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Diapause is an endocrine-mediated metabolic and growth arrest state in response to unfavorable external environments. The nematode Caenorhabditis elegans can enter diapause/arrest during embryonic, larval, or adult stages when subjected to detrimental external environments. Larval stage 1 (L1) arrest happens when animals hatch without food. Previous work has shown that the insulin pathway plays a prominent role in regulating L1 arrest. However, the downstream signal molecular mechanisms and biomarkers are still missing. In this study, we showed that SaPosin-like Protein family member SPP-5 is significantly upregulated during L1 arrest, suggesting that it could act as an L1 arrest biomarker. Using RNA interference we demonstrated that spp-5 knockdown accelerated larval development, while the overexpression resulted in L1 arrest. Consistently, SPP-5 level was significantly up-regulated in the L1 arrest daf-2(e1370) mutants, and spp-5(RNAi) suppressed the daf-2(e1370) induced L1 arrest. These results suggest that SPP-5 can serve as an L1 arrest biomarker and promote the arrest probably via the insulin signaling pathway. [ABSTRACT FROM AUTHOR]

Trissolcuss grandis Thomson, is an important egg parasitoid of Eurygaster integriceps Puton that can control its population in wheat and barley fields. Despite valuable results from previous studies, the thermal development of T. grandis over a wide range of temperatures had not been elucidated completely. This study was conducted to evaluate the thermal effect on the development of T. grandis using Sunn pest eggs as hosts in a wide range of temperatures (12.5 to 40 ±0.5ºC, 65 ± 5% RH., and a photoperiod of 16L:8D h) in the laboratory condition. The development times of the immature stage (Egg-Adult) of T. grandis decreased with increasing temperatures up to 35 ºC for both sexes. Patterns of temperature-dependent development times of the immature stage of females and males (i.e. emergence of females and males of T. grandis adults) were modeled and simulated with linear and nonlinear regression analyses. The estimated low-threshold temperatures (Tb) were 10.61 and 10.62 ºC for females and males, respectively. Thermal constants (k) of the immature stage of females and males were 179.85 and 161.03 degree-days (DD), respectively. Stage transition models for females and males adults of T. grandis were constructed using two basic components of nonlinear development rate (modified Sharpe & DeMichele model function) and distribution models (two-parameter Weibull function) to simulate the proportion of individuals shifted from egg to adult. These models will be useful in building a T. grandis population model that will describe its seasonal occurrence pattern and population dynamics under various wheat and barley fields and optimize environmental conditions in mass rearing. [ABSTRACT FROM AUTHOR]

Trissolcuss grandis Thomson, is an important egg parasitoid of Eurygaster integriceps Puton that can control its population in wheat and barley fields. Despite valuable results from previous studies, the thermal development of T. grandis over a wide range of temperatures had not been elucidated completely. This study was conducted to evaluate the thermal effect on the development of T. grandis using Sunn pest eggs as hosts in a wide range of temperatures (12.5 to 40 ±0.5℃, 65 ± 5% RH., and a photoperiod of 16L:8D h) in the laboratory condition. The development times of the immature stage (Egg-Adult) of T. grandis decreased with increasing temperatures up to 35 ºC for both sexes. Patterns of temperature-dependent development times of the immature stage of females and males (i.e. emergence of females and males of T. grandis adults) were modeled and simulated with linear and nonlinear regression analyses. The estimated low-threshold temperatures (Tb) were 10.61 and 10.62 ºC for females and males, respectively. Thermal constants (k) of the immature stage of females and males were 179.85 and 161.03 degree-days (DD), respectively. Stage transition models for females and males adults of T. grandis were constructed using two basic components of nonlinear development rate (modified Sharpe & DeMichele model function) and distribution models (two-parameter Weibull function) to simulate the proportion of individuals shifted from egg to adult. These models will be useful in building a T. grandis population model that will describe its seasonal occurrence pattern and population dynamics under various wheat and barley fields and optimize environmental conditions in mass rearing.

Avian eggs develop outside of the female body, and therefore embryonic development is subject to multiple internal (physiological) and external (ecological) factors. Embryonic developmental rate has important consequences for survival. Within species, embryos that develop too quickly often experience deformities, disorders, or mortality, while embryos that develop slowly risk inviability and increase the time they are exposed to various sources of mortality in the nest. These contrasting forces may lead to interspecific variation in developmental rates. We investigated potential factors affecting embryonic heart rate (EHR), a proxy of development, across 14 passerine species in the field. More specifically, we investigated if nest predation risk, clutch size, seasonality, and egg volume influenced EHR. From previous research, we expected, and found, that EHR was positively associated with embryonic age and egg temperature. Species with greater nest predation risk had higher EHR, shorter incubation periods, and lower nest temperature variance. EHR increased as the season progressed and with egg volume, while EHR declined with clutch size. Bird species exhibit varying strategies to increase nestling and fledgling survival in response to predation risk, and these results suggest that variation in embryonic development may be related to species‐specific differences in nest predation risk. [ABSTRACT FROM AUTHOR]

Mitochondrial functions are intimately reliant on proteins and RNAs encoded in both the nuclear and mitochondrial genomes, leading to inter-genomic coevolution within taxa. Hybridization can break apart coevolved mitonuclear genotypes, resulting in decreased mitochondrial performance and reduced fitness. This hybrid breakdown is an important component of outbreeding depression and early-stage reproductive isolation. However, the mechanisms contributing to mitonuclear interactions remain poorly resolved. Here, we scored variation in developmental rate (a proxy for fitness) among reciprocal F2 interpopulation hybrids of the intertidal copepod Tigriopus californicus and used RNA sequencing to assess differences in gene expression between fast- and slow-developing hybrids. In total, differences in expression associated with developmental rate were detected for 2925 genes, whereas only 135 genes were differentially expressed as a result of differences in mitochondrial genotype. Upregulated expression in fast developers was enriched for genes involved in chitin-based cuticle development, oxidation-reduction processes, hydrogen peroxide catabolic processes and mitochondrial respiratory chain complex I. In contrast, upregulation in slow developers was enriched for DNA replication, cell division, DNA damage and DNA repair. Eighty-four nuclear-encoded mitochondrial genes were differentially expressed between fast- and slow-developing copepods, including 12 subunits of the electron transport system (ETS) which all had higher expression in fast developers than in slow developers. Nine of these genes were subunits of ETS complex I. Our results emphasize the major roles that mitonuclear interactions within the ETS, particularly in complex I, play in hybrid breakdown, and resolve strong candidate genes for involvement in mitonuclear interactions.

