Mean Total Number Of Eggs Research Articles

Redclaw, Cherax quadricarinatus sex-separated rearing strategy enhances reproduction in females

Redclaw crayfish Cherax quadricarinatus, a tropical freshwater species, native to Northern Australia and is regarded as a promising species for global expansion of aquaculture. However, poor female fertility is a hindrance towards the commercial production of redclaw. The present study investigated if dissociated; pre-exposure of female redclaw to males can stimulate spawning and increase reproductive efficiency. The study was conducted in dissociated (111 days) and associated (34 days) phases. Redclaw were held in vertical recirculating aquaculture systems with each system consisting of 42 individual compartments (45 cm length x 33 cm width x 25 cm height) arranged as six compartments horizontally and seven compartments vertically. The average body weight of females was 66 ± 2.2 g. In the dissociated phase, females were either kept alone (0M, n = 36) or were exposed to either 1 (1M, n = 36) or 2 (2M, n = 36) males suspended in the uppermost row of the system. During the associated phase, females (n = 108) were maintained at a sex ratio of 1M:1F. During the dissociated phase, the spawning rate was less in the control compared to the male exposed groups (2.8%, 1/36, 18.1%, 13/72 respectively; p = 0.026). However, the moulting rate was greater in the control compared to the male exposed groups (22.2%, 8/36; 5.6%, 4/72 respectively; p = 0.009). During the associated phase, there were no significant differences in spawning rate (22.2%, 8/36 and 33.3%, 24/72), mean days to spawning (21.88 ± 3.06 and 16.38 ± 2.35), moulting rate (11.1%, 4/36 and 6.9%, 5/72) and mean days to moulting (24.50 ± 3.97 and 22.40 ± 3.93) in the control and male exposed groups, respectively (p > 0.05). However, the mean total number of eggs (670.9 ± 26.0 and 507.0 ± 29.36), fecundity (11.00 ± 0.59 and 6.14 ± 0.47), the hatching rate (89.70 ± 1.31% and 77.50 ± 9.24%) and the total number of juveniles produced (545.70 ± 42.50 and 343.30 ± 37.47) during the associated phase were greater in the male exposed groups compared to the control group respectively; p < 0.05). It was concluded that pre-exposure of redclaw females to males in a dissociated recirculation system, increases spawning rate during a dissociated phase, and after exposure to males improves egg and juvenile production during an associated phase. Such a breeding strategy has potential to increase hatchery productivity.

Leatherback Sea Turtle (Dermochelys coriacea) Nesting and Health Parameters in St. Kitts, 2003–2016

The St. Kitts Sea Turtle Monitoring Network (SKSTMN) began implementation of a leatherback sea turtle (Dermochelys coriacea) monitoring program in 2003 on the main leatherback nesting beaches on St. Kitts, Keys Beach and North Friars Beach. From March 2003 to July 2016, a total of 2,419 adult female leatherback emergence events were recorded and evaluated. A notable decrease in adult leatherback emergence activity was observed over the course of the study period. The nesting season ranged from February to August. April and May were the months with the highest frequency of nesting. The number of females individually identified (flipper tagging and/or passive integrated transponder) from 2004-2016 was 259 with a mean curved carapace length (CCL) (n=720) of 153 cm and mean curved carapace width (CCW) (n=719) of 113 cm. Remigration intervals ranged from one to five years with a median of two years. Mean clutch frequency for nesting females in St. Kitts over the course of the study period was 3 (standard deviation (SD) 2.9) and during a reproductive season was 2.2 (SD 1.44). Mean total number of eggs laid per nest was 113 with mean number of yolked eggs being 83.5 and yolkless 29.3. The mean incubation period was 59.5 days overall (SD 3.5) with a hatch success overall of 16.75%. Relocated nests had significantly lower hatch success than in situ nests and poaching rates decreased over the course of this study. From 2006-2016 a total of 191 blood samples were collected from 118 individual animals.

