Bemerkungen zur Biologie sowie Haltung und Vermehrung des Sokotra-Riesengeckos, Haemodracon riebeckii (Peters, 1882)

The Socotra Giant Gecko, Haemodracon riebeckii, is the largest species of lizard on Socotra Island. The nocturnal, arboreal and rupiculous living geckos are omnivorous. Two pairs were kept in terrariums and were fed with various insects (crickets, locusts, cockroaches), sweet fruits and other feeding stuff (such as meat, fish). Temporarily H. riebeckii was kept together with other lizards (Eublepharis macularius, Trachylepis socotrana), without any signs of aggressive behaviour. Juveniles and adults of both sexes are able to produce a sound. These acoustic signals seem to be related to predators, because never any intraspecific function could be observed. Within seven years of captive breeding two females produced 253 eggs. Usually two white and sticky soft-shelled eggs were laid within one clutch, more rarely a single egg was laid. The two eggs of a clutch were always laid on the same day. H. riebeckii belongs to the geckos that bury their eggs and practice some brood care, but no special parental care. The female is able to proof with her hind legs the deep and shape of a hollow in the substrate to bury the eggs, which were buried in a sticky and soft-shelled condition. They are oval in shape (egg length 16.4-19.8 mm, egg width 12.4-17.8 mm, quotient EL:EW 1.22±0.05) and have in the beginning a weight ranging from 1.7100 to 2.5201 g. As typical for geckos with hard-shelled eggs the egg weight decreases during the incubation period. The loss can be between 5.59 to 30.29%. The development of eggs up to hatching of young depends upon temperature and the germinal stage in the laid egg. The time difference between the hatching of the young within one clutch of two eggs was usually 1 to 5 days. In some cases there were, however, longer differences (up to 61 days), which are probably caused by different developmental stages of the embryos during the time of egg laying. The shortest incubation period recorded during our investigations was 83 days for eggs incubated at constant temperature of 28 to 29.5 °C and the longest 359 days at 26 to 26.5 °C. Constant high incubation temperatures caused a premature hatching of young. In normal hatched young were the yolk sac retracted and the navel closed. In premature hatched young were the yolk not resorbed and the mortality within the first three month comparatively high. The snout-vent length (SVL) of newly hatched young is from 27 to 39 mm and the tail length (TL) from 25 to 38 mm (SVL:TL index 0.90-1.27), the weight is from 0.7688 to 1.5366 g. Young specimens are distinguished from adults by the brown/white striped lower jaw and the white-banded tail. Young which hatched in the terrarium were eaten by the adults. A loss of young can be avoided if they are raised individually.     

Survival and behavioral characteristics of amphidromous goby larvae of Sicyopterus japonicus (Tanaka, 1909) during their downstream migration

To understand the ecology and environmental tolerances of newly hatched larvae of the amphidromous fish Sicyopterus japonicus during their downstream migration, the salinity tolerance of eggs, 0-15 day old larvae, and adults, and the temperature tolerance, specific gravity and phototaxis of hatched larvae were examined. Tolerances of adults were measured as survival after a 24 h challenge in freshwater (FW), brackish water (1/3 SW) and seawater (SW). The survival rate of adult S. japonicus was 100% in FW and 1/3 SW, while none survived in SW. Hatching success of eggs (30 eggs each) was significantly higher in FW (mean: 73%) and 1/3 SW (73%) than in SW (19%). Tolerance of newly hatched larvae to salinity and temperature was investigated in different combinations of salinities (FW, 1/3 SW and SW) and temperatures (18, 23 and 28 °C). Larval survival was significantly different in each salinity and temperature. Survival rate was significantly higher in 1/3 SW than in FW and higher in SW than in FW at 23 °C and 28 °C. At the latter part of the experiment, there was no survival in FW and at 28 °C. Survival was higher in lower temperatures, but larval development did not occur in FW. Specific gravity of newly hatched larvae was 1.036 at 28 °C and 1.034 at 23 °C. When exposed to a light source on one side of an aquarium, larval distribution was not affected. Our results indicated larval S. japonicus are more adapted to brackish water and seawater than freshwater, while the adults and eggs are more adapted to freshwater and brackish water than seawater. This is consistent with their amphidromous life history with growth and spawning occurring in freshwater and the larval stage utilizing marine habitats.     