Broad geographical distributions that include marked climatic variation may expose populations to distinct selective pressures. Local adaptation to differences in developmental conditions may lead to divergence in embryonic and hatchling traits for populations of oviparous reptiles. Among‐population differences in hatchling size and the duration of development are often observed in lizards with wide and climatically diverse distributions. Variation in hatchling phenotypes can arise from variation in maternal allocation, developmental plasticity or selection acting on embryonic traits. We studied variation in hatchlings of the Australian water dragon (Intellagama lesueurii), comparing traits related to growth and patterns of developmental plasticity. We recorded marked differences in hatchling sizes among populations from different climate types, which did not result from differences in maternal investment or from a plastic response to incubation temperatures. Embryos from southern, temperate populations exhibited shorter incubation times when incubated at cold temperatures but utilized less yolk during development and hatched smaller, with more residual yolk, regardless of incubation treatment. We suggest that these findings represent the first example of among‐population variation in patterns of embryonic resource allocation and a novel mechanism mediating offspring size in reptiles. We further suggest that variation in embryonic resource allocation in I. lesueurii, together with evolutionary changes in reaction norms for developmental rate, evolved as adaptations to seasonal length and conditions associated with a tropical‐temperate gradient. [ABSTRACT FROM AUTHOR]

Abstract Avian eggs develop outside of the female body, and therefore embryonic development is subject to multiple internal (physiological) and external (ecological) factors. Embryonic developmental rate has important consequences for survival. Within species, embryos that develop too quickly often experience deformities, disorders, or mortality, while embryos that develop slowly risk inviability and increase the time they are exposed to various sources of mortality in the nest. These contrasting forces may lead to interspecific variation in developmental rates. We investigated potential factors affecting embryonic heart rate (EHR), a proxy of development, across 14 passerine species in the field. More specifically, we investigated if nest predation risk, clutch size, seasonality, and egg volume influenced EHR. From previous research, we expected, and found, that EHR was positively associated with embryonic age and egg temperature. Species with greater nest predation risk had higher EHR, shorter incubation periods, and lower nest temperature variance. EHR increased as the season progressed and with egg volume, while EHR declined with clutch size. Bird species exhibit varying strategies to increase nestling and fledgling survival in response to predation risk, and these results suggest that variation in embryonic development may be related to species‐specific differences in nest predation risk.

Simple Summary: Wolbachia, the intracellular symbiont of insects, is of big interest and importance for its numerous effects on the host's life-history traits. However, the details of Wolbachia–host interaction are still not well studied and understood. Here, we present data on the influence of two different Wolbachia strains on the life-history traits of two different wild-type D. melanogaster lines. The results obtained allow us to assume that the effect of Wolbachia on the flies' life-history traits depends on the genotypes of both the host and the symbiont, but the fact of recent transfer of the symbiont to a new host could also be a factor. The best-known effect of the intracellular bacterium Wolbachia is its mostly negative influence on the reproduction of the host. However, there is evidence of a positive influence of Wolbachia on the host's resistance to stress, pathogens, and viruses. Here, we analyzed the effects of two Wolbachia strains belonging to wMel and wMelCS genotypes on D. melanogaster traits, such as fertility, survival under acute heat stress, and developmental rate. We found that D. melanogaster lines under study differ significantly in the above-mentioned characteristics, both when the natural infection was preserved, and when it was eliminated. One of Wolbachia strains, wMel, did not affect any of the studied traits. Another strain, wMelPlus, had a significant effect on the development time. Moreover, this effect is observed not only in the line in which it was discovered but also in the one it was transferred to. When transferred to a new line, wMelPlus also caused changes in survival under heat stress. Thus, it could be concluded that Wolbachia–Drosophila interaction depends on the genotypes of both the host and the symbiont, but some Wolbachia effects could depend not on the genotypes, but on the fact of recent transfer of the symbiont. [ABSTRACT FROM AUTHOR]

The thermal sensitivity of early life stages can play a fundamental role in constraining species distributions. For egg‐laying ectotherms, cool temperatures often extend development time and exacerbate developmental energy cost. Despite these costs, egg laying is still observed at high latitudes and altitudes. How embryos overcome the developmental constraints posed by cool climates is crucial knowledge for explaining the persistence of oviparous species in such environments and for understanding thermal adaptation more broadly.Here, we studied maternal investment and embryo energy use and allocation in wall lizards spanning altitudinal regions, as potential mechanisms that enable successful development to hatching in cool climates. Specifically, we compared population‐level differences in (1) investment from mothers (egg mass, embryo retention and thyroid yolk hormone concentration), (2) embryo energy expenditure during development, and (3) embryo energy allocation from yolk towards tissue.We found evidence that energy expenditure was greater under cool compared with warm incubation temperatures. Females from relatively cool regions did not compensate for this energetic cost of development by producing larger eggs or increasing thyroid hormone concentration in yolk. Instead, embryos from the high‐altitude region used less energy to complete development, that is, they developed faster without a concomitant increase in metabolic rate, compared with those from the low‐altitude region. Embryos from high altitudes also allocated relatively more energy towards tissue production, hatching with lower residual yolk: tissue ratios than low‐altitude region embryos.These results are consistent with local adaptation to cool climate and suggest that this is underpinned by mechanisms that regulate embryonic utilisation of yolk reserves and its allocation towards tissue, rather than shifts in maternal investment of yolk content or composition. [ABSTRACT FROM AUTHOR]

Many amphibian species inhabit temporary aquatic habitats for reproduction to maximize larval growth under favorable conditions, but accelerate developmental rate to rapidly undergo metamorphosis under stress conditions when high desiccation risk exists. Desiccation affects different aspects of amphibian biology such as developmental rate, body size and mass, and growth rate. We studied the responses of yellow‐bellied toad (Bombina variegata) to different water levels (constant high, decreasing water level, and constant low water level) in the laboratory using individuals collected from natural ponds. To assess the effects of experimental pond drying, we investigated the effects on life‐history and morphological traits at metamorphosis as well as carry‐over effects on post‐metamorphic traits and locomotor performances. We found that B. variegata cannot accelerate developmental rate in response to pond drying. The metamorphs from decreasing and constant low water levels had similar size, mass, growth rate and body condition indices at metamorphosis, and all these traits were lower than in the constant high water level treatment. These changes in life‐history traits at metamorphosis did not affect tail shape although they had carry‐over effects on life‐history and morphological traits after metamorphosis. Post‐metamorphic individuals reared in desiccation treatments had similar but smaller lengths of femur and tibiofibula, but these changes did not have negative consequences on jumping performances. We show that responsiveness to pond drying of B. variegata is probably associated with maximum growth rate in favorable conditions and inability to increase growth rate as well as developmental rate in desiccation conditions. This resulted in prolonged developmental time to reach the minimum size and mass for metamorphosis. [ABSTRACT FROM AUTHOR]

