Showing papers on "Larva published in 1981"
Journal Article•
TL;DR: Evidence was not found that disease due to Aeromonas hydrophila was a primary cause of declining Rana pipiens populations in Minnesota.
Abstract: Frogs and tadpoles were captured at 14 sites in and near Minnesota during 1978-79 and nearly all appeared healthy. Aeromonas hydrophila was isolated from 94 of 294 (32%) juvenile and adult frogs and from 66 of 104 (63%) tadpoles. Of the isolates from frogs and tadpoles respectively, 68% and 47% were from the intestine only, 12% and 32% were from the intestine and the other sites, and 20% and 21% were from extraintestinal sites only. Isolations were more frequent from frogs collected in March-June than in August-November. Evidence was not found that disease due to Aeromonas hydrophila was a primary cause of declining Rana pipiens populations in Minnesota.
60 citations
TL;DR: Most of the duties in an incipient colony of the fungus-growing termiteMacrotermes michaelseni (Sjöstedt) are perfomed by the workers, while foraging was observed only in major workers and all of the other elements were seen in both major and minor workers.
Abstract: Most of the duties in an incipient colony of the fungus-growing termiteMacrotermes michaelseni (Sjostedt) are perfomed by the workers. While foraging was observed only in major workers, all of the other elements were seen in both major and minor workers. The behavioural elements were grouped as follows: (I) Alarm behaviour, shown by shaking of the whole body; (II) Building behaviour, including palpation of the inner surface of the nest, picking up of a piece of soil, transport of the soil, and deposition of the soil; (III) Procurement of food by foraging, chewing and swallowing of hay pieces, deposition of semi-liquid faecal pellets on the fungus comb, claning of the fungus comb and the fungus nodules, and feeding from fungus nodules and old fungus comb; (IV) Moisture regulation either by water intake with the hypopharynx or water release through the mouth cavity; and (V) Interindividual behaviour, consisting of cleaning all the termite castes as well as the larvae, cleaning and moistening the eggs, feeding reproductives and larvae with a liquid and soldiers with fungus comb material, liquid transfer between workers, faecal intake from the larvae, facilitation of hatching and moulting of the larvae. Reproductives showed alarm, building and grooming behaviour as well as moisture regulation only before the workers emerged in the incipient colony. The minor soldiers showed alarm and defensive behaviour but the only recorded behaviour of the larvae was shaking of the body.
53 citations
TL;DR: All combinations of 0, 5, 10, 20, and 40 hatchlings of two species of frogs, Hyla femoralis and H. gratiosa, were raised in a replicated experiment in which food and space were controlled.
Abstract: All combinations of 0, 5, 10, 20, and 40 hatchlings of two species of frogs, Hyla femoralis and H. gratiosa, were raised in a replicated experiment in which food and space were controlled. Models of density-dependent growth and metamorphosis can be extended to include the effects of competing species by inclusion of linear, additive terms. Hyla gratiosa has a strong, negative effect on the rate of metamorphosis and size at metamorphosis of Hylafemoralis. Hylafemoralis has no effect on the survival or mean size at metamorphosis of H. gratiosa, but it does lengthen both the minimum and mean larval period. Interspecific density effects on growth may increase both the risk of predation and the risk of desiccation in natural populations.
49 citations
TL;DR: Development to the three- setiger stage appears to be genetically preprogrammed, and Larval muscles play a part in the shape changes occurring during metamorphosis.
Abstract: Larval behaviour in G. caespitosa is described from trochophore to settled juvenile. The trochophore swims, spiralling counterclockwise, with the apical tuft outstretched. Large cilia on the lips of the mouth assist in food intake. Two sphincter muscles control passage of food along the gut. By 4-5 days; the trochophore has circular, oblique, radial and longitudinal larval muscles. The radial muscles move the apical tuft. The other muscles brace the larval body and assist the passage of food through the gut. At 6-7 days the larva becomes demersal. Feeding and growth continue. At 8-9 days three pairs of setal sacs develop in rapid succession. Metamorphosis now takes place. beginning at 11 days with collapse of the prototroch. Tentacle buds and thoracic membrane rudiments develop even if settlement is not achieved. Other events of metamorphosis (collar evagination, tube secretion. tentacle growth and shrinkage of the head region) require prior settlement. Larval muscles play a part in the shape changes occurring during metamorphosis. Settlement conditions are complex and may include a response to light-coloured surfaces. Development to the three- setiger stage appears to be genetically preprogrammed. Metamorphosis and settlement must involve an interplay of several internal and external causal processes in a sequential manner.
