Among calyptraeid gastropods, males become females as they get older, and egg capsules containing developing embryos are maintained beneath the mother's shell until the encapsulated embryos hatch. Crepipatella dilatata is an interesting biological model considering that is an estuarine species and thus periodically exposed to elevated environment-physiological pressures. Presently, there is not much information about the reproductive biology and brooding parameters of this gastropod. This paper describes field and laboratory observations monitoring sex changes, brooding frequencies, sizes of brooding females, egg mass characteristics, and embryonic hatching conditions. Our findings indicate that C. dilatata is a direct-developing protandric hermaphrodite, changing from male to female when individuals were between 18 and 20 mm in shell length. At our study site in Quempillén estuary, females were found to be brooding almost continuously throughout the year, having an average maximum of 85% of simultaneous brooding, with a short rest from April through June. No relationship was found between the number of capsules per egg mass and the size of the brooding female. However, capsule size and the number of embryos and nurse eggs were strongly related to female size. The offspring hatched with an average shell length > 1 mm. About 25% of the hatched capsules were found to contain both metamorphosed (juveniles) and non-metamorphosed (veliger) individuals. The sizes of the latter were < 1000 μm. The length of hatching juveniles was inversely related to the number of individuals per capsule, which seems related to differences in the availability of nurse eggs per embryo. Although fecundity per reproductive event of this species is relatively low (maximum approx. 800 offspring per egg mass) compared with those of calyptraeid species showing mixed development, the overall reproductive potential of C. dilatata seems to be high considering that females can reproduce up to 5 times per year, protecting their encapsulated embryos from physical stresses until well-developed juveniles are released into the population, avoiding a dangerous pelagic period prior to metamorphosis.
Different aspects of reproductive biology of S. plagiostomus were studied in this work from February 2014 to January 2015. Fishes were collected from Sheringal valley right from Kumrat thal valley to Chukyatan Dir Upper. Fecundity and Gonado-somatic index was studied using gravimetric to infer about breeding season and reproductive potential. The mean value of absolute fecundity recorded was 14670.39 while mean value of relative fecundity was noted as 34.78. The mean value recorded for conditioned factor was 0.912 g/cm(3). Relationship of fecundity with body length, body weight, ovary weight and the interrelationship of body length and body weight was established statistically using Linear Regression. The values of determination coefficient (R-2) at P 0.05). The study provides basic information about the reproductive potential and behavior of S. plagiostomus which will be handy towards its culture.
Spotted wing drosophila, Drosophila suzukii, is a devastating invasive pest of small and stone fruits in the Americas and Europe. To better understand the population dynamics of D. suzukii, we reviewed recent work on juvenile development, adult reproduction, and seasonal variation in life history parameters including the abiotic/biotic factors that influence these processes. Juvenile development is optimal at moderately warm temperatures, and larvae exhibit some immunity to parasitism. Adults use visual cues and substrate-borne vibrations for courtship and exhibit a bimodal locomotor activity pattern (except mated females). Under 20–27 °C and various conditions, development from egg to adult can take 10–17 days, females first lay eggs within 1–8 days and their lifetime fecundity varies from 400. Oviposition is consistently high in raspberry hosts and fruits with lower penetration force, and the presence of Wolbachia endosymbionts can lower fertility. Drosophila suzukii exhibit seasonal variation with a darker winter morph that is more cold tolerant. Also, D. suzukii likely undergo reproductive diapause in the fall, with colder temperatures and shorter day lengths influencing reproduction. To develop viable IPM programs for D. suzukii, knowledge of abiotic and biotic conditions that impact D. suzukii life history parameters and population dynamics is critical, and gaps in the current knowledge are discussed.
