High Fecundity Research Articles

High-throughput measurement of plant fitness traits with an object detection method using Faster R-CNN.

Summary Revealing the contributions of genes to plant phenotype is frequently challenging because loss‐of‐function effects may be subtle or masked by varying degrees of genetic redundancy. Such effects can potentially be detected by measuring plant fitness, which reflects the cumulative effects of genetic changes over the lifetime of a plant. However, fitness is challenging to measure accurately, particularly in species with high fecundity and relatively small propagule sizes such as Arabidopsis thaliana.An image segmentation‐based method using the software ImageJ and an object detection‐based method using the Faster Region‐based Convolutional Neural Network (R‐CNN) algorithm were used for measuring two Arabidopsis fitness traits: seed and fruit counts.The segmentation‐based method was error‐prone (correlation between true and predicted seed counts, r 2 = 0.849) because seeds touching each other were undercounted. By contrast, the object detection‐based algorithm yielded near perfect seed counts (r 2 = 0.9996) and highly accurate fruit counts (r 2 = 0.980). Comparing seed counts for wild‐type and 12 mutant lines revealed fitness effects for three genes; fruit counts revealed the same effects for two genes.Our study provides analysis pipelines and models to facilitate the investigation of Arabidopsis fitness traits and demonstrates the importance of examining fitness traits when studying gene functions.

Predicting spatially heterogeneous invasive spread: Pyracantha angustifolia invading a dry Andean valley in northern Argentina

Understanding the drivers of invasive species spread is key to designing optimal management programmes for controlling them. Population models, parameterized from demographic and dispersal data, are useful for simulating invasion when long-term observations are lacking, which is particularly important when invasions are occurring rapidly. We aimed to understand how the spread of Pyracantha angustifolia (an invasive ornamental shrub) is influenced by heterogeneity in local conditions within a dry inter-montane valley in northwestern Argentina that is currently experiencing rapid urban expansion and concomitant reduction in cattle farming. Field surveys demonstrated that individuals growing in shrublands have a higher fecundity than those in grassland and rocky habitats. Furthermore, grazing pressure of cattle and horses substantially reduces fecundity and impacts the relationship between age and fecundity. We incorporated our field-estimated habitat and age-specific fecundities into both analytical integro-difference equation models and individual-based models to predict rates of spread across each habitat type in the presence or absence of grazing pressure. Results indicate that the rate of spread would be substantially higher in shrublands (by up to 33%) and highlight that grazing pressure can, through direct consumption of seeds by livestock, substantially depress the rate of spread (by up to 53%). These results suggest that shrubland areas in the valley are most vulnerable to invasion and that grazing may help to reduce the impact of Pyracantha. This suggests that a synergism between urban expansion and reduction in domestic livestock density contributes to the spread of an invasive species in this environment.

Effects of domestication on quality control parameters of the Queensland fruit fly Bactrocera tryoni (Diptera: Tephritidae)

AbstractThe Queensland fruit fly (Q‐fly), Bactrocera tryoni (Froggatt), is a major horticultural pest in Australia. Sterile insect technique (SIT) is increasingly used in area‐wide integrated management of Q‐fly, as well as for eradication of outbreaks in Q‐fly‐free regions. Quality control (QC) procedures are important to monitor and maintain high standards of mass‐reared insects for SIT. Effective use of QC procedures, and the setting of meaningful standards, requires a clear understanding of the short‐term factors that can cause changes in key parameters, such as failures in production systems, and also of the longer‐term effects of domestication on the performance of mass‐reared colonies. Artificial rearing conditions impose substantial selection pressures that can lead to changes in performance, and hence changes in the expected baseline values in QC assays. We investigated the effects of domestication on QC parameters of old and young Q‐fly colonies originating from three distant geographical locations in Australia: Sydney (Generation >100 and 7), Brisbane (Generation 59 and 14) and Cairns (Generation 29 and 9). Standard QC parameters including development time, pupal recovery, pupal weight, adult emergence, sex ratio, flight ability, fecundity, egg hatchability and longevity were assessed. Regardless of their origin, older Q‐fly colonies had lower egg hatchability, shorter developmental time, higher fecundity, higher survival under stress and greater longevity. We emphasize the importance of understanding the effects of continued domestication on QC measures when setting standards for assessment of fruit fly strains used in SIT programmes, particularly when using strains that are regularly replaced or infused with wild stock.

