Successful gonadal development and maturation of tench (Tinca tinca L.) in small concrete ponds

The experiments were performed in a tench farm from autumn until the spawning season (June–July). Tench broodstocks from natural habitats were maintained in 25 × 6 × 1 m concrete ponds and fed on commercial trout pellets. Females and males were separated and maintained under natural photoperiod and temperature conditions at densities around 2 kg m^?2. Water flow throughout was supplied at the rate of 15 L s^?1. When females showed external signs of advanced gonadal development, induction of spawning was made by luteinizing hormone releasing factor (LH‐RH) synthetic analogue administration at three different periods of the reproductive season (June–July). A single intramuscular injection (20 μg kg^?1 body weight) was administered to 110 mature females selected from a total of 150. The females were stripped 42 h (22°C) after hormone administration. The mean rate of stripped females to the number injected was 77%. Mean relative egg weight in relation to the weight of the stripped females was 5.61%. More than 90% of the males provided semen without hormonal induction. Differences in egg production and external egg quality were observed at different times of the spawning period. It was proven that tench maintained in small concrete tanks and fed on artificial diets were able to reach gonadal maturation.     

Effects of delayed mating and male mating history on the reproductive potential of Leucoptera coffeella (Lepidoptera: Lyonetiidae)

Abstract 1 Despite the importance of Leucoptera coffeella (Guérin‐Mèneville) in coffee production worldwide, there is a lack of information on its reproduction. This knowledge will help in mass rearing, and support the development of behavioural control techniques for this insect. The present study determined the effects of delayed mating and previous matings of male L. coffeella on fecundity, egg viability and frequency of female remating. 2 The highest levels of fecundity and egg viability were obtained from matings of 1–3‐day‐old females. When females mated at 5 days of age, there were reductions of 40% in oviposition and of 43% in egg viability. 3 Females mated with 2‐day‐old virgin males were more fecund than those mated with older males; egg viability was also low (18%) from females mated with older males. 4 Virgin females that mated with virgin males laid a greater number of eggs than those mated with previously copulated males. Egg viability decreased with the increase in the number of previous male matings. 5 Five‐day‐old females remated in greater proportion than 2–3‐day‐old females. Females that copulated with males that had previously mated three times had higher rates of remating than those that copulated with virgin males. 6 The results obtained indicate that 1–3 days after emergence is the optimum age for mating. The implications of these findings for the control of L. coffeella by synthetic sex pheromone are discussed.     

Comparison of performance of genome manipulated and standard tench, <Emphasis Type="Italic">Tinca tinca</Emphasis> (L.), groups under pond management conditions

A triennial performance test of five groups of tench, Tinca tinca (L.): Vodnany induced triploid V3n, Vodnany meiotic gynogenic Vgyn, diploid Vodnany V2n, Hungarian H2n and German G2n) in pond monoculture was carried out with diploid golden tench as control (C) to compute corrected weight of the groups tested. Survival rate ranged from 11.6% (V2n) to 30.6% (Vgyn) in yearlings, from 71.2% (V2n) to 91.5% (H2n) in 2 year-olds, from 60.0% (Vgyn) to 75.7% (V2n) in 3 year-olds while that of the control group was 8.5, 38.3 and 40.2% in the respective seasons. After three growing seasons the corrected weight of the fish in the groups H2n (254.6^bg), V3n (257.0^cg) and G2n (371.4^cg) was higher (P < 0.05, Tukey HSD test) than that from the C (183.3^ag) and V2n(205.6^abg) groups. Among the chromosomally manipulated groups, ANCOVA test found the least slaughtering value for Vgyn (84.3%); among the purebreds the highest value was found for H2n (87.32%), significantly differing from V2n and G2n strains. A high gonadosomatic index in females (2.94 vs. 0.44% in males) resulted in inferior slaughtering values.     

