Laboratory-reared Specimens Research Articles

Comparative unpalatability of mimetic viceroy butterflies (Limenitis archippus) from four south-eastern United States populations.

Viceroy butterflies (Limenitis archippus), long considered palatable mimics of distasteful danaine butterflies, have been shown in studies involving laboratoryreared specimens to be moderately unpalatable to avian predators. This implies that some viceroys are Müllerian co-mimics, rather than defenseless Batesian mimics, of danaines. Here, I further test this hypothesis by assessing the palatability of wild-caught viceroys from four genetically and ecologically diverse populations in the southeastern United States. Bioassays revealed that viceroys sampled from three sites in Florida and one in South Carolina were all moderately unpalatable to captive redwinged blackbird predators, which ate fewer than half of the viceroy abdomens presented. Red-wings commonly exhibited long manipulation times and considerable distress behavior when attempting to eat a viceroy abdomen, and they taste-rejected over one-third of viceroys after a single peck. These findings, the first based on wild-caught butterflies, support the hypothesis that the viceroy-danaine relationship in some areas represents Müllerian mimicry, prompting a reassessment of selective forces shaping the interaction. Moreover, considerable variation in palatability of individual viceroys, and in behavior of individual birds, contributes to the complexity of chemical defense and mimicry in this system.

Hepatocarcinogenesis in western mosquitofish ( Gambusia affinis) exposed to methylazoxymethanol acetate

To assess the potential of western mosquitofish (Gambusia affinis) for the detection of environmental carcinogens, laboratory-reared specimens were exposed to methylazoxymethanol acetate 10 mg per 1 for 2 h and then examined periodically for the onset of neoplastic lesions. Approximately 33 per cent of the exposed fish developed liver neoplasms within 25 weeks of exposure and 52 per cent within 40 weeks. The lesions were mostly hepatocellular carcinomas and cholangiocarcinomas. No neoplastic lesions were detected in other organs. The carcinogen sensitivity and the widespread distribution of the mosquitofish suggest that this species would be useful as a warm water sentinel for environmental contamination.

Larval development of the hermit crab Clibanarius albidigitus (Crustacea: Anomura: Diogenidae) reared under laboratory conditions

The larval development of Clibanarius albidigitus Nobili is described and illustrated from laboratory-reared specimens. At 30°C, this species passes through four zoeal stages before molting to the megalopa. Of the 120 individual larvae reared, survival was high, with 88% reaching the megalopal stage. Zoeal stage durations varied from 3 to 18 d. Rearing was terminated after 45 d, and at that time no megalopae had molted to the firstcrab stage. Among known larvae of Clibanarius species, C. albidigitus is immediately distinguished by the presence of dorsomedial and dorsolateral carapace keels.

Abbreviated Larval Development in the Australian Terrestrial Hermit Crab Coenobita Variabilismcculloch (Anomura: Coenobitidae)

ABSTRACT The complete larval development of the Australian terrestrial hermit crab Coenobita variabilis McCulloch is described from laboratory-reared specimens. Development consists of two brief, nonfeeding zoeal stages and one megalopal stage. The megalopal stage does feed, but will metamorphose only on land. This is the first case of abbreviated development known in the Coenobitidae. Both zoeal stages exhibit character development typical of all stages of other coenobitids, allowing for easy identification of the species but preventing a clear determination of which stages were eliminated during the evolution of the abbreviated developmental mode. Compared to known megalopae of other coenobitids, the megalopa shows no evidence of advanced development.