Biology and functional Response of Andrallus spinidens (F) to the rice army worm Spodoptera mauritia (Boisduval)

The pentatomid bug, Andrallus spinidens (F.), is a polyphagous predator on lepidopteran larvae in rice fields in India. The basic biology and predatory potential of the bug was studied under laboratory conditions. The nymphs were reared in petri dishes and were fed 3 rd to 5 th instar Spodoptera mauritia (Boisduval) larvae. The mean development period from egg to adult was 21 days. Eggs were laid in batches of 45 to 95 and the mean total number of eggs laid by each female was 259. The second, third and fourth stage nymphs fed on 7.99, 8.32, 26.33 number of third instar larvae instar larvae of S. mauritia , respectively. The predator exhibited a type II functional response to S. mauritia larvae with a disc equation of Y’ = 0.41(5-0.74) x to the increasing density of S. mauritia . This study provides important life history information for using the predator A. spinidens as a possible biological control agent for army worm management in rice.

Conservation Aquaculture of Northern Leatherside Chub and Effects of Temperature on Egg Survival

AbstractWe present 4 years of data that refine aquaculture protocols for the northern leatherside chub Lepidomeda copei, a species of conservation concern in the Intermountain West. Experiments examined life history traits (age at first spawning and thermal limits to egg hatching success) and aquaculture techniques (brood density, spawning substrate type and surface area, and feeding methods for fry). Tests showed that leatherside chub can reproduce as early as age 2. Multiple spawns per female during a year were also documented. Survival of eggs was compared at incubation temperatures of 18.4, 23.0, 24.6, and 26.8°C. Eggs at 18.4°C had the highest survival to hatching (54.0%); eggs at 26.8°C had significantly lower survival (1.5%). Egg survival at 23.0°C and 24.6°C (32–33%) was significantly lower than survival at 18.4°C. Aquaculture experiments showed that the mean total number of eggs produced did not significantly differ between brood densities of 8.4 (1,246 ± 1,236 eggs [mean ± SD]) or 16.8 (2,224 ± 1,600 eggs) fish/m3. Studies showed that leatherside chub preferred spawning over natural cobble substrate to spawning over marble substrate. More eggs were recovered from a three‐substrate tray treatment (1,350 cm2) than from a single tray treatment (450 cm2). Fry given brine shrimp Artemia spp. with probiotic bacteria or fed with an automated, more continuous drip feeder did not show any advantages in growth over time. Juveniles at rearing densities of 800, 1,700, and 3,400 fish/m3 did not differ significantly in growth rates, deformities, or mortalities. This research provides general guidelines for rearing northern leatherside chub and some additional information on the species’ life history.

Reproduction, survival, and life table parameters of the predatory mite Cheyletus malaccensis (Acari: Cheyletidae) at various constant temperatures

Reproduction, survival, and life table parameters of the predatory mite Cheyletus malaccensis Oudemans were evaluated at six constant temperatures: 17.5, 20, 25, 30, 32.5 and 35°C, feeding on Tyrophagus putrescentiae (Schrank). Preoviposition period of fertilized and virgin females varied with temperature from ca. 9 days at 17.5°C to ca. 1.5 day at 32.5°C and then increased to ca. 3 days at 35°C. Virgin female oviposition period was significantly shorter than for fertilized females at the temperatures examined with the exception of 17.5°C. The mean total number of eggs per fertilized (169.7 ± 6.6) and virgin female (60.7 ± 4.3) was highest at the temperature of 30°C. The data indicated a significant positive and nearly doubling effect of fertilization on female fecundity at the temperatures examined with the exception of 17.5°C. Age-specific fecundity was described by a temperature dependent model from which the maximum daily fecundity rate was estimated for fertilized and virgin females at 10.3 (at 30°C) and 6.8 (at 32.5°C) eggs/female, respectively. Virgin female longevity was significantly shorter than for fertilized females at 20, 30 and 32.5°C, and decreased from ca. 57 days at 17.5°C to ca. 17 days at 35°C. The Weibull function that was used to describe the age specific survival of fertilized and virgin females produced excellent fits to the survival data. Estimates of intrinsic rate of increase, net reproductive rate, mean generation time, doubling time and finite rate of increase, were obtained. The r(m) value increased with temperature from 0.03 (day(-1)) at 17.5°C to 0.21 (day(-1)) at 32.5°C, after which it decreased to 0.15 (day(-1)) at 35°C. These data indicate that C. malaccensis can reproduce at temperatures between 17.5 and 35°C and can be used for biological control of astigmatid mites within the temperature range where the pest occurs.