Studies on reproduction of the dragonfishes, Bathydraconidae, are scarce, and within this family, the reproductive biology of Parachaenichthys charcoti was poorly understood. Herein we present a histologic analysis of P. charcoti ovaries together with data on reproductive effort using fish collected with trammel nets in austral summer at Potter Cove, South Shetland Islands (SSI), and compare this information with that reported for the South Georgia congener Parachaenichthys georgianus. In gravid females of P. charcoti, GSI of 16–31%, mature oocytes of 1.8–3.9 mm and total fecundity (TF) of 9025–18,937 oocytes/individual (X ± SD = 12,617 ± 4019, n = 7) were recorded. The histology of the ovaries confirmed the common characteristics of the Notothenioidei observed macroscopically, i.e., two distinct batches of oocytes, one in the previtellogenic stage (primary growing or cortical alveoli stages) and the other in vitellogenesis and likely to be released in the current season. A longer incubation period of P. charcoti compared with P. georgianus is associated to the colder waters at the SSI. Based on our sampling and reproductive effort data, together with the reported nesting behavior for P. charcoti, it is assumed that this species spawns in nearshore, sheltered waters in summer, presumably from late December to February. Spawning periods of both congeners differ from those reported for other notothenioids in the same Seasonal Pack-ice Zone, suggesting divergence in some aspects of the life strategies in the genus Parachaenichthys. Likewise, although there are no substantial differences between P. charcoti and other notothenioids regarding gonadal development, the genus Parachaenichthys shows distinct features in its reproductive strategies (e.g., higher TF) compared with other bathydraconid species.
Development of the parasitoid : the female laid and egg longitudinally between the first and second abdominal sternite of the host larvae (a), the parasitoid larvae developed as semi-ectoparasitoid (b), and spun a cocoon some centimetres away after the host body was devoured (c, d). The overall development time changed significantly between the two sexes of . (Hymenoptera: Bethylidae) is reported as a cosmopolitan parasitoid of coleopteran including a major pest of stored products, the confused flour beetle . The reproductive biology, and hence biocontrol potential of is relatively little known. Here we describe and evaluate aspects of egg size, immature development, adult mating behaviour, pre-oviposition time, fecundity, host attack and use, and adult longevity. Our key findings are that ≈72% of presented immatures presented to females were attacked and ≈39% of these were fed on destructively with the remainder oviposited onto. First instar host larvae and host pupae were only utilized for feeding, second and third instar larvae were commonly used for either feeding or oviposition while fourth, fifth and sixth instar hosts were almost exclusively used for oviposition. Females usually laid single egg clutches and their average lifetime fecundity was ≈16.5 eggs. Females regularly provisioned with hosts often ceased laying eggs up to several weeks before their death but continued to kill and feed on hosts during this period. Adult longevity was greatly enhanced by the provision of hosts (females) or by non-host food sources (males). We conclude that the inoculative biocontrol potential of is likely to be limited by a low realized fecundity and the combination with other control methods in an IPM-approach is needed. Its ability to find and kill hosts may make it more suitable for inundative deployment.
A histological analysis of ovaries was conducted to examine reproductive characteristics of female Pacific bluefin tuna, (Temminck and Schlegel, 1844), in the known spawning ground in the Sea of Japan. A total of 1040 females caught with purse seines were sampled from late May to early August in 2011 and 2012. The spawning season began in mid-June and continued until early August. The sex ratio for the catch in 2012 was nearly 1:1. The estimated spawning time was 1700–2200 h based on the occurrence of 0 h postovulatory follicles. The estimated mean spawning frequency and mean spawning interval were 0.91 per day and 1.10 days, respectively, indicating that mature females spawn nearly every day in the Sea of Japan. The fork lengths at 50% and 95% mature were 114.4 cm and 133.6 cm, respectively. Batch fecundity was positively correlated with fork length, gilled and gutted body weight, and gonad weight. The mean batch fecundity was 6.4 million oocytes, and the mean relative batch fecundity per gilled and gutted body weight was 122 oocytes. This study provides some comprehensive information on reproductive biology of female Pacific bluefin tuna in the Sea of Japan.