Captive breeding and larval morphology of Tylototriton shanjing Nussbaum, Brodie & Yang, 1995, with an updated key of the genus Tylototriton (Amphibia: Salamandridae)

Tylototriton shanjing Nussbaum, Brodie & Yang, 1995 was described as a distinct species hidden before under the widely distributed T. verrucosus Anderson, 1871. Therefore, papers published before 1995, including those on reproductive biology, could not distinguish between these two close relatives. Consequently, data on the reproductive biology of T. shanjing are scarce. Here, we report on the first captive breeding of T. shanjing in the Aquarium of the Cologne Zoo, and we document the ontogenetic developmental stages and describe the larva for the first time. Moreover, we give a literature review for both T. verrucosus and T. shanjing and compare our data with published information referring undoubtedly to the latter species. To avoid future misidentifications and to facilitate the composition of breeding groups, we present an identification key for the East Asian salamandrid genera in general, and for the species of Tylototriton in particular.     

Burrowing behaviour of the softshell clam (Mya arenaria) following erosion and transport

Erosion and transport of juvenile individuals may alter the distribution pattern of intertidal bivalves. The burrowing success of recently transported juvenile softshell clams (Mya arenaria) was studied in a laboratory flume under a wide range of hydrosedimentary environments. Juvenile individuals (5-20 mm) were observed under a simulated 30 min slack tide before initiating the flow for a period of 60 min. Five different free-stream velocities (0, 3, 5, 10 and 24 cm s^− 1) and four sediment types (mud, sandy-mud, sand and gravel) were used. The mean proportion of juvenile clams that initiated (MPI) or completed (MPC) a burial decreased with increasing shell length. Erosion from the sediment was more important in large juveniles suggesting that large juveniles may have more difficulty successfully relocating once transported. The MPI increased with increasing flow speed in experimental runs held at speed < 24 cm s^− 1. This was observed in all sediment types. Most individuals were unable to burrow at 24 cm s^− 1 because they got eroded. The MPC also increased with increasing flow speed in mud, sandy-mud and sand. The MPC's response to flow was more complex in gravel because of a shell length × flow speed interaction effect. Our observations suggest that water movement may induce the burrowing behaviour of recently eroded juvenile clams. Results are discussed in an ecological and aquacultural context.     

Cost of oviposition site selection in a water strider Aquarius paludum insularis: Egg mortality increases with oviposition depth

Females generally avoid selecting sites for oviposition which have a high predation risk to increase offspring survival. Previous studies have focused on costs to ovipositing females. However, although offspring may also incur costs by being oviposited at low predation risk sites, no studies have focused on costs to offspring. Such costs to offspring were examined by using Aquarius paludum insularis, females of which avoid eggs parasitism by ovipositing at deep sites. Deep sites are safe from egg parasitism but may be unsuitable for hatching due to environmental factors. We examined the costs to offspring at deep sites by comparing the hatching rate, the duration to hatching and the proportion of drowned larvae between eggs that were set at three levels of water depth (0 cm, 25 cm and 50 cm depth). While the hatching rate at 50 cm was lower than that at 0 cm, the rate at 25 cm did not differ from that at 0 cm. Duration to hatching and the proportion of drowned larvae did not differ between the three depths. It is suggested that the declining survival rate of A. paludum eggs was due to increased water pressure at greater depth. Such a cost may exist in other species and such an observation may aid in understanding oviposition site selection.     