Characterization of age and cuticular hydrocarbon variation in mating pairs of house fly,Musca domestica,collected in the field

House flies, Musca domestica L., were collected in copula over two summers from six dairies located in three climatically distinct regions in the U.S.A. southern California, Minnesota and Georgia. Ages of males and females from a total of 511 mating pairs were estimated using pterin analysis. Cuticular hydrocarbon profiles and gonotrophic ages of females also were evaluated. Mean age of mating males ranged from 54 to 102 degree‐days (DD) (4–10 days based on field air temperatures), depending on the farm. Very young males (< 10–20 DD) and old males (> 200 DD) were rare in mating pairs. Mean female age at mating ranged from 20 to 46 DD (2.5–4 days). All mating females had eggs in the early stages of vitellogenesis and 99.2% were nulliparous. However, some older and parous females were collected, demonstrating that re‐mating can occur in the field. Head width measurements of mating pairs suggested that assortative mating by size did not occur. The cuticular hydrocarbon profiles of females were determined, with emphasis on (Z)‐9‐tricosene (muscalure). Overall, only 55% of mating females had detectable amounts (> 4 ηg per fly) of (Z)‐9‐tricosene. Of the females that had detectable (Z)‐9‐tricosene, variation in amount per female was high in all fly populations, and thus was not statistically related to the size or age of the mating female. The proportion of mating females with detectable levels of (Z)‐9‐tricosene varied by geographic region. Seventy‐one, 63, and 27% of females from southern California, Minnesota and Georgia had detectable amounts of (Z)‐9‐tricosene. Principal components analysis of the eight most abundant hydrocarbons from mating females, by state, revealed state‐level distinctiveness of hydrocarbons in house fly populations, which may reflect genetic variation associated with environmental stresses in those geographical zones.     

Breeding,production and marketing of golden tench (<Emphasis Type="Italic">Tinca tinca</Emphasis> (L.)) in Gan Shmuel Fish Breeding Center,Israel

A first attempt to introduce tench (Tinca tinca (L.)) to Israel, followed by comparative growth experiments, was carried out in 1947. A batch of 200 fingerlings, which were supposed to serve later as brood fish, was imported from Switzerland to Fish Culture Experimental Station at Sdeh Nahum. However, after 2 years tench were considered unsuitable for culturing in Israel and the trials were abandoned. Two factors affected negatively these historically early trials: (1) Tench was just second exotic species introduced to Israel some years after introduction of the common carp, and the Israeli fish farming expertise at that time was low. (2) The Independence War temporarily delayed advancement of aquaculture. A second introduction of tench was performed in 1992, when a golden mutant of tench was imported to Gan Shmuel Fish Breeding Center (GS-FBC) from the Research Institute of Fish Culture and Hydrobiology at Vodňany, Czech Republic. Currently, GS-FBC is the only Israeli fish hatchery that maintains golden tench as a part of breeding program as well as a number of other varieties of ornamental fish and species, all of them produced mostly for export. Tench (800–1,000 g) females are maintained separately from males, in order to prevent uncontrolled reproduction. Routinely, in April, the fish are transferred indoors and induced to spawn artificially with a single injection of GnRH synthetic analog—DAGIN. Dry method of stripping is used to obtain eggs and sperm. After fertilization the sticky eggs are spread in a single layer on walls of 230 dm³ cylindrical incubators provided with conical bottom, or they are degummed using a solution of milk/water. At a water temperature of 24°C, hatching (70% hatching rate) occurs 36–40 h after fertilization. The larvae absorb their yolk sac 2–3 days after fertilization and they start feeding on small size (200 μm) Artemia nauplii. At the age of 7–10 days, if fry are retained indoors, they are fed with regular size Artemia and starter feed, or are released into a nursing 0.5–1.0 ha pond. Usually, the fish are grown to the marketing size (5–15 cm) and exported abroad, mainly to Europe. About 100,000 golden tench fingerlings, with a total value of € 40,000 are produced and marketed annually.     

Humidity‐controlled cold storage of Neoseiulus californicus (Acari: Phytoseiidae): effects on male survival and reproductive ability

Humidification can suppress water loss from an organism and has great potential for improving the cold storage of short‐lived arthropods, such as predatory mites. The effectiveness of humidity‐controlled cold storage was recently verified for Neoseiulus californicus (McGregor) females but was not examined for males. Combining both males and females in one storage protocol might increase the predator population because it would enhance the opportunity for multiple mating, which is necessary for females to maximize their egg production. Newly emerged adult males were stored at an air temperature of 5°C and relative humidity (RH) of 100% or 80%. The median survival time (LT₅₀) was 32 days at 100% RH and 14 days at 80% RH; the survival curves differed significantly. Males stored at 100% RH for 0, 10, 20 and 30 days were introduced to virgin females for mating at 25°C to evaluate their reproductive ability. The pre‐oviposition period was significantly prolonged in the females mated with males stored for ≥20 days. No negative effects of storage were observed on the oviposition period, total number of eggs or net reproduction rate (R₀) in the females mated with males stored for ≤20 days or on the mean generation time (T) for those stored for 30 days. A slight decrease in the intrinsic rate of increase (r_m) was observed in the females mated with males stored for ≥20 days. Our storage method can preserve N. californicus males for 20 days with only a minor reduction in their survival and reproductive ability.     

