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Proceedings from the 6th European Workshop on Insects Parasitoids, Valencia, 1-4 March 1997. ; The effects of photoperiod on development time, longevity and progeny of Apanteles militaris (Hymenoptera: Braconidae) were investigated using Mythimna unipuncta (Lepidoptera: Noctuidae) as host. Three groups of parasitized host larvae were exposed to 15.5±0.5°C of temperature, 75±0.5 of R.H. Each group was submitted to a different photoperiod, 8:16, 12:12 and 16:8 (L:D). Significant differences were found in the egg-larvae development time, pupal period and in the total development time. The adults longevity was higher and significantly different between 8:6 (L:D) and the others photoperiods. Concerning the progeny, the mean total and the mean number of cocoons per host did not differ significantly. However, the mean number of parasitoids that emerged from host larva but failed to spin a cocoon was significantly different between 8:6 and 16:8 (LD). Length of photophase did not significantly affect parasitoid sex-ratio but the emergence of adult progeny was different between 8 and 16 hours light.

In Vertical Farms with Artificial Lighting (VFALs), optimal light management is a crucial determinant of both economic and environmental viability. Applications of LED technologies to plant cultivation are still recent, and research has to date mainly targeted the definition of optimal spectral and light intensity features. On the other hand, despite the relevant implications on production costs, literature on optimal photoperiod management is to date limited. Indeed, the number of hours per day correlates with the total light supplied to the crop - expressed as Daily Light Integral (DLI) - and the associated energetic costs. The present study aims at defining how photoperiods of 16 h d-1 (DLI= 14.4 mol m-2 d-1), 20 h d-1 (DLI= 18 mol m-2 d-1) and 24 h d-1 (DLI= 21.6 mol m-2 d-1)of light affect growth performances and resource use efficiency in leafy vegetables and herbs, represented by lettuce (Lactuca sativa L.), basil (Ocimum basilicum L.), rocket (Eruca sativa Mill.), and chicory (Cichorium intybus L.). Plants were cultivated indoor under a red (R) and blue (B) LED light (RB=3, photosynthetic photon flux density (PPFD)=250 µmol m-2 s-1). Photoperiod variations' effects differed according to the considered plant species. In lettuce and chicory, the adoption of a DLI of 14.4 mol m-2 d-1 at 16 h d-1 photoperiod resulted in a greater plants fresh biomass and leaf area, which also contributed to generally obtain higher energy use efficiency (fresh biomass per unit of electricity input), light use efficiency (dry biomass per unit of light input) and, in chicory, also water use efficiency (fresh biomass per liter of water consumed). Contrarily, although photoperiod variations did not affect basil and rocket growth parameters (e.g., fresh biomass and leaf area) and the plant capacity to transform resources (e.g., water use efficiency and light use efficiency), energy use efficiency in basil also presented a downward trend in response to growing DLI. Accordingly, the adoption of a DLI of 14.4 mol m-2 d-1 at 16 h d-1 photoperiod resulted to be the optimal option among the ones tested in the presented research. ; The research leading to this publication has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 862663. The publication reflects the authors views . The research Executive Agency (REA) is not liable for any use that may be made of the information contained therein.

The passion fruit (Passiflora edulis Sims.) propagates by sexual reproduction and presents slow and uneven seed germination. This work has the goal of identifying a temperature and photoperiod that provide greater germination of the cultivar SCS 437 Catarina. We used an entirely randomized experimental design in a 2 x 3 + 1 factorial: two temperatures (alternating between 20/30 ºC and constant 25 ºC) and three photoperiods (8/16 – 8 hours of light and 16 hours of darkness; 12/12 – 12 hours of light and 12 hours of darkness; and absence of light), and for alternating temperature, an absence of light treatment was added, being classified as neutral photoblastic, and at a constant temperature of 25 ºC made germination unfeasible, while the 20/30 ºC alternating temperatures provided an average germination of 75%. The seeds showed an indifferent behavior to light, and the temperature alternated with 12/12 h photoperiod was the ideal condition to promote a higher percentage of germination.

