Search

In mid‐May, 2019, the fall armyworm (FAW) Spodoptera frugiperda invaded Jiangxi Province, China, and caused extensive damage to corn crops. However, little attention has been given to the life‐history traits of the FAW. In the present study, we systematically investigated the life‐history traits of the newly invasive FAW on corn leaves at 19, 22, 25, 28, and 31°C under a photoperiod of LD 15:9 hr. The FAW thrived on the corn leaves with short developmental periods, high survival rates of larvae and pupae, very high mating success rates, and high fecundity. The pupal developmental stage was significantly longer in males than females at all temperatures, thus resulting in a protogyny phenomenon. The pupal weight was heaviest after a relatively shorter larval development stage at a higher temperature (25°C); thus, the FAW did not follow the temperature–size rule. Females were smaller than males, indicating sexual size dimorphism. A small proportion of females delayed their pre‐oviposition period and began to lay eggs on the 7th to 9th day after adult emergence. There were positive relationships between pupal weight and larval developmental time and between adult weight and fecundity. There was a negative relationship between fecundity and longevity. These findings can help us to predict the population dynamics of the FAW on corn and to develop a suitable and practical management strategy.

Orientador : Irani Quagio-Grassiotto Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia Resumo: Os peixes teleósteos exibem vários padrões sexuais durante sua ontogenia, nos quais as gõnadas se transformam em ovários ou testículos funcionais. Nas distintas Ordens podem ser encontradas espécies gonocóricas, assim como hermafroditas, tanto simultâneas quanto seqüenciais ou consecutivas. No hermafroditismo seqüencial (protândrico ou protogínico), a mudança de sexo nos indivíduos adultos envolve a degeneração do tecido gonadal do primeiro sexo e o crescimento e maturação do tecido do sexo oposto, passando por uma fase de intersexo. Nas espécies hermafroditas protogínicas, mais frequentemente observada nos teleósteos, os individuos desenvolvem-se como fêmeas e, posteriormente, na vida adulta, seus ovários funcionais são substituídos por testículos, transformando-as em machos reprodutivamente ativos. Fatores internos e externos (ambientais) parecem controlar a mudança de sexo nas espécies hermafroditas seqüenciais. Nos vertebrados, o funcionamento do sistema reprodutor envolve o sistema nervoso e complexas vias de feedback hormonais, ambos integrados no chamado eixo hipotalâmico-hipofisário-gonadal. Nos peixes teleósteos, os esteróides sexuais, assim como os hormônios hipotalâmicos e adenohipofisários são considerados os principais fatores que controlam o desenvolvimento sexual gonadal, e podem estar envolvidos na inversão de sexo em espécies hermafroditas. Synbranchus marmoratus é um peixe hermafrodita protogínico diândrico e, na busca das possíveis correlações entre as alterações morfológicas gonadais e variações plasmáticas dos esteróides sexuais, observou-se que, na dependência do grau de decréscimo da oogênese e aumento da atividade do tecido masculino, o processo de inversão de sexo foi dividido em três fases: inicial, intermediária e final. A gõnada transicional de S. marmoratusfoi caracterizada pela a) desorganização da estrutura típica ovariana; b) massiva degeneração de células germinativas femininas; c) surgimento das células germinativas masculinas iniciais nas bordas das lamelas ovigeras, em associação com prováveis células de Sertoli; d) intensa proliferação e migração de células mióides; e) intensa atividade macrofágica, com a presença de melanomacrófagos e centros melanomacrofágicos; e f) aparecimento de grupos de células de Leydig no compartimento intersticial. As células de Leydig constituíram estruturas masculinas pioneiras a surgirem no ovário, então considerada gônada transicional inicial. Assim, estas células foram consideradas marcadores mortológicos e funcionais do processo de inversão sexual nesta espécie. As células de Leydig apresentaram as típicas características ultraestruturais associadas à esteroidogênese, bem como alta atividade esteroidogênica (3j3-HSD),provavelmente, produzindo andrógenos necessários ao desenvolvimento do tecido masculino gonadal e à espermatogênese. Na fase intermediária, a arquitetura masculina gonadal começa a ser definida, com a proliferação de numerosos cistos com células germinativas em diferentes fases de desenvolvimento. Nas gônadas transicionais finais, apenas poucos oócitos em degeneração e centros melanomacrofágicos permanecem. A mortologia da gônada transicional nesta fase é caracterizada pela completa formação das "lamelas testiculares" e dos túbulos seminíferos, os quais podem ser classificados como do tipo lobular irrestrito. Em nível hormonal, o início da transição sexual está associado à diminuição dos níveis plasmáticos de 17'beta'-estradiol, e o aumento da testosterona circulante, sugerindo a implicação destas circunstâncias para dar início à inversão de sexo natural em S. marmoratus. Os níveis plasmáticos de 11-cetotestosterona apenas sofrem baixas variações durante o início e progresso do referido processo, indicando um papel secundário deste andrógeno na inversão de sexo em S. marmoratus. A identificação