The Antarctic midge, Belgica antarctica, is the only insect that is endemic to the Antarctic Peninsula and its offshore islands. The final (fourth) instar larvae exhibit high inherent thermal tolerance to short-term temperature exposure, and many studies have focused on the underlying molecular physiological mechanisms of their thermal tolerance. In contrast, the thermal strategy of embryos has received little attention, and the effects of long-term thermal exposure on newly hatched larvae have not been investigated. The present study reports that the average supercooling point of egg masses was − 4.7 °C and that the first instar larvae successfully emerged from the frozen egg masses. The embryos also demonstrated significant heat tolerance and the first instar larvae successfully emerged from the egg masses kept at temperatures ranging from 0 to 15 °C. These indicate that embryos have sufficient tolerance to cold and heat during Antarctic summer. Interestingly, the first instar larvae developed into fourth instar larvae at 4 °C, but not at other temperatures. Early instar larvae have a narrow temperature window for their development, suggesting that they are susceptible to environmental changes. [ABSTRACT FROM AUTHOR]

In this work, we use developmental rate models to predict egg laying activity and succession of generations of T. urticae populations under field conditions in the Prespa lakes region in Northern Greece. Moreover, the developmental rate model predictions are related to accumulated heat summations to be compared with actual bean damage and to generate pest-specific degree-day risk thresholds. The oviposition was predicted to start at 57.7 DD, while the first peak in egg laying was estimated to be at 141.8 DD. The second and third peak in egg production were predicted to occur at 321.1 and 470.5 DD, respectively. At the degree-day risk threshold, half development of the first summer generation was estimated at 187 DD and 234 DDm while for the second, it was estimated at 505 DD and 547 DD for 2021 and 2022, respectively. According to the model predictions, no significant differences were observed in the mean generation time (total egg to adult development) of T. urticae between the two observation years (t = 0.01, df = 15, p = 0.992). The total generation time was estimated at 249.3 (±7.7) and 249.2 (±6.7), for 2021 and 2022, respectively. The current models will contribute towards predictions of the seasonal occurrence and oviposition of T. urticae to be used in pest management decision-making. Moreover, the development of population model is a prerequisite for the buildup and implementation of smart plant protection solutions. [ABSTRACT FROM AUTHOR]

The best-known effect of the intracellular bacterium Wolbachia is its mostly negative influence on the reproduction of the host. However, there is evidence of a positive influence of Wolbachia on the host’s resistance to stress, pathogens, and viruses. Here, we analyzed the effects of two Wolbachia strains belonging to wMel and wMelCS genotypes on D. melanogaster traits, such as fertility, survival under acute heat stress, and developmental rate. We found that D. melanogaster lines under study differ significantly in the above-mentioned characteristics, both when the natural infection was preserved, and when it was eliminated. One of Wolbachia strains, wMel, did not affect any of the studied traits. Another strain, wMelPlus, had a significant effect on the development time. Moreover, this effect is observed not only in the line in which it was discovered but also in the one it was transferred to. When transferred to a new line, wMelPlus also caused changes in survival under heat stress. Thus, it could be concluded that Wolbachia–Drosophila interaction depends on the genotypes of both the host and the symbiont, but some Wolbachia effects could depend not on the genotypes, but on the fact of recent transfer of the symbiont.

Abstract Background After embryonic development, Caenorhabditis elegans progress through for larval stages, each of them finishing with molting. The repetitive nature of C. elegans postembryonic development is considered an oscillatory process, a concept that has gained traction from regulation by a circadian clock gene homologue. Nevertheless, each larval stage has a defined duration and entails specific events. Since the overall duration of development is controlled by numerous factors, we have asked whether different rate-limiting interventions impact all stages equally. Results We have measured the duration of each stage of development for over 2500 larvae, under varied environmental conditions known to alter overall developmental rate. We applied changes in temperature and in the quantity and quality of nutrition and analysed the effect of genetically reduced insulin signalling. Our results show that the distinct developmental stages respond differently to these perturbations. The changes in the duration of specific larval stages seem to depend on stage-specific events. Furthermore, our high-resolution measurement of the effect of temperature on the stage-specific duration of development has unveiled novel features of temperature dependence in C. elegans postembryonic development. Conclusions Altogether, our results show that multiple factors fine tune developmental timing, impacting larval stages independently. Further understanding of the regulation of this process will allow modelling the mechanisms that control developmental timing.

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The diversity of insect eggs is astounding but still largely unexplained. Here, we apply phylogenetic analyses to 208 species of stick and leaf insects, coupled with physiological measurements of metabolic rate and water loss on five species, to evaluate classes of factors that may drive egg morphological diversification: life history constraints, material costs, mechanical constraints, and ecological circumstances. We show support for all three classes, but egg size is primarily influenced by female body size and strongly trades off with egg number. Females that lay relatively fewer but larger eggs, which develop more slowly because of disproportionately low metabolic rates, also tend to bury or glue them in specific locations instead of simply dropping them from the foliage (ancestral state). This form of parental care then directly favors relatively elongated eggs, which may facilitate their placement and allow easier passage through the oviducts in slender species. In addition, flightless females display a higher reproductive output and consequently lay relatively more and larger eggs compared with flight-capable females. Surprisingly, local climatic conditions had only weak effects on egg traits. Overall, our results suggest that morphological diversification of stick insect eggs is driven by a complex web of causal relationships among traits, with dominant effects of resource allocation and oviposition strategies, and of mechanical constraints. [Display omitted] • We analyzed patterns of evolution of egg traits from over 200 stick insect species • Egg traits have diversified within a complex network of causal relationships • Variation in size is mainly explained by adult size and a trade-off with egg number • Egg shape evolution is mainly driven by oviposition strategy and female body shape Boisseau and Woods investigate factors influencing the evolution of egg morphology in stick insects. Relative egg size appears to be influenced primarily by a trade-off with egg number, while egg shape reflects mechanical constraints arising from the diameter of the female oviduct and oviposition strategy. [ABSTRACT FROM AUTHOR]