A growth model for a hyperiid amphipodThemisto japonica (bovallius) in the Japan Sea, based on its intermoult period and moult increment

Themisto japonica was reared at 1, 5, 8, and 12°C in the laboratory to estimate its intermoult period (IP) and increase in body length (BL) at each moulting (ΔBL).IP was found to be a function of temperature andBL of the specimens, longerIPs being associated with lower temperature and larger specimens.ΔBL was not affected by temperature but increased with growth of the specimens. Observations on consecutive moults indicated that one new segment was added to pleopod rami at each moulting.ΔBLs obtained from the measurement of the segment number of pleopod rami andBL of wild specimens were slightly larger than values obtained from laboratory-raised specimens.IP data obtained from laboratory-reared specimens are combined withΔBL data from wild specimens to establish a growth model forT. japonica from its release from the marsupium (1.31 mmBL) to the maximum size (17 mmBL) as a function of temperature. This growth model predicts that a total of of 18 moultings is needed forT. japonica to reach the maximum size regardless of temperature, although the time needed to reach the maximum size is highly dependent on temperature. The life cycle, from the newly released larvae (1.31 mmBL) to the spent females (10–17 mmBL), was estimated as 333–593 days at 1°C, 195–347 days at 5°C, 118–210 days at 10°C and 82–146 days at 15°C; the last may be the upper temperature limit forT. japonica. Growth rates ofT. japonica expressed on the basis of body mass are comparable to the rates of euphausiids of equivalent size when the effect of temperature is accounted for. Feeding conditions ofT. japonica in the field are also discussed.

Postembryonic expression of the serotonin phenotype in Helisoma trivolvis: comparison between laboratory-reared and wild-type strains

In a laboratory-reared albino strain of the snail Helisoma trivolvis, the number of neurons expressing the serotonin phenotype increases markedly during postembryonic life. To address whether these latent changes occur selectively in the laboratory-reared strain, postembryonic expression of serotonin immunoreactivity was directly compared in laboratory-reared and wild-type specimens. The spatial pattern of serotonin-immunoreactive neurons was generally the same in the two strains. In contrast, the time course over which this pattern was generated was more prolonged in the wild types than in the laboratory-reared strain. The cerebral, left parietal, and visceral ganglia of laboratory-reared animals completed their postembryonic acquisition of serotonin-immunoreactive neurons by stage P10. Acquisition of serotonin-immunoreactive neurons after stage P10 occurred only in the pedal ganglia. In the wild types, addition of serotonin-immunoreactive neurons continued at least until stage P20 in all of the ganglia examined. Analysis of serotonergic clusters within the cerebral and pedal ganglia revealed distinct developmental patterns for individual clusters. Therefore, the acquisition of the serotonin phenotype during postembryonic life is a normal component of nervous system development in wild-type H. trivolvis.

STUDIES ON THE PROVENZANOI AND OTHER PAGURID GROUPS: III. THE LARVAL AND EARLY JUVENILE STAGES OF PAGURUS KENNERLYI (STIMPSON) (DECAPODA: ANOMURA: PAGURIDAE) REARED IN THE LABORATORY

The complete larval sequence, megalopa, and early juvenile stages of Pagurus kennerlyi (Stimpson), a member of the capillatus group, are described from laboratory-reared specimens. Development consisted of four zoeal and one megalopal stage. No prezoeal stage was observed. Of the broods obtained from three females, approximately one-third of zoeal stages III and IV from one female exhibited developmental abnormalities, particularly in the second maxilliped. These abnormalities were presumed to be caused by genetic misfortune. Comparisons are made among species of pagurid and diogenid crabs for which juvenile descriptions exist.

Development of the cottid fish,Pseudoblennius percoides, reared in the laboratory, with brief descriptions of juvenileP. marmoratus andP. zonostigma

Embryonic, larval and juvenile development of the cottid fish,Pseudoblennius percoides were described on the basis of a series of laboratory-reared specimens. The eggs were demersal, adhesive, almost spherical in shape, measuring 1.66–1.82 mm in diameter, and with numerous various-sized oil globules. Neighboring eggs adhered to each other to form an egg mass. Hatching occurred between 13 and 16 days after spawning at a water temperature of 15.4 to I6.5°C. Newly hatched larvae measured from 6.5 to 7.3 mm, averaging 6.9 mm TL, and possessed 40 myomeres. Absorption of the yolk was completed at about 7.5 mm TL. Flexion of the notochord started and finished at about l0 mm TL and about 14 mm TL, respectively. Aggregate numbers of all fin rays were completed at over 16 mm TL, when the larvae reached the juvenile stage. The pigment pattern became the same as that of adults in juveniles longer than 25 mm TL. Lateral lines were completed at over 44 mm TL, when the juveniles attained to the young stage. The early stages of this species were clearly distinguished from those ofP. cottoides, and the juveniles of fourPseudoblennius species, i.e.P. percoides, P. cottoides, P. marmoratus andP. zonostigma, could be identified mainly by their pigment patterns.

