Embryonic Development Of Eggs Research Articles

Some features of embryonic development of eggs and larvae of three stripe rockfsh Sebastes trivittatus (Sebastidae) at Primorye (Japan Sea)

Later embryonic development ofSebastes trivittatuspasses in 20 days under water temperature 10 оС (in June-July). During this period, the embryos ofS. trivittatusincrease in diameter from 0.1 mm to 1.3 mm and change their shape from spherical to elliptical. Within gonads of pre-hatching females, the embryos have different stages: from prelarvae on late stages of development in the internal layers to pre-hatching larvae in the external layer. The pre-hatching larva hasTL4.1 mm, 5–6 melanophores on the top of head, 20 melanophores in ventral row, some melanophores on peritoneum, and oil globule in the frontal part of intestine; its notochord is not flexed, yolk sac is absent, body myotomes are poor visible, number of tail myotomes is 24.

Особенности эмбрионального развития яиц нематод Trichuris skrjaвini (Baskakov, 1924), паразитирующих у овец

Specific features of embryonic development of eggs isolated from gonads of Trichuris skrjabini nematodes females, obtained during helminthological opening in sheep, were studied. It is proved that during the growth and development of this species of trichurises eggs there are significant changes in the metric indices of their length and width, as well as in the length and width of their lids. It is determined that at 27 °С in laboratory conditions T. skrjabini eggs become infectious during 51 days with survival rate of 80.0±0.82 % (20.0±0.81% of eggs stop in development and subsequently die). The embryogenesis process has six morphologically distinct stages: protoplast (from the 1 st to the 12 th day); blastomeres formation (from the 6 th to the 24 th day); bean-like embryo (from the 12 th to the 33 d day), tadpole-like embryo (from the 15 th to the 36 th day); larval formation (from the 27 th to the 48 th day); and mobile larva (from the 27 th to the 51 st day). The development of T. skrjabini eggs to the infectious stage in laboratory conditions is characterized by their lengthening to 75.7±0.36 μm (by 2.0%, р < 0.05), narrowing to 37.3±0.30 μm (by 2.4%, р < 0.05) and lengthening to 12.2±0.42 μm (by 16.4%, р < 0.01) and thinning to 12.1±0.10 μm (by 5.5 %, р < 0.01) of the egg lids. The changes of egg shell thickness were not statistically significant. Considering the data on the morphological structure and the period of nematodosis pathogens eggs development it is possible to plan the time of taking measures to prevent and control trichurosis in sheep.

Efficiency of Azadirachtin, A Chitin Synthesis Inhibitor on Growth, Development and Reproductive Potential of Tribolium confusum after Adult Treatment

Abstract Azadirachtin, a neem derivative, which considered as insect growth regulator due to its chitin inhibitor activity was tested topically at four doses (0.5, 1, 1.5 and 2 µg / insect) on adults of Tribolium confusum (Coleoptera: Tenebrionidae) and first evaluated on fecundity, hatchability and viability of eggs, longevity and morphometric of oocytes. Our results show that the compound reduce the longevity and the fecundity. Generally, treatment with azadidrachtin affected growth and development of oocytes and egg-viability as shown by calculating the number of oocytes per ovaries and the size of basal follicle. The width of the follicle has not been affected significantly by these treatments. In the second group of experiments, this IGRs don’t induce significant reduction in percentage of hatchability, the hatching rate of eggs laid by F1 females was not affected by the treatment (F=2.86, DF=99, P=0.5), but it affect very significantly the viability rate of eggs laid by first female generation F1 (F=7.5, DF=99, P>0.0001). However, the azadirachtin lengthened very significantly the total duration of life cycle. Duration of the embryonic and post embryonic development of eggs laid by treated female increase when the concentration varied from 0 to 2 µg / µl. This data confirm the efficiency of growth regulators derived from neem plant, on the development of stored product insect pests.

