Number Of Viable Larvae Research Articles

On the study of the wheat nematode Anguina tritici chitwood, 1935 and their importance in wheat cultivation in Uzbekistan conditions

In our study, the wheat nematode Anguina tritici Chitwood, 1935 was registered in wheat ears in surveyed grain-growing farms in 5 regions of Uzbekistan. Larval stages of two- and three-year-old nematodes were observed at different stages of development in plant organs and root soil. The population density, depending on the living conditions, ranged from 8 to 60 larvae per 100 cm3 of soil and roots, and in stems and leaves from 12 to 25 larvae per 20 g. In heavily infected ears of wheat, the number of galls ranged from 9 to 50 copies. For the effectiveness of agrotechnical measures, such as crop rotation in the fight against wheat nematode, experiments were conducted to assess the viability of wheat nematode larvae. One-year-old, two-year-old and three-year-old galls were selected and the number of larvae was counted. It turned out that the number of viable larvae in annual galls is higher than in two-year and three-year-old galls.This is due to the fact that after a period of time, the accumulated food reserves in the body were used up for the viability of the larvae.

Terminalia catappa leaf extract is an effective rearing medium for larviculture of gouramis

ABSTRACTGouramis require soft and acidic waters for optimal development, and in this context, a cheap and effective culture medium is required. In this study, Pearl and Blue gourami larvae were raised in Terminalia catappa leaf extract (TCE), clear water, and green water, the latter containing 1 × 105 cells/ml Chlorella from Tilapia cultures. Larval survival and specific growth rate (SGR) were determined after 10 days of incubation. TCE was most effective in promoting survival of both gourami species, with the number of viable larvae augmented twofold and 30% in comparison to clear water and green water respectively. TCE was acidic, and this may have played a significant role in boosting survival, although larvae potentially benefited from the antioxidant and therapeutic properties of TCE. TCE significantly boosted growth, as evidenced by a significant increase in the specific growth rate, perhaps explained by the occurrence of additional live food such as Paramecium, Colpidium, and other infusorians. Although the effects of TCE are uncertain, its application enhanced larval performance of gouramis and perhaps blackwater fishes, a finding with potential application in aquaculture.

Conditioning of the European flat oyster (Ostrea edulis, Linnaeus 1758): effect of food ration

To establish a reliable protocol for the broodstock conditioning of the oyster Ostrea edulis (Linnaeus 1758) in hatcheries is important to obtain the best number of viable larvae all year even outside the natural season for maturation and spawning. Hatchery production of bivalves depends on their initial gonadal maturation state, which is linked to season and several other factors, such as temperature, daylight, salinity and food supply. Ration and diet composition are important in broodstock conditioning because food availability affects fecundity and gametogenic development. In this work, the effect of food ration on O. edulis conditioning was studied in autumn and winter. The results of this study showed that the broodstock conditioned with a food ration of 6% and 9% produces the highest number of larvae in autumn and winter. These food rations produced rapid gonadal development and larval release in a short period with a similar larval production. The oysters conditioned with a food ration of 3% delayed larval release and produced a significantly lower number of larvae in autumn. In the 9% ration treatment, the percentages of mortality were significantly higher in both autumn and winter. Thus, a 6% food ration is likely to be the most suitable for flat oyster conditioning combined with a gradient of temperature (14–18°C) and a gradient of daylight (8–16 h).

The Effectiveness of Cinnamomum zeylanicum, Punica granatum Flower and Capsicum annuum Extracts Against Parascaris equorum Infective Larvae

Recent investigations have shown that plants with medicinal peculiarities as good alternative to anthelmintics for livestock. In this study, the anthelmintic effects of three medicinal herbs (Cinnamomum zeylanicum, Punica granatum flower and Capsicum annuum) were screened in vitro against the infective larvae of Parascaris equorum. The recovered larvae of the parasite were exposed to four concentrations (50, 75, 100 and 125 mg/mL) of the extracts and then they examined for the viability at 0, 10, 20, 30 and 40 minutes after the challenge. The results revealed that all the concentrations of each plant extract had anthelmintic effects on P. equorum larvae. Also, the statistics indicated that there were significant interactions between the concentration of the extracts and time of exposure on the number of viable larvae. In addition, C. annuum extract seemed to be a strong potency to kill larvae at all concentrations from the beginning of the experiment. These results confirmed that those herbal extracts possess good antiparasitic effects against infective larvae of P. equorum and thus could be considered in anthelminth treatment strategies.