A simple technique for measuring buoyant weight increment of entire, transplanted coral colonies in the field

Estimating the impacts of global and local threats on coral reefs requires monitoring reef health and measuring coral growth and calcification rates at different time scales. This has traditionally been mostly performed in short-term experimental studies in which coral fragments were grown in the laboratory or in the field but measured ex situ. Practical techniques in which growth and measurements are performed over the long term in situ are rare. Apart from photographic approaches, weight increment measurements have also been applied. Past buoyant weight measurements under water involved a complicated and little-used apparatus. We introduce a new method that combines previous field and laboratory techniques to measure the buoyant weight of entire, transplanted corals under water. This method uses an electronic balance fitted into an acrylic glass underwater housing and placed atop of an acrylic glass cube. Within this cube, corals transplanted onto artificial bases can be attached to the balance and weighed at predetermined intervals while they continue growth in the field. We also provide a set of simple equations for the volume and weight determinations required to calculate net growth rates. The new technique is highly accurate: low error of weight determinations due to variation of coral density (< 0.08%) and low standard error (< 0.01%) for repeated measurements of the same corals. We outline a transplantation technique for properly preparing corals for such long-term in situ experiments and measurements.     

Relatively low upper threshold temperature in lizards from cool habitats

We used the slender forest skink (Scincella modesta) as a model animal to test for the hypothesis that the upper threshold of incubation temperature is relatively low in lizards using shaded (and thus, cool) habitats. Eight gravid females were collected in early May 2005 from a population in Hangzhou, Zhejiang (eastern China). All females laid a single clutch of 7–13 eggs between mid-May and early June. Eggs were incubated at 24, 28 and 30 (±0.2) °C. None of eggs incubated at 30 °C hatched. Eggs incubated at 24 and 28 °C differed in incubation length but not in hatching success. The incubation length at 24 and 28 °C averaged 22.3 and 20.3 days, respectively. Hatchlings from eggs incubated at 24 and 28 °C did not differ in all examined morphological traits, but hatchlings from eggs incubated at 28 °C performed apparently worse in the racetrack than did their counterparts from eggs incubated at 24 °C. The temperature of 28 °C is close to the upper thermal threshold for successful embryonic development in S. modesta. Compared to other oviparous lizards using open (and thus, warm) habitats, the upper thermal threshold and the range of optimal temperatures for embryonic development are both lower in S. modesta. Our study supports the previous conclusion that species living in thermally different habitats may differ in the upper thermal threshold and the range of optimal temperatures for embryonic development.     

Lake water level increase during spring affects the breeding success of bream Abramis brama (L.)

In Lake Constance, Eurasian bream Abramis brama (L.) spawn in very shallow littoral areas by the beginning of May. They attach their adhesive eggs to pebble and cobble substratum at <40 cm depth. Increasing water levels before spawning inundate bare substratum to which bream eggs may attach better than to deeper substratum covered by epilithon. Consequently, the water level increase prior to spawning should determine the amount of pristine spawning substratum available to bream and thus influence their breeding success. In order to test this hypothesis, the influence of hydrology and climate on the abundance of age-0 bream was combined with the results from field investigations on the egg survival and abundance of age-0 bream. A strong positive correlation between the mean water level increase during the spawning season of bream (April–May) and the abundance of juvenile bream was found. In contrast, the absolute water level during spawning and during the nursery stage in summer, the cumulative temperature during the egg, larval and juvenile stages and two North Atlantic Oscillation (NAO) indices did not affect the abundance of juvenile bream. The field investigations confirmed that bream eggs attach better to and have higher survival rates on bare substratum than on substratum with epilithon cover. Accordingly, eggs within a spawning habitat of bream were most abundant between 10 and 20 cm depth, where the epilithon cover was lower than at depths exceeding 30 cm. The results of this study confirm an adverse influence of epilithon cover on the attachment and subsequent survival of bream eggs and emphasize the importance of spring inundations for the successful breeding of the bream. Handling editor: J. A. Cambray     

Effects of current speed, shell length and type of sediment on the erosion and transport of juvenile softshell clams (Mya arenaria)