Ecological studies on fishes of Zostera bed at the mouth of Ago Bay, Mie Prefecture - III. Development of eggs, larvae and juveniles of the tidepool gunnel Pholis nebulosa, reared in the laboratory.

Embryonic, larval and juvenile development of the tidepool gunnel Pholis nebulosa were described based on a series of laboratory-reared specimens. The eggs were demersal, almost spherical in shape, measuring 1.70-2.18mm in diameter, and with a large oil globule and several small ones. Neighboring eggs adhered to each other to form a spherical egg mass. Hatching occurred between 25 and 35 days after spawning at a water temperature of 11.5-13.5°C. Newly hatched larvae measured 8.3-11.6mm TL, and possessed 85-88 myomeres. Absorption of the yolk was completed at about 11.5mm TL. Flexion of the notochord started and finished at about 15mm and about 25mm TL, respectively. Aggregate numbers of all fin rays were com-pleted at over 27mm TL, when the larvae reached the juvenile stage. Squamation started in juveniles over 30mm TL.

Experimental infection with Schistosoma mansoni of Biomphalaria straminea from different parts of the Northeast of Brazil.

In the western part of the State of Bahia Biomphalaria straminea and B. glabrata both occur, but in the majority of cases they do not share the same habitat. In the State of Ceará, however, B. straminea is the sole snail host of Schistosoma mansoni. In this survey, no naturally infected B. straminea was found among snails collected from Bahia and Ceará, evidently because of the very low infection rates. The susceptibility of laboratory-reared specimens to infection with a Puerto Rican strain of S. mansoni was then tested experimentally. In general, the snails showed very low susceptibility. The infection rates were 1.1% among snails from Redenção (Ceará); 2.3% in those from Pentecoste (Ceará); 2.9% in snails from São Desidério (Bahia), while they were very high among an albino strain (NIH) of B. glabrata used as control. Another group of B. straminea from São Desidério was exposed to a Bahian strain of S. mansoni and the infection rate was still very low (3.6%) Apparently, the very low susceptibility of B. straminea, despite high snail density, is correlated with moderate infection rates with S. mansoni among humans, as shown by the results of stool examinations conducted by SUCAM in the municipalities of Redenção and Pentecoste, in Ceará.

The immature stages of Phlebotomus langeroni (Diptera: Psychodidae).

The immature stages of Phlebotomus langeroni are described from laboratory-reared specimens originating from Al Agamy, Alexandria, Egypt, where this species is the presumed vector of visceral leishmaniasis.

BEHAVIORAL, ELECTROPHYSIOLOGICAL, AND MORPHOLOGICAL INVESTIGATIONS OF STATOCYST FUNCTION IN THE NUDIBRANCH MOLLUSCHERMISSENDA CRASSICORNIS

Laboratory-reared specimens of the nudibranch Hermissenda crassicornis (Eschscholtz, 1813) possess statocysts that contain either one, several, or a species-typical number of statoconia (150-200). The number of statoconia per statocyst is significantly related to the growth rate of the animal during its first month post-metamorphosis, with slower-growing individuals (<0.88 mm/day) tending to possess a single statoconium bilaterally. Laboratory-reared animals with statocysts containing a single statoconium exhibited significantly weaker conditioning effects as expressed by faster response latencies to enter an illuminated area one and two days following behavioral training as compared with laboratory-reared animals with more than one statoconium per statocyst. Rotation of the isolated nervous systems of preparations with a single statoconium revealed that caudal hair cells exhibited reduced depolarization and the hyperpolarization of Type B photoreceptors in response to rotation was absent. As the number o...