Food‐related dominance between two carcharhinid shark species,the Caribbean reef shark,Carcharhinus perezi,and the blacktip shark,Carcharhinus limbatus

Although tench (Tinca tinca Linnaeus 1758) has been cultured traditionally in Eurasia, Central and Southern Europe mostly by low intensity methods, investigations of the optimum intensive culture conditions for the species have recently been initiated. This work was aimed to investigate the effect of food ration level on growth and survival of sub-adult tench, under intensive culture conditions. One hundred and twenty individuals (24.55?g?±?3.28) were fed for 102 days at three feeding levels: 0.5%, 1%, 2% b.w.d^?1. Higher body weights (b.w.) have been achieved with the 2% ration level in all experimental phases. However, by the end of the experiment (up to the b.w. of 34?g), fish fed with the ration level of 1% b.w.d^?1 resulted in better indices (FCR, SGR, % weight gain). These findings conform to the ones previously observed for tench juveniles and indicate that the 1% b.w.d^?1 ration level (below satiation) could be advantageous for tench sub-adults as well.     

Dynamics of male residence and female oestrus during a breeding season of blue monkeys in the Kakamega Forest, Kenya

Blue monkeys (Cercopithecus mitis stuhlmanni) are seasonal breeders with a dynamic mating system in which typical one‐male social units are regularly disrupted and replaced by multi‐male ones. The number of males in the group is correlated with the number of oestrous females. We used observations of male presence and female oestrus on individual days during a 6‐month period to assess whether the presence of multiple males in a group stimulates female oestrus or whether oestrous females attract multiple males to the group. We confirmed prior observations with our finding that the number of males in a group was significantly correlated (r_s = 0.435, P < 0.0001) with the number of oestrous females across 126 observation days. A transition matrix did not show an obvious relationship between day‐to‐day changes in the numbers of oestrous females and males. However, cross‐correlation analysis provided stronger support for the idea that the number of oestrous females attracts males to a group than for the idea that the influx of strange males stimulates oestrus in female blue monkeys. Autocorrelation analysis showed that while female oestrus appeared to show a high degree of synchrony, as expected in a seasonal breeder, there was no evidence that the number of males accompanying a group of females influenced the likelihood of other males joining or leaving the group. Overall, our results confirm that female oestrous behaviour stimulates changes in male residence patterns. However, other observations suggest that changes in male residence may also stimulate female oestrus in some circumstances.     

Efficiency of sulphur in garlic extract and non‐sulphur homeopathy in the control of the cattle tick Rhipicephalus (Boophilus) microplus

The objective of the present work was to evaluate the efficacy of a non‐sulphur‐based homeopathic preparation and a sulphur‐containing natural product derived from Allium sativum (Linnaeus) against infestation by the cattle tick Rhipicephalus (Boophilus) microplus (Canestrini) (Acari: Ixodidae). A total of 24 crossbred calves (7 : 8 Holstein : Zebu), aged 6–8 months and maintained in individual stables under tick‐free conditions, were divided into three groups. Group 1 (control group) received no treatment; Group 2 was treated with 0.01 g/day of the homeopathic preparation Fator C&MC^®, and Group 3 was treated with 20 g/day of Enxofre‐Allium sativum^®. After adaptation to the diet for 1 month, each calf was subjected to artificial infestation with 8000 R. (B.) microplus larvae (aged 7–14 days) twice per week over a 5‐month period. Numbers of engorged females were recorded every 14 days and samples of freely released engorged females were collected at 14‐day intervals commencing 3 months after the start of the experiment. The engorged females were weighed, incubated for 15 days under biochemical oxygen demand conditions at 27 ± 1 °C and relative humidity >85%, and the weights of the egg masses produced were recorded. Other biological parameters, including reproduction estimate, reduction in oviposition and efficiency of treatment, were determined. A significant reduction in the number of engorged females was detected on animals treated with Enxofre‐Allium sativum^® (Group 3) in comparison with the other two groups. The overall efficiency of the treatment with the sulphur‐containing product was 64%, whereas that of the homeopathic preparation was 26%. Under the experimental conditions established, Enxofre‐Allium sativum^® can reduce the intensity of the R. (B.) microplus infestation.     

