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.
The seasonal developmental rhythm, floral and fruit morphology, anthesis, and fructification of Asarum sieboldii were studied in a natural plant community in the southern part of the Russian Far East. The flower structure was investigated in ditails. It was found that the flower does not have a gynostemium. The flowers are protogynous. At the first anthesis stage, the anthers are closed and cross-pollination may be realized by ants (Hymenoptera) or flies (Dolichopodidae, Diptera). At the second stage of anthesis, there is direct contact of anthers with the pistil stigma and self-pollination occurs. The perianth is involved in the formation of fruit. The fruit is a six-locular, fleshy, half-inferior capsule. Asarum sieboldii has a high productivity of fruits and seeds. The fruit set is 89% after self-pollination. Viable seeds per fruit is 29 ± 2, the seed set is 69 ± 5%. The agents of seed dissemination are ants: Leptothorax acervorum and Myrmica ruginodis (Formicidae, Hymenoptera).
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.
Ascidians are abundant and well-represented members of worldwide benthic communities, including Antarctica and the Arctic. These organisms exhibit different reproductive patterns usually related to a latitudinal gradient, as do many marine invertebrate species. Reproductive seasonality varies from one or two annual peaks in cold and temperate water species to continuous reproduction throughout the year in warm water species. Styela rustica (Linnaeus 1767) and Halocynthia pyriformis (Rathke 1806) are solitary species with external fertilization and a wide distribution range, from the North Atlantic to the Arctic. The reproductive patterns of these two species were assessed for Arctic populations by year-round sampling and structural analysis of the gonads. Both species are hermaphrodites and showed marked seasonality in oocyte maturity and spawning; S. rustica peaked during the boreal summer and H. pyriformis in late spring. The two species also showed marked differences in mature oocyte sizes: H. pyriformis almost doubled those of S. rustica and, while spermatocytes of H. pyriformis were mature year-round, the maturity of male and female gametes was synchronized in S. rustica. The species thus showed an annual reproductive cycle coupled with a higher production period in the ecosystem, but also exhibited different strategies developed under the same environmental pressures.
Durvillaea antarctica (Chamisso) Hariot is a large kelp commonly found on the exposed rocky shores of the Chilean coastline. It is endemic to the Southern Hemisphere and is used for direct consumption in the human diet and for alginate extraction; it is commonly known as “cochayuyo” (word from Chilean indigenous population “Mapudungun” language). The species occurs in the sub-Antarctic region and is found from Coquimbo (30° S) to Cape Horn (56° S). This study investigates and describes the seasonal reproductive strategies of D. antarctica located in the far south of the Chilean coast, in the region of the Magallanes (51–56° S), Chile, during the period of a year. Samples were taken in quadrants of 10 m2 parallel to the coastline in the intertidal zone of three locations during consecutive seasons. Both the phenological stages and the different states of maturity in individuals were determined. These findings were used to describe the main characteristics of the reproductive cycle and the spatial heterogeneity that may exist between the reproductive processes within each studied area. The results indicate that in all three studied localities of D. antarctica reproductive individuals are present throughout the year. The largest amount of reproductive individuals tends to exist in autumn and winter, with the numbers subsequently decreasing in spring and summer. In all studied localities, it was possible to identify male and female non-reproductive individuals. The largest number of male and female plants in the studied populations was found from autumn to winter; however, there were shifts in the proportions during these periods that lead to an increase in male over female fronds. In all localities, both male and female individuals in different stages of maturity were found, with the level of maturity depending on locality and season. Mature fronds were found more frequently during autumn and winter although the measures of maturity vary between different localities. Based on these results we conclude that D. antarctica is a species with present reproductive individuals throughout the year, similar to populations of this species described for other sub-Antarctic latitude. It is possible that there could be a cryptic species in the region, presenting morphological and reproductive variability that did not agree well with the circumscription of the species. Therefore, studies of ecophysiological and molecular aspects are needed to clarify the taxonomic status of this species in the sub-Antarctic region of Magallanes.
Members of Oncidiinae are widely known for their interactions with oil-collecting bees that explore lipophilic secretions on flowers. They may also be pollinated through food deception and the offering of nectar. Although data on breeding systems are available for many Oncidiinae orchids, little is known about the reproductive strategies in Rodriguezia, a neotropical genus of ca. 55 species. In this paper, we explore the reproductive biology of two species of Rodriguezia with distinctive morphologies: R. decora and R. lanceolata. Floral features, spectral reflectance, pollinators and pollination mechanisms, and breeding systems were studied. Both species are scentless and produce nectar as a reward. Floral nectar is secreted by a gland at the base of the labellum and stored into the sepaline spur. Rodriguezia decora reflects mainly in the blue and red regions of the light spectrum, while R. lanceolata reflects in the red region. Rodriguezia decora is exclusively visited and pollinated by butterflies, while Trochilidae hummingbirds are the pollinators of R. lanceolata. Pollinaria attach to the upper third of the proboscis of butterflies (R. decora), and to the bill of hummingbirds (R. lanceolata), during the collection of nectar from the spur. Both Rodriguezia species are self-sterile. Flower features and floral reflectance support the occurrence of psychophily in R. decora and ornithophily in R. lanceolata.
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.
Carinotetraodon travancoricus, is endemic to rivers of Western Ghats of India and supports a lucrative export trade of live aquarium fishes from India. Aspects of its reproduction are studied from fishes collected from the Pampa River, South India. Among 966 fishes analyzed females predominated in March and males in May. However, the overall sex ratio was close to 1 : 1. Ripe gonads could be encountered in almost all months, but registered significantly higher preponderances during May to August. A total length of 18.33 mm is observed as the size at first maturity in males and 18.0 mm in females. Highest mean gonadosomatic index was recorded in August (1.4%) in males and in June in females (6.1%). Significant variation in oocyte diameter among different ovary maturity stages has been observed. Primary oocytes at the previtellogenic stages, oocytes with perinulceolar stage as well as with advanced vitellogenic stage were present in ripe ovaries, indicating asynchronous maturation. The absolute fecundity ranges from 139 (21 mm TL) to 480 (29 mm TL). The present results indicate that though fishes with ripe gonads occur throughout the year, the peak spawning period for C. travancoricus inhabiting the Pampa River extends from May to August concurring with South-West monsoon period.
The reproductive biology of Epinephelus morio (red grouper) and Mycteroperca bonaci (black grouper) were evaluated based on 533 specimens collected from artisanal fisheries landings in the Abrolhos Bank, Brazil, between May 2005 and September 2012. Sex ratio for the black grouper was 1:14 (n = 155 females and 11 males; 26.1–147 cm TL) and 1:10 for the red grouper (n = 334 females and 33 males; 15.0–96.0 cm TL). For both species, highest values of the gonadosomatic index (GSI) for females were recorded between July and October, indicating spawning during the austral winter. The length at first maturity (L50) for females was estimated at 62.0 and 47.0 cm TL for the black and red grouper, respectively. Batch fecundity based on TL and TW ranged from 2 to 15.4∗106 and 1.5 to 13.7∗106 for the black and red grouper, respectively. Interviews with experienced fishers revealed that spawning seasons of both groupers are largely unrecognized. Results demonstrate a positive relationship between GSI peaks, lower temperatures and stronger winds. The information provided herein may help decision-making regarding fisheries management and conservation for E. morio and M. bonaci at various levels of governance in the Abrolhos Bank, the region with the largest and richest coralline reefs in the South Atlantic.