Different effects of warming treatments in forests versus hedgerows on the understorey plant Geum urbanum

ABSTRACT The effectiveness of hedgerows as functional corridors in the face of climate warming has been little researched. Here we investigated the effects of warming temperatures on plant performance and population growth of Geum urbanum in forests versus hedgerows in two European temperate regions. Adult individuals were transplanted in three forest–hedgerow pairs in each of two different latitudes, and an experimental warming treatment using open‐top chambers was used in a full factorial design. Plant performance was analysed using mixed models and population performance was analysed using Integral Projection Models and elasticity analyses. Temperature increases due to open‐top chamber installation were higher in forests than in hedgerows. In forests, the warming treatment had a significant negative effect on the population growth rate of G. urbanum. In contrast, no significant effect of the warming treatment on population dynamics was detected in hedgerows. Overall, the highest population growth rates were found in the forest control sites, which was driven by a higher fecundity rather than a higher survival probability. Effects of warming treatments on G. urbanum population growth rates differed between forests and hedgerows. In forests, warming treatments negatively affected population growth, but not in hedgerows. This could be a consequence of the overall lower warming achieved in hedgerows. We conclude that maintenance of cooler forest microclimates coul, at least temporarily, moderate the species response to climate warming.

Some aspects of the reproductive biology of Labeo victorianus (Boulenger, 1901) from Kuja-Migori River basin, Kenya

Labeo victorianus is an endemic species to Lake Victoria basin and also a species threatened with extinction status. This study investigated reproductive biology of L. victorianus from Kuja- Migori River basin, Kenya with a view to determining the length weight relationship (LWR), condition factor, fecundity, egg diameter gonado-somatic index (GSI), length at 50% maturity (LM50) and sex ratio. Sampling was done by electrofishing from January 2018 to June 2019. The LWR showed a negative allometric pattern (p < 0.05). The mean condition factor for combined sexes was 1.02. Fecundity ranged from 47842 – 101902 eggs (mean ± SD: 83663 ± 2605 eggs) and correlated highly with body size (r2 = 0.9137). Egg diameter ranged from 0.5 – 0.7 mm. Mean GSI was 6.3 ± 1.6 and 2.8 ± 0.45 for females and males respectively. The LM50 was estimated at 18 cm total length (TL) and 20 cm TL for males and females respectively. Sex ratio did not differ from the expected 1:1. This species has a high fecundity with small sized eggs and males attain sexual maturity earlier than females. The findings of this study provide useful information towards sustainable conservation of L. victorianus in the Lake Victoria basin.

The psychoactive effects of Bryophyllum pinnatum (Lam.) Oken leaves in young zebrafish.

Bryophyllum pinnatum (Lam.) Oken (BP) is a plant that is used worldwide to treat inflammation, infections, anxiety, restlessness, and sleep disorders. While it is known that BP leaves are rich in flavonoids, the extent of the beneficial and toxic effects of its crude extracts remains unclear. Although some neurobehavioral studies using leaf extracts have been conducted, none has examined the effects of water-extracted leaf samples. The zebrafish is a powerful animal model used to gain insights into the efficacy and toxicity profiles of this plant due to its high fecundity, external development, and ease of performing behavioral assays. In this study, we performed behavioral testing after acute exposure to different concentrations of aqueous extract from leaves of B. pinnatum (LABP) on larval zebrafish, investigating light/dark preference, thigmotaxis, and locomotor activity parameters under both normal and stressed conditions. LABP demonstrated dose-and time-dependent biphasic effects on larval behavior. Acute exposure (25 min) to 500 mg/L LABP resulted in decreased locomotor activity. Exposure to 300 mg/L LABP during the sleep cycle decreased dark avoidance and thigmotaxis while increasing swimming velocity. After sleep deprivation, the group treated with 100 mg/L LABP showed decreased dark avoidance and increased velocity. After a heating stressor, the 30 mg/L and 300 mg/L LABP-treated groups showed decreased dark avoidance. These results suggest both anxiolytic and psychoactive effects of LABP in a dose-dependent manner in a larval zebrafish model. These findings provide a better understanding of the mechanisms underlying relevant behavioral effects, consequently supporting the safe and effective use of LABP for the treatment of mood disorders.

Pest categorisation of Toumeyella parvicornis.