The rate of uptake of sex steroids from water by Tinca tinca is influenced by their affinity for sex steroid binding protein in plasma

Two experiments were carried out in which male and female tench Tinca tinca were placed in individual containers and tritiated steroids then added to the water. Water samples were collected over the next 6 or 7 h and the fish then sacrificed, bled and the gall bladder removed. Radioactivity was counted in all the samples. Over the course of the exposure period in the first experiment (7 h), radioactivity of 11‐ketotestosterone (11‐KT) in the water was depleted by 11%, 17,20β‐dihydroxypregn‐4‐en‐3‐one (17,20ß‐P) and 17,20α‐dihydroxypregn‐4‐en‐3‐one (17,20α‐P) by 28%, testosterone (T) by 56% and androstenedione (AD) by 68%. HPLC analysis of water samples at 3 h indicated that none of the steroids was extensively metabolized during the experiment. Females had a faster rate of uptake of AD than males. In the second experiment (6 h), radioactivity of cortisol in the water was depleted by 5%, 11‐KT by 7%, 17‐hydroxypregnen‐4‐ene (17‐P) by 17%, 17β‐oestradiol (E₂) by 35%, T by 37% and AD by 44%. In both experiments, the amounts of radioactivity that were recovered from the gall bladder and plasma were positively correlated with the rate of disappearance of radioactivity from the water. The ability of the steroids to bind to sex steroid binding protein (SBP) of tench plasma was tested by incubating plasma with radioactive steroids and then separating bound and free with ice cold dextran‐coated charcoal. When plasma at a final dilution of 1 : 60 (v/v) was incubated with 5 nM of each steroid, the percentage of radiolabel bound to SBP was: T 48% AD 44%, E₂ 30%, 17‐P 17%, 11‐KT 13·2%, 17,20α‐P 10·3%, 17,20β‐P 4·5% and cortisol 0%. Saturation analysis established dissociation constants (K_d; mean ± s .e .) of 3·4 ± 0·4, 2·2 ± 0·2, 4·0 ± 0·3. 9·0 ± 2·8 and 51·8 nM and binding capacities (B_max) of 201 ± 29, 201 ± 33, 165 ± 3, 187 ± 15 and 13·4 nM for T, AD, E₂,17‐P and 17,20β‐P respectively. The ability of steroids to displace tritiated T and AD from SBP was in the rank order AD > T > E₂ > 17,20αP = 17,20β‐P = 11‐KT = 17‐P > cortisol. Thus, the ability of tench plasma to bind certain steroids showed a relatively strong correlation with the ability of the fish to take up these steroids from water. Modelling of data for AD and 17,20β‐P helped to show why and how plasma binding had a strong influence on the rate of uptake (and hence release) of the steroids.     

Predicting Sirex noctilio and S. nigricornis emergence using degree days

The study of temporal interactions between native insects and alien invaders can be facilitated by the ability to forecast adult emergence. We used field‐collected adult emergence data of Sirex noctilio Fabricius (Hymenoptera: Siricidae), a woodwasp native of Eurasia that has recently invaded northeastern North America, and Sirex nigricornis Fabricius, a woodwasp native to North America, to develop and test cumulative degree‐day (CDD) models. Five data sets were collected each in Ontario, Canada (S. noctilio) and Louisiana, USA (S. nigricornis) over 4 years; three data sets were used to develop models and two were used to test them. Males and females of each species were modelled separately. After testing several potential temperatures, chosen thresholds for CDD were 0 °C lower threshold and 25 °C upper threshold for both Sirex spp. We used a three‐parameter Gompertz growth function to model Sirex spp. emergence against CDD. Models predicted 10% emergence of S. noctilio in Ontario after 1 239 and 1 280 CDD, for males (start date = 1 April; R² = 0.91) and females (start date = 1 April; R² = 0.86), respectively. Models predicted 10% emergence of S. nigricornis in Louisiana after 3 980 and 5 016 CDD, for males (start date = 1 May; R² = 0.83) and females (start date = 1 March; R² = 0.73), respectively. Cumulative degree‐day models predicted 10 and 90% emergence of woodwasp populations with less error (1–13%) than they did 50% emergence (5–27%). For both Sirex spp., male emergence began a few days before and concluded at about the same time as that of females. In southern Ontario, models predict that S. noctilio adults will be in flight between 1 015 and 2 430 CDD (1 April start date for CDD; from early‐July until mid‐September). In Louisiana, models predict that S. nigricornis adults will be in flight between 3 854 and 4 700 CDD (1 May start date for CDD; from early‐October until late‐November).     