Background: After embryonic development, Caenorhabditis elegans progress through for larval stages, each of them finishing with molting. The repetitive nature of C. elegans postembryonic development is considered an oscillatory process, a concept that has gained traction from regulation by a circadian clock gene homologue. Nevertheless, each larval stage has a defined duration and entails specific events. Since the overall duration of development is controlled by numerous factors, we have asked whether different rate-limiting interventions impact all stages equally. Results: We have measured the duration of each stage of development for over 2500 larvae, under varied environmental conditions known to alter overall developmental rate. We applied changes in temperature and in the quantity and quality of nutrition and analysed the effect of genetically reduced insulin signalling. Our results show that the distinct developmental stages respond differently to these perturbations. The changes in the duration of specific larval stages seem to depend on stage-specific events. Furthermore, our high-resolution measurement of the effect of temperature on the stage-specific duration of development has unveiled novel features of temperature dependence in C. elegans postembryonic development. Conclusions: Altogether, our results show that multiple factors fine tune developmental timing, impacting larval stages independently. Further understanding of the regulation of this process will allow modelling the mechanisms that control developmental timing. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to investigate whether blastocyst morphology and developmental rate are associated with euploidy and live birth rates (LBRs) in single euploid frozen–thawed embryo transfer (FET) cycles. Design: Retrospective cohort study. Methods: This study included 431 preimplantation genetic testing for aneuploidy (PGT-A) cycles followed by 393 FET cycles performed at our center from June 2017 to March 2021. All cycles were analyzed for euploidy based on blastocyst morphology (good, average and poor), developmental stage (day 5 and 6) and maternal age (< 35 and ≥ 35 years old). Multivariate logistic analysis models were used to identify the independent effects of conventional blastocyst morphology, developmental rate and morphological parameters (degree of blastocoele expansion, and grade of inner cell mass and trophectoderm (TE)) on LBRs. Results: In the group of women aged < 35 years, compared with poor-quality blastocysts, good-quality blastocysts (62.90% vs. 32.46%; odds ratio (OR) 3.163, 95% confidence interval (CI) 2.247–4.451; P < 0.001) and average-quality blastocysts (46.70% vs. 32.46%; OR 1.665, 95% CI 1.287–2.154; P < 0.001) had significantly higher euploidy rates. Additionally, day 5 blastocysts were associated with higher euploidy rates than day 6 blastocysts (49.28% vs. 35.02%; OR 1.506, 95% CI 1.191–1.903; P = 0.001). In the group of women aged ≥ 35 years, euploidy rates were also associated with blastocyst morphology, with 41.86%, 45.65% and 24.39% of good, average and poor-quality embryos, respectively, exhibiting euploidy. However, no relationship was seen between euploidy and blastocyst developmental rate. Multiple logistic regression analysis show that overall blastocyst morphology of euploid embryos was not associated with LBR, only embryos with A-grade TE had significantly higher LBRs than those with C-grade TE (62.71% vs. 45.40%; OR 2.189, 95% CI 1.166–4.109; P =0.015). Similarly, LBRs were significantly higher when day 5 blastocysts were transferred than when day 6 blastocysts were transferred (57.75% vs. 41.67%; OR 2.132, 95% CI 1.370–3.318; P = 0.001). Conclusion: Poor-quality embryos have reduced rates of euploidy. However, blastocyst developmental rate only significantly associates with euploidy rates in women aged younger than 35. Furthermore, only TE grade and blastocyst developmental rate are significantly associated with LBRs following FET cycles. [ABSTRACT FROM AUTHOR]

ObjectiveThe aim of this study was to investigate whether blastocyst morphology and developmental rate are associated with euploidy and live birth rates (LBRs) in single euploid frozen–thawed embryo transfer (FET) cycles.DesignRetrospective cohort study.MethodsThis study included 431 preimplantation genetic testing for aneuploidy (PGT-A) cycles followed by 393 FET cycles performed at our center from June 2017 to March 2021. All cycles were analyzed for euploidy based on blastocyst morphology (good, average and poor), developmental stage (day 5 and 6) and maternal age (< 35 and ≥ 35 years old). Multivariate logistic analysis models were used to identify the independent effects of conventional blastocyst morphology, developmental rate and morphological parameters (degree of blastocoele expansion, and grade of inner cell mass and trophectoderm (TE)) on LBRs.ResultsIn the group of women aged < 35 years, compared with poor-quality blastocysts, good-quality blastocysts (62.90% vs. 32.46%; odds ratio (OR) 3.163, 95% confidence interval (CI) 2.247–4.451; P < 0.001) and average-quality blastocysts (46.70% vs. 32.46%; OR 1.665, 95% CI 1.287–2.154; P < 0.001) had significantly higher euploidy rates. Additionally, day 5 blastocysts were associated with higher euploidy rates than day 6 blastocysts (49.28% vs. 35.02%; OR 1.506, 95% CI 1.191–1.903; P= 0.001). In the group of women aged ≥ 35 years, euploidy rates were also associated with blastocyst morphology, with 41.86%, 45.65% and 24.39% of good, average and poor-quality embryos, respectively, exhibiting euploidy. However, no relationship was seen between euploidy and blastocyst developmental rate. Multiple logistic regression analysis show that overall blastocyst morphology of euploid embryos was not associated with LBR, only embryos with A-grade TE had significantly higher LBRs than those with C-grade TE (62.71% vs. 45.40%; OR 2.189, 95% CI 1.166–4.109; P=0.015). Similarly, LBRs were significantly higher when day 5 blastocysts were transferred than when day 6 blastocysts were transferred (57.75% vs. 41.67%; OR 2.132, 95% CI 1.370–3.318; P = 0.001).ConclusionPoor-quality embryos have reduced rates of euploidy. However, blastocyst developmental rate only significantly associates with euploidy rates in women aged younger than 35. Furthermore, only TE grade and blastocyst developmental rate are significantly associated with LBRs following FET cycles.

In this work, we use developmental rate models to predict egg laying activity and succession of generations of T. urticae populations under field conditions in the Prespa lakes region in Northern Greece. Moreover, the developmental rate model predictions are related to accumulated heat summations to be compared with actual bean damage and to generate pest-specific degree-day risk thresholds. The oviposition was predicted to start at 57.7 DD, while the first peak in egg laying was estimated to be at 141.8 DD. The second and third peak in egg production were predicted to occur at 321.1 and 470.5 DD, respectively. At the degree-day risk threshold, half development of the first summer generation was estimated at 187 DD and 234 DDm while for the second, it was estimated at 505 DD and 547 DD for 2021 and 2022, respectively. According to the model predictions, no significant differences were observed in the mean generation time (total egg to adult development) of T. urticae between the two observation years (t = 0.01, df = 15, p = 0.992). The total generation time was estimated at 249.3 (±7.7) and 249.2 (±6.7), for 2021 and 2022, respectively. The current models will contribute towards predictions of the seasonal occurrence and oviposition of T. urticae to be used in pest management decision-making. Moreover, the development of population model is a prerequisite for the buildup and implementation of smart plant protection solutions.

