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At least 19 recordsLinked to original sources
PubMed2026

Seawater type shapes larval development, intestinal microbiota, and water quality in Macrobrachium rosenbergii.

Giant freshwater prawn (Macrobrachium rosenbergii) has high economic value and extensive aquaculture prospects, and larval quality critically restricts the sustainable development of the industry. To investigate the effects of different seawater sources on larval survival and growth, artificial seawater, natural seawater from Beibu Gulf (China) and East China Sea (China) were used as culture media to compare their influences on larval development and intestinal microbiota of M. rosenbergii. Significant intergroup differences were observed in cultivation outcomes. The larval emergence rate reached the maximum value of 52.1% in Group G (Beibu Gulf natural seawater), followed by 43.57% in Group R (artificial seawater), and only 36.4% in Group Z (East China Sea natural seawater), indicating distinct larval emergence gaps and a gradual decline in larval development efficiency. Intestinal microbiota analysis indicated that Pseudomonadota, Actinomycetota and Bacillota were the dominant phyla in all three groups. The relative abundance of Bacillota increased significantly in Group G on day 10. LEfSe analysis proved that this group owned the most stable microbial structure and highest community diversity, and pronounced structural fluctuations occurred in Group R, suggesting that intestinal microbial profiles can reflect larval developmental conditions. Correlation analysis showed that gut microbial composition was closely correlated with water environmental parameters, and microbial metabolic pathways were strongly associated with larval growth and development. This study indicates that natural seawater from the Beibu Gulf of China is more suitable for healthy larval cultivation of M. rosenbergii. Structural stability and diversity of intestinal microbiota are key factors affecting larval growth. The results offer theoretical references for optimizing artificial seawater formula and improving larval rearing efficiency.

16S rRNA↗
PubMed1977

On the use of the scrotum for feeding larval ixodid ticks on hosts.

The efficacy of feeding larval stages of Amblyomma variegatum, Hyalomma rufipes and Boophilus decoloratus on the ears and scrotum of sheep is compared. The effect of age of larvae on the number that engorged on the animal was also investigated. A significantly greater number of larvae fed on scrotum than on ears. The greatest number of larvae engorged when they were fed on the scrotum or ear within 1-4 days of hatching. The older the larvae, the less the number that fed. The economic advantages of adopting the scrotal method for rearing larval tick stages as well as the implication under natural conditions of younger larvae feeding in large numbers are discussed.

Animal Feed↗
PubMed1978

Factors affecting the larval growth and development of laboratory-reared Ambystoma gracile (Baird) from natural populations of different temperature regimes.

Temperature-transfer of Ambystoma gracile larvae from 11 degrees C to 21 degrees C does not significantly alter growth rates at the higher temperature when compared to larvae continuously grown at 21 degrees C. Temperature-transfer does not alter the incidence of neoteny within populations, even though interpopulation neotenic tendencies differ. Salamander larvae from the high altitude population exhibit larvae from the high altitude population exhibit faster growth rates than the larvae reared from eggs from the low altitude-population. These high altitude larvae exhibit faster growth rates both at the lower and higher temperatures suggesting a greater sensitivity to growth-promoting factors and/or higher rates of synthesis or secretion of such factors. Experiments utilizing ovine prolactin indicated that prolactin-injected experimentals were significantly longer (P less than 0.025) after 60 days of treatment than were placebo-injected controls. A prolactin-like hormone is suggested as thepossible growth-promoting factor in larval Ambystoma gracile.

Altitude↗
PubMed1975

The effect of Imidocarb treatment on Babesia in the bovine and the tick (Boophilus microplus).

Treatment of calves with 5 mg/kg Imidocarb (3,3-1-bis-(2 - imidazolin - 2 - yl)carbanilide dipropionate) given intramuscularly 14 days before and 14 days after exposure to Babesia infected Boophilus microplus larvae rendered the next generation of larvae incapable of transmitting Babesia infection. When administered to calves 14 or 28 days before tick exposure, the drug prevented the development of clinical babesiosis; the larval progeny of ticks reared on the calf which was treated 28 days before infestation were infective. Treatment of a calf 42 days before exposure to infective larvae did not prevent the development of a Babesia parasitaemia but appeared to reduce the severity of infection.

Animals↗
PubMed1976

[Circulating ecdysone levels in late larval stages and the induction of the nymphal diapause in Pieris brassicae].

Ecdysone titers of hemolymph are measured during 5th larval instar of Pieris brassicae reared under either conditions inducing pupal diapause or continuous development. The peak values for the two conditions are not different and, therefore, seem not to be related to the mode of development. A few hours before larval-pupal ecdysis, a new secretory activity begins only in the non diapausing prepupae. Ecdysone injections in diapausing prepupae give results that agree well with those above.