Bionomics of Eucosma womonana Kearfott (Lepidoptera: Tortricidae), A Root Borer in Sunflowers

Female Eucosma womonana Kearfott had a preoviposition period of 4.4 ± 0.5 days, after which they laid an average of 236.8 ± 18.1 eggs in the laboratory at 27 ± 2°C. Incubation averaged 6.3 ± 1.5 days. Larvae passed through five stadia in ca. 85.8 ± 6.8 (females) or 86.5 ± 6.9 days (males). The total life cycle for laboratory-reared specimens averaged 106.7 ± 4.7 days. Infestation of roots of sunflowers, Helianthus annuus L., by E. womonana larvae on the High Plains of Texas was significantly reduced in plantings made after late April in 1982 and mid-May in 1983.

Early ontogeny ofLabeo capensis(Pisces: Cyprinidae)

The early ontogeny of Labeo capensis (A. Smith 1841) is described from wild-spawned, laboratory-reared specimens which were monitored for five months. Fertile eggs were non-adhesive, demersal and 2,9 mm (2,7-3,4 mm) in diameter. Total length at hatching was 5,4 mm (5,3-5,7 mm); at yolk absorption 7,9 mm and at pelvic bud formation 11,1 mm. Pigment patterns during larval development are described. Pigmentation began on the head and covered most of the body by the juvenile period. Myomere number remained constant after hatching and fin rays appeared in the order of caudal, dorsal, anal, pelvic and pectoral. Larvae periodically swam upwards and then passively sank, as has been reported for other Labeo species. Egg buoyancy and larval behaviour are discussed with relevance to spawning habitat.

Variation and timing of the cranial ossification sequence of the oriental fire-bellied toad, Bombina orientalis (Amphibia, Discoglossidae).

The sequence of appearance of the 17 different skull bones in the oriental fire-bellied toad, Bombina orientalis, is described. Data are based primarily on samples of ten or 11 laboratory-reared specimens of each of 11 Gosner developmental stages (36-46) representing middle through late metamorphosis. Ossification commences as early as stage 37 (hind limb with all five toes distinct), but the full complement of adult bones is not attained until stage 46 (metamorphosis complete). Number of bones present at intermediate stages is poorly correlated with external morphology. As many as four Gosner developmental stages elapse before a given bone is present in all specimens following the stage at which it may first appear. The modal ossification sequence is frontoparietal, exoccipital, parasphenoid, septomaxilla, premaxilla, vomer, nasal, maxilla, angulosplenial, dentary, squamosal, quadratojugal, pterygoid, prootic, interfrontal, sphenethmoid, and mentomeckelian. Most specimens are consistent with this sequence, despite the poor correlation between cranial ossification and external development as assayed by Gosner stage. The timing of cranial ossification in Bombina orientalis differs in many respects from that described for two other, distantly related anurans, the leopard frog (Rana pipiens) and the western toad (Bufo boreas). These include the total number and sequence of appearance of bones, and the timing of ossification relative to the development of external morphology. Interspecific variation may reflect differences in the timing of the tissue interactions known to underlie skeletal differentiation and evolution.

Squamation of larval greenling Hexagrammos otakii (Pices: Hexagrammidae) reared in the laboratory.

Early squamation of Hexagrammos otakii was observed on approximately 100 laboratoryreared specimens ranging from 20 to 56mm in standard length (SL). Alizarin staining was used to observe the appearance of scales on the body of different larval stages. Scales first appeared on larvae 27 to 32mm SL on the anterior portion of the trunk and midlaterally on the caudal peduncle. Sequence of squamation is illustrated and figured. Fully squamated specimens were longer than 53.0mm in standard length.