Oviposition preference of swallowtail butterfly, Papilio polytes (Lepidoptera: Papilionidae) on four Rutaceae (Sapindales) host plant species

Abstract Oviposition preference and egg deposition site selection by the butterfly, Papilio polytes L. (Lepidoptera: Papilionidae) on four rutaceous host plants, Citrus aurantofolia (Christm.) Swing., Citrus hystrix DC., Citrus reticulata Blanco, and Murraya koenigii (L.) Sprengel, were assessed in field cages measuring 2 × 2 × 2 m. Simultaneous two‐choice and four‐choice oviposition tests of whole host plants were conducted. The mean total number of eggs laid per plant on C. reticulata in the two‐choice test was significantly higher (P &lt; 0.01) than those on C. aurantifolia, C. hystrix, and M. koenigii. Among the three other host plants, C. aurantifolia was preferred over C. hystrix, and M. koenigii (P &lt; 0.01) and C. hystrix was preferred over M. koenigii (P &lt; 0.01). In the four‐choice test, C. reticulata was highly preferred and significantly different from C. hystrix and M. koenigii. However, no oviposition preference was detected with C. aurantifolia. Among the various plant parts in the two‐ and four‐choice tests, eggs on leaves of each plant were the highest, followed by numbers on stems, and negligible numbers on pots. These numbers on leaves of C. reticulata and C. aurantifolia were not significantly different (P &gt; 0.05), but differed significantly (P &lt; 0.01) from those on leaves of C. hystrix and M. koenigii. The quantitative trend of egg‐laying on stems was very similar to that observed for the leaves. Papilio polytes showed strong preference to lay eggs on the underside of leaves of all host plants than on the upper side or on the petiole. More eggs were laid on the upper side of each host plant than on its petiole. The four host plants in descending order of preference were C. reticulata≥C. aurantifolia &gt; C. hystrix &gt; M. koenigii. Although M. koenigii was the least preferred, it has the potential to serve as an alternative host plant for P. polytes which can be manipulated when necessary, to alleviate the infestation of this pest to the citrus industry.

Fecundity, Age and Growth, and Diet of Fundulus diaphanus (Banded Killifish) in Presque Isle Bay, Lake Erie

Abstract Fundulus diaphanus (banded killifish) were the most abundant fish collected in the shallow water areas of Presque Isle Bay, making up 86% of fish collected. Peak spawning dates based on gonadosomatic index and ovary observations were July 9, 2003 and July 18, 2004. Females became sexually mature at age 1. During 2004, the majority of spawning occurred over a 20-day period between July 9 and July 29. Total fecundity increased with both size and age, and the mean total number of eggs produced was 526 ± 37 at age 1 (67 mm ± 1.8), 744 ± 38 at age 2 (79 mm ± 2.4), and 1062 ± 43 at age 3 (93 mm ± 4.1). Based on comparison of the total number of eggs and number of eggs with yolk contained within ovaries, three clutches of eggs may be released during each spawning season. Diets were similar between summer and fall; banded killifish fed almost exclusively on cladocerans and benthic macroinvertebrates.

捕食性天敵シロヘリクチブトカメムシの増殖能力と捕食量について

The pentatomid bug, Andrallus spinidens (F.), is a polyphagous predator on lepidopteran larvae in crop fields in southern Japan. The basic life history biology of the bug was studied using a laboratory incubator with temperature set at 25°C. The nymphs were reared in Petri dishes in groups of 10 and were fed on the 3rd–5th instar Spodoptera litura larvae. The mean development period from egg to adult was 32 d. The pre-oviposition period lasted 7 to 8 d, after which eggs were laid in batches every 2–3 d. The mean number of eggs per mass was 75.4 and the mean total number of eggs laid by each female was 499. The net reproductive-rate (R0), mean generation time (T) and intrinsic rate of natural increase (r) were 153.8, 49.8 d and 0.101/d/female, respectively. Groups of 10 nymphs attacked 4–8 of the 3rd–5th instar S. litura larvae per day. Pairs of adult pentatomids killed 3–5 of the 5th instar S. litura larvae weighing 450–550 mg each day. This study provides important life history information for using the predator A. spinidens as a possible biological control agent.