Animals↗
PubMed1979

The time scale of tooth development and replacement in Xenopus laevis (Daudin).

One hundred and seventy two larval specimens of Xenopus laevis were reared in such a way that their rates of development (as measured by external criteria) were similar, and so the course of dental development could be examined histologically in a cross sectional study. In this way the events of tooth development were observed, and a time scale constructed for these events. The teeth took an average time of 26 days to develop, erupt and become ankylosed to the bony pedestal, after which each tooth was in a functional position for only about 7 days. Individual tooth replacement was assessed to occur about every 16 days. By comparing the number and size of the odontoblasts responsible for dentinogenesis in 18 months old adult Xenopus laevis with the odontoblasts in the larval specimens, the conclusion was drawn that, despite the larger size of the adult teeth, the time involved in their development and replacement may well be of similar duration to the smaller larval teeth. The significance of the findings for the Zahnreihen Theory is discussed.

Animals↗
PubMed1976

Growth and development of the American bollworm Heliothis armigera Hubn. under laboratory mass rearing conditions.

A kidney bean meal diet was the most satisfactory laboratory diet for the larvae of the American bollworm Heliothis armigera Hubn. Optimum rates of survival (63.5%) occurred and the larval growth was better than that of larvae reared on castor oil plant leaves. The pupal weight and the fecundity of the resulting adults were also much better than those on the control host plant.

Animals↗
PubMedDate not supplied

[Life cycle of Paramphistomum togolense n. sp. (Trematoda, Paramphistomidae)].

Mature worms were obtained from a sheep experimentally infested with metacercariae issued from cercariae emitted by naturally infested snails: Bulinus (Bulinus) forskalli collected near Lomé (Togo). Miracidia were used for infection of these laboratory-reared snails which gave numerous cercariae. Larval stages are studied. Morphological and histological characters of the adult and the very peculiar shape of the sporocyst distinguish this trematode from the other known species of the genus. The superficial argentophilic structures of the miracidium and cercaria are described in detail because, to our point, they constitute the best criteria for the taxonomy of this group.

Animals↗
PubMed1975

[Indirect effect of the larval food of an alternative host (Galleria mellonella L., Lepidoptera, Galleriidae) on the reproduction of an entomophagous insect (Lixophaga distraeae Towns, Dipt. Tachinidae)].

G. mellonella reared on its natural food, beeswax and pollen, is not suitable for a continuous rearing of L. diatraeae. As a matter of fact, L. diatraeae cannot be maintained for more than 10 generations on G. mellonella because the effect of adverse factors during the larval stage progressively reduces both mating rate and female fertility. But adding vitamin E to the natural larval food of G. mellonella eliminates these reproduction disturbances of the parasite, and L. diatraeae rearing can be continued on this alternative host, the diet of which has been enriched with vitamin E.

Animals↗
PubMed1977

[Age specificity of the effect of 5-bromdeoxyuridine on the differentiation and puff spectrum of the salivary gland chromosomes of Drosophila virilis Sturt. I. Relationship between the viability of individuals and induction of new puffs and the period of action of 5-bromdeoxyuridine].

5-Bromodeoxyuridine (BUdR) influences the differentiation of the imaginal discs, larval viability and the chromosome puffing throughout the larval development. The differentiation of imaginal discs is more sensitive during the early 3rd instar. "cryptocephal" phenocopy appeared if the larvae were reared in the BUdR medium till the late 2nd instar. 2nd and 3rd instars are critical for the larval viability. During the period of the middle 3rd instar BUdR induced the complete spectrum of the newly forming specific puffs.

Age Factors↗
PubMed1978

Bot fly myiasis of the cottontail rabbit, Sylvilagus floridanus mallurus in Virginia with some biology of the parasite, Cuterebra buccata.

Twenty four percent of 2,643 cottontail rabbits (Sylvilagus floridanus) collected in Virginia from 1949-1975 showed evidence of Cuterebra parasitism. Occurrence was seasonal with greatest prevalence from July to November. Some Oryctolagus cuniculus, S. palustris and one S. transitionalis also showed Cuterebra myiasis. Juvenile rabbits had higher infection rates (28%) than did adult rabbits 14.5%, P less than .001). Juveniles had greater numbers of larvae per host than adults, with means of 2.14 and 1.62, respectively. Larval development sites were in the genital region of most hosts. Twenty flies reared from wild cottontails were identified as C. buccata. Duration of induced infections in Oryctalagus was 30-33 days. Minimal generation time for C. buccata is concluded to be 11 weeks, allowing up to four generations of flies to occur annually in the southern and one generation to occur in the northern distributional limits of this bot fly. Peromyscus hosts were refractory to C. buccata infections. C. buccata fecundity averaged 1316 eggs. Field observations of adult flies are described.