The EFSA Panel on Plant Health performed a pest categorisation of Toumeyella parvicornis (Cockerell) (Hemiptera: Coccidae) for the EU territory. This species is not included in EU Commission Implementing Regulation 2019/2072. T. parvicornis is a soft‐scale insect native to North America and has been introduced to the Caribbean region and the EU. It has been present in Italy since 2014 (Abruzzo, Campania, Lazio, and Apulia regions) and in France since 2021 (Provence–Alpes–Côte d'Azur region) and is under official control. It develops on Pinus spp. (Pinaceae), feeding on the needles and twigs, especially on new growth. It is sexually reproductive, has one or more generations each year (three in southern Italy), and adult females overwinter on the Pinus needles. It has a high fecundity, up to 1,014 eggs per female in Italy, with an average of 199 eggs for the summer generation and 730 for the overwintering generation. The main natural dispersal stage is the first instar, which crawls over the plant or may be dispersed further by wind and animals. The species can be transported over longer distances with plants for planting. Large populations cause yellowing, needle loss, reduction in growth and recruitment, flagging, dieback and tree mortality. It has had a significant impact to P. pinea (stone pine) in Italy and caused a catastrophic decline of P. caribbea var. bahamensis (Caribbean pine) in the Turks and Caicos Islands. Adult and immature T. parvicornis could enter the EU with Pinus plants for planting; however, the import of Pinus from third countries where the scale is found is prohibited. Host availability and climate suitability indicate that most of the EU would be suitable for establishment. Phytosanitary measures are available to inhibit further introductions and slow the spread within the EU. T. parvicornis satisfies all the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest.

Effects of climate variability on the demography of wild geladas.

Nonhuman primates are an essential part of tropical biodiversity and play key roles in many ecosystem functions, processes, and services. However, the impact of climate variability on nonhuman primates, whether anthropogenic or otherwise, remains poorly understood. In this study, we utilized age‐structured matrix population models to assess the population viability and demographic variability of a population of geladas (Theropithecus gelada) in the Simien Mountains, Ethiopia with the aim of revealing any underlying climatic influences. Using data from 2008 to 2019 we calculated annual, time‐averaged, and stochastic population growth rates (λ) and investigated relationships between vital rate variability and monthly cumulative rainfall and mean temperature. Our results showed that under the prevailing environmental conditions, the population will increase (λ s = 1.021). Significant effects from rainfall and/or temperature variability were widely detected across vital rates; only the first year of infant survival and the individual years of juvenile survival were definitively unaffected. Generally, the higher temperature in the hot‐dry season led to lower survival and higher fecundity, while higher rainfall in the hot‐dry season led to increased survival and fecundity. Overall, these results provide evidence of greater effects of climate variability across a wider range of vital rates than those found in previous primate demography studies. This highlights that although primates have often shown substantial resilience to the direct effects of climate change, their vulnerability may vary with habitat type and across populations.

Oxidative Damage Is Influenced by Diet But Unaffected by Selection for Early Age of Oviposition in the Marula Fly, Ceratitis cosyra (Diptera: Tephritidae).

The expression of life-history traits, such as lifespan or reproductive effort, is tightly correlated with the amount and blend of macronutrients that individuals consume. In a range of herbivorous insects, consuming high protein to carbohydrate ratios (P:C) decreases lifespan but increases female fecundity. In other words, females face a resource-based trade-off between lifespan and fecundity. Redox metabolism may help mediate this trade-off, if oxidative damage is elevated by reproductive investment and if this damage, in turn, reduces lifespan. Here, we test how diets varying in P:C ratio affect oxidative damage and antioxidant protection in female and male of the marula fly, Ceratitis cosyra (Diptera: Tephritidae). We use replicated lines that have been subjected to experimental evolution and differ in their lifespan and reproductive scheduling. We predicted that high fecundity would be associated with high oxidative damage and reduced antioxidant defences, while longer lived flies would show reduced damage and elevated antioxidant defences. However, higher levels of oxidative damage were observed in long-lived control lines than selection lines, but only when fed the diet promoting lifespan. Flies fed diets promoting female fecundity (1:4 and 1:2 P:C) suffered greater oxidative damage to lipids than flies fed the best diet (0:1 P:C) for lifespan. Total antioxidant capacity was not affected by the selection regime or nutrition. Our results reiterate the importance of nutrition in affecting life-history traits, but suggest that in C. cosyra, reactive oxygen species play a minimal role in mediating dietary trade-offs between lifespan and reproduction.