Due to the speed of climate changes, rapid buffering mechanisms such as phenotypic plasticity – which may depend on breeding phenology – could be key to avoid extinction. The links between phenology and plasticity, however, remain understudied. Here we explored the matching between phenology and the thermal sensitivity of standard (SMR) and routine metabolic rates (RMR), metabolic scope (i.e. the difference between RMR and SMR), survival and growth‐development trajectories in larvae of a prolonged breeder amphibian Alytes almogavarii acclimated to 10 and 20°C, belonging to three cohorts: autumn pre‐overwintering, autumn overwintering and spring tadpoles. At 20°C, survival of autumn pre‐overwintering larvae was lower than for the rest. Although all cohorts showed acclimation potential, patterns for SMR and RMR differed, leading to differences in metabolic scope. Regardless of temperature, overwintering tadpoles arrested growth and development, while pre‐overwintering and spring tadpoles showed higher growth and development at 20°C. At 10°C pre‐overwintering tadpoles allocated more energy to development compared to spring tadpoles to advance development before winter. Overall, we demonstrate that the effects of temperature depend on phenology, consistent with future, expected thermal regimes. This suggests that extreme events can yield different vulnerability to climate change within populations (e.g. associated to discrete within‐year cohorts), and not only between species or populations. [ABSTRACT FROM AUTHOR]

Developmental time of the predatory mite Neoseiulus cucumeris (Oudemans) fed on cattail and almond pollen was determined under laboratory conditions at nine constant temperatures: 10, 15, 20, 25, 27, 30, 32, 35 and 38°C. No development was observed at 10°C. The lower temperature threshold (T 0) was estimated to be 10. 97 and 10. 29°C for the almond and cattail pollen, respectively, using the Ikemoto linear model. Thermal constant (K) for pre-adult development of N. cucumeris was 112.8 and 123.5 DD fed on almond and cattail pollen, respectively, using the Ikemoto linear model. The interaction between diet and temperature had a significant effect on the developmental rate of N. cucumeris. The nonlinear Pradhan-Taylor, Janisch/Kontodimas, Briere-1, and Janisch/Rochat models best described the developmental rate of pre-adult stages of N. cucumeris. The estimated T fast by Pradhan-Taylor model was 31.9 and 33.9°C when fed on almond and cattail pollen, respectively, which was similar to the observed shortest developmental time at 32°C. Our results revealed that N. cucumeris could develop over a wide temperature range (15–35°C), which is a desirable characteristic for a biocontrol agent in biological control programs. [ABSTRACT FROM AUTHOR]

The longfin yellowtail Seriola rivoliana is an emerging commercial species in aquaculture. However, there is little information regarding environmental conditions and their influence on early larval development that come from natural spawning. Temperature is one of the main factors affecting embryo and larval development. Therefore, the purpose of this research was to determine the impact of different temperatures (16–32 °C) on S. rivoliana hatching rate, larvae quality (survival, growth, yolk sac and oil droplet consumption, protein and lipid contents) and early developmental events (eye pigmentation and mouth opening). Eggs incubated at 23 °C showed the highest hatching rate (75.5%), but the larvae died 24 h after hatching (hah). Nonetheless, larvae cultivated at 24 °C had the highest survival rates at 48 hah and survived without being fed for over 100 hah. The temperature exhibits a direct effect on protein and lipid content, notochord size and oil droplet volume. In S. rivoliana, the larvae notochord size decreased after the oil droplet was more than half consumed, and at the higher temperature the faster the embryo and larvae depleted their endogenous reserves for growth. Finally, after 96 hah, the optimal mouth opening to ingest adequate rotifers for first feeding has been observed at 22 °C, while best eye pigmentation has been obtained at 24 °C. Therefore, we recommend incubating S. rivoliana eggs at 23 °C. After hatching, we suggest adjusting the temperature to 24 °C to increase the survival percentage and start eye development. Ultimately, after 48 h we encourage to low down the temperature at 22 °C to preserve notochordal length and allow faster mouth formation for further feeding. These optimal temperatures could be operated in the aquaculture industry to improve the management of larval development of S. rivoliana in captivity.

Pronuclear transfer has been successfully used in human-assisted reproduction to suppress the adverse effects of a defective oocyte cytoplasm or to bypass an idiopathic developmental arrest. However, the effects of the initial parental genome remodelling in a defective cytoplasm on the subsequent development after pronucleus transfer have not been systematically studied. By performing pronuclear transfer in pre-replication and post-replication mouse embryos, we show that the timing of the procedure plays a critical role. Although apparently morphologically normal blastocysts were obtained in both pre- and post-replication pronuclear transfer groups, post-replication pronuclear transfer led to a decrease in developmental competence and profound changes in embryonic gene expression. By inhibiting the replication in the abnormal cytoplasm before pronuclear transfer into a healthy cytoplasm, the developmental potential of embryos could be largely restored. This shows that the conditions under which the first embryonic replication occurs strongly influence developmental potential. Although pronuclear transfer is the method of choice for mitigating the impact of a faulty oocyte cytoplasm on early development, our results show that the timing of this intervention should be restricted to the pre-replication phase., (© The Author(s) 2024. Published by Oxford University Press on behalf of European Society of Human Reproduction and Embryology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Amphibians are highly vulnerable and diverse vertebrates for which we still have modest genomic resources. Amphibian larvae are key components of continental wetlands, where they have strong influences on energy fluxes, nutrient cycling, and community structure. Amphibian larvae are highly sensitive to environmental conditions and can often alter their physiology, behavior and even morphology in response to the local conditions experienced, although we still know relatively little about the transcriptomic changes that enable such plasticity. Here we contribute the larval transcriptomes of two spadefoot toad species with divergent developmental rates and degree of developmental plasticity in response to pond drying.

Polo-like kinase 1 (Plk1) has been known to be a critical element in cell division including centrosome maturation, cytokinesis and spindle formation in somatic, cancer, and mammalian embryonic cells. In particular, Plk1 is highly expressed in cancer cells. Plk1 inhibitors, such as BI2536, have been widely used to prevent cell division as an anticancer drug. In this study, the fertilized murine oocytes were treated with BI2536 for 30 min after recovery from the oviduct to investigate the effect of down-regulation of Plk1 in the in vivo-fertilized murine embryos. Then, the localization and expression of Plk1 was observed by immunofluorescence staining. The sperm which had entered into the oocyte cytoplasm did not form male pronuclei in BI2536-treated oocytes. The BI2536-treated oocytes showed significantly lower expression of Plk1 than non-treated control group. In addition, alpha-tubulin and Plk1 gathered around sperm head in non-treated oocytes, while BI2536-treated oocytes did not show this phenomenon. The present study demonstrates that the Plk1 inhibitor, BI2536, hinders fertilization by inhibiting the formation of murine male pronucleus.

