Average Number Of Eggs Research Articles

Distribution, reproduction and growth of the catfish, Chrysichthys walkeri (Gunther) in the Lekki Lagoon, Nigeria

An investigation was made on the biology of the catfish, Chrysichthys walkeri (Gunther) occurring in the Lekki Lagoon. The catfish was evenly distributed over the six sampled stations of the lagoon with the sites of the shallow water stations probably serving both as breeding and nursery grounds.Fecundity estimates for this species ranged from 896 to 4168 eggs. The average number of eggs per female was 2084. Laboratory incubated eggs hatched after 3 days with the yolk sac being completely absorbed on the seventh day. The fry averaged 8.6 mm on their first day of life.The catfish attained a maximum total length of 25.7 cm within a period of 2 years. There were no significant differences in the growth pattern of this species during the dry and rainy seasons.

Life History and Biology of Samea multiplicalis1 , 2

The life history and biology of Samea multiplicalis was studied in Gainesville, FL. Specimens reared individually on Pistia and Salvinia at 28±1°C with a 14 h light, 10 dark photoperiod, had either 5 (64%) or 6 (36%) larval instars. The average duration of egg, larval and pupal stages was 4, 15.6 and 5.2 days respectively. Head and frons widths and stage durations are reported for each instar. S. multiplicalis has 3 main host plants in Florida: Azolla caroliniana , Pistia stratiotes and Salvinia rotundifolia . Under rare circumstances S. multiplicalis may attack Eichhornia crassipes . Oviposition was significantly higher on Pistia vs. either Salvinia or Azolia , and higher on the top of Pistia leaves rather than the bottom. Oviposition could not be induced on Eichhornia . The average number of eggs laid by females reared and mated in the laboratory was 73. Wild collected females averaged 94 eggs. The maximum number of eggs laid by a female was 291. One dipterous and 3 hymenopterous parasites were reared from S. multiplicalis . Parasitism was estimated to be 52% at Port Charlotte, FL.

Demonstration Of Helminth Eggs And Larvae From Vegetable Cultivating Soil

In order to clarify the contamination of vegetable gardens with human intestinal helminths, the soil samples were examined for the presence of eggs and larvae during the period from September 1973 to August l974. When soil samples collected from the vegetable gardens in Taegu were examined, four species of helminth eggs (ascarid, whipworm, hookworm and liver fluke) and a number of unknown eggs were found. Ascarid was found to be highest in the rate of detection(82.5%), followed by whipworm. The rates of hookworm, liver fuke and Trichostrongylus species were unexpectedly low. There was no difference between detection rate of vegetable gardens and that of vinyl green houses. However, the average number of helminth eggs detected from the soil of vinyl green houses was higher than the number of vegetable gardens. In the monthly incidence of ascarid eggs, the highest rate was found in September, and the least often was observed in August. While, the peak in the average number of the egg was encountered in August. There was no distinct trend in the monthly incidence of whipworm. However, it is likely that the detection number of whipworm per 100 gm of soil examined was relatively abundant in a period from May to August, and very little from October to April of next year. When the soil of vegetable gardens was divided into superficial, intermediate and deep layers and examined for presence of ascarid egg. The average number of the eggs found of the superficial layer was more abundant than those of the intermediate and deep layers, but the rate for the former was similar with the latter. In the demonstration of larval nematodes from the soil of vegetable gardens and vinyl houses, there found the filariform and rhabditoid larvae of hookworm and the larvae of Trichostrongylus species and unknown one. The majority of the larvae detected was belonged to unknown species, followed by hookworm larvae. The least was found in the rate of Trichostrongylus species. Generally, the filariform larva of hookwom could be detected during the hot season from May to August, but no larva was found in the winter. This suggests that the soil of vegetable gardens and vinyl green houses in Taegu is contaminated with human intestinal helminths.

A comparison of the life cycles, reproductive ecologies, and size–weight relationships of Helisoma anceps, H. campanulatum, and H. trivolvis (Gastropoda, Planorbidae)

Helisoma anceps, H. campanulatum, and H. trivolvis were studied separately in three ponds near Waterloo, Ontario, and were found to differ in the following parameters, respectively: life span, 2.1, and 2 years; mean growth rate during the first 2 months after hatching, 0.2, 1.0, and 0.06 mm/week; minimum size at which snails laid eggs, 8, 10, and 18 mm shell diameter; number of breeding periods during the life cycle, 2, 1, and 1: length of the spawning season, 18, 10, and 8 weeks; date by which 50% of the eggs had been laid, July 2, May 14, and May 15; mean number of eggs per egg capsule, 14, 14, and 24. Although mature H. trivolvis occurred throughout the pond during the spawning season, eggs were laid only along the margin. The average number of eggs laid during the life span of a snail was 300 for H. campanulatum and 590 for H. anceps. Linear regression equations relating size to live weight, shell weight, and shell-free dry weight were calculated for each species. Differences between the three species in geographic distribution, tolerance to environmental perturbations, and frequency of congeneric associations seem to be related to differences in their life histories.