Effects of crushed fresh Cleome viscosa L. (Capparaceae) plants on the cowpea storage pest, Callosobruchus maculatus Fab. (Coleoptera: Bruchidae)

Laboratory assays were carried out to evaluate the effects of fresh Cleome viscosa on the reproduction and survival of Callosobruchus maculatus. Significant control was achieved by the two treatments with the highest quantity of crushed leaf. Fresh crushed C. viscosa also led to complete inhibition of embryonic development of eggs exposed for 48h in all botanical treatments. On-farm storage trials, using 5, 15 and 25 g C. viscosa crushed plant per 1 kg of cowpeas, showed a dose-dependent reduction in bruchid numbers of 35.4, 59.5 and 86.4%, respectively, after 120 days of storage. Moreover, the pea losses were relatively low (≤11%) and pea germination was unaffected (>80%) in all batches where C. viscosa was introduced. Our results indicate that C. viscosa has significant potential for controlling the pest. The conditions for optimal use of the plant in stored cowpea management are discussed.

Efeito da idade de Trichogramma exiguum e do desenvolvimento embrionário da Traça-das-Crucíferas sobre as características biológicas do parasitóide

The objective of this work was to evaluate the influence of the embryonic development of eggs from the P. xylostella host on Trichogramma exiguum females of different ages. Fifty females – either just-emerged or 24, 48, 72 and 96 hours after emergence of this parasitoid were divided into five groups. Each female was offered a recipient with 30 P. xylostella eggs, which were 1-, 2- and 3-days-old. The greatest rates of parasitism were observed on eggs with 3 days of embryonic development, with exception of those 72-hours-old. Viability was not influenced by parasitoid age or host embryonic stage. Sex ratio was similar in all three embryonic host stages for T. exiguum females that were 24-, 48- and 72-hours-old. While evaluating parasitoid progeny obtained from eggs with 3, 2 and 1 days of embryonic development, it was verified that the highest values of longevity were obtained when the females used were just-emerged, or 48- and 72-hours-old, respectively. These results indicate the importance of the age of the parasitoid, as well as the host embryonic development period, in order to maintain quality of T. exiguum at laboratory conditions, in mass culture, as well as in field releases for biological pest control.

Biology and Biometry of Sharpshooter &lt;I&gt;Homalodisca coagulata&lt;/I&gt; (Homoptera: Cicadellidae) Reared on Cowpea

Abstract Stage-specific survival, growth, developmental biology, and biometry of the sharpshooter Homalodisca coagulata (Say) were studied in the laboratory under controlled conditions of 27 ± 1°C, 65 ± 5 RH, and a photoperiod of 14:10 (L:D) h. Nymphs and adults were individually reared on excised cowpea, Vigna unguiculata L. Walp., plants maintained in floral aquapics containing a hydroponic solution. Embryonic development of eggs was completed in 7.1 ± 0.8 d with 92.6% of the incubated eggs hatching. Nymphs molted five times, and the nymphal period of 61 ± 2.9 d for females was 1.2-fold significantly longer than that of males. The second nymphal stage was the shortest for both sexes (6.1 ± 0.5 d for females and 5.8 ± 0.8 d for males), whereas the last instar was the longest for females only. Stage-specific mortality was similar between instars; ≈36% of the nymphs molted to adults. H. coagulata adult sex ratio was not significantly different from a 1:1 ratio. Adult females lived 52 ± 11 d, and females de...

Cold-hardiness of Dermacentor marginatus (Acari: Ixodidae).

The cold-hardiness of Dermacentor marginatus using laboratory-reared offspring of ticks collected in Germany was characterized. Investigations of unfed stages revealed that adult ticks suffered 50% mortality at -10 degrees C after 4-5 months, but larvae and nymphs suffered mortality within few days, whereas -15 degrees C was lethal for all stages within a very short period. Larval hatch and moulting of engorged larvae and nymphs did not occur at < or = 10 degrees C. Embryonic development of eggs with larval hatch was considerably reduced by exposure of eggs to < or = 10 degrees C. Engorged females did not lay eggs at < or = 10 degrees C, the oviposition capability, however, persisted over 6 months at 10 degrees C, 5 months at 5 degrees C, 3 months at 0 degree C and 2 months at -10 degrees C without substantial decrease of the oviposition capacity or reduction of viable eggs. These results present evidence that unfed adult ticks are the ecoepidemiologically most effective stages, which are capable to tolerate long and extremely cold winters without substantial impairment of the population density. It is also considered that engorged females interrupt their oviposition at low and subzero temperatures delaying it for months and so contribute in bypassing winter conditions. None of the stages survived supercooling indicating that D. marginatus is freeze intolerant. Mean supercooling point (SCP) ranged between -26 degrees C in eggs and -12, 6 degrees C in engorged females. Compared with eggs, the SCP of the other stages was significantly higher. In conclusion, the SCP is considered to have no predictive value in the context with cold-hardiness.