Sublethal Effects of Some Essential Oils on the Cotton Leafworm Spodoptera littoralis (Boisduval)

Our paper demonstrates the effect of sublethal doses of essential oils (EOs) from 13 aromatic plant species on the development and fertility of Spodoptera littoralis. EOs were applied to 4th instar larvae in dosages corresponding to the estimated LD30. The application-surviving larvae were maintained until the end of their development. Larval and pupal mortalities were monitored during their development. All EOs caused a total mortality significantly higher compared to the control. Application of LD30 of EOs from 4 plant species (Pimenta racemosa, Origanum vulgare, Salvia sclarea and Thymus vulgaris) even caused total mortality higher than 70 %. A significant difference in the number of hatched adults was also found. However, the lowest number of adults hatched after application of the EO from P. racemosa (18.7 %), O. vulgare (28.0 %), S. sclarea (28.7 %) and T. vulgaris (30.7 %). The highest number of adults hatched after application of the EO from Mentha pulegium (64.0 %) and Lavandula angustifolia (59.3 %). Longevity, fecundity, fertility and natality were monitored in the surviving adults. The most significant effect of EOs was determined with respect to natality. Compared to the control, all the tested EOs caused a significant reduction in natality. While 1,101 viable larvae were obtained in the control, the number of viable larvae obtained from those treated was lower, ranging from 41.5 % (for M. pulegium) up to 80.6 % (for P. racemosa). Based on the presented results, EOs of P. racemosa, O. vulgare, S. sclarea and T. vulgaris can be recommended for further development of botanical insecticides designed to protect plants against the important polyphagous pest S. littoralis. These EOs caused the highest mortality during larval development when applied in sublethal doses, with subsequent reduction of adult natality by more than 75 % in this pest.

Effect of tributyltin on reproduction in Japanese whiting, Sillago japonica

We examined the effect of tributyltin (TBT) on reproduction in the Japanese whiting, Sillago japonica. Mature fish were placed in indoor 500-L polyethylene tanks (five males and three females per tank) with a flow-through system and received dietary exposure to tributyltin oxide at concentrations of 2, 20, or 200 microg/g for 30 days during the active spawning period. Eggs spawned from the fish were collected daily, and the floating egg rate, larval deformity, hatchability, and viable hatch were monitored. TBT concentration in eggs of 200-microg/g group ranged from 85.0 to 159.6 ng/g in the evaluation period (days 5-30). In this period, the floating egg rate (83.2%), viable hatchability (82.2%), and total number of viable larvae (422,000 larvae per 100 g of female) were all significantly decreased in the 200-microg/g group compared with the control group (93.0%, 91.9%, and 709,000 larvae, respectively). The rate of deformity (2.6%) in the 200-microg/g group was about three times that in the control group (0.8%), although this difference was not significant. From these results, the lowest observed effect concentration of TBT in eggs on reproduction in Japanese whiting was estimated to be less than 159.6 ng/g-eggs.

Fall Control of Japanese Beetle Larvae in Bluegrass Turf, 1982

Abstract The experiments were conducted in the left rough of No. 3 fairway at Blackhawk Golf Course, Westerville, OH. The turf was composed of approximately 90% Kentucky bluegrass and 10% crabgrass. Mowing height was 2.5-3 in. There was no measurable thatch at this site. The predominent soil type was Alexandria-Cardington, characterized as a greyish brown, strongly acid, friable silt loam 8-12 in thick. Environmental conditions at application time were as follows: air temperature, 70 F; relative humidity, 90%; wind from the NW at 0-4 mph; overcast skies; and dry soil. Nine treatments replicated 4 times were applied to 6ft × 8 ft (1.8m × 2.4m) experimental plots arranged in a RCB design. Liquid applications were made using a CO2 pressurized sprayer with 3 8020 nozzles mounted on a 4 ft aluminum boom, operating at 25 psi with a 4 gal/1000 ft spray rate. Granular materials were applied with a 2 ft Gandy drop spreader. All treatments were irrigated with 0.25 in of water immediately after application on Sep 15. Pretreatment counts showed a range of 16-30 grubs/ft. The experimental plots were evaluated at 40 DAT (Oct 25), by randomly sinking four 7.75 in diameter cylinders (ca. 0.33 ft) into the turf to a depth of 8-10 in and counting the number of viable larvae in the plugs of soil.

Japanese Beetle Control in Kentucky Bluegrass Turf, 1982

Abstract The experiments were conducted in the left rough of No 3 fairway at Blackhawk Golf Course, Westerville, OH. The turf was composed of approximately 70% Kentucky bluegrass and 30% crabgrass. Mowing height was 2.5 to 3 in. There was no measurable thatch. The predominant soil type was Alexandria-Cardington, characterized as a greyish brown, strongly acid, friable silt loam 8-12 in thick. Environmental conditions at application time were as follows: air temperature, 75°F; relative humidity, 30-40%; wind from the NW at 8-10 mph; and sunny.skies with a few scattered clouds. The soil was wet from previous irrigation. Ten treatments replicated 4 times were applied to 5 ft × 10 ft (1.5m × 3m) plots arranged in an RCB design. Liquid applications were made usJng a CO2, pressurized sprayer with three 9520 nozzles mounted on a 5 ft aluminum boom, operating at 25 psi with a 4 gal/1000 ft spray rate. Granular materials were applied with a 2 ft Gandy drop spreader. All treatments were irrigated with 0.25 in of water immediately after application on Sep 3. Pretreatments counts showed a range of 20-40 larvae/ft. The experimental plots were evaluated 28 DAT (Oct 28) by randomly sinking four 7,75 in diameter cylinders (ca. 0.33 f t) into the turf to a depth of 6 in and counting the number of viable larvae in the soil plugs.