Response of juvenile tench Tinca tinca (L.) to the anaesthetic 2-phenoxyethanol

The response of tench Tinca tinca aged 40–171 days post‐hatch (22–49 mm TL) to the anaesthetic 2‐phenoxyethanol was studied at 25°C. The lowest effective concentration of 2‐phenoxyethanol increased with age, while the highest safe concentration decreased. The fish aged 40 days post‐hatch required a significantly (P ≤ 0.05) shorter time to become anaesthetized than did older fish. The recovery time after 15 min of exposure to 2‐phenoxyethanol at 0.45 g dm^?3 was significantly shorter in the 40‐day‐old fish than in older fish. In juveniles of the same age, induction time or recovery time did not depend on their size or condition (Fulton's coefficient). At 25°C, 2‐phenoxyethanol at 0.5 g dm^?3 may be used to efficiently and safely anaesthetize T. tinca juveniles.     

Life history of the Asian longhorn beetle Anoplophora glabripennis (Coleoptera Cerambycidae) in southern Europe

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Genetic influences on growth traits of BMI: a longitudinal study of adult twins

Objective: To investigate the interplay between genetic factors influencing baseline level and changes in BMI in adulthood. Methods and Procedures: A longitudinal twin study of the cohort of Finnish twins (N = 10,556 twin individuals) aged 20–46 years at baseline was conducted and followed up 15 years. Data on weight and height were obtained from mailed surveys in 1975, 1981, and 1990. Results: Latent growth models revealed a substantial genetic influence on BMI level at baseline in males and females (heritability (h²) 80% (95% confidence interval 0.79–0.80) for males and h² = 82% (0.81, 0.84) for females) and a moderate‐to‐high influence on rate of change in BMI (h² = 58% (0.50, 0.69) for males and h² = 64% (0.58, 0.69) for females). Only very weak evidence for genetic pleiotropy was observed; the genetic correlation between baseline and rate of change in BMI was very modest (−0.070 (–0.13, −0.068) for males and 0.04 (0.00, 0.08) for females. Discussion: Our population‐based results provide a basis for identifying genetic variants for change in BMI, in particular weight gain. Furthermore, they demonstrate for the first time that such genetic variants for change in BMI are likely to be different from those affecting level of BMI.     

Age,growth and mortality of invasive sharpbelly,Hemiculter leucisculus (Basilewski, 1855) in Erhai Lake,China

The sharpbelly Hemiculter leucisculus, an invasive species, has expanded its range throughout much of Asia and into the Middle East. However, little is known of its adaptive changes regarding life history traits such as age, growth and mortality that could possibly explain its success as an invasive species. A detailed study of the invasive sharpbelly was conducted based on 4539 samples collected from July 2009 to June 2011 in Erhai Lake, China. Standard length ranged from 4.3–19.1 cm for females and 4.6–12.3 cm for males. Length–weight relationships for females and males were significantly different and described as W = 0.0076SL^3.2608 and W = 0.0084SL^3.1901, respectively. Otoliths are ideal for age determination because of the single annulus formed each year. Based on marginal increment analysis, the total mean CV for age estimate between two readings was 3.55%. The von Bertalanffy growth curves computed by observed length‐at‐age data were expressed as L_t = 25.6 (1 ? e^{?0.176 (t + 1.347)}) for females and L_t = 16.4 (1 ? e^{?0.354 (t + 0.819)}) for males. According to the age, growth and mortality data, there are three possible reasons for H. leucisculus attaining such dominance within a short time in Erhai Lake. First, because of the simple age structure of this species: 97.58% of males were 1–2 years old with a maximum age of only 3 years; 93.14% of females were 1–3 years old, with a maximum age of 6 years. Second, females grew larger than males at any age. Third, instantaneous mortality rates were much higher for males (4.22 year^?1) than for females (1.17 year^?1).     