45 citations
TL;DR: It took about 5 months for a fertilized egg to become an adult in P. longiceps, a pycnogonid from observations of the development of an individual egg to a sexually mature adult.
Abstract: Summary Post embryonic development of a pycnogonid, Propallene longiceps, is described from observations of the development of an individual egg to a sexually mature adult. A fertilized egg hatches after 6 to 7 days as a second instar larva, because it completes the first moulting at the time of hatching. No protonymphon larval stage was observed. The larva of P. longiceps undergoes 3 moults during its attaching larval stage and 6 moults during its free-swimming larval stage. With the 9th moult, the larva becomes an adult. It took about 5 months for a fertilized egg to become an adult in P. longiceps. Some aspects of the intraclass relationship of the Family Pallenidae are discussed.
38 citations
TL;DR: In laboratory studies the effect of parasitism by the egg-larval endoparasitoidChelonus insularisCresson on the resulting larvae of 2 host species, Heliothis virescens and Spodoptera ornithogalli, were determined by comparing daily measurements of larval weights.
Abstract: In laboratory studies the effect of parasitism by the egg-larval endoparasitoidChelonus insularisCresson on the resulting larvae of 2 host species,Heliothis virescens (F.) andSpodoptera ornithogalliGuenee) were determined by comparing daily measurements of larval weights. Growth of parasitized larvae of both host species was slower than growth of unparasitized larvae. Injections of fluids from the female parasitoid's calyx or poison gland intoH. virescens eggs retarded subsequent larval growth. However, a combination of fluids from these 2 organs produced the most significant reduction in the host larval growth rate. The growth reducing factor(s) was also effective when injected into 5-day-old host larvae.
23 citations
TL;DR: Seven species of amphibian larvae were exposed to toxaphene and endrin in a continuous-flow dosing system to determine differences in sensitivity to the two compounds, and EC50 and LC50 estimates varied from those for Rana sphenocephala by no more than one order of magnitude.
21 citations
TL;DR: Ephemeral rain pools on rock surfaces are common in Africa and are inhabited by dense populations of aquatic dipteran larvae and support large numbers of tadpoles of the frog Ptychadena anchietae.
Abstract: . 1. Ephemeral rain pools on rock surfaces are common in Africa and are inhabited by dense populations of aquatic dipteran larvae. About 30% of the pools also support large numbers of tadpoles of the frog Ptychadena anchietae.
2. Experiments reveal that the presence of tadpoles suppress eclosion of the rock pool dwelling midge Chironomus imicola.
3. However, the presence of tadpoles also shortens the larval life-span of C. imicola by speeding up growth rates. Since the larval stages must be completed before the pool dries tadpoles may help ‘fine-tune’ the dipteran to the rock pool habitat.
4. A change in the diet of Cimicola larvae is associated with the accelerated development. Grazing by tadpoles results in algae, growing on the water surface, reaching the mud in tadpole faeces. These algae represent a high protein and energy food not otherwise accessible to mud dwelling dipteran larvae.
5. When pools dry tadpoles are killed, but a second species of dipteran Dasyhelea thompsoni have larvae able to survive to dry phase in situ. These larvae are scavengers so that on reflooding dead tadpoles are available as food. Experiments show that the presence of tadpoles again increase larval growth rates.
6. Both alive and dead tadpoles therefore are responsible for increasing the quality and quantity of food available to dipteran larvae and are thus among the mechanisms ensuring an abundance of food for rock pool dwelling insect larvae.
18 citations
TL;DR: The ‘transfer larva’ migrates from the litter habitat to live tree hosts, where it establishes a tunnel, and is characterised by expansion and fusion of the dorsal pinacula, which results in a darker overall coloration.
Abstract: A larval phase of Aenetus virescens (Doubleday) morphologically distinct from the young larvae found on dead wood and fungi (litter phase) and the older larvae in live trees (tree phase) is described, and designated the ‘transfer phase’. It is characterised by expansion and fusion of the dorsal pinacula, which results in a darker overall coloration. The transfer phase is a single instar, but its exact position in larval development seems to vary. The ‘transfer larva’ migrates from the litter habitat to live tree hosts, where it establishes a tunnel. Chaetotaxy and other morphological features of A. virescens larvae are described and compared. The diagnostic value of certain features of a range of hepialid larvae is discussed.
18 citations
01 Jan 1981
TL;DR: Perron et al. as discussed by the authors used a modified version of the technique devised by Brownell (1977) to re-harvest the planktonic larvae of C. pennaceus, C. quercinus and C. striatus.