Effects of temperature on hatchability, development and growth of eggs and yolksac fry of Oreochromis mossambicus (Peters) under artificial incubation

. The eggs and yolk sac fry of the mouth brooding tilapia. Oreochromis mossambicus (Peters), were artificially reared in an experimental hatchery system at different temperatures. The hatchability, embryonic development of eggs and growth of yolk sac fry were studied under controlled conditions. It was shown that the upper lethal temperature for O. mossambicus eggs was above 40°C and the lower lethal temperature between 11°C and 17°C. For yolk sac fry these values lay between 34 and 40°C and 17 and 20°C respectively. Fry survival between 24·3 and 34·0°C was near to 100% while al 20°C it was less than 60%. The somatic growth rates of fry at temperature between 20 and 34·5°C up to 10 days post hatch are presented and were found to differ significantly. At 34·6°C a negative SGR was recorded during the period 6–9 days post hatching, but, during the first 6 days, the SGR at this temperature was more than four times higher than at 20°C. At the elevated temperatures, the utilization of yolk is faster and the loss of weight observed was due to starvation. This should be taken into account when incubating under artificial rearing condition so that initiation of exogenous feeding is timed most appropriately.

The effect of diamino diphenyl sulfone on the embryonic development of eggs from the sea urchin ( Lytechinus variegatus)

1. Diamino diphenyl sulfone (DDS), a chemotherapeutic compound used in the treatment of leprosy, was studied with regard to its effects on the embryonic development of eggs from the sea urchin Lytechinus variegatus. 2. DDS disturbs the normal development of fertilized eggs by interfering with the mitotic apparatus and producing spheroid-shaped bodies shown to be aster-like bodies by staining techniques. 3. A typical colchicine effect (formation of kidney-shaped cells) was also demonstrated.

Cytogenetics of Ticks (Acari: Ixodoidea): Chromosomes and Timing of Spermatogenesis in Amblyomma inornatum

low humidity adversely affected the hatching process but not the rate of embryonic development of eggs of the closely related Ophionyssus natricis (Gervais). Similar information for the northern fowl mite is not available. II. Effect of constant relative hum dity on the li of northern fowl mite e gs.* Very low humidity caused only a small decrease in egg hatch (74.2% hatch at 20% relative humidity). Thus, the effect of relative humidity on the hatching percentage was less marked than that of temperature (no hatch at 40 C). The effect of relative humidity on the incubation period of eggs of parasitic mites has been studied little. Changes in relative humidity did not seem to affect the incubation period of northern fowl mites (Combs and Lancaster, 1965, loc. cit.) or Ornithonyssus bacoti (Hirst) (Skaliy and Hayes, 1949, American Journal of Tropical Medicine 29: 759772), at least at optimal temperatures. Thus, under the conditions of the present experimental study, temperature was probably the chief factor influencing embryonic development.

The permeability and the effect of anthracene-like compounds on the embryonic development of eggs from the sea-urchin ( Lytechinus variegatus var. atlanticus)

1. Acridine orange, lucanthone HCl and promethazine, three compounds bearing an anthracene-like structure similar to that carried by actinomycin D, were shown to permeate eggs from the sea-urchin Lytechinus variegatus. Lamarck, var. atlanticus. 2. Eggs pretreated with these compounds showed, after fertilization, morphological abnormalities as well as changes in synchronism during embryonic development.