A comparative study of the developmental rate and oxygen consumption in Rana arvalis tadpoles from the population of the Bryansk region (Southern) and Moscow region (Northern) in laboratory conditions at a temperature of 20°C was carried out. The rates of growth and development, the rate of oxygen consumption, and the specific rate of oxygen consumption in individuals from a Northern population were significantly higher. This result corresponds to the previously detected higher growth rate of tadpoles from populations with a relatively short season of activity (Northern) and indicates that these tadpole metabolism features are probably genetically determined. [ABSTRACT FROM AUTHOR]

Genome size, known also as the C-value, has been proposed as an important determinant of life-history variation in numerous animal taxa. We assessed the relationships between genome size and fitness-related life-history traits in six species of interstitial marine annelids of the genus Ophryotrocha. Life-history traits and genome size data obtained from 18 additional annelid species were included in our analyses to have a broader phylogenetic scope. Unexpectedly, genome sizes assessed here by flow cytometry in four Ophryotrocha species were three times larger than previously reported values obtained using Feulgen densitometry. This has implications for the hypothesis that harsh interstitial habitats select for small genomes in meiofaunal annelids. Within the genus Ophryotrocha, significant and positive relationships were found between genome size and nucleus size, and between genome size, age at first egg mass deposition, body size and lifespan. These relationships held up in the broader phylogenetic comparison. Our study provides evidence for the important role played by genome size in the evolution of life-history traits in annelids. [ABSTRACT FROM AUTHOR]

The biology and seasonal phenology of Aacanthocnema dobsoni (Froggatt) were studied at a single site in Victoria over a 2 year period between 2013 and 2015. This species is monophagous on the dioecious host, Allocasuarina verticillata (Lam.) L. Johnson (Casuarinaceae). Laboratory studies found that females attained reproductive maturity 24 h post‐eclosion, lived for 28.6 ± 2.8 (mean ± SE) days and laid 182 ± 23 (mean ± SE) eggs each. Egg development was most rapid at 26 °C, ceased below 7 °C and above 33 °C; hatching required 188 degree‐days. Nymphs could not be reared to adulthood on excised host branchlets maintained under controlled conditions, so no developmental data were obtained for these life stages. Seasonal phenology data revealed pronounced developmental asynchrony, i.e. with overlapping generations and multiple life stages occurring simultaneously. Three generations per year were observed, and there was no evidence of either developmental (egg and nymph) or reproductive diapause. A 4 day heat wave in January 2014 drastically reduced psyllid abundance at the study site and the size of the adults that eclosed from the surviving nymphs. These smaller adults produced substrate‐borne vibrational signals with altered characteristics, i.e. with significantly higher intensities and power. The altered signals might have facilitated communication over longer distances and increased mate finding opportunities when populations were low. The abundance of adults had recovered to preheat wave levels 3 months after the heat wave. High fecundity, multivoltinism and effective mate attraction signalling are life history traits that may mitigate against localised extinction of populations as a consequence of extreme weather events. [ABSTRACT FROM AUTHOR]

Background: It is demonstrated that optimal preincubation time improves oocyte quality, fertilization potential and developmental rate. This study aimed to evaluate the effect of preincubation time in the simple and myo-inositol supplemented medium on the oocyte quality regarding oxidative stress and mitochondrial alteration. Methods: Cumulus oocyte complexes (COCs) retrieved from superovulated NMRI mice were divided in groups of 0, 4 and 8 hr preincubation time in the simple and 20 mmol/L myo-inositol supplemented media. Intracellular reactive oxygen species (H2O2), glutathione (GSH), mitochondrial membrane potential (MMP), ATP content, and mitochondrial amount were measured and analyzed in experimental groups. One-way ANOVA and Kruskal-Wallis were respectively used for parametric and nonparametric variables. Statistical significance was defined as p<0.05. Results: In comparison to control group, variables including ROS, GSH, mitochondrial amount, fertilization and developmental rates were significantly changed after 4 hr of preincubation in the simple medium, while MMP decreased following 8 hr of preincubation in the simple medium (p˂0.001). Preincubation of oocytes up to 8 hr in the simple medium could not decrease ATP content. For both 4 and 8 hr preincubation times, myo-inositole could decrease H2O2 and increase GSH and MMP levels and consequently could improve fertilization rate compared to oocytes preincubated in the simple culture. Conclusion: It seems that 4 hr or more preincubation time can decrease the oocyte quality and lead to reduced oocyte fertilization and developmental potential. Howevere, myo-inositol may prevent oocyte quality reduction and improve fertilization potential in comparision to the equivalent simple groups. [ABSTRACT FROM AUTHOR]

It has been claimed that artificial insemination (AI) of cows with frozen-thawed semen treated with commercially produced kits, Wholemom (in favour of female gender) increases the birth chance of calves with desired sex ratio by approximately 85% without decrease of pregnancy rates. Hence, this study was conducted to investigate the efficacy of wholemom kits as combined with frozen-thawed bovine semen during in vitro fertilization on the in vitro fertilization and developmental efficiency and sex ratios such as some reproductive parameters in bovine. For this, 1,737 oocytes were in vitro fertilized and developed. Agglutination effects on bovine after treatment of Wholemom kit were observed by time passage and dose respectively. To determine sex of embryos, Bovine embryo Y-specific gene primers(ConEY) and Bovine specific universal primer(ConBV) were used as multiple PCR method. Fertilization rate of wholemom-treated group was significantly lower than its of control group[66.9% (1,156/1,737) in Wholemom-treated group; 75.0% (610/813) in control group]. However, developmental rate after fertilization of both wholemom-treated and control groups were not significantly different [26.1% (404/1,156) in Wholemom-treated group; 27.4% (224/610) in control group]. Sex ratio of in vitro fertilized embryo with frozen-thawed semen treated with wholemom kit was determined by multi PCR. Female ratio in wholemom-treated group [85.4% (173/201)] was significantly higher than its of control group [47.2% (66/141)]. In conclusion, wholemom treatments of semen used in the in vitro fertilization and development of bovine oocytes provided increase in female ratio with decrease of fertilization rate.