The erosion and transport of juvenile softshell clams (Mya arenaria) was studied in a laboratory flume in relation to free-stream velocity (0, 7, 16, 29 and 35 cm s^− 1), shell length (0-5, 5-10, 10-15, 15-20 mm) and type of sediment (mud, sandy-mud, sand and gravel). Our results showed that these factors interact together on the erosion of clams from the sediment. Juveniles were eroded in great numbers in sand while mud retained them more easily. Bedload transport was initiated at speeds of 16 cm s^− 1. Most of the clams were eroded in sandy sediments at speeds of 29 and 35 cm s^− 1. The smallest individuals were highly vulnerable to erosion compared to the other size classes studied. A results-based model using the logistic regression statistics was proposed. This allowed the estimation of erosion probabilities for a given hydrosedimentary environment. A field validation of the model was then carried out. Field results confirmed the importance of free-stream velocity, shell length and type of sediment on the erosion rate of clams. The differences observed between predicted and field results suggest that the model underestimated the erosion rate in the field. Results are discussed in the context of hydrosedimentary environments found off the eastern coast of Canada.     

Germination and early growth of Nymphaea odorata at different water depths

We experimentally determined the effects of water depth on seed germination and seedling growth and morphology, and we documented the transition from submerged to emergent plants in the white water lily, Nymphaea odorata. Seeds of N. odorata were germinated at 30, 60, and 90 cm water depth in outdoor mesocosms and percent germination and morphology measured after a month. The presence of self-seeded seedlings in pots at the same 3 water levels was also recorded over two years. To examine juvenile growth, seeds planted in soil were placed at the same mesocosm depths; germination and growth were monitored for three months, when the plants were harvested for morphological and biomass measurements. N. odorata germinated equally well in 30, 60 and 90 cm water; seedlings grew as submerged aquatics. After one month, seedlings in 90 cm water had less biomass than those in 30 cm (1.1 vs. 3.3 mg and 1.0 vs. 1.8 mg for different seed sources, respectively) and allocated relatively more biomass to shoots (97.5 vs. 67.8% and 73.1 vs. 58.0%, respectively). Seedlings in 60 cm water were intermediate. After 3 months of submerged growth, plant biomass remained less in 90 vs. 60 and 30 cm water (22.5 vs. 36.4 and 33.3 mg, respectively). Plants in 90 and 60 cm water had greater biomass allocation to shoots than plants in 30 cm water (85.7 and 72.6% vs. 64.4%, respectively) and produced larger laminae on longer petioles (lamina length = 33.3 vs. 25.2 mm in 90 vs. 30 cm; petiole length = 99.0 vs. 36.0 mm, respectively). After about 3 months, submerged plants produced floating leaves that had 39% shorter laminae but 267% to 1988% longer petioles than submerged leaves on the same plant. Lamina length to width allometric relations of submerged leaves were >1 at all water levels, distinguishing them from the equal allometry of adult floating leaves. The switch from production of submerged to emergent leaves resembles submergence-escape growth in other aquatics, but because the seedlings have been submerged throughout their life, submergence itself cannot be the stimulus to produce emergent leaves in these totally immersed plants. Our data show that N. odorata plants can establish from seeds in up to 90 cm water and that seedlings grow as submerged aquatics until they switch abruptly to production of floating leaves.     

Location of Biomphalaria pfeifferi by Schistosoma mansoni miracidia in stagnant and running water under field conditions