Longevity, fecundity, and fertility of the red palm weevil, Rynchophorus ferrugineus Olivier (Coleoptera: Curculionidae) on natural and artificial diets

Life parameters including pre-oviposition period, oviposition period, larval and pupal periods, adult male and female development times, and generation span, were obtained for the red palm weevil, Rhynchophorus ferrugineus Olivier, reared on artificial diets of oat, potato, pineapple, and palm fiber sheath, and on natural diets of sugarcane, palm heart, and palm leafbase. Significant differences in the duration of all life parameters were found when fed on various diets. The pre-ovipositional periods ranged from 3.15 to 3.61 d, while the oviposition periods ranged from 3.2 d to 3.8 d. The developmental times of larvae ranged from 70.8 d to 102.2 d, while the development time of pupae ranged from 16.1 d to 22.2 d. The developmental time of adults previously reared on natural diets were longer than those fed on artificial diets. Differences in the development time occurred between males and females reared on different diets, except on sugarcane and palm leafbase. The generation span ranged from 93.2 d to 131.3 d. Significant differences in the average number of eggs deposited per female, previously reared in their larval stages on various diets, ranged from 68.2 eggs to 185.2 eggs, while the average number of eggs deposited per female per day ranged from 1.28 eggs to 3.03 eggs. The percentage of hatchability (viability of eggs) ranged from 74.3% to 93.3%. The mean total number of eggs laid by females, eggs deposited 30 d after one full copulation with males of similar age, and rate of egg hatch decreased significantly with increasing weevil age, and ranged from 65.5 eggs (1-d-old female) to 43.5 eggs (45-d-old female). The rate of egg hatch, also decreased significantly with increasing weevil age, and ranged from 75.8% (1-d-old weevils) to 47.4% (45-d-old weevil). The short copulatory period was adequate for insemination of the female during copulation. Feeding of R. ferugineus on different diets resulted in different life parameters.

Biological studies on three Micromus species in Japan (Neuroptera: Hemerobiidae) to evaluate their potential as biological control agents against aphids: 1. Thermal effects on development and reproduction

We investigated the developmental period, survival rates during the larval and pupal stages, adult longevity, and fecundity of Micromus numerosus, M. angulatus and M. linearis at five constant temperature conditions (10, 15, 20, 25 and 30°C), under a 15L–9D photoregime with Aphis craccivora as prey. The lower thermal thresholds and thermal constants for total development were estimated, respectively, at 7.7°C and 343 degree-days (DD) for M. numerosus, 9.0°C and 297 DD for M. angulatus, and 5.2°C and 447 DD for M. linearis. M. linearis eggs did not hatch at 30°C. At 20°C, the mean total number of eggs laid by a female was 544 in M. numerosus, 399 in M. angulatus, and 614 in M. linearis. The mean longevity of female adult in days was 55 in M. numerosus, 46 in M. angulatus, and 46 in M. linearis. From these results, we evaluated suitable temperature ranges as approximately 20°C for M. numerosus, 15–25°C for M. angulatus, and 10–25°C for M. linearis.

Biological characteristics of the mirids Macrolophus costalis and Macrolophus pygmaeus preying on the tobacco form of Myzus persicae (Hemiptera: Aphididae).

Biological and population parameters of the predatory bugs Macrolophus costalis Fieber and Macrolophus pygmaeus Rambur preying on the tobacco aphid Myzus persicae (Sulzer) were examined. Tobacco was used as host plant and all experiments were carried out at 23 degrees C and L16:D8. In M. costalis, the developmental time for eggs and the total duration of nymphal instars was 13.1 and 22.2 days and in M. pygmaeus 13.0 and 20.2 days, respectively. Both species completed their nymphal development feeding only on plant juices although they required significantly more time to attain adulthood than when feeding on prey. The longevity of M. costalis females and the preoviposition period were 49.9 and 5.6 days and those of M. pygmaeus were 50.3 and 6.3 days, respectively. Adult males showed a higher longevity than females in both species. The intrinsic rate of increase and the mean total number of eggs laid were 0.0644 and 121 in M. costalis and 0.0615 and 104 in M. pygmaeus, respectively. Mean total aphid consumption by nymphs of M. costalis was 61 aphids, about twice that of M. pygmaeus (37 aphids). Total aphid consumption by a male and female pair of M. costalis and M. pygmaeus until the death of the female was 244 and 285 aphids, respectively. The results of the study are discussed in relation to the impact of the two predatory bugs on tobacco aphid populations.

