However, in the spore-originated fraction, a generation ratio close to 0.5 was observed. Female gametophytes bearing cystocarps were always present, with a maximum in summer and autumn. Biological data were related to environmental factors by means of canonical correspondence analysis (CCA). The first year was characterized by higher biomass values of G. gracilis and Undaria pinnatifida, lower epiphytism, larger Gracilaria thalli and greater proportion of mature tetrasporophytes and gametophytes. The second year was characterized by a high proportion of Gracilaria vegetative thalli and high epiphyte density. The best time to obtain spores from cystocarpic thalli would be in summer and early autumn.     

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.     

Evidence for multiple year classes of the giant Australian cuttlefish Sepia apama in northern Spencer Gulf, South Australia

Giant Australian cuttlefish form a mass spawning aggregation at a single site in northern Spencer Gulf (NSG) in South Australia every austral winter. Samples of cuttlefish were collected from this region over three consecutive years. Analysis of regular growth increments in the cuttlebones of these individuals, revealed a polymorphism in growth pattern for both sexes. Three distinct “bone patterns” were identified based on the variation in increment widths over the lengths of the bones. All bones analysed conformed to one of the three bone patterns, and the increment width patterns were consistent between years. Interpretation of the patterns, suggested that Sepia apama have two alternative life cycles. The first involves rapid juvenile growth during the first summer after hatching, with maturity reached within 7–8 months. These individuals return to spawn in their first year as small individuals. The second life cycle involves much slower juvenile growth during the first summer, with maturity deferred until their second year, when they return to spawn as much larger individuals. Thus, the age compositions of populations of S. apama in the NSG appear to consist of two year classes for both sexes.     

The pelagic and benthic phases of post-metamorphic Munida gregaria (Fabricius) (Decapoda,Anomura)

Some post-metamorphic individuals of Munida gregaria (Fabricius) are permanent members of the benthos while others spend at least part of their time in the water column. These two types of individual are distinct, both morphologically and in the composition of the body. Pelagic specimens have a low density throughout the moult cycle, brought about by a high water content, and low ash and calcium contents. Benthic individuals have this low density for only the first few days post-moult. Normally the pelagic habit is retained only during the first summer as post-larvae but on occasions it is extended over the whole year. In captivity specimens collected at the surface quickly settle on the bottom of the tanks and do not reappear at the surface. The strong positive phototactic response, seen when the animals are collected from the surface, is lost in the first few weeks and the low density persists only until they moult.     

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.     

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.     

Identification,accumulation, and biosynthesis of the cuticular hydrocarbons of the southern armyworm,Spodoptera eridania (cramer) (lepidoptera: Noctuidae)

The accumulation and biosynthesis of cuticular and internal hydrocarbons in the Southern armyworm, Spodoptera eridania, were examined at closely timed intervals during larval and pupal development. Gas chromatography-mass spectrometry (GC-MS) was used to identify n-alkanes, monomethylalkanes, and dimethylalkanes ranging in chain length from 23 to 35 carbons. The amount of cuticular hydrocarbon stayed relatively constant during each stadium, while the amount of internal hydrocarbon increased dramatically during the first half of each larval stadium, presumably to replace the cuticular hydrocarbon lost on the shed cast skin with each molt. The accumulation of internal hydrocarbon was mirrored by large increases in the rate of incorporation of labeled acetate into the hydrocarbon fraction. Hydrocarbon production fell to very low rates during the latter part of the fourth and fifth larval stadia. Relatively high rates of hydrocarbon production were observed during the first and last one-third of the pupal stage and essentially all of the hydrocarbons produced during this stage remained internal. These data document large changes in the rates of hydrocarbon production during development in S. eridania and suggest that most of the hydrocarbon produced during each stage was stored internally and then transported to the cuticle of the next stage.     

Preliminary studies on the reproduction and population dynamics of Monodonta lineata and Gibbula umbilicalis (Mollusca,Gastropoda) on the central coast of Asturias (N. Spain)

Summary Populations of Monodonta lineata and Gibbula umbilicalis were studied at Aramar beach (Luanco, Asturias) from October 1982 to November 1983. Both species show a sexual ratio of 1: 1 but differ in their gonadal cycle patterns. M. lineata gonadal development stages are found from November to May–June in a significant part of the population. Breeding stages occur from June–July to September, and in some individuals to November, with complete discharge of all spawn at the end of the reproductive season. Some degree of inter-annual variation is detected. Spawning stages of mature G. umbilicalis are found through the year but the higher frequencies occur in summer and autumn samples, with development phases predominating in January to May. Animals over 10 mm in shell diameter maintain their gonads close to spawning stages, completely spawned individuals being less than 10 percent. In both species variability in gonad stages for a given month reduces as size increases, indicating a certain synchrony.The new recruits of M. lineata are detected on the bare rock by September to November and are recognizable through their first year. Due to the amplitude of the breeding period and differing growth rates size distribution within an age class is wide. Size class frequencies rapidly decrease after the second year of life. The data for G. umbilicalis are difficult to interpret given the scarce number of juveniles and size overlapping.