Abstract: The planktotrophic larvae of Conus lividus, C. quercinus, C. jlavidus, C. striatus, and C. marmoreus were reared through metamorphosis in the laboratory and were described and figured . Minimum planktonic periods of these species were found to be 50, 30, 23, 20, and 10 days, respectively. The lecithotrophic larvae of C. pennaceus metamorphosed within 24 hours of escape from their egg capsules. Early post-ha tching growth rates of planktotrophic veligers were related to hatching size and the developmental state of the velum at hatching. In C. pennaceus, metamorphosis was induced by the presence of a biological film. Substratum texture had no effect on rates of metamorphosis. The lecithotrophic larvae of C. pennaceus were observed to ingest unicellular algae. Experiments showed that this facultative feeding may impro ve the surviva l of C. pennaceus when the larval period is art ificially prolonged. GASTROPODS IN THE GENUS Conus are important and conspicuous components of tropical coral reef ecosystems. Although extensive ecological research has been carried out on populations of adult Conus (Kohn 1959, Kohn and Nybakken 1975, Leviten 1974), little work has been done on the early life histori es of these mollusks. Information on the larval biology of benthic marine in. vertebrates is important because the large and small scale distribution patterns of these species are often determined to a large extent by the dispersal potential and site-specificity at recruitment of their larvae. Scheltema (1961 , 1971) and Hansen (1978) have commented on the impact of larval biology on the distribution of gastropod species in space and time respectively, and Kohn and Leviten (1976) have suggested that patterns of larval sett lement may have an effect on the population density and species diversity of Conus assemblages. This paper will describe laboratory rearing studies on the larvae of 6 species 1 This study was supporte d in par t by grants from the Hawaiian Malacological Society. Manuscript accepted 22 December 1980. 2 Pacific Biomedical Research Center, 41 Ahui St., Honolulu, Hawaii 96813. 25 of Conus and present the results of experiments on the larval settlement and metamorphosis of C. pennaceus. The vast majority of tropical gastropod species have planktotrophic larvae which must feed in the plankton before settling and metamorphosing in the benthic environment (Thorson 1946). The necessity of finding the correct food for planktotrophic larvae has frequently discouraged laboratory cultivation of these species (Berg 1972, Kohn 1961a). Recently, however, Scheltema (1962) and others have developed rearing techniques that are applicable to a wide variety of gastropod larvae. Perron (1980) successfully reared the planktotrophic larvae of Conus textile using a modification of the technique s devised by Brownell (1977), and additional data on Conus comp arative larval biology are presented by Perron (1 98l a). Informat ion on the intracapsular development of Conus embryos has been contributed by Ostergaard (1950), Na tarajan (1957), Kohn (1961a,b), Nybakken (1970), Bandel (1976), Cruz, Corpuz, and Olivera (1978), and Perron (1 981 b). Taylor (1975) has identified, described, and figured the plank tonic larvae of 9 species of Hawaiian Conus.
17 citations
TL;DR: It is examined the possibility that the observed differences in adult densities reflect differences in the ability of larvae to capture aphids, and the larval search parameters estimated here are also used in the broader study of the complete predator-prey relationship.
Abstract: We studied first and fourth instar larvae of Coccinella trifasciata L., C. Californica Mannerheim, C. undecimpunctata L., and Cycloneda polita Casey searching for Acyrthosiphon pisum (Harris) on alfalfa seedlings and for A. dirhodum (Walker) on oat seedlings, in the laboratory. Styles of search varied considerably, but each species of larva could capture aphids on each species of plant. Observed differences in relative abundance of the four species of adult coccinellid in alfalfa and oat fields are not related to the success of their larvae in finding aphids.
TL;DR: The vertical distribution of green peach aphids on potato plants was studied to estimate its impact on a model simulating the effects of a predator on GPA populations, and it is suggested that C. maculata would be an effective early season predator, and that the model should over-predict the effect of C. Maculata late in the season.
Abstract: The vertical distribution of green peach aphids (GPA) on potato plants was studied to estimate its impact on a model simulating the effects of a predator on GPA populations. This model is based on laboratory studies of a ladybird beetle feeding on GPA that was placed exclusively on the bottom leaf of a three leaf stem section. The model predicts the impact ofColeomegilla maculata (DeGeer) adults and third instar larvae on GPA populations over a range of temperatures and GPA densities.
01 Jan 1981
01 Jan 1981
TL;DR: The nymph and larva of Dermacentortaiwanensis Sugimoto, 1935, is described on the materials mainly from Amami-oshima, Japan, where the adults are parasites of large wild animals and the immature ticks are those of small or medium-sized mammals in southern half of Honshu, Kyushu and the Nansei Islands.