Comparative Transcriptomic Analysis of Hu Sheep Pituitary Gland Prolificacy at the Follicular and Luteal Phases.

The pituitary gland directly regulates the reproduction of domestic animals. Research has increasingly focused on the potential regulatory mechanism of non-coding RNA in pituitary development. Little is known about the differential expression pattern of lncRNAs in Hu sheep, a famous sheep breed with high fecundity, and its role in the pituitary gland between the follicular phase and luteal phase. Herein, to identify the transcriptomic differences of the sheep pituitary gland during the estrus cycle, RNA sequencing (RNA-Seq) was performed. The results showed that 3529 lncRNAs and 16,651 mRNAs were identified in the pituitary gland. Among of them, 144 differentially expressed (DE) lncRNA transcripts and 557 DE mRNA transcripts were screened in the follicular and luteal phases. Moreover, GO and KEGG analyses demonstrated that 39 downregulated and 22 upregulated genes interacted with pituitary functions and reproduction. Lastly, the interaction of the candidate lncRNA XR_001039544.4 and its targeted gene LHB were validated in sheep pituitary cells in vitro. LncRNA XR_001039544.4 and LHB showed high expression levels in the luteal phase in Hu sheep. LncRNA XR_001039544.4 is mainly located in the cytoplasm, as determined by FISH analysis, indicating that XR_001039544.4 might act as competing endogenous RNAs for miRNAs to regulate LHB. LncRNA XR_001039544.4 knockdown significantly inhibited LH secretion and cell proliferation. LncRNA XR_001039544.4 may regulate the secretion of LH in the luteal-phase pituitary gland via affecting cell proliferation. Taken together, these findings provided genome-wide lncRNA- and mRNA-expression profiles for the sheep pituitary gland between the follicular and luteal phases, thereby contributing to the elucidation of the molecular mechanisms of pituitary function.

Optimizing the gonadal performance of broodstock Helostoma temminckii with addition of enrichment ingredients in feed

The problem in the development of Kissing gourami fish culture was quality seeds that cannot be available continuously. Purpose of this research was to examine the need for additional enrichment materials in feed that can optimize the process of gonad maturation of Kissing gourami fish. Treatment A=Commercial feed added with Vegetable Oil, Glutathione, and Egg White; B=Commercial feed added with Vegetable Oil, Vitamin E 300 mg/Kg, Glutathione, and Egg White; C=Commercial feed added with Vegetable Oil, Vitamin E 500 mg/Kg, Glutathione, and Egg White. and D=Commercial feed added with Vegetable Oil, Vitamin E 700 mg/Kg, Glutathione, and Egg White. The results showed that all treatments with the addition of glutathione and vitamin E fortifications with levels of 300 mg-700 mg gave the effect of increasing IGS, IHS, higher fecundity and larger egg diameter than treatment A. The amount of initial IGS increase in treatment A was 33.49%, treatment B was 172.52%, treatment C was 208.60% and treatment D was 691.20%. While the IHS value at the end of the study decreased in treatment A by 35.30% and treatment C which also experienced a decrease in IHS by 26.23%. While in treatments B and D there was a not too large increase, in the range of 42.56% (B) and 5.66% (D).

Notes on Hypericum fasciculatum (Clusiaceae) in South Florida depression marshes: With attention to structural adaptations, to the biological context, and to floral biology1

Hypericum fasciculatum and Stillingia aquatica are abundant codominant shrubs in South Florida depression ponds. Hypericum fasciculatum was studied from multiple perspectives: its competitive context, its adaptations to depression marsh seasonal extremes, and its reproductive biology. Hypericum fasciculatum showed slight intraspecific competition among mature individuals. Its seedling densities diminished with water depths. Interspecific competition with S. aquatica was not detected, probably due in part to markedly divergent root systems. Hypericum fasciculatum is more tolerant of competition from neighboring graminoids than is S. aquatica. The former has wide-spreading sinuous shallow main roots topped with short branch roots rising vertically into the overlying wet substrate. The leaves are dimorphic, with the mature foliage needlelike, having the stomates in abaxial slits. The inner bark is spongy, water-retentive, and substantially thicker than that of other measured local shrubs. Flowering is year-round with usually high fecundity, although flowers abort during drought stress. Seeds per fruit diminished in the wet vs. dry season and with insect-exclusion vs. open pollination. Flowering is protogynous, the buds opening before dawn with the stamens clumped at the base of the style. As the day progresses, the stamens become erect serially with the stigmatic pollen load increasing correspondingly, including with pollinators excluded. Evidence supports extensive self-pollination mixed with entomophily. Insect visitors are diverse.