das células adenohípofisárias de S. marmoratus durante a inversão de sexo não mostra qualquer alteração no padrão de imunomarcação das células produtoras dos diferentes hormônios ao longo do processo, excetuando-se as células gonadotrópicas, cuja atividade de síntese foi bastante alta nos intersexos iniciais. Provavelmente, estas células ofereçam suporte hormonal para a inversão de sexo nessa espécie. Assim, a inversão de sexo em S. marmoratus parece ocorrer sob controle do eixo hipotalâmico-hipofisário-gonadal. Por sua vez, as alterações morto lógicas necessárias à efetivação do processo propriamente dito - desestruturação do tecido gonadal feminino e desenvolvimento do tecido do sexo oposto - são gradualmente promovidas, seja pela falta ou escassez de estrógenos, e/ou pelo aumento dos níveis de andrógenos. Por conseguinte, S. marmoratus constitui um excelente modelo para o estudo dos eventos morto-funcionais da inversão de sexo Abstract: Teleost fishes exhibit several sexual patterns during their ontogeny, in which the gonads change into functional ovaries or testes. In distinct Orders, both gonochoristic and hermaphrodite species, simultaneous as well as sequential or consecutive, can be found. In sequential hermaphroditism (protandrous or protogynous), sex change in adult individuais involves the degeneration of the primary sex gonadal tissue and the growth and maturation of the opposite sex, passing through an intersex phase. In protogynous hermaphrodite species, most frequently observed in teleosts, individuais first develop into females and later, at adulthood, their functional ovaries are gradually replaced by testes, becoming them into active reproductively males. Internal and external (environmenta) factors seem to control the sex change in sequential hermaphrodite species. In vertebrates, the dynamic of reproductive system involves the nervous system and complex hormonal biosynthetic pathways, all of them integrated in the called brain-pituitary-gonad axis. In teleost fish, sex steroids, as well as brain and pituitary hormones, are considered to be the main factors controlling gonadal sex development, and may be involved in sex reversal in hermaphrodite species. Synbranchus marmoratus is a protogynous diandric fish. Depending on the degree of female gametogenesis decrease and male tissue activity increase, the sex reversal process was divided into three phases: early, intermediate, and final. S. marmoratus transitional gonad was characterized by the: a) disorganization of the typical ovarian structure; b) massive degeneration of the female germ cells; c) appearance of initial male germ cells . at the border of ovigerous lamellae in association with putative Sertoli cells; d) intense proliferation and migration of myoid cells; e) intense macrophage activity with the presence of melanomacrophages and melanomacrophage centers; and f) appearance of clusters of Leydig cells in the interstitial compartment. Leydig cells constitute the pioneer male structures to arise in the ovary, considered the early transitional gonad at this point. Thus, these cells were considered morphological and functional markers of the sex reversal process in this species. Leydig cells presented the typical fine structures associated to steroidogenesis, such as high steroidogenic activity (3'beta'-HSD), probably, producing androgens necessary to development of gonadal male tissue, and spermatogenesis. In the intermediate phase, the male gonadal architecture begins to be defined, with the proliferation of numerous spermatocysts containing germ cells at different developmental stages. In final transitional gonads, only few degenerating oocytes and melanomacrophage centers remain. The morphology of transitional gonad at this phase is characterized by the complete formation of the testicular lamellae and the seminiferous lobules, which can be classified as unrestricted lobular type. At hormonal level, the beginning of the sexual transition is associated with the decrease of plasma estradiol-17 'beta' levels and the increase of circulating testosterone, suggesting the implication of such circumstances to trigger the natural sex change in S. marmoratus. Plasma 11-ketotestosterone levels onlysuffered weak variations during the initiation and progress of such process, which may indicate the secondary role of this androgen in S. marmoratus sex reversal. The identification of the adenohypophyseal cells of Synbranchus marmoratus during sex reversal does not show any alteration in the immunomarcation pattern of secretory cells of different hormones during the process, except for gonadotropin-producing oolls, which synthesis activity was very high in the initial intersexes. Probably, these cells offer hormonal support for sex reversal in this species. Therefore, sex reversal in S. marmoratus seems to occur under hypothalamic-hypophyseal-gonadal axis control. Morphological alterations necessary to sex reversal process accomplishment - disorganization of female gonadal tissue and development of the tissue of opposite sex - are gradually promoted by the estrogens privation, and/or by the androgens levels increase. Therefore, S. marmoratus constitutes an excellent model for the studying of morpho-functional eventsof sex change Doutorado Biologia Celular Doutor em Biologia Celular e Estrutural