Senegalia bahiensis (Fabaceae family, Mimosoideae subfamily) is typical of an anthropic environment, and thus tolerates high levels of disturbance, which supports its use in restoration planting. However, widespread use and marketing of S. bahiensis seeds requires seed quality control, for which there is a dearth of protocols. The aim of the present study was to evaluate the influence of temperature and photoperiod on the germination of Senegalia bahiensis seeds from different matrix trees. Seeds were collected from fruits of 15 matrix trees in the municipality of Castro Alves, Bahia, Brazil. Two assays were performed, one for each parameter tested. The experimental design of both assays was completely randomized in a factorial design, and included three replicates of 25 seeds. The design of the first assay was 15 (matrix trees) × 3 (conditions - 25°C, 30°C and alternating temperatures between 25 and 30°C) and the design of the second assay was 14 (matrix trees) × 3 (conditions - 8 or 12 hours of light, or continuous light). The percentage of germination of normal seedlings, germination speed index, mean root length based on total seed number, shoot length, root length and total length were determined. The Tukey's test was used to compare mean values. The S. bahiensis matrix trees used in this study have different requirements in terms of temperature and photoperiod for seed germination. According to our findings, combining a temperature of 30°C and an 8 h period of light conveys the most suitable conditions to conduct germination tests for most matrix trees.

6 páginas, 2 figuras, 4 tablas ; The present study provides new and practical information on the maturation of females seahorses Hippocampus guttulatus and Hippocampus hippocampus exposed to different temperatures (15 °C constant, 15–18 °C or 15–21 °C) and photoperiods (10L:14D–16L:8D cycle or 10L:14D constant). Egg production (total eggs, clutch size and clutches per female) resulted notably reduced under both short photoperiods and low temperature, especially in H. guttulatus. Egg clutches were mainly released with temperatures above 16 °C and increasing photoperiods beyond 14L:10D. The highest efficiency under a natural light regime was achieved at 21 °C. Biometrics performed in H. guttulatus eggs showed that egg volume (VE) was not affected by temperature level but yolk volume (VY) and VY/VE ratio in eggs of females exposed at 15 °C were lower than in eggs released at 15–18 °C and 15–21 °C cycles. VE, VY and VY/VE in eggs were not correlated with the photoperiod regimes applied. The present study also provides the first results on shifting of maturation in H. guttulatus females submitted to photothermic manipulation of the environment (Treatment D — advanced and drastic change; Treatment A — advanced and accelerated change) or to natural conditions (Treatment N). The response of females to artificial environmental changes was successful and fast. First egg clutches in treatments D and A were released 11 (Treatment D) and 9 (Treatment A) weeks before than in females exposed to natural temperature and photoperiod regimes. However, the best overall results were achieved under natural regimes. In Treatment N, total eggs production and average egg clutch size (3690 and 461 eggs, respectively) were noticeable higher than in treatments D (3533 and 294 eggs, respectively) and A (150 and 1809 eggs, respectively). The study demonstrates the feasibility of shifting in female maturation of seahorses and its practical use in the artificial manipulation of the breeding season under captive conditions. ; The study was financed by the Spanish Government (Plan Nacional, Projects CGL2005-05927-C03-01 and CGL2009-08386) and the Regional Government of Galicia (Xunta de Galicia, Projects 2005/PC091 and 09MDS022402PR). ; Peer reviewed

This work identified the presence of AQPs in frozen-thawed sperm of wild ruminants and assessed the influence of the interaction between photoperiod and thyroxine on AQP expression, and on testosterone secretion. Thyroxine and melatonin were administered to ibexes. In a second experiment, performed in mouflons, circulating thyroxine was reduced via treatment with propylthiouracil (PTU), and an artificial long day (LD) photoperiod established. In the ibexes, the melatonin treatment increased the blood plasma testosterone concentration, reduced the cryoresistance ratio (CR) for sperm viability and the presence of an intact acrosome, and increased the percentage of sperm with AQP7 in the acrosome and of AQP3 and AQP10 in the midpiece. In the mouflons, neither the PTU treatment, the LD, nor the combination of both affected the CR of any sperm variable. The percentage of sperm with AQP3 increased in the post-acrosome region but decreased in the tail in the LD+PTU group. The percentage of sperm with AQP10 in the principal piece and endpiece was lower in the PTU+LD group than in the control and LD groups. The influence of photoperiod/melatonin on AQP expression might be indirectly exerted through changes in the testosterone concentration, and thus ultimately affect sperm cryoresistance. ; Funding Agencies|MCINN/AEI/FEDER; EUEuropean Commission [AGL2017-85753-R, PID2020-113288RB-I00]; Spanish Ministry of Science, Innovation and UniversitiesSpanish Government [PRX19/00149]; Swedish Research Council FORMAS, Stockholm, Sweden [2017-00946, 2019-00288]