Phenotypic plasticity of insect thermal reaction norms (TRNs) (the lower thermal threshold, coefficient of thermal sensitivity, and sum of degree-days) ensures precise adjustment of the seasonal cycle to local environments by changing the pattern of temperature-dependence of developmental rate. In different geographic populations the plasticity of TRNs can be manifested in different ways. We investigated the photoperiodic and diet-induced plasticity of TRNs, body mass and structural size (hind femur length) of the multicolored Asian ladybird, Harmonia axyridis, from native (Irkutsk) and invasive (Sochi) laboratory populations. Each population was tested in 16 experimental treatments that represented combinations of 4 temperatures (17, 20, 24, and 28°C), 2 photoperiods (10 and 16 h of light per day), and 2 larval diets (frozen eggs of the grain moth Sitotroga cerealella and larvae and adults of the green peach aphid Myzus persicae). The lady beetle eggs developed at a temperature of 20°C; first instar larvae were distributed among experimental treatments. We have demonstrated that under both photoperiodic regimes larval feeding on a low-quality diet (grain moth eggs) resulted in a disproportional (more strongly manifested at a low temperature) retardation of preimaginal development of individuals from both populations. The lower temperature thresholds for preimaginal development were also greater on the inferior diet. When fed on grain moth eggs, larvae from the Irkutsk population showed weaker temperature-sensitivity of development, whereas in the Sochi population the slope of the TRN did not differ between the two diets. In contrast, H. axyridis from Irkutsk showed practically no photoperiodic plasticity of TRN, whereas those from Sochi were sensitive to photoperiod on both diets. Under short-day conditions, the lower temperature threshold in the latter population was smaller and temperature-sensitivity was weaker so that at the temperatures of 17 and 20°C, development under short-day conditions was faster than that under long-day conditions, whereas at 28°C, on the contrary, it was slightly slower. In both studied populations the thermal plasticity of adult body mass and hind femur length was manifested in different ways and to varying degrees, depending on the larval photoperiodic conditions and diet. Adult body mass could decrease or increase with larval developmental temperature or show no change. Despite being maintained in the laboratory for many generations, the H. axyridis populations from Sochi and Irkutsk have retained differences in physiological responses to photoperiodic conditions and larval diet. [ABSTRACT FROM AUTHOR]

The present attempt revealed influence of salinity, temperature, pH, light intensity and diet on survival, fecundity, population density and embryonic development of the marine calanoid copepod, Pseudodiaptomus annandalei. Various levels of salinity viz., 15, 20, 25, 30, 35, and 40 ppt; temperature (21, 24, 27, 30, 33, and 36 °C); pH (6.5, 7, 7.5, 8.0, and 8.5); light intensity (500, 1500, 3000, and 4500 lux); and different microalgal feed viz., Chlorella marina (CHL), Isochrysis galbana (ISO), Tetraselmis suecica (TET), Nannochloropsis occulata (NAN), Dunaliella salina (DUN), Picochlorum maculatum (PICO) and mixed microalgae (MIX) at equal ratio were employed to determine the impact on biology of P. annandalei. The better survival and reproduction was achieved under the salinity 25 ppt, temperature 27 °C, pH 8, light intensity 500 lux and with ISO diet. The developmental time was recorded to be short at 25 ppt, 30 ºC, pH 8 and light intensity 500 lux with ISO diet. Although, the highest yield was obtained under those parameter regimes, P. annandalei seems to be optimistic with wide range of environmental conditions. This study has confirmed that P. annandalei can be cultured at commercial scale as aqua feed and as model organism in toxicity experiments. [ABSTRACT FROM AUTHOR]

The purpose of this investigation was to study the effect of acute γ-irradiation of parent adults on the endoreduplication of giant chromosomes in F1 generation of Drosophila melanogaster Meig. A wild-type Oregon-R strain was used as the material. Virgin females and males of Drosophila adults at the age of 3 days were irradiated with doses of 8, 16 and 25 Gy. Giant chromosomes were studied by cytomorphometry on squashed preparations of Drosophila salivary glands stained with acetoorsein. The preparations were obtained at late third instar larvae. The mean values of the polyteny degree of chromosomes (PDC) in males increased after 8 Gy by 10.6%, after 25 Gy by 7.4%, and did not change after the dose of 16 Gy. In females, the PDC did not differ from the control irrespective of the irradiation dose. An increase in endoreduplication was also evidenced by the accelerated development of offsprings of both sexes after irradiation of parents with 25 Gy, and in males also at a dose of 16 Gy. The statistical impact of power of radiation on polyteny was 26.8%, while the impact of sex was 4.9%. The impact of power of radiation on the developmental rate of offspring was 4.4% in males and 7.5% in females. The enhancement of endoreduplication is considered as a consequence of increasing selection pressure after irradiation. The possible involvement of epigenetic effects in the effect of ionizing radiation on endoreduplication is discussed. [ABSTRACT FROM AUTHOR]

In response to nutrient limitation, many animals, including Caenorhabditis elegans, slow or arrest their development. This process requires mechanisms that sense essential nutrients and induce appropriate responses. When faced with nutrient limitation, C. elegans can induce both short and long‐term survival strategies, including larval arrest, decreased developmental rate, and dauer formation. To select the most advantageous strategy, information from many different sensors must be integrated into signaling pathways, including target of rapamycin (TOR) and insulin, that regulate developmental progression. Here, how nutrient information is sensed and integrated into developmental decisions that determine developmental rate and progression in C. elegans is reviewed. [ABSTRACT FROM AUTHOR]

Helicoverpa armigera is intensively researched in laboratory settings, yet developmental rates can vary considerably even under controlled conditions. Here, dietary choice and light spectra were tested as possible factors influencing this variability, a range of fitness indicators were collected and dietary choice behaviour in early instars was observed. We show that early instars of H. armigera exhibited self‐selection of nutrient intake, a novel finding. Larvae given a choice between two artificial diets varying in macronutrient ratios were heavier, exhibited a higher relative growth rate, shorter developmental time and longer eclosion time compared with larvae reared on a single diet. Wing size relative to body mass was higher for larvae on extreme no choice treatments and smallest for those on the choice diets, indicating a potential adaptation to escape poor nutrient landscapes. Light spectra had an effect on the size of pupae, with H. armigera reared under white LED light having larger pupae than those reared under fluorescent white light. Larvae reared under LED light took longer to emerge from pupation. Giving larvae a choice of diets with a range of nutrients may reduce developmental variability rather than assuming that one diets suits all. [ABSTRACT FROM AUTHOR]