The efficiency of S. mansoni miracidia in locating and infecting Biomphalaria pfeifferi in Gezira canals has been studied under field conditions. When S. mansoni eggs were introduced into clean stagnant water in small field channels, the miracidia hatched to infect 100% of 30 snails in cages at the release point. Fifteen metres upstream and downstream 13% of caged snails were infected but no infections were found in snails 20 m away.When eggs were released into the same canal in flowing water (8.3 cm · s^–1), no infections were detected in any of the caged snails placed 0–100 m downstream. Releasing hatched miracidia instead of eggs resulted in infections in all cages at 5 m intervals from 0-100 m. The release of eggs into flowing water was likened to the method by which S. haematobium eggs are deposited during urination. The 0% infection suggests that eggs will be swept away from the point of contamination by the flow. Thus only urination into stagnant water will lead to heavy snail infection rates.When eggs were released into a small pond-like minor canal tail end snail infection rates were only 3%. This was probably due to the larger water volume, smaller number of caged snails, and the presence of vegetation and other fauna which may be decoys or predators.The results highlight how very high snail infection rates can be produced under ideal conditions but also show how large snail and miracidia numbers are required in natural situations.     

Parental size and environmental conditions affect egg capsule production by Nassarius reticulatus (Linnaeus 1758) (Gastropoda: Nassariidae)

In shallow coastal habitats scavenging netted whelks Nassarius reticulatus attached egg capsules to the stipes of red algae Chondrus crispus and occasionally on Furcellaria lumbricalis and Plumaria plumose. In the laboratory egg capsules were laid on aquaria sides and lids by individuals ≥ 21 mm shell length. Larger size classes produced more egg capsules and spawned over a longer period and in doing so partitioned less energy into shell growth. Large netted whelks (25-28.9 mm) produced larger capsules which contained significantly more and larger eggs than those produced by smaller individuals (21-24.9 mm). Egg capsule production continued throughout the year by regularly fed N. reticulatus held at ambient seawater temperatures. Egg production increased in the spring and summer with peak production during June (15 °C), decreased between August and October and resumed again during the winter (November to February at ∼ 7 °C). During the summer (15-16 °C) egg capsules were smaller and contained smaller eggs than those deposited during the winter (7-10 °C), although the number of eggs · capsule⁻¹ was similar. Enforced food limitation reduced the number and size of the egg capsules, the number and size of eggs produced · female⁻¹ and the duration of the breeding period. Hatching success of N. reticulatus egg capsules was high (95%) even at winter seawater temperatures (11-8.5 °C) and the duration of embryonic development was fastest between 15 and 17.5 °C.     

Effect of Acanthocephala infection on the reproductive potential of crustacean intermediate hosts

The effect of a naturally acquired infection by three acanthocephalan parasites Dentitruncus truttae, Echinorhynchus truttae, and Polymorphus minutus on the reproductive potential of their intermediate host, Echinogammarus tibaldii (Amphipoda) from Lake Piediluco (Centre of Italy) was assessed. During May 2007, 1135 amphipods were collected from two different samplings and examined for larval helminths. Forty-five amphipods were infected and of those, 16 were infected with D. truttae (intensity = 1-3 larvae), 15 with E. truttae (intensity = 1-2 larvae), and 14 with P. minutus (intensity = 1 larva). The sex ratio was nearly 1:1 in all examined amphipods. One female infected with D. truttae contained six eggs in the brood pouch and another female infected with E. truttae contained five eggs. However, none of the eight female amphipods harbouring P. minutus larva contained eggs in their brood pouch. Uninfected females of the same size and body length as that of the infected females contained between 20 and 32 eggs. No acanthocephalan species were found to co-occur.     

The reproductive output of sea lice Caligus rogercresseyi under controlled conditions

Gravid females of Caligus rogercresseyi were collected from Atlantic salmon (Salmo salar) from a farm located at Chiloe Island (42°40′S73°15′W), Chile, to obtain information about the reproductive output of this parasite in vitro. The egg strings removed from the females were incubated under controlled conditions to obtain virgin adult females. One female which had mated only once produced eleven generations of eggs strings in a period of 74 days. The first egg strings of the females obtained in vitro were produced at 389 degree days (°D) after egg incubation, while the next generations of eggs strings were produced with a periodicity between 4 and 6 days dependent on the water temperature. The average length of the egg string was 3.1 mm and the mean number of eggs per string was 31. The values recorded in captivity for the egg string length and the number of eggs per string, were lower than the values recorded in gravid females from the field. One female survived for 79 days and males, maintained separately from the females, survived for 60 days.     