Cereal Leaf Beetle:1 Relationships between Feeding, Oviposition, Mating, and Age2

The relationship of feeding to oviposition under laboratory conditions was studied for unmated, once-mated and weekly mated postaestival female cereal leaf beetles. Peak daily egg deposition was reached early in the oviposition period for mated beetles and much later for unmated beetles. Mated females laid 2.2 to 2.6 times the average number of eggs per day as unmated females. It appears that mating exerted a physical or chemical stimulus which induced greater efficiency (food/egg ratios) and egg production. Females mated once oviposited as many as 300 fertile eggs, which is considerably higher than the number of eggs deposited by the average ovipositing cereal leaf beetle under field conditions. When the daily efficiency of ingested food was compared with daily egg deposition, females that mated weekly were more efficient than once-mated females, which were more efficient than unmated females. The daily food consumed and eggs deposited were found to be related linearly. Polynomial equations were derived that define feeding, oviposition, or efficiency for the 3 groups of beetles.

Studies on the Housing Density of the Fowl

About twenty years have passed since the cage system for the layer was introduced into Japan. A high percentage of layers operation are utilizing cage system as a method of housing the bird. But there are a few reports concerning the effect of cage size and number of bird per cage. This study was done to obtain information of the effect of cage size and bird density in the cage on the performance of egg production type pullets.A most popullar individual laying cage size in Japan, is about 24cm width, 39cm depth and 40cm height.A total 249 commercial strain pullets (Babcock B 300) were confined in cage at 120 days of age under five treatments: birds were put in 18cm cage individually (Treatment 1), in 24cm cage individually (Treatment 2), two birds to 24cm cage (Treatment 3), two birds in 30cm cage (Treatment 4) and three birds in 48cm cage (Treatment 5). All cages were 39cm depth and 40cm height. Birds were debeaked by cutting off their both mandibles. Feeding experiment was conducted over the one year from 120 to 500 days of age.There were no differences in days to 50% egg production, percent of egg production on a hen day basis from 150 to 500 days of age, average number of eggs of survival hens and average egg weight among the treatments. Feed conversions of Treatment 4 and 5 were a little higher than other treatments, because of much feed intake. Mortality did not increased and cannibalism in high density treatment were not observed. Percent of cracked, brocken and stained shell egg were not differrent among the treatments.These results suggested the possibility of making higher housing density of cage laying house than that common in Japan.

Selection for Increased Hatchability at High Altitude

A line of medium white turkeys developed at an altitude of 105 meters above sea level was reproduced and reared at 1524 meters above sea level for seven generations. One half of the population was selected for seven generations for increased hatchability based on individual hen performance. The other half of the population was selected at random each year. Records were kept of percent hatchability, percent fertility, average number of eggs set, average egg weight, body weight at two, eight, and 20 weeks of age for all birds in each generation. When the birds were thirty-two weeks of age, body depth, keel length, and shank length were recorded for each bird in generation 6 and 7. Percent hatchability increased in both the selected and the nonselected groups during the first four generations but decreased during the last three generations. Percent hatchability and fertility in the selected group was consistently higher than in the nonselected group each generation. Average egg weight decreased in both lines. No consistently significant correlations were found between hatchability and any of the traits measured.

BIOLOGY OFTACHINAEPHAGUS ZEALANDICUS(HYMENOPTERA: ENCYRTIDAE), PARASITOID OF SYNANTHROPIC DIPTERA

AbstractThe synonymy, distribution, host range, and life history of the gregarious larval–pupal parasitoidTachinaephagus zealandicusAshmead, is discussed. Laboratory studies of its biology were conducted at 25° ± 2 °C usingMusca domesticaL. as host. Its developmental stages are described. Under laboratory conditions its life cycle lasted 23–27 days. Parasitoid development accelerated with higher average densities per host. Single standardized hosts produced 3–18 adult parasitoids. Mated females provided with hosts lived 50.4–67.2 h. The average length of the reproductive period and number of hosts parasitized were independent of host density; however, the average number of eggs deposited per host increased at lower host densities. Adult emergence displayed circadian rhythmicity independent of photoperiod over 3+ days.