The Effect of Temperatures and Hosts on the Life Cycle of Spodoptera frugiperda (Lepidoptera: Noctuidae).

Simple SummaryFall armyworm (FAW), Spodoptera frugiperda (J E Smith) (Lepidoptera: Noctuidae) is an invasive worldwide agricultural pest that seriously threatens the safety of grain production. Temperatures and hosts play vital roles in the performance of S. frugiperda. In this study, we studied the effects of three different temperatures (20, 25, and 30 °C) and three different host plants (maize (Zea mays L. (Poaceae)), sorghum (Sorghum bicolor (L.) Moench), and coix seed (Coix lacryma-jobi L.)) on the whole life cycle of S. frugiperda. The results showed that both temperatures and host plants significantly influenced the mortality, developmental time, reproduction, and population parameters of FAW. In the treatment with host plants, the developmental period of S. frugiperda at each stage shortened significantly with the increasing of temperatures. At each temperature, the type of host plant did not affect the development time of S. frugiperda eggs. However, there was no significant difference when S. frugiperda 1st to 6th instar larvae were fed different host plants at 20 °C, while 2nd to 5th instar larvae developed rapidly on maize at 25 and 30 °C. Moreover, there were no significant differences in the longevity of FAW when fed sorghum and coix seed at 20 and 25 °C, but a significant difference in the longevity was observed at 30 °C. Feeding on maize achieved a higher intrinsic rate of increase (r), finite rate of increase (λ), and net reproductive rate (R0) of S. frugiperda at 25 and 30 °C than those FAW fed on sorghum and coix seed.The interactions between ambient temperatures and host plants are central to the population dynamics of invasive animal species. Despite significant research into the effects of temperatures, the performance of invasive species is also influenced by host plants. The effects of different temperatures (20, 25, and 30 °C) and host plants (maize, sorghum, and coix seed) were tested on the mortality, development, reproduction, and population parameters of the fall armyworm (FAW), Spodoptera frugiperda (J E Smith) (Lepidoptera: Noctuidae), using an age-stage, two-sex life table. The results support the hypothesis that temperature and the species of the host plant significantly influences the performance of FAW. Feeding on maize at 30 °C resulted in a lower mortality rate, a shorter developmental time and longevity, a higher fecundity, intrinsic rate of natural increase (r), finite rate of increase (λ), and net reproductive rate (R0). However, at 20 °C, the host plant could eliminate temperature-mediated synergism in FAW performance, which did not reach statistical significance at 20 °C. Similar results induced by a relatively low temperature (20 °C) on different host plants were also found in the age-stage specific survival curves (sxj), fecundity (mx), maternity (lxmx), and reproductive value (vxj) curves of FAW. Consequently, we also need to pay more attention to FAW outbreaks on different host plants mediated by relatively low temperatures.

Propagule size and sex ratio influence colonisation dynamics after introduction of a non-native lizard.

The composition of founding populations plays an important role in colonisation dynamics and can influence population growth during early stages of biological invasion. Specifically, founding populations with small propagules (i.e. low number of founders) are vulnerable to the Allee effect and have reduced likelihood of establishment compared to those with large propagules. The founding sex ratio can also impact establishment via its influence on mating success and offspring production. Our goal was to test the effects of propagule size and sex ratio on offspring production and annual population growth following introductions of a non-native lizard species (Anolis sagrei). We manipulated propagule composition on nine small islands, then examined offspring production, population growth and survival rate of founders and their descendants encompassing three generations. By the third reproductive season, per capita offspring production was higher on islands seeded with a relatively large propagule size, but population growth was not associated with propagule size. Propagule sex ratio did not affect offspring production, but populations with a female-biased propagule had positive growth, whereas those with a male-biased propagule had negative growth in the first year. Populations were not affected by propagule sex ratio in subsequent years, possibly due to rapid shifts towards balanced (or slightly female biased) population sex ratios. Overall, we show that different components of population fitness have different responses to propagule size and sex ratio in ways that could affect early stages of biological invasion. Despite these effects, the short life span and high fecundity of A. sagrei likely helped small populations to overcome Allee effects and enabled all populations to successfully establish. Our rare experimental manipulation of propagule size and sex ratio can inform predictions of colonisation dynamics in response to different compositions of founding populations, which is critical in the context of population ecology and invasion dynamics.