Biology of Ixodes Rubicundus Ticks under Laboratory Conditions: Observations on Oviposition and Egg Development

Observations on oviposition and egg development of Ixodes rubicundus were made under laboratory conditions. Engorged females were exposed to temperatures in the range 10–25°C and relative humidities (RHs) of 33 and 93%. The pre-oviposition period, oviposition period, incubation period, conversion efficiency index (CEI) values and fecundity were determined. The mean pre-oviposition period varied from 13.3 days (temperature 25°C and RH 33%) to 68.3 days (temperature 10°C and RH 93%). Oviposition extended from a mean of 39 days (temperature 25°C and RH 93%) to 201.7 days (temperature 10°C and RH 93%). The developmental zero temperature for the pre-oviposition period was 9.2°C. The mean total number of eggs produced by engorged I. rubicundus females varied from 2045.7 (temperature 10°C and RH 93%) to 3777.7 (temperature 20°C and RH 93%). Both female mass and RH significantly (p < 0.01) influenced the number of eggs produced. CEI values varied between 43.1–54.4% (RH 93%) and 34.1–42.5% (RH 33%). At 93% RH females produced between 14.2 and 17.7 eggs per mg body mass compared to the 13.2–14.6 eggs per mg body mass at 33% RH. The shortest mean incubation period recorded was 164.3 days (temperature 25°C and RH 93%). The developmental zero temperature for incubation was 6.5°C. Both the pre-oviposition and oviposition periods of I. rubicundus are more extended compared to other species of the genus. Ixodes rubicundus produces a large number of small eggs compared to other prostriate ticks.

モモアカアブラムシを寄主とする２種のアブラバチＤｉａｅｒｅｔｉｅｌｌａ ｒａｐａｅ（Ｍ’Ｉｎｔｏｓｈ）とＡｐｈｉｄｉｕｓ ｇｉｆｕｅｎｓｉｓ Ａｓｈｍｅａｄの産卵数，産卵期間及び寿命

The fecundity, oviposition period and longevity of Diaeretiella rapae (=Dr) and Aphidius gifuensis (=Ag) were examined under a 20±1°C, 15L-9D regime. Single newly emerged and female adults that had already mated were provided with 20 second or third instar larvae of Myzus persicae and honey droplets daily throughout their life. The aphids were then dissected to count the number of eggs deposited. The mean total number of eggs deposited per female was 238.7 (range 152-322) in Dr and 531.5 (290-865) in Ag. The mean oviposition period and the mean longevity of the female adults were respectively 11.1 and 14.7 days in Dr. The corresponding figures were respectively 14.9 and 17.6 days in Ag.

Oviposition Biology of the Pine Sawyer, Monochamus carolinensis (Coleoptera: Cerambycidae)

Several aspects of the oviposition biology of Monochamus carolinensis were observed. The oviposition sites of M. carolinensis varied in appearance with the thickness of the bark. The sexual maturation period ranged from 7 to 12 days. On Scotch pine ( Pinus sylvestris L.), mean (±SD) number of eggs per site in the laboratory was 0.76 ± 0.50 (n = 1,402), and 0.87 ± 0.35 ( n = 652) in the field. Mean life span of adult females was 61.4 ± 19.2 days ( n = 5) and the mean total number of eggs deposited was 200.0 ± 89.0 eggs per female. Most oviposition occurred at night and in the middle to upper portions of the bole. Jack pine ( P. banksiana Lamb.) had a higher oviposition-site density than Scotch pine, shortleaf pine ( P. echinata [Mill.]), and eastern white pine ( P. strobus L.).