Studies on ticks of veterinary importance in Nigeria—IV. Microscopic observations on embryonic development of eggs of some ticks

The structure and size of the eggs and layers of eggshells of some ticks of veterinary importance in Nigeria were studied. The ticks included Amblyomma variegatum, Boophilus decoloratus, B. geigyii, Hyalomma Impressum, H. impeltatum, H. truncatum and H. rufipes. The embryonic development of the eggs from the day of oviposition to hatching was also studied. The freshly laid egg was found to possess 10 protuberances, and the biggest of them are the anterior and posterior ones. The eggs of A. variegatum were found to be the longest, and those of H. truncatum the shortest. The eggshell of all the species is two-layered on one lateral side and three-layered on the other; the middle layer originating from the anterior and posterior protuberances. Several phases of embryonic development are described. The major difference between the embryonic development of the eggs of A. variegatum and that of the others is that there are always phases during which the egg becomes canoe-shaped and later folds back to the normal egg shape. Eggs of B. decoloratus occasionally developed this way as well as those of some Hyalomma species when incubated at 37°C. The period of accomplishment of each phase of development was shortened by high temperatures. Observations on the occlusion periods of various types of eggs showed that the very small eggs would not hatch into larvae. The relevance of these observations to field tick control is highlighted, while the necessity of following up these studies with electron microscopic views of some aspects of the results is stressed.

Ovacidal activity of febantel

Abstract Febantel [N-2-([2,3-bis-(methoxycarbonyl)-guanidine] 5-(phenylthio)-phenyl)-2-methoxyacetamide] was found to inhibit the embryonic development of Trichuris muds and Haemonchus contortus ova. After oral treatment of T.muris-infected mice with 500 mg/kg febantel, the majority of eggs excreted from 31 hours after treatment did not develop into the larval stage. A more pronounced ovacidal effect was shown for H.contortus after treatment of sheep with low doses of febantel. The embryonic development of eggs had completely stopped from 24 hours after treatment with 2.5 mg/kg febantel. The commercially recommended dose-rate for febantel in sheep is 5 mg/kg.

Embryonic Development and Induced Dominant Lethality in F 1 Eggs of Chilo partellus (Swinhoe)

Observations were made on the embryonic development of fertilized eggs from unirradiated parents and parents whose males were irradiated at 10 and 15 kR or females at 10 kR. The observations were also made on unfertilized eggs laid by virgin females. Phenotypically, no difference was observed in color, general appearance, and embryonic development of 1-day-old eggs from all the matings; eggs laid by virgin females, however, had wrinkled surfaces and showed no sign of embryonic development (hollow center). Recognizable differences in embryonic development were observed 2 days after laying, when the embryos from normal females mated with irradiated males and irradiated females mated with normal males did not develop the orange spots which were visible in all the eggs from unirradiated parents. The embryonic development of eggs from irradiated females mated with normal males was much more affected than eggs from normal females mated with irradiated males; however, in both cases most of the dominant lethals acted late in the development.

Biochemical and physiological studies of certain ticks (Ixodoidea). Activity of juvenile hormone analogs during embryogenesis in Hyalomma (H.) dromedarii Koch (Ixodidae).

Three juvenile hormone analogs (JHA), an acyclic terpene (ACT) [ethyl-3,7,11-trimethyldodeca-2,4-dienoate], a non-terpenoid compound (NT) [acetaldehyde-2-(2-ethoxyethoxy)-ethyl-4-(methylthio)-m-tolyl acetal], and an aromatic terpenoid ether (ATE) [1-(4-ethylphenoxy)-6,7-epoxy-3,7-dimethyl-2-octene] were studied to determine their effect on the embryonic development ofHyalomma (H.) dromedarii. ACT completely blocked embryonic development of eggs that had not yet reached the vitellogenesis stage or were in this stage at the time of ACT application to the female. Development of eggs between vitellogenesis and ovulation stages was partially blocked. Embryogenesis was more or less blocked by NT and ATE, except in a few egg batches from females that had received high NT doses. F1 larval mortality after JHA application to parent females was 100% with ACT, 5 to 100% with NT, and 5 to 85% with ATE.