Experimental visceral larva migrans in monkeys. I. Clinical, hematological, biochemical and gross pathological observations on monkeys inoculated with embryonated eggs of the dog ascarid, Toxocara canis.

Nine Macaca monkeys were inoculated experimentally with 100, 000 to 400, 000 embryonated eggs of Toxococara canis. Of them, four belonged to Macaca fascicularis, one to M. nemestrina, two to M. cyclopis, and two to M. fuscata. Six infected monkeys, Nos. 1 to 3, 5, 6 and 9, which suffered from a mild invasion of the CNS by larvae of T. canis, showed no clinical abnormality, except mild or moderate inappetence and depression for several weeks together with occasional mild coughing. The remaining three infected monkeys, Nos. 4, 7 and 8, harbored considerable numbers of viable larvae not only in the thoracic and abdominal viscera but also in the CNS, and began to develop such clinical signs as anorexia, weakness and coughing 4 to 7 days after infection. Severe neurological signs that terminated in paralysis were also noted in these three animals on the 8th to 16th days. The postmortem examination of them revealed parasitic granuloma formation and focal tissue destruction with hemorrhage at numerous sites on the cut surfaces of the brain and spinal cord. From these results, it should be emphasized that the severe neurological disorders resulted from the CNS damage which had been caused by the invasion of T. canis larvae in the brain and spinal cord. Hematological findings of the infected animals included transiently reduced erythrocyte counts and marked eosinophilia. The latter appeared soon after inoculation, increased to a high degree between the 2nd and the 4th week, and declined as the infection progressed. Analysis of their blood plasma also showed increased globulin concentrations, reduced albumin values, and decreased albumin/globulin ratio, in addition to elevated plasma transaminase levels. No important changes were found in any other parameter.

Effects of Salinity and Temperature on Embryonic Development of the Petrale Sole (Eopsetta jordani)

Newly fertilized eggs were incubated at 13 combinations of levels of salinity and temperature between 20 and 35‰, and 4.1 and 8.5 C. Average egg density throughout development was 1.0252, and the incubation period ranged from 6.2 to 13.5 days. Larval length at mean hatching time averaged 2.84 mm for all trials. External features of the larvae are described. The percentages of eggs hatching (total hatch) and producing viable larvae (viable hatch) are examined with respect to salinities and temperatures of incubation. Calculated optima were: total hatch 29.47‰ S, 6.65 C; viable hatch 27.93‰ S, 7.00 C. At 6.3, 7.2, and 8.1 C, larvae grew to 5.5–5.7 mm total length prior to exhaustion of yolk 246–393 hr after hatching. It was concluded that greatest numbers of viable larvae of largest size at yolk exhaustion would occur from incubation at 27.5–29.5‰ S and 6–7 C.Laboratory results are related to available hydrographic and meteorological data for a spawning area off the west coast of Vancouver Island. Estimates are given of direction, depth, and duration of drift of the pelagic stages until exhaustion of the yolk. Environmental variability in the spawning period is related to existing measures of year-class strength. Effect of temperature on egg development is related to the range of the species in terms of estimated temperatures available at spawning depths.

PARTHENOGENESIS IN DROSOPHILA

Most of the work to be reported in this paper was done with strains of Drosophila purthenogenetica STALKER originally derived from a single strain established by the University of Texas workers from a collection made in Atlixco, Mexico (PATTERSON and MAINLAND 1944) and generously supplied by the Texas laboratory. The specimens of Drosophila polymorpha used were derived from a Brazilian strain supplied through the kindness of DR. TH. DOBZHANSKY. Both of the above forms belong to the D. curdini species group. In the measurements of rates of parthenogenesis reported in this paper, the virgin females were kept, either singly or in groups, in vials with standard cornmeal-Karo-agar-Moldex food medium. All work was done at 25°C unless otherwise indicated. The virgin females were transferred to fresh food vials every day, or in some cases every second day. The vials from which the females had been transferred were examined under a dissecting microscope daily up to and including the fourth day after oviposition. In these examinations the numbers of dead embryos and inviable larvae, the numbers of viable larvae, and the numbers of apparently undeveloped eggs were recorded. The dead embryos were detected by the discoloration associated with their decomposition. When the typically mottled-looking brownish-black eggs were discovered they were in most cases removed, cleaned of food, crushed under a coverslip in saline and examined under high power with a compound micro