Messa hortulana (Klug.) (Hymen., Tenthredinidae) als Pappelschädling in den Niederlanden

Incidence of Messa hortulana (Klug) (Hym., Tenthredinidae) in poplar windbreaks in the Netherlands In the southwest of the Netherlands at Philippine (province of Zeeland) in one orchardMessa hortulana had become a pest in recent years, increasingly damaging the poplar windbreak. So the fruitgrower concerned carried out a more and more intensive control campaign in 1969, 1970 and 1971, but without noticeable results, owing to unfamiliarity with the way of life of this insect. In 1972 it became possible to determine the correct moment for a control compaign by means of a study of the insect's life cycle. First of all the flight of the sawfly was ascertained by means of a suctiontrap. Secondly the moment when the eggs had been laid was determined, including the average number of eggs laid on one leaf. When the larvae were found to be emerging, the grower was given advice to spray immediately. The result of this one control, carried out on May 6, 1972, was a total one.

Life History and Population Dynamics of Tetranychus tumidus in Florida (Acarina: Tetranychidae)

Tetranychus tumidus Banks, is a polyphagous spider mite that can thrive in the laboratory on over 70 host plants of various families, especially on many belonging to the Leguminosae, Malvaceae, Compositae and Gramineae; those in the Solanaceae appear unpalatable. The female mite developed slowly at 19@* C and required 21.5 days (20 for male) as compared to its development at 29@* C which required 8 days (7.5 days for male). At 24@* C the average daily rate of oviposition (4.21 eggs) and average number of eggs per female lifespan (49.67 eggs) were both higher than at 19 and 29@* C. Optimal temperatures appeared to be closer to 24 than to 29@* C. Field populations appeared in spring once morning low temperatures climbed into the upper teens and day-time highs into the twenties. Populations decreased in early summer and virtually disappeared when rains appearing in May and June established, together with the high temperature, optimal conditions for a spider mite fungus, Entomophthora, epidemic. Precipitation also reduced the population mechanically if occurring at 3 in. or more per 24 hr. The population remained practically negligible until early autumn when precipitation ceased. The 2nd population growth in autumn was halted and its decline commenced once temperatures dropped in October, or if prior to that, optimal conditions for fungus infection were established again. Phytoseiulus macropilis (Banks) was the only predator found in significant numbers among several predatory species recorded.

Fecundity and Egg Size of a Brood Stock of Salvelinus fontinalis × S. namaycush Hybrids (Splake)

Estimates of average egg diameter and average number of eggs per female from a brood stock of Salvelinus fontinalis × S. namaycush (splake) hybrids were 0.468 cm and 1169 eggs, respectively. Variation in egg size between females was attributable to variation in both size and age of the fish, whereas differences in fecundity were attributed only to differences in female size. At a given size a splake had more and larger eggs than have been reported for lake trout. The significance of the findings is discussed in relation to the reestablishment of a viable trout population in Lake Huron.

Zur Kenntnis der Kleinen Kiefern‐Buschhornblattwespe, Diprion (Microdiprion) pallipes (Fall.) (Hym., Diprionidae)

AbstractContributions to the Knowledge of Diprion (Microdiprion) pallipes (Fall.) (Hym., Diprionidae). Part 2: Bionomy and Ecology. Part 2 contains the results of biological and ecological studies on eggs, larvae, cocoons and adults of the sawfly.The inclination of the sawflies to copulate was very low. The size of egg pods as well as the distribution of eggs on the needles depended on pine species, length of needles, locality and constitution of trees. The average number of eggs located in the needles of a twig amounted to 34.6 ± 16.4 (n = 119). The female laid an average number of 63 eggs during its life time. The male larvae run 4, the female 5 Stages. There were 2 generations per year. Zero of development of eggs amounted to 8.8° C; the thermal constant (K) for the development of eggs amounted to 119 and that of larvae to 272. The eggs hatched of 7 days (26° C). The larval period was completed in 16.5 days (26–27° C, Pinus silvestris). The average quantity of food consumed by a male larva on Pinus silvestris during its life span amounted to 500 mg. The female larva consumed about 1.7 times more than a male larva. The cocoons of the first generation were spun on buds and needles of pines. The cocoons of the second generation overwintered in or near the soil. The duration of the eonymphal stage in the cocoon (diapause) was mainly determined by the photoperiod effecting upon the old larvae.