Interaction between sexes and between different circadian phenotypes affects lifespan in the fruit fly Drosophila melanogaster

Circadian clocks regulate the daily temporal structure of physiological and behavioural functions. In the fruit fly Drosophila melanogaster Meigen, disruption of daily rhythms is suggested to reduce the fly's lifespan. In the present study, because pairs of mixed‐sex flies are known to show an activity pattern different from that of individual flies, this hypothesis is tested by measuring the lifespan of flies housed same‐sexually or mixed‐sexually under an LD 12 : 12 h photocycle at a constant temperature of 25 °C. The effect of housing wild‐type (Canton‐S) flies with period (per) circadian clock mutant flies is also examined because the mutant flies have different daily activity patterns. When males and females of wild‐type flies are housed together, their lifespan is substantially lengthened (males) or shortened (females) compared with same‐sex housed flies. The shortening of the lifespan in females is significantly enhanced when mated with per mutant males. The shortening effects are significantly reduced when the mixed‐sex interaction is limited for the first 5 days after emergence. A slight elongation in lifespan, rather than a reduction, occurs when wild‐type females are housed same‐sexually with per⁰ or per^L mutant flies. In male flies, the elongation of lifespan occurs not only when wild‐type males are housed with wild‐type, per⁰ or per^L females, but also when housed with per⁰ or per^S mutant males. Mixed‐sex couples always show altered daily locomotor rhythms with an enhanced night‐time activity, whereas same‐sex couples show daily behavioural profiles slightly altered but essentially similar to a sum of the respective two flies. No significant correlation is found between the lifespan and reproductive capacity. These results suggest that the alteration of daily activity rhythms and sexual interaction may have significant impact on the fly's lifespan.     

Juvenile hormone III produced in male accessory glands of the longhorned beetle,Apriona germari,is transferred to female ovaries during copulation

We report on juvenile hormone (JH) biosynthesis in vitro by male accessory glands (MAGs) in the longhorned beetle, Aprionona germari, accompanied by the transfer of JH from males to females during copulation. JH was extracted from the MAGs and separated by reversed‐phase high‐performance liquid chromatography. JH III was identified as the major JH by gas chromatography–mass spectrometry. A radiochemical assay and a non‐radioactive method were used to measure the in vitro rate of JH biosynthesis by the MAGs. After 4 h of incubation with ³H‐methionine in the medium, the radioactivity in the MAGs substantially increased. In a separate assay, incubation of the MAGs with non‐radioactive methionine for 4 h resulted in a 39% increase in JH III. Seven‐day‐old males were injected with medium 199 containing ³H–methionine and 24 h later they were mated with virgin females. Hemolymph and the MAGs were collected from the mated males and hemolymph, ovaries and eggs were collected from the mated females for assaying radioactive JH. The radioactivity incorporated into JH in the MAGs was transferred to the females during copulation and later transferred into their eggs. Assayed 1 h after copulation, JH III level in the MAGs decreased 42% and the content of JH III in the male hemolymph did not change, whereas the content of JH III in the female hemolymph and ovaries both increased. © 2010 Wiley Periodicals, Inc.     

Gonad maturation and spawning of cobia,Rachycentron canadum (Linnaeus, 1766) off the Dungun coast,Malaysia