In mid‐May, 2019, the fall armyworm (FAW) Spodoptera frugiperda invaded Jiangxi Province, China, and caused extensive damage to corn crops. However, little attention has been given to the life‐history traits of the FAW. In the present study, we systematically investigated the life‐history traits of the newly invasive FAW on corn leaves at 19, 22, 25, 28, and 31°C under a photoperiod of LD 15:9 hr. The FAW thrived on the corn leaves with short developmental periods, high survival rates of larvae and pupae, very high mating success rates, and high fecundity. The pupal developmental stage was significantly longer in males than females at all temperatures, thus resulting in a protogyny phenomenon. The pupal weight was heaviest after a relatively shorter larval development stage at a higher temperature (25°C); thus, the FAW did not follow the temperature–size rule. Females were smaller than males, indicating sexual size dimorphism. A small proportion of females delayed their pre‐oviposition period and began to lay eggs on the 7th to 9th day after adult emergence. There were positive relationships between pupal weight and larval developmental time and between adult weight and fecundity. There was a negative relationship between fecundity and longevity. These findings can help us to predict the population dynamics of the FAW on corn and to develop a suitable and practical management strategy., Fall armyworm thrived on the corn leaves with short developmental periods, high survival rates, high fecundity, etc., indicating that the species can easily adapt to a new environment wherever it invades.

Seagrasses form extensive meadows in shallow coastal waters and are among the world's most productive ecosystems. Seagrasses can produce both clonally and sexually, and flowering has long been considered infrequent, but important for maintaining genetically diverse stands. Here we investigate the molecular mechanisms involved in flowering of the seagrass Posidonia oceanica, an iconic species endemic to the Mediterranean. We generated a de novo transcriptome of this non-model species for leaf, male and female flower tissue of three individuals, and present molecular evidence for genes that may be involved in the flowering process and on the reproductive biology of the species. We present evidence that suggests that P. oceanica exhibits a strategy of protogyny, where the female part of the hermaphroditic flower develops before the male part, in order to avoid self-fertilization. We found photosynthetic genes to be up-regulated in the female flower tissues, indicating that this may be capable of photosynthesis. Finally, we detected a number of interesting genes, previously known to be involved in flowering pathways responding to light and temperature cues and in pathways involved in anthocyanin and exine synthesis. This first comparative transcriptomic approach of leaf, male and female tissue provides a basis for functional genomics research on flower development in P. oceanica and other seagrass species.