Fecundity of the mirror carp Cyprinus carpio L. at the Serow Fish Farm (Egypt)

The fecundity of 50 female carp Cyprinus carpio L. of total length ranging between 16–48 cm and 1–5 years old was estimated. The average number of eggs per gram of ovary was 929 ± 146. The relationships between fecundity and length, weight and age were expressed by various formulae that showed increased fecundity with increased length, weight and age of fish. The fecundity—weight formula gave the best description of egg production. The relative fecundity of Cyprinus carpio L. was 123 eggs/g body weight.

イネ科飼料作物ソルゴーを加害するヒエノアブラムシの生態 (第2報) 産卵雌虫の産卵生態

The sexuals of Longiunguis sacchari (ZEHENTNER) on sorghums appear in autumn, and the oviparous females deposit the overwintering eggs on the host plants in a field. In this paper, oviposition of the oviparous female was reported. The average ovipositing period was 7 days, and the average number of eggs per female was 5.7, being deposited within a few days for the most part after the beginning of oviposition. The oviparous females were reared on the mature leaves of sorghum Sorghum vulgare) in the laboratory (mean temperature 17.7°C) and began to deposit within 2 days after mating. Eggs were usually deposited on the underside of leaf blade or leaf sheaths in the lower parts of plants in the field.

The population dynamics and host utilization of Geomydoecus oregonus, a parasite of Thomomys bottae.

This study treats the population dynamics and host utilization of Geomydoecus oregonus Price and Emerson, a mallophagan parasite of the pocket gopher, Thomomys bottae (Eydous and Gervais). Over 135000 lice were collected from 393 gophers over a period of 20 months. Average infestation on all gophers was 357 lice. Bimonthly mean densities showed an increase in June-July of both years, and these data were statistically different from the rest. Population age structure remained relatively constant in time with 9.3% females, 7.2% males, 47.4% nymphs and 36.1% eggs. Sex-age class separation of the gophers showed juveniles of both sexes to average 86 lice; subadult males averaged 210 lice; adult males averaged 544 lice; subadult and adult females averaged 255 and 296 lice, respectively.Lice were not randomly distributed on the gopher, but were most numerous on the head and anterior dorsal body. Lice eggs were restricted to hairs around the ears and eyes of the host. Over 80% of the animals sampled had eggs restricted to that region.Embryonic development and eclosion of G. oregonus proceeded over a wide range of environmental parameters. Over 80% of the ova tested survived and hatched in conditions between 33° and 37°C and 22% and 84% relative humidity. The greatest survival was 98% at 35°C, 75% R. H. and in a 3% CO2 atmosphere.The generation time of G. oregonus was 40±6 days. Duration of embryogenesis and nymphal stadia approximated 10±2 days for each. Adult lice lived 30+ days on gophers.Age frequency mortalities were calculated as 0.02 for eggs, 0.18, 0.24, and 0.06 for nymphal instars and 0.50 for adult lice. This indicates a Type II survivorship curve.There was direct linear relationship between the number of female lice on a gopher and the number of lice eggs. The average number of eggs per female was four. Using the pivotal frequency for reproductives, it was possible to calculate R 0 for the louse at 1.272. Thus, r was equal to 0.24 per generation or 0.006 per day, and the population doubles in 2.8 generations.Speculations regarding population regulation are also included.

Biology of the Predaceous Mite, Pergamasus quisquiliarum1 on the Garden Symphylan, Scutigerella immaculata2 in the Laboratory3

The parasitid mite, Permagasus quisquiliarum Canestrini, was observed preying on the garden symphylan, Scutigerella immaculata (Newport), in a field near Corvallis, OR. All stages, except larvae, were collected in April and successfully reared on symphylans in the laboratory. The life cycle of P. quisquiliarum from oviposition to adult was 16.9±5.1 days at 20±1.0°C in the laboratory. The average developmental period for eggs was 4.6±0.7 days, larvae 1.2±0.4 days, protonymphs 5.4±1.9 days, and deutonymphs 5.7±2.1 days. The average number of immature symphylans consumed during the protoand deutonymphal stages was 3.6±1.3 and 3.7±1.3, respectively. Larvae did not feed. Adult mites lived an average of 37.0±12.8 days, during which time an average of 4.8±2.1 symphylans was consumed (1:1 ratio). The number of symphylans consumed in 1:2 and 1:5 predatorprey ratios was 7.7±3.4 and 11.0±5.5, respectively. The average number of eggs deposited per female was 32.6, with an average of 14.2 symphylans consumed/♀.