Phyllosoma and nisto stage of the Morton Bay bug, Thenus orientalis (Lund) (Crustacea : Decapoda : Scyllaridae), from shelf waters of the Great Barrier Reef

Samples of macrozooplankton collected from the shelf area of the Great Banier Reef (between 18�35'S. and 19�10'S. and 146�30'E. and 147�00'E.) contained phyliosomes of several different species of scyllarid lobster, including those of T. orientalis. Four larval stages of T. orientalis are described from the plankton and are related to laboratory-reared specimens of the first stage and of the postlarval nisto. An attempt is made to clarify discrepancies in the existing literature relating to descriptions of larval T. orientalis.

LIFE CYCLE OF LABORATORY-REARED TOBACCO HORNWORMS,MANDUCA SEXTA, A STUDY OF DEVELOPMENT AND BEHAVIOR, USING TIME-LAPSE CINEMATOGRAPHY

1. Time-lapse cinematography was used with laboratory-reared specimens of M. sexta to obtain information on and timing of behavioral activities.2. Insects used in this study were selected as the most advanced group within any instar and thus were the first of the gate-I insects. Use of these insects avoided timing irregularties involving the gating phenomenon. These advance insects varied less than ±0.9% s.d. from hatch through pupation.3. A detailed description was given for each of more than 20 timed events. Emphasis was placed on the events that occurred between the fifth ecdysis and pupation.4. Hatch occurred four days after oviposition (time 0), and ecdyses of the remaining four larval instars were at 6.4, 8.4, 10.6, and 13.7 days; pupation occurred at 22.8 days. The larvae underwent molt sleep in which they did not feed, defecate, or move until ecdysis. Durations of molt sleep were from 14 to 25 hr for each of the larval-larval ecdyses. The fifth instar did not have a comparable stage.5. Growth rate was highest for the first-instar larvae and slowest for the fifth instar, with weight-doubling times of 11.3, 17.6, 11.4, 17.3, and 21.2 hr for the first through fifth instar feeding periods, respectively, at 25° C.6. Body wetting, found only in the last instar, was induced by the onset of the scotophase. Use of this event marker allowed the selection of a group of insects that were capable of pupating five days later within one hour of each other.

Age Grouping of Anopheline Malaria Vectors (Diptera: Culicidae) by the Cuticular Growth Lines

The cuticular growth lines of several anopheline malaria vectors, both field-collected and laboratory-reared, were examined. The lines in the cuticle of the laboratory-reared specimens showed a daily arrangement in all species examined and, it is assumed on this and previous evidence that the lines in the cuticle of mosquitoes collected in the wild are also daily. The clarity of staining of the lines enabled counting, and thus age grading, in about 80% of the specimens. Age determination by this method is limited by the duration of cuticular growth to a maximum of 10%14 days. The age dispersion of the specimens studied showed that most of the mosquitoes had less than 9 days of cuticular growth and the maximum observed was 14 days.

Phenology of the Adult Spotted Cutworm 1 in the Yakima Valley

In Washington, there were 2 flights of adult spotted cutworm, Amathes c-nigrum (L.), yearly and 2 generations of larvae; the 2nd-generation larvae overwintered and completed development in the spring. A partial, small 3rd flight appeared occasionally. The sex ratio of laboratory-reared specimens was 1♂:1♀. Blacklight (BL) traps caught as many as or more females than males 16% of the time, which indicated that both sexes were attracted equally, but 84% of the time BL traps caught 15–20% more males than females because of the abundance and behavioral differences of males. The sex ratio became skewed in favor of males in the 2nd flight; females diminished to as little as 5–10% of the catch in Sept. and Oct. The female spotted cutworm proved to be polygamous, and some mated as many as 9 times. The average number of matings was 2 for 1st flight and 3 for 2nd flight females. There were seasonal increases in mating frequency in each flight. Most mated females that were trapped were in a reproductive condition. Populations were observed to grow and decline in response to environmental factors and not necessarily as a reflection of the size of the preceding population. The specific environmental factors that cause such fluctuations have not been isolated.