Reproduction of the American Dog Tick, Dermacentor variabilis1 , under Laboratory and Field Conditions

Female American dog ticks, Dermacentor variabilis (Say), engorged on an albino rat, wild-caught porcupines and a raccoon, were held at 6 constant temperatures in the laboratory and at fluctuating temperatures at ground level in grassland and woodland of a study area in southwestern Nova Scotia. Mean weights of engorged females ranged from 309.4 to 665.9 mg following detachment from porcupines and the raccoon, respectively. The highest mean total number of eggs deposited per female engorged on porcupines and the albino rat and held at 25°C was 4877 (range 597–7187). The number of eggs laid and weight of engorged preoviposition ticks were positively correlated for most temperatures except that at the suboptimal constant temperatures of 15° and 35.6°C the correlations were still positive but not statistically significant. The pattern of daily oviposition rates varied in shape and magnitude of peaks depending on the temperature at which the ticks were held. The avg peak daily oviposition was as high as 528 eggs/female on the 3rd day of oviposition and as low as 79 eggs/female on the 32nd day of oviposition for the ticks held at 29.7° and 15°C, respectively. Fluctuating temperatures in grassland and woodland and the porcupines and raccoon as hosts during May and June, 1976, were suboptimal for female ticks which produced less than half the mean total number of eggs that were produced by females engorged on the albino rat and held at a constant 25°C during the same period. Ticks feeding on the 3 host species produced viable eggs which had similar weights during the peak oviposition period. The viability of eggs was reduced towards the end of the oviposition period. Under field conditions, less optimal temperature ranges may reduce the maximum reproductive potential of D. variabilis .

Laboratory observations on oviposition by the predaceous tree-hole mosquito, Toxorhynchites rutilus septentrionalis (Diptera: Culicidae)

The number and hatchability of eggs laid each day was observed for 15 consecutive days in 24 females isolated individually. During the first 5 days of oviposition, the proportion of females laying eggs varied from 0.45 to 0.82 and then decreased to an average value of 0.30. There was no relationship between female age and hatchability, and with one exception, unhatched eggs were not embryonated. For the 18 females surviving to day 15, the mean total number of eggs laid was 38.89 and the mean total number of retained mature eggs was 62.44. There was no relationship between the total numbers laid and retained.Oviposition was diurnal, with a minor peak during the 1st h of the photophase and a major peak during the hour preceding evening twilight.Females showed an oviposition preference for Aedes aegypti (L.) rearing medium over deionized water.Results are discussed in relation to the behaviour and ecology of Toxorhynchites mosquitoes.

The influence of temperature on development, longevity, and fecundity in the Rutherglen bug, Nysius vinitor (Hemiptera : Lygaeidae)

The mean duration of the egg stage of N. vinitor at constant temperatures ranged from 36.8 days at 15C to 3.8 days at 32C and that of the nymphs from 45 days at 20C to 12.0 days at 32C. Within the range 20-35C egg and nymphal mortalities were low; temperatures of 12 or 40C were lethal to both eggs and nymphs. Mean nymphal development times for males and females were similar. The threshold temperature for egg development was 14.5C and that for nymphs 15C; 70 and 225 day-degrees were required for completing egg and nymphal development respectively. The immature stages developed more rapidly at fluctuating temperatures out of doors than they did indoors at constant temperatures equal to the mean of the fluctuating temperatures. Within the range of screen temperatures 21.5-23.0C the difference between mean development in shade and in sun was 9-10 days. Age-specific fecundity and mortality schedules were determined for N. vinitor at constant temperatures. Temperature and longevity were inversely related and males survived longer than females. Thus at 22OC mean longevity of males was 115 days and of females 90 days, as compared with 31 and 18 days respectively at 30�C. After a maturation period that was longer at lower temperatures, daily egg-laying per female decreased with age from a maximum that occurred before there was significant mortality of females. The rates of the cumulative egg-laying increased with temperature from 22 to 35C. Mean total number of eggs per female was significantly higher at 25 and 30�C than at 22 or 35�C. However, life-table calculations revealed that a temperature of 35�C yielded the maximum rate of population increase. Within the range 22-35C, temperatures and rc values were linearly related. Unmated females laid significantly fewer eggs than those that had mated, but survived longer.