Exposure of Copper Nano-Particles (CuNPs) Impairs Developmental Stages and Hatchability in the Fresh Water Snail Indoplanorbis exustus (Planorbidae: Pulmonate)

Pollution of water bodies by humans, in our day-to-day activities impairs the quality of water, thereby making the water sources unsuitable for aquatic fauna and also for human health. Various sources of pollutants in excess may negatively affect the diversity of living organisms. The evolving growth of nanotechnology has attracted a great deal of attention due to its concern in assessing their environmental and health safety. The present study was conducted to investigate toxicity of copper nanoparticles (CuNP) on the development of fresh water snail Indoplanorbis exustus. Acclimatized snails were exposed to increasing concentration of CuNP for 96 h and acute toxicity experiment was carried out to determine LC50, followed by exposure of snails to sublethal concentrations of CuNP to observe developmental deformities and to estimate percentage hatchability and survivability of young ones. The projected LC50 value for 96h of CuNPs was found to be 5.8mg/L, followed by exposure to sub-lethal concentrations of 1/6th(0.96mg/L), 1/5th(1.16mg/L), 1/4th(1.45mg/L), and 1/3th (1.93mg/L). The highest concentration of (1.93mg/L;1/3thof LC50) retarded hatching and caused morphological deformities in the larvae. However, no significant difference was observed in the weight of embryos in 7 days. These results revealed that CuNP exposure at sub lethal concentrations exerted developmental stress.
 HIGHLIGHTS
 
 Most of the invertebrate models used in aquatic toxicity are from phylum Mollusca, the gastropods are considered as the best model organisms for NPs toxicity because they are adapted to various environmental disturbances due to their dual habitat, easy availability, high fecundity, small size, short generation time and adaptability.
 Snails, Indoplanorbis exustus were exposed to increasing concentration of copper nanoparticles (CuNPs) for 96 h and acute toxicity experiment was carried out to determine LC50, followed by exposure of snails to sublethal concentrations of CuNPs to observe developmental deformities and to estimate percentage hatchability and survivability of young ones
 The highest concentration of (1.93 mg/L; 1/3th of LC50) retarded hatching and caused morphological deformities in the larvae. However, no significant difference was observed in the weight of embryos in 7 days. These results revealed that CuNP exposure at sub lethal concentrations exerted developmental stress on snails

Role of Egg Parasitoids in Controlling the Pine Processionary Moth in the Cedar Forests of Chréa National Park (Algeria)

The sustainable protection of cedar stands in Chréa National Park can only be accomplished through the stability of the ecosystem. Outbreaks of Thaumetopoea pityocampa are a major threat and are largely attributed to the high population fecundity, changes in the diversity of natural enemies and global interactions within the ecosystem. Egg parasitoids (Hymenoptera) are essential in the biological control of T. pityocampa. To assess the impact of the parasitoids on the populations of the pine processionary moth, egg masses from cedar plantations were collected, reared in a laboratory and checked regularly for the emergence of the egg parasitoids: Trichogramma embryophagum, Baryscapus servadeii and Ooencyrtus pityocampa. Observations showed an inter-annual variation in the abundance of the three parasitoids as a result of the variation in the population density of the processionary moth, and on the underlying effect of temperature. Parasitoids had variable parasitism rates, with yearly averages ranging from 3.86% to 51.14%, dependent on the spatiotemporal distribution of the host populations. The aggregate effect of multiple parasitoid species could optimize control of T. pityocampa in cedar stands.