Diversity and abundance of sponges in bathyal coral reefs of Rockall Bank, NE Atlantic, from boxcore samples

Recent (2004) boxcoring on the SW Rockall Bank, west of Ireland (approx. 55°N 15°W, depths between 557 and 1407 m) yielded 95 species of sponges in 20 boxcore attempts. There are no published reports of Rockall Bank coral reef sponge fauna, but comparison with trawl and dredge efforts in neighbouring parts of the NE Atlantic (east of Rockall Trench, off the Scottish coasts) made in the late 19th and early 20th century leads to the conclusion that our boxcoring efforts yielded similar numbers of species as these more elaborate collecting programs. Numbers of specimens for all boxcore samples combined was 466, together occupying a total volume of approx. 3.38 l, based on length x width x height measurements of all individuals. These results indicate a generally low biomass of sponges contributing to the deep water coral reef fauna. Species composition in this bathyal habitat shows a high heterogeneity (Eveness J': 0.81-0.97) and the majority of sponge individuals does not exceed 1 cm³ in volume. Nevertheless, high densities of a large hexactinellid species, Asconema aff. setubalense (up to 30 cm in height), were encountered locally. Sponge community analysis showed that there was no clear correlation between coral cover and sponge diversity, and only a weak correlation between coral cover and abundance and volume of sponges. This, combined with the overall very small size of the sponges, suggests that substratum is not a limiting factor for their occurrence.     

Captive breeding and larval morphology of Tylototriton shanjing Nussbaum,Brodie & Yang, 1995, with an updated key of the genus Tylototriton (Amphibia: Salamandridae)

Tylototriton shanjing Nussbaum, Brodie & Yang, 1995 was described as a distinct species hidden before under the widely distributed T. verrucosus Anderson, 1871. Therefore, papers published before 1995, including those on reproductive biology, could not distinguish between these two close relatives. Consequently, data on the reproductive biology of T. shanjing are scarce. Here, we report on the first captive breeding of T. shanjing in the Aquarium of the Cologne Zoo, and we document the ontogenetic developmental stages and describe the larva for the first time. Moreover, we give a literature review for both T. verrucosus and T. shanjing and compare our data with published information referring undoubtedly to the latter species. To avoid future misidentifications and to facilitate the composition of breeding groups, we present an identification key for the East Asian salamandrid genera in general, and for the species of Tylototriton in particular.     

The effect of temperature, water level and burial depth on seed germination of Myriophyllum spicatum and Potamogeton malaianus

The effects of temperature, water level and burial depth on seed germination of two submerged species, Myriophyllum spicatum and Potamogeton malaianus, were investigated under controlled laboratory conditions. There was no significant difference in final germination of M. spicatum among water level treatments, but P. malaianus germinations at 1 cm and 12 cm water levels were better than at 0 cm water level at temperatures of 20 °C and 30 °C. Little to no germination was observed for either species at the temperature of 10 °C. At 15 °C, however, germination increased significantly to 66.3-70.6% for M. spicatum and to 29.4-48.1% for P. malaianus under all three water level treatments. Increased temperature from 15 °C to 30 °C had no significant effect on the final germination of M. spicatum except at the 1 cm water level, but enhanced significantly the germination of P. malaianus. Analysis of the mean time to germination revealed that M. spicatum was a faster germinator relative to P. malaianus. The two species’ germination differed markedly in response to burial depth. Germination percentage of M. spicatum was 71.3% at 0 cm burial depth, but decreased to 5.0% and to 2.5% at depths of 1 cm and 2 cm, respectively; whereas germination percentages of P. malaianus were 40.0%, 23.8%, 12.5%, 7.5% and 1.3% at depths of 0 cm, 1 cm, 2 cm, 3 cm and 5 cm, respectively. We concluded that the two species respond differently to germination strategies. The findings provided further insight into how germination strategy contributes to the seed bank formation and species invasion.     