The reproductive biology of cobia, Rachycentron canadum, from the coastal waters of Dungun, Malaysia was studied from June 2014 to May 2015. From commercial trawls, a total of 201 samples (combined sexes) were collected (fork lengths [FL] 37.5–124.0 cm; body weights 0.5–20.4 g). The overall sex ratio of females to males was 1:0.9, which was not significantly different (χ² = 2.12, df = 1; p < .05). Estimations of length at 50% maturity (L₅₀) showed that both sexes matured at approximately 75 cm FL; estimated spawning frequency was 6 days. Mean batch fecundity (BF) ranged from 0.55 to 4.32 million eggs. The average number of eggs per gram of ovary was from 2,100 to 5,400 eggs, and relative fecundity 147 eggs/g. There was a weak positive correlation (r² = .48) between BF and female FL as well as BF with an ovary‐free body weight (r² = .56), possibly due to females being in a continuous spawning condition and some possibly half‐spent, based on the histological examination of the female gonads. Despite cobia being asynchronous spawners, the gonadosomatic index in both males and females showed peaks in June, November, and particularly March. Based on histological examination, spawning‐capable males were encountered throughout the study period, whereas spawning‐capable females in the late developing subphase were found mostly in March and April. This is the first study on the reproductive aspects of cobia in Malaysian waters.     

Survival,fecundity, and body mass of Amplicephalus curtulus influenced by ‘Candidatus Phytoplasma ulmi’ (16SrV‐A) infection

The leafhopper Amplicephalus curtulus Linnavuori & DeLong (Hemiptera: Cicadellidae) can transmit ‘Candidatus Phytoplasma ulmi’ (16SrV‐A) from a native Chilean shrub, Ugni molinae Turcz. (Myrtaceae), to ryegrasses. A recent study showed that this phytoplasma reduced the total protein content and the activity of detoxifying enzymes in A. curtulus, which could also affect its vector fitness. This study evaluated the effect of ‘Ca. Phytoplasma ulmi’ on the longevity, fecundity, and body mass of A. curtulus. Both females and males were exposed to ‘Ca. Phytoplasma ulmi’‐infected plants for 96 h, whereas a control group remained unexposed. Quartiles from adult emergence to 75% (t₇₅), 50% (t₅₀), and 25% (t₂₅) survival rates were determined for each leafhopper survival distribution. The dry weight was also established at the end of the experiment. The adult lifespan of phytoplasma‐infected males and females was significantly lower than that of the uninfected leafhoppers in quartile survival distributions t₅₀ and t₂₅. The phytoplasma‐infected males and females lived 3 and 4 weeks less than uninfected ones in the last quartile, respectively. Fecundity was established by number of nymphs per female (in four periods) in phytoplasma‐infected and uninfected assays. In general, the weekly pattern of the number of nymphs per phytoplasma‐infected female was lower than that of uninfected leafhoppers; it was 37% lower at the end of the experiment. Phytoplasma‐infected females weighed significantly less (11%) than uninfected individuals. Phytoplasma‐infected males weighed 8% less than uninfected ones, but this difference was not significant. Our data indicated that ‘Ca. Phytoplasma ulmi’ negatively affected the fitness of A. curtulus, and nymphs produced by phytoplasma‐infected females varied over time, which may influence the disease dynamics in nature or in field crops.     

Age,growth and reproduction of the sand smelt Atherina boyeri Risso, 1810 in Mellah Lagoon (Eastern Algeria)

This aim of this paper was the study of the reproductive biology and growth of the sand smelt, Atherina boyeri, in Mellah Lagoon (Algeria). These data are important for the sustainable exploitation of the stocks of this species. Examined was a total of 1402 Atherina boyeri specimens captured monthly from March 2010 to March 2011, in a population with a 3‐year life cycle. Length–weight relationship was estimated as W = 0.0047 L^3.077 (r² = 0.935) for males and W = 0.0047 L^3.176 (r² = 0.935) for females. Using scales, the von Bertalanffy growth function fitted to back‐calculated size‐at‐age data was Lt = 9.49 [1 ? e^{?0.316 (t + 0.928)}] for males, and Lt = 11.67 [1 ? e^{?0.179 (t + 1.514)}] for females; using otoliths this was Lt = 9.68 [1 ? e^{?0.3 (t + 1.02)}] for males, and Lt = 11.93 [1 ? e^{?0.171 (t + 1.55)}] for females. The growth performance index (Φ) indicated that males (Φ_scales = 3.34, Φ_otoliths = 3.33) grew at the same rate as females (Φ_scales = 3.19, Φ_otoliths = 3.24), with a sex ratio of 1 : 1.6 in favor of females. The reproductive season extended from February to June. Individual length at first sexual maturity was 4.20 cm for 1‐year‐old males and 4.35 cm for 1‐year‐old females.