Animals↗
PubMed1975

Field studies on inhibition of Haemonchus contortus.

The epidemiology of Haemonchus contortus was studied in north east England in lambs reared under field conditions with infected ewes. The parasite population was monitored by pasture larval counts, faecal egg counts and lamb postmortems. From 25 June to 11 November, eight lambs were slaughtered each month, together with eight worm-free tracer lambs. Postmortem worm counts showed that on 25 June, small numbers of adult H. contortus were present but no inhibited larvae. However, subsequently the number of worms recovered rose rapidly to 1000-5000 and the percentage inhibition increased to 57% in July, 75% in August and virtually 100% in September, October and November. On each sampling occasion no significant differences in worm count or percentage inhibition were recorded between experimental and tracer lambs. These results suggest that neither autumn climatic effects nor host immunity were responsible for inhibition in this strain of H. contortus.

Animals↗
PubMed1975

Present progress towards the laboratory colonization of African Simuliidae (Diptera).

The laboratory colonization of African simuliids would facilitate critical work on many aspects of their biology and onchocerciasis vectors could be studied away from natural breeding-sites. In addition to a review of the literature of past achievements in this field, the authors' own studies are described: these centred on the Simulium damnosum and S. neavei complexes because they include vectors of human onchocerciasis. Other species studied included vectors of Onchocerca gutturosa and avian Haematozoa. Techniques for collecting the various developmental stages of African simuliids are discussed. Adult simuliids may be kept singly in small containers, or together in larger vessels, and fed on sugar-solutions, fruits or flowers. Only two members of the S. damnosum complex (one not yet identified) and one S. bovis complex species are so far known to mate in captivity. Many African simuliids have been blood-fed in captivity from sources including blood-soaked filter paper, birds, rabbits, man and the McMahon feeding apparatus, but results have been inconsistent and a few species have rarely taken blood. Blood/sugar mixtures have given better results, but in most cases normal oogenesis has not subsequently occurred. Some African simuliids lay eggs when kept in tubes, while others do so if placed in water and/or after decapitation. Although some females either fail to oviposit or retain many eggs, others lay a large number, but usually not all develop. The eggs of one species have been temporarily stored at low temperatures, but required protection from fungal attack. Larval development requires adequate water-flow and correct hydro-chemical conditions. Various rearing techniques are described. An apparatus in which the conditions of the water may be regulated has recently been modified for use with the S. damnosum complex and three members of the complex have been reared successfully so far. The Kibwezi form of the S. damnosum complex has been successfully induced to complete every stage of its life-cycle in the laboratory. The reduction of wastage throughout the life-cycle is now being attempted.

Africa↗
PubMed1975

Theileria mutans: experimental transmission by Haemaphysalis punctata.

T. mutans (Essex), originally isolated from a farm in the County of Essex in South-east England by allowing field-collected H. punctata tickes to feed on a splenectomized calf, was syringe-passaged once between calves and then resecured in a laboratory-reared strain of H. punctata. From subsequent studies it was found that only transstadial transmission of the parasite occurred. Thus, only the larval and the nymphal stages of the ticks were capable of acquiring the infection and subsequently nymphs and adults respectively were capable of transmitting the parasite. It was noted that once infected ticks transmitted T. mutans, the succeeding stages were uninfected. After 7 tick passages between cattle there was no evidence of increasing virulence of the parasite.

Animals↗
PubMed1977

Life history and host specificity of Mediorhynchus centurorum Nickol 1969 (Acanthocephala: Gigantorhynchidae).

Examination of 1905 arthropods from a swamp and surrounding pasture in sothern Louisiana revealed larval specimens of Mediorhynchus centurorum in 8 of 228 woodroaches, Parcoblatta pensylvanica, but in no other species. The life cycle was confirmed by feeding eggs of M. centurorum to laboratory-reared woodroaches. Cystacanths later recovered from the woodroaches developed into mature worms when pipetted into esophaguses of red-bellied woodpeckers, Centurus carolinius: red-headed woodpeckers, Melanerpes erythrocephalus; yellow-shafted flickers, Colaptes auratus; and a hairy woodpecker, Dendrocopos villosus. Infection was achieved in all woodpeckers fed cystacanths at least 47 days old and the mean prepatent period was 35 days. Cystacanths fed starlings, Sturnus vaulgaris, and red-winged blackbirds, Agelaius phoeniceus, did not produce infections although cystacanths from the same pool were infective to control woodpeckers. Larval development of Mediorhynchus centurorum in woodroaches did not differ significantly from that of M. grandis in grasshoppers. M. centurorum is the only species of the Gigantorhynchidae for which the life cycle has been confirmed by laboratory infections using an intermediate host species known infected nature.

Acanthocephala↗