Kissing bugs, Triatoma recurva (Stål) (Hemiptera: Reduviidae: Triatominae), live in an environment with high seasonal variability in rainfall, humidity, temperature, and food sources, and are an ideal organism for testing adaptive plasticity in rate of maturation to adult and in reproduction. Under simulated natural conditions, the effect of abundant, moderate, and infrequent feeding opportunities upon developmental rate, growth, and fecundity of the bugs was determined. Insects afforded frequent feeding opportunities matured to adult faster than those on lower frequency feeding diets. Insects on limited frequency feeding diets often delayed maturation until the second year of life and gained weight relative to those that matured in the first year. The females fed the least frequently and that delayed maturation until the second year doubled in weight relative to those maturing the year-earlier. In this species living near the climatic extremes of members of its genus, developmental and reproductive plasticity appear to be viable options to minimize the effects of catastrophes and reduce the possibility of local extinction during extreme environmental conditions. [ABSTRACT FROM AUTHOR]

German cockroach, Blattella germanica L., is one of the most health pests around the world. Development-temperature relationship and temperature-dependent parameters of B. germanica were determined in present study. The experiment was conducted in the incubators with five constant air temperatures, 23, 28, 31, 36, and 40 ℃. The photoperiod of 16 h light / 8 h dark and the relative humidity of 74%-76% were fixed for all incubators. Three replicates were set for each temperature. Based on linear regression equations, the estimated starting temperature for development of 1st to 5th instar nymphs of B. germanica is 14.26±3.157, 13.70±2.284, 14.59±3.575, 16.58±2.398, and 18.47±1.442 ℃, respectively. The estimated effective accumulated temperature of 1st to 5th instar nymphs is 99.18±19.68, 97.01±13.47, 92.06±21.17, 80.26±9.784, and 64.06±9.784 d ℃ (day degrees), respectively. B. germanica had the highest survivorship and hatching rate, and the least instars for eclosion and hatching time, around 31 ℃, which is the optimum temperature range for development and survival of B. germanica. B. germanica could not survive at 40 ℃. Even at 36 ℃, all eclosed adults had vestigial wings and could not normally mate and reproduce.

Allotropa subclavata Muesebeck (Hymenoptera: Platygasteridae) is one of the most effective natural enemies of the Japanese mealybug Planococcus kraunhiae (Kuwana) (Hemiptera: Pseudococcidae), a serious pest in Japanese orchards. We examined the developmental and reproductive traits including host deprivation effect on oviposition of A. subclavata to evaluate its potential as a biological control agent for P. kraunhiae. The developmental zero and effective accumulative temperature of A. subclavata females and males reared on second-instar nymphs, a suitable host stage for this parasitoid, were 12.3 °C and 514.3 degree days and 12.8 °C and 432.8 degree days, respectively. The longevity of A. subclavata maintained with honey was longer than that of those maintained with water or no feeding. The average numbers of mature eggs in ovaries of the 0- and 30-day-old A. subclavata females were 301.1 and 290.4, respectively, and were not significantly different. Offspring production of 30-day-old A. subclavata females was approximately 80% that of 0-day-old female parasitoids. On average, 50% of all eggs were laid within 24 h of the start of oviposition. The intrinsic rate of increase at 25 °C was 0.115, which is considered to be approximate to that of the host, P. kraunhiae. [ABSTRACT FROM AUTHOR]

[Objective] Telenomus dingus is a kind of dominant natural enemy, which plays an important role to stem borer control in Guan-gxi. In order to provide a foundation for artificial rearing of T. dingus in the laboratory and protecting the natural enemy in the fields to control sugarcane borers, the effects of temperature on the development of T. dingus were investigated. [Method] The developmental duration and developmental rate of T. dingus under different temperature conditions (17, 20, 23, 26, 29 and 32°C) were studied. The relationships between the developmental rate and temperature were also analyzed by using the three methods of Linear, S and Logistic regression. And the developmental threshold temperature and effective accumulated temperature were made out and compared by using the linear regression method and the direct optimal method. [Result] T. dingus could development normally under the temperature from 17 to 32 °C, the developmental duration decreased under high temperature conditions, and the developmental rate accelerated with the increasing temperature. The Logistic model could fit the relationships between developmental rate and temperature better, the regression equation was V = 0. 1755/ (1 + e4.0166 -0.1529T). The optimal temperature was 26. 27 3C and developmental duration was 11.40 d. The analysis by direct optimal method, the developmental threshold temperature and the effective accumulated temperature was 11.25 and 172.31 d |°C respectively. [Conclusion] Temperature was very important in the development of T. dingus, and the optimum temperature range for its development. These findings will provide a scientific basis for rearing in the laboratory and protecting the natural enemy in the fields to control sugarcane borers. [ABSTRACT FROM AUTHOR]

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Ascidians are marine benthic organisms, which attach to the surfaces of both natural and artificial substrates from shallow to deep waters around the world. Invasive ascidians are reported to have spread widely through maritime activities, especially as a fouling on ship hulls. Ciona robusta has been reported as an invasive ascidian species of the marine ecosystem in Korea since it was first recorded in 1967 and was designated as an organism causing marine ecological disturbance by the Ministry of Oceans and Fisheries, Korea in 2017. In the current study, in order to provide some basic ecological data for the management and control of C. robusta, we investigated the effects of temperature and salinity on egg development and larval settlement. The egg development and larval settlement of C. robusta were investigated at five constant temperatures, 10, 12, 16, 20, and 24°C, and at eight constant salinities ranging from 26 to 40 psu (increments of 2 psu). The highest hatching rate was 64.2 ± 7.8% at 16°C and 34 psu, and the lowest was 2.2 ± 2.0% at 20°C and 28 psu. No eggs hatched at salinities of 26 and 40 psu. The highest developmental rate (1/h) was 0.075 ± 0.015 at 24°C and 32 psu, and the lowest was 0.015 ± 0.000 at 20°C and 28 psu. The highest settlement rate was 47.1 ± 10.3% at 20°C and 34 psu, and the lowest was 0.7 ± 0.0% at 20°C and 28 psu. The highest rate of settlement time (1/h) was 0.034 ± 0.012 at 24°C and 34 psu, and the lowest was 0.011 ± 0.000 at 20°C and 28 psu. The approximate optimal temperature and salinity ranges for egg development and larval settlement of C. robusta were estimated to be 16−20°C and 32−34 psu, respectively. This study suggests that the development of C. robusta was affected by both salinity and temperature and that these factors may have a significant effect on the occurrence of C. robusta in Korea. [ABSTRACT FROM AUTHOR]