Abstract: The nymph and larva of Dermacentortaiwanensis Sugimoto, 1935,is described on the materials mainly from Amami-oshima, Japan. The adults are parasites of large wild animals and the immature ticks are those of small or medium-sized mammals in southern half of Honshu, Kyushu and the Nansei Islands.
01 Jan 1981
TL;DR: The egg, larva and pupa of the bloodsucking midge Culicoides homotomus Kieffer is described based on the materials reared in the laboratory and also collected from breeding sites in Chungking, Szechuan Province.
Abstract: This paper describes the egg, larva and pupa of the bloodsucking midge Culicoides homotomus Kieffer based on the materials reared in the laboratory and also collected from breeding sites in Chungking, Szechuan Province The abdominal micro setae and anal spine of larva, the ventro-median and ventro-posterior setae of pupae, are described for the first time It is suggested that the term ventro-anterior tubercule (ventro-anterior setae) is applied to those structures previously described as the ventro-median tubercule (ventro-median setae) in the pupa of CulicoidesThere are four larval instars, which differ from one another in size and the numbers of the 4th rows of mola cibaralis The numbers of the 4th rows of mola cibaralis in 1st, 2nd, 3rd and 4th instar larvae are constant, being 8, 12, 16, 20 respectively The larval exuviae of Culicoides homotomus is membranous in structure, difficult to mount, and is not a good material for microscopical use The main differences of the larva and pupa of Culicoides homotomus and its allied species, C nubeculosus Meig are tabulated
TL;DR: The constricted ‘waist’ of the metamorphosing larva of the polychaete Arenicola cristata is described, using light and electron microscopy and Morphological differentiation of neuro-effector and interneuronal contacts is initiated.
Abstract: The constricted ‘waist’ of the metamorphosing larva of the polychaete Arenicola cristata is described, using light and electron microscopy. The constriction is shown to be the consequence of the discharge and collapse of a post-trochal ring of epithelial cells which remain as functional components of the post-metamorphic juvenile. Morphological differentiation of neuro-effector and interneuronal contacts is initiated at this time. Muscular and neural changes are discussed in terms of their role in effecting metamorphosis.
TL;DR: The larval biology of Aproctella is very similar to that of Cardiofilaria, confirming the close relationship of these two genera and there is not a distinct separation between the Splendidofilariinae and the Lemdaninae.
Abstract: Aproctella alessandroi n. sp., parasitic in various Passeriformes in Colombia and Guadeloupe, and A. golvani n. sp., a similar species with smaller microfilariae parasitic in sparrows in Guadeloupe, are described. The life cycle of A. alessandroi was studied in Aedes togoi (development in 13 days in the flight muscles; first-stage larva cylindrical; third-stage larva 1 330-1 600 microns long; oesophago-intestinal junction distinct). The larval biology of Aproctella is very similar to that of Cardiofilaria, confirming the close relationship of these two genera. The biology differs from that of two other genera of Splendidofilariinae of birds, Splendidofilaria and Chandlerella (vectors: Culicoides and Simuliids; development in flight muscles and haemocoel; first stage larva almond-shaped; third stage larva 400-600 microns de long; oesophago-intestinal junction indistinct). In these latter genera, the larval biology is remarkably similar to that of Lemdaninae of reptiles and birds (Saurositus, Eufilaria). It seems there is not a distinct separation between the Splendidofilariinae and the Lemdaninae.
TL;DR: The body form and life style of animals change dramatically during development from the larval to the adult stages, including the change of a caterpillar to a butterfly or moth, which is referred to as metamorphosis.
Abstract: THE BODY FORMS of many animals change dramatically during development from the larval to the adult stages. Most dramatic, of course, is the change of a caterpillar to a butterfly or moth. This change in body form and function is referred to as metamorphosis. Some vertebrates also undergo an equally dramatic change in body form and life style. Most aquatic amphibians hatch from eggs and spend the initial stages of their life as swimming larvae after which they metamorphose into frogs, toads, or salamanders. This transition from an aquatic to a terrestrial environment requires a large number of physiological and morphological changes. The larvae must
01 Jan 1981
TL;DR: The adults of both sexes, pupa and fourth instar larva of CuZex R.kZexJ pajoti, a new species, are described and illustrated and the diagnoses of the female, male, larva and pupa of the new taxon are given.
Abstract: The adults of both sexes, pupa and fourth instar larva of CuZex R.kZexJ pajoti, a new species, are described and illustrated. The diagnoses of the female, male, larva and pupa of the new taxon are given, as well as its known distribution. Lastly, the systematics of CX. pajoti sp. n. are discussed, its affinity to CX. i~~grmni Edwards and related species being examined.