This article belongs to the Section Plant Physiology and Metabolism. ; Plant respiration provides metabolic flexibility under changing environmental conditions by modulating the activity of the nonphosphorylating alternative pathways from the mitochondrial electron transport chain, which bypass the main energy-producing components of the cytochrome oxidase pathway (COP). While adjustments in leaf primary metabolism induced by changes in day length are well studied, possible differences in the in vivo contribution of the COP and the alternative oxidase pathway (AOP) between different photoperiods remain unknown. In our study, in vivo electron partitioning between AOP and COP and expression analysis of respiratory components, photosynthesis, and the levels of primary metabolites were studied in leaves of wild-type (WT) plants and cytochrome c (CYTc) mutants, with reduced levels of COP components, under short- and long-day photoperiods. Our results clearly show that differences in AOP and COP in vivo activities between WT and cytc mutants depend on the photoperiod likely due to energy and stress signaling constraints. Parallel responses observed between in vivo respiratory activities, TCA cycle intermediates, amino acids, and stress signaling metabolites indicate the coordination of different pathways of primary metabolism to support growth adaptation under different photoperiods. ; This research was funded by FONDECYT No. 1191118 from the National Agency for Research and Development (ANID) and by the Agencia Nacional de Promoción Científica y Tecnológica, grant PICT-2018-01439. In addition, I.F.-S. has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 753301, the 'Ramon y Cajal' contract RYC2019-027244-I/AEI/10.13039/501100011033 and the European Social Fund. ; Peer reviewed

We studied the humoral innate immune responsiveness (HII), i.e. a hemolysis of rabbit erythrocytes by complement proteins, and adaptive humoral (antibody production) immune responsiveness (AHI) to SRBC, morphological and hormonal reproductive characteristics and stress level in male Campbell hamsters kept under long-day (LD; 16D: 8N) and short-day (SD; 8D: 16N) photoperiods. The results indicate lower HII, but not AHI in SD. In SD males we observed body mass, anogenital distance, midventral gland size and level of testosterone in the peripheral blood (but not the level of cortisol) decreased. Comparison of SD non-responders, SD responders and LD individuals demonstrated a statistically significant increase of HII in SD photosensitive hamsters, but not in non-responders compared to LD. There was no link between HII and AHI, which indicates an independent photoperiodic responsiveness of different branches of the immune system in Campbell's hamster.

12 páginas, 5 figuras, 3 tablas. ; We studied the reproductive cycle of the sea urchin Arbacia lixula in a subtidal population from northeast Spain over four years using a gonadosomatic index (GSI) and gonad histology. Our results show that the GSI of A. lixula follows a seasonal cycle which peaks in May– July and attains its lowest values in October–November every year. The time course of the GSI matched closely the photoperiod cycle. We also found a remarkable interannual variability in the maximum value of GSI, which correlated with mean water temperature during the gonad growth period (winter and spring). Gonad histology was also in agreement with a single gametogenic cycle per year in this species. We explored the application of circular statistics to present and analyse gonadal development data, which allowed us to adequately handle the high intraindividual variability detected, with several developmental stages commonly found within the same gonad. The picture that emerged is one of a gametogenic timing driven by photoperiod, while the amount of reproductive output is determined by temperature. This is coherent with the tropical origin of the species and lends support to recent warnings about an increase in the abundance of this species in the Mediterranean as a result of global warming, with associated increased impact potential in sublittoral communities. ; This work was funded by projects CTM2010-22218 from the Spanish Government, 2009SGR-484 from the Catalan Government, BIOCON 08-187/09 from BBVA Foundation and 287844 (COCONET) of the European Community's Seventh Framework Programme (FP7/2007–2013). ; Peer reviewed