Stage-specific Population Development and Fecundity of Paratrichodorus minor

A conceptual model of the life cycle of Paratrichodorus minor consisting of the egg stage, four juvenile stages, and the adult stage was proposed. Development of an individual from one stage to the next was described by a probability distribution defined by the mean length of time spent in the stage and the standard deviation associated with the mean duration. Experiments were conducted to estimate stage durations, stage-specific survivorships, and a fecundity rate for females. Eggs hatched on agar plates at a mean time of 53.3 ± 7.3 degree-days using a basal threshold of 10 C (DD₁₀) with a range of 40-64 DD₁₀ after deposition. Forty-five percent of the eggs observed ultimately hatched. Of the eggs that died, 44% died before the nematode form could be observed in the egg and 56% died after movement had been observed. First generation population peaks following inoculation with first-stage juveniles occurred at 28 DD₁₀ for second-stage juveniles, 67 DD₁₀ for third-stage juveniles, 109 DD₁₀ for fourth-stage juveniles, and 143 DD₁₀ for adults. Adult males are rare and were never observed in these studies. The fecundity rate was 0.784 eggs/(female-DD₁₀⁻¹), but the maximum length of the egg-laying period was not determined. The minimum egg-laying period was 73-113 DD₁₀, and minimum egg production was 57-86 eggs per female. The preovipositional period for adult females was estimated to be 79 DD₁₀. In the presence of a host, total population numbers increased, but in the absence of a host, the population declined to 33 % of the initial level after 300 DD₁₀.     

大竹蛏胚胎发生及稚贝发育基本特征

在人工培育条件下,对大竹蛏(Solen grandis)胚胎发生及稚贝发育进行显微观察,探究大竹蛏胚胎及幼虫发育规律。结果表明,大竹蛏胚胎及幼虫发育过程为:受精卵、卵裂、囊胚期、原肠期、担轮幼虫、D形幼虫、稚贝。在日平均水温为22.4℃时,受精后20～24 h发育成D形幼虫,5～7 d变态为稚贝,38 d稚贝已具备成贝形态,壳长壳高比为2.60。从受精卵到附着所需积温为3 088.79～5 005.19℃.h。稚贝先形成出水管,后形成进水管,最终形成"一管双孔"。壳长与壳高关系式为y=150.37e0.002 7 x,x为壳高(μm),y为壳长(μm),R2=0.985 5,P0.01;壳长与日龄关系式为y=143.38e0.091 6 x,x为日龄(d),y为壳长(μm),R2=0.979 5,P0.01;壳高与日龄关系式为y=33.979 x-15.450,x为日龄(d),y为壳高(μm),R2=0.987 3,P0.01。     

Chill sensitivity and cryopreservation of eggs of the greater wax moth Galleria mellonella (Lepidoptera: Pyralidae)

There is an increasing need for methods of cryopreservation of arthropods. In particular, Lepidoptera are extremely important in entomological applications for the protection of agricultural crops and forest ecosystems and also in many aspects of biodiversity conservation. Yet, few studies have dealt with cryopreservation techniques in species of this insect order.The aim of this study was to examine the chill sensitivity of eggs of the greater wax moth Galleria mellonella (L.) and the possibility to cryopreserve the eggs by vitrification methods.One day-old eggs were dechorionated with water solutions of 1.25% sodium hypochlorite and 0.04% Tween 80, treated with cryoprotective agents in two steps, subjected to rapid cooling by immersion in LN and stored in a mechanical freezer for 48 h at −140 °C. They exhibited survival rates of 1.6 ± 0.5% after being cooled in LN and 0.6 ± 0.2% after being stored in the mechanical freezer. 92.9% of the larvae that hatched from cryopreserved eggs completed development regularly, producing adults that bred and laid fertile eggs.The hatching rate of eggs in the F1 and F2 generations was higher than 90%. Adult emergences of the progeny of eggs stored at ultra-low temperatures allowed us to establish a laboratory colony.