In the common sandpiper both sexes do not participate equally in brood rearing. The attendance of females progressively declines and by the third week after hatching, most of them leave their broods. To check if this unequal parental care results in different migration phenology of males and females, adult common sandpipers were caught at four ringing sites in Poland during their autumn migration and were sexed using a discriminant equation. The median date of female migration was 6 days earlier than that of males. In the first days of July, males comprised only 22% of common sandpipers caught, while later their percent share increased gradually and in August reached up to 80% of captured birds. However, birds of both sexes were present among migrants during the whole migration period and migration period of both sexes overlapped to a great extent. Most probably birds migrating through the study area came from a vast breeding area, where the period of egg laying differs between its northernmost and southernmost parts by at least 1 month.

This paper describes the vegetative and reproductive morphology of Cabombaceae species in Brazil, discussing its strategies for survival in an aquatic habitat. Through studies in the field, in cultivation and in the herbarium, we examined the following species: Cabomba aquatica, C. caroliniana, C. furcata and C. haynesii. In cultivation, only C. aquatica, C. furcata and C. haynesii produced flowers. In those three species, the flowers opened during the day on two consecutive days, submerging during the night, although the stigmata of the first two were receptive only on the first day, their anthers dehiscing on the following day. The flowers of C. haynesii remained unreceptive on the first day of anthesis, the stigmata and anthers maturing only on the second day, at different times. Fruit developed when the flowers were submerged. The data provided here are useful for the identification of these species, as well as laying the groundwork for future taxonomic and ecological studies.

Background and aims This paper is about pollen ecophysiology, anther opening, pollen dispersal and the timing of the male and female phases in Parietaria judaica (Urticaceae). Methods Ecophysiological (effects of different relative humidities (RHs) and osmotic relationships) and cytological methods (stigmatic receptivity, pollen viability, histology and histochemistry) were used to determine pollen and pollination features during the long blooming period of this species. Key results Pollen is dispersed by rapid uncurling of the filament and anther opening. The filament and anther lack cells with lignified wall thickenings, which are usually responsible for anther opening and ballistic pollen dispersal. Instead, dispersal is the result of the sudden movement of the filament. Pollen is of the partially hydrated type, i.e. with a water content greater than 30% at shedding, and readily loses water, and hence viability, at low RH. Pollen carbohydrate reserves differ with season. Starchless grains germinate quickly and are less subject to water loss. Flowers are protogynous, pollen release occurring only after complete cessation of the female phase within an inflorescence. Conclusion Parietaria has partially hydrated pollen which differs from typical pollen of this type because of its reduced size and the absence of callose. Because of its low water content at the time of shedding it survives better at higher RH. Dispersal and pollination are adapted to pollen features.

In order to understand the differences of life-history traits between diapause and direct development individuals in the cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), the development time, body size, growth rate, and adult longevity were investigated between the two populations, which were induced under 12:12 L:D and 16:8 L:D photoperiods, respectively, at 20, 22, and 25°C. The results indicated that the larval development time, pupal weight, adult weight, and growth rate were significantly different between diapause and direct developing individuals. The diapause developing individuals had a significantly higher pupal and adult weight and a longer larval time compared with direct developing individuals. However, the growth rate in diapause developing individuals was lower than that in the direct developing individuals. Analysis by GLM showed that larval time, pupal and adult weight, and growth rate were significantly influenced by both temperature and developmental pathway. The pupal and adult weights were greater in males than females in both developmental pathways, exhibiting sexual size dimorphism. The dimorphism in adult weight was more pronounced than in pupal weight because female pupae lost more weight at metamorphosis compared to male pupae. Protogyny was observed in both developmental pathways. However, the protogyny phenomenon was more pronounced at lower temperatures in direct developing individuals, whereas it was more pronounced in diapause developing individuals when they experienced higher temperatures in their larval stage and partial pupal period. The adult longevity of diapause developing individuals was significantly longer than that of direct developing individuals. The results reveal that the life-history strategy was different between diapause and direct developing individuals.