Feeding behaviour of the predatory mite Acaropsis docta (Berlese)

The behaviour of Acaropsis docta as a predator on the eggs of Trogoderma granarium was studied. The mite approached the beetle egg with her chelicerae and rostrum extended and both were inserted into the egg for feeding. The structure of the feeding apparatus is described. The average number of eggs per day consumed by different stages of the mite were: larva 0·74, protonymph 0·90 and deutonymph 1·06. During development from larva to adult in 8·3 days, an individual consumed 9·3 eggs. The female consumed an average of 19·2 eggs in 10 days of her feeding life, compared with 10·2 eggs by the male during a similar feeding period. There was a positive correlation between the number of Trogoderma eggs consumed and the number of eggs laid by a female.

Computation of Decrease or Increase in Filial Generations Following Insecticidal Treatment of Spodoptera littoralis1

A method for computing the expected number of off-spring following insecticidal treatment was devised. Survivors of LD30 were allowed to perpetuate. The net total number of the filial generation = Pe × Ef × Nf where Pe is the percentage of egg hatching, Ef is the average number of eggs per female, and Nf is the average number of emerged adult females capable of depositing fertile eggs. This method was applied to Spodoptera littoralis (Boisduval). In comparison to the control, DDT, endrin, and fenitrothion decreased the total number by 89.90, 84.29, and 22.66%, respectively, during 13 successive generations, whereas carbaryl increased it by 28.84%.

Oviposition and Orientation of the Cereal Leaf Beetle1,2

The orientation of the cereal leaf beetle, Oulema melanopus (L.) (Coleoptera: Chrysomelidae), during oviposition in the laboratory on seedlings of ‘Hudson’ barley, ‘Clintland’ 64 oats, or ‘Genesee’ wheat was similar, based on egg position. Oviposition on the blade apex of all 3 plants was less than on the other 4 transverse regions, but only 15% of the eggs were deposited on the blade base when the seedlings were illuminated from overhead compared with over 40% when they were illuminated from the side. When the width of the barley blade was decreased by removing the blade on one side of the midvein for the length of the leaf, oviposition on the narrow blades was reduced nearly 8-fold. The orientation of ovipositing beetles confined with inverted seedlings was inferred from the position of the egg; that these beetles had difficulty ovipositing was detected by the 3-fold increase in fallen or horizontal eggs. Also. the inversion forced the beetles to choose to oviposit either with or against gravity, and given this choice, nearly 50% of the eggs were deposited by beetles oriented upside down. Thus, the orientation of the host was found to modify female oviposition behavior. About 12% of the oviposition occurred during the scotophase of a 16-hr light:8-hr dark photoperiod at 26.7°C, and 76% of the eggs deposited during scotophase were deposited in the first half of this interval. Beetles that fed and overwintered in the field and then initiated normal spring oviposition, oviposited twice as long, an average of 34.3 days, as beetles from the same generation collected in the field and fed and stored in the laboratory about 20 weeks. The daily average number of eggs deposited per female ranged from 8.7 to 12.2 eggs.

Mating and Oviposition of Tingis ampliata H.-S. (Het. Tingidae)

AbstractPeriod of mating varies annually from 46 to 65 days during April to late June or early May to July. Lacebugs mated at any time of day but peak of pairing tended to occur about afternoon at field temperatures around I5°C. Duration of mating and angle between the sexes varies between pairs. In 55 % of pairs, males were to the right of females with dorsal surface of tip of male abdomen in contact with ventral aspect of that of female. Eggs are usually laid singly but occasionally in groups of 2-6 in thistle leaves. Oviposition in stems may occur at high adult densities in the laboratory. About 78-99 % of total eggs were laid in primary leaves, others in leaflets of axillary buds. Eggs were predominantly laid in midribs and other veins. Tingis eggs were implanted to varying degrees or seldom unembedded in leaf mesophyll with extrusion of part of chorion beyond non-oviposition surface in thin leaves. Oviposition rhythm was positively correlated with daily rhythm of physical conditions especially temperature. Six-hourly oviposition rate, proportion of females laying, and number of eggs laid per female increased from minimum between 00.00 and 06.00 hours to a peak at 12.00 to 18.00 hours and declined afterwards. Rate of oviposition and average fecundity varied annually according to temperature differential between pre-peak oviposition period of different years. Oviposition rate increased with temperature (in I965 and I966) and age (in I965) during pre-peak phase; but it decreased with aging of bugs in the post-peak phase when temperature had insignificant effects. Total fecundity in the laboratory or field varies considerably between individual females. At I5 and 20°C constant temperature, average numbers of eggs laid per female were 20 and 6I, respectively. Oviposition in laboratory tended to be periodic and females die without completing oviposition. Oviposition period varies annually in the field from I0 to I2 weeks, usually from early May to late July. In the laboratory this period varied with individuals and temperature from about 5.2 weeks at I5°C to at least 7.6 weeks at 20°C.