The reproductive biology of albacore tuna, Thunnus alalunga, in the western Indian Ocean was examined through analysis of the sex ratio, spawning season, length-at-maturity (L-50), spawning frequency and fecundity. From 2013 to 2015, a total of 923 female and 867 male albacore were sampled. A bias in sex ratio was found in favor of females with fork length (L-F) < 100 cm. Using histological analyses and gonadosomatic index, spawning was found to occur between 10 degrees S and 30 degrees S, mainly to the east of Madagascar from October to January. Large females contributed more to reproduction through their longer spawning period compared to small individuals. The L-50 (mean standard error) of female albacore was estimated at 85.3 +/- 0.7 cm LF. Albacore spawn on average every 2.2 days within the spawning region and spawning months, from November to January. Batch fecundity ranged between 0.26 and 2.09 million oocytes and the relative batch fecundity (mean standard deviation) was estimated at 53.4 +/- 23.2 oocytes g(-1) of somatic-gutted weight. The study provides new information on the reproductive development and classification of albacore in the western Indian Ocean. The reproductive parameters will reduce uncertainty in current stock assessment models which will eventually assist the fishery to be sustainable for future generations.
This study presents information on the reproductive biology of Psammobatis rutrum based on 55 males and 53 females obtained as by‐catch from bottom trawlers off southern Brazil during July 2013 and September 2014 and includes a detailed description of the egg capsule. Total lengths ( L T ) ranged from 22·3 to 31·6 cm and most of the sample comprised larger individuals, although there were no sexual differences in length‐frequency distributions. Significant sexual differences were found for total length‐disc width, L T –body mass and L T –eviscerated body mass relationships, with females being heavier and larger. Males started to mature at 25·5 cm L T and females, at 25·9 cm L T , while L T at maturity was calculated in 26·67 and 26·81 cm, respectively. Attaining larger sizes and mass may represent a reproductive investment for females, as observed in other rajoid species. Egg bearing females were first observed over 27·1 cm L T and ovarian fecundity was 1–12 vitellogenic follicles. The egg capsules were 2·22–2·62 cm length and had attaching fibrils on both lateral sides. Microscopically, the ventral face of the egg capsule was rougher than the dorsal face.
Reproductive characteristics of Aphanius isfahanensis, an Iranian endemic Cyprinodontid fish in the Zayandehrud River were examined. Samples were taken monthly, from June 2016 to May 2017. Some 485 specimens (245 females, 240 males) were caught by a hand net. Age of males and females ranged from 0+ to 2+ years. The largest female and male in total length and weight was 5.36 cm, 2.39 g and 4.49 cm, 1.56 g, respectively. The overall sex ratio was 1 M:1F (p > 0.05). The highest mean gonadosomatic index in females and males was in May (19.19), and July (3.77), respectively. Oocyte diameter ranged from 0.12 to 1.40 mm, and monthly mean oocyte diameter were significantly different (P < 0.05). The minimum, maximum, and average absolute fecundity was 7, 250 and 120 ± 5SD, respectively. The relative fecundity was 90 ± 30 egg/g body weight. Macroscopic analysis of gonads and gonadosomatic index (GSI) values showed that spawning of A. isfahanensis occurs from April to July with a peak in May and June. Aphanius isfahanensis is a group synchronous spawner and produces more than one oocyte clutch in a single reproductive season.
In this study, we describe the female reproductive cycle of Philodryas patagoniensis in south Brazil, which was described through morpho‐anatomical and histological analyses. The peak of secondary vitellogenesis occurred during winter–spring (July–December), ovulation in spring (October–December), mating and fertilization in spring–summer (October–February), oviposition in spring–autumn (October–May) and births from late spring to autumn (December–July). The diameter of vitellogenic follicles/eggs was larger in winter–spring than in other seasons. The diameter of the shell glands was also larger in winter–spring. In spite of the clear reproductive peak, gonads only showed reduced activity in the autumn. Therefore, at the individual level, females have a discontinuous cyclical reproduction; in the populational level, the reproductive cycle is seasonal semisynchronous. We support the hypothesis that P. patagoniensis have the ability to produce multiple clutches with long‐term stored sperm. Sexual dimorphism in body size was evident, and females are significantly larger and heavier than males. Larger females were able to produce follicles and eggs in larger amount and size. The maternal body size was positively related to the reproductive effort and fecundity. To conclude, we deliberated about the proximal and distal causes that influence the reproductive traits and patterns of P. patagoniensis .