A variety of field studies suggest that sex change in animals may be more complicated than originally depicted by the sizeadvantage hypothesis. A modification of the size-advantage hypothesis, the expected reproductive success threshold model, proposes that sperm competition and size-fecundity skew can strongly affect reproductive pay-offs. Size-fecundity skew occurs if a large female’s fecundity is markedly higher than the aggregate of the other members of her social group and, together with paternity dilution from sperm competition, can produce situations in which large females benefit by deferring sex change to smaller females. Deferral by large females can create sex-size distributions characterized by the presence of large females and small sex-changed males, and it is precisely these distributions that the traditional size-advantage model cannot explain. We tested the predictions of the new model with the bucktooth parrotfish, Sparisoma radians, on coral reefs in St. Croix, U.S. Virgin Islands. Collections and spawning observations determined that the local environmental regime of S. radians is characterized by pervasive sperm competition (accompanying 30% of spawns) and factors that can produce substantial size-fecundity skew in social groups. Dominant male removal experiments demonstrate that the largest females in social groups often do not change sex when provided an opportunity. Instead, smaller, lower-ranking females change sex when a harem vacancy arises. This pattern of sex change is in contrast to virtually all previous studies of social control of sex change in fishes, but provides strong support for the general predictions of the expected reproductive success threshold model. Key words: coral reefs, Labridae, protogyny, Scaridae, seagrass beds, size-fecundity skew, social control of sex change, sperm competition. [Behav Ecol 15:129–136 (2004)]

39 Pags., Figs. The definitive version is available at: http://www.amjbot.org/, • Premise of the study: Factors affecting floral receptivity in angiosperms remain opaque, but recent studies suggest that the acquisition of stigmatic receptivity associated with cell-wall-related arabinogalactan proteins (AGPs) may be a widespread feature of flowering plants. Here, the time during which a stigma is receptive is evaluated and related to the secretion of AGPs in Magnolia virginiana, a protogynous member of an early-divergent angiosperm clade (magnoliids) with a clearly discernible female receptive phase. • Methods: Magnolia virginiana flower phenology was documented, and histochemical changes in the stigma before and after pollination were examined. Stigmatic receptivity was evaluated in relation to the secretion of AGPs detected in whole mounts and immunolocalized in sectioned stigmas. • Key results: Protogynous Magnolia flowers had a precise window of stigmatic receptivity, which is concomitant with the secretion of two AGPs labeled for different epitopes. After pollen germination and tube growth, these two AGPs could no longer be detected in the stigmas, suggesting that these AGPs interact with the growing male gametophytes and could be markers of stigmatic receptivity. • Conclusions: These results show that the period of stigmatic receptivity is finely coordinated with the secretion of two arabinogalactan proteins on stigmas of flowers of M. virginiana. This first report of AGP presence in stigmatic tissues in a member of the magnoliids, together with recently described similar patterns in eudicots, monocots, and members of early-divergent lineages of flowering plants, suggests an ancient and widespread role for AGPs on stigmatic receptivity in angiosperms., J.M.L. has been supported by an FPI fellowship from the Spanish Ministry of Science and Innovation, a Deland Award for student research and a Putnam Scholar Award, both from the Arnold Arboretum of Harvard University. Research was supported in part by NSF grants to W.E.F. (IOS-0919986) and by grants from the Spanish Ministerio de Economía y Competitividad to M.H. (AGL2012-40239) and J.I.H. (AGL2013-43732-R).