Effects of primary seed dormancy on lifetime fitness of Arabidopsis thaliana in the field

Background and AimsSeed dormancy determines the environmental niche of plants in seasonal environments, and has consequences for plant performance that potentially go far beyond the seed and seedling stages. In this study, we examined the cascading effects of seed dormancy on the expression of subsequent life-history traits and fitness in the annual herb Arabidopsis thaliana.MethodsWe planted seeds of >200 recombinant inbred lines (RILs) derived from a cross between two locally adapted populations (Italy and Sweden), and both parental genotypes at the native site of the Swedish population in three consecutive years. We quantified the relationship between primary seed dormancy and the expression of subsequent life-history traits and fitness in the RIL population with path analysis. To examine the effects of differences in dormancy on the relative fitness of the two parental genotypes, we planted dormant seeds during the seed dispersal period and non-dormant seeds during the germination period of the local population.Key ResultsIn the RIL population, strong primary dormancy was associated with high seedling survival, but with low adult survival and fecundity, and path analysis indicated that this could be explained by effects on germination timing, rosette size and flowering start. The relationship between primary seed dormancy and germination proportion varied among years, and this was associated with differences in seasonal changes in soil moisture. The planting of dormant and non-dormant seeds indicated that the lower primary dormancy of the local Swedish genotype contributed to its higher germination proportion in two years and to its higher fecundity in one year.ConclusionsOur results show that seed dormancy affects trait expression and fitness components across the life cycle, and suggest that among-year variation in the incidence of drought during the germination period should be considered when predicting the consequences of climatic change for population growth and evolution.

Conservation of genetic resources for sustainable aquaculture

Conservation of genetic resources for sustainable aquaculture

Demography of Tetranychus urticae (Acari: Tetranychidae) under different nitrogen regimes with estimations of confidence intervals

In order to study the effect of nitrogen fertilization on the population growth rate of two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), life table data on common bean, Phaseolus vulgaris L. (Fabaceae), were collected at 25 ± 1 °C, 60 ± 5% RH and a photoperiod of 16:8 (L:D) h. Bean plants were treated with four nitrogen levels (0, 75, 150, and 225 kg N ha-1). Data were analyzed based on the age-stage, two-sex life table. The better performance of T. urticae (e.g., shorter total preadult duration, shorter total preoviposition period, longer adult longevity, more oviposition days, and higher fecundity) were observed with 225 kg N/ha (r = 0.2918 d-1) and 150 kg N/ha (r = 0.2744 d-1). Because the application of nitrogen fertilizer should be aimed to maintain optimal plant physiology while minimizing pest growth (i.e., optimize crop protection), we recommend the optimal N fertilization as 150 kg N/ha. By using the multinomial theorem, we demonstrated that 100,000 bootstrap resamplings can generate stable and precise estimates of population parameters and their confidence intervals. On the contrary, the 1000 bootstrap resamplings might underestimate the confidence intervals and lead to failure of pest control.

Four MicroRNAs, miR-13b-3p, miR-278-5p, miR-10483-5p, and miR-10485-5p, Mediate Insecticide Tolerance in Spodoptera frugiperda.

Spodoptera frugiperda is the world’s major agricultural pest and has the distinctive features of high fecundity, strong migratory capacity, and high resistance to most insecticides. At present, the control of S. frugiperda in China relies mainly on the spraying of chemical insecticides. MicroRNAs (miRNAs) are a class of small, single-stranded, non-coding RNAs and play crucial regulatory roles in various physiological processes, including the insecticide resistance in insects. However, little is known about the regulatory roles of miRNAs on the resistance of S. frugiperda to insecticides. In the present research, the miRNAs that were differentially expressed after cyantraniliprole, spinetoram, and emamectin benzoate treatment were analyzed by RNA-Seq. A total of 504 miRNAs were systematically identified from S. frugiperda, and 24, 22, and 31 miRNAs were differentially expressed after treatments of cyantraniliprole, spinetoram, and emamectin benzoate. GO and KEGG enrichment analyses were used to predict the function of differentially expressed target genes of miRNAs. Importantly, ten miRNAs were significantly differentially expressed among the treatments of three insecticides. miR-278-5p, miR-13b-3p, miR-10485-5p, and miR-10483-5p were significantly downregulated among the treatments of three insecticides by RT-qPCR. Furthermore, the overexpression of miR-278-5p, miR-13b-3p, miR-10485-5p, and miR-10483-5p significantly increased the mortality of S. frugiperda to cyantraniliprole and emamectin benzoate. The mortality was significantly increased with spinetoram treatment after the overexpression of miR-13b-3p, miR-10485-5p, and miR-10483-5p. These results suggest that miRNAs, which are differentially expressed in response to insecticides, may play a key regulatory role in the insecticide tolerance in S. frugiperda.