Pre-dispersal seed mortality in <em>Centaurea cyanus</em>

International audienceSeed production is reduced by various kinds of pests, including those hosted by the fruit that impact seed ripening and viability indirectly, and those directly attacking the seeds before they are released. This results in pre-dispersal seed mortality, which may have strong effects on plant population dynamics. However, compensative evolution (or co-evolution) could select for fruits with adapted morphology. We wonder if pre-dispersal mortality could limit the population growth rate and contribute to the decline of Centaurea cyanus L. (also Cyanus segetum, Hill). The present study focused on the occurrence and abundance of seed-feeding insects of cornflower flower heads, and their relationships to capitula size, seed viability and germination. Larger capitula had lower proportion of healthy seeds. Although no visible damage was observed to the seeds of C. cyanus, the presence of cecidomye larvae inside the capitula correlated with seed loss. It seems that gall midges could have a significant impact on ovule fertilization, seed abortion and viability of fully developed seeds of cornflower. A higher rate of aborted seeds in presence of gall midge larvae could have resulted from fewer visits by pollinators, which may have been repelled, or from the deprivation of resources (by the larvae).The viability of the apparently healthy seeds is lower when the capitulum contains aborted seed and/or larvae. In conclusion, pre-dispersal mortality could select against the evolution of the species toward larger capitula, and have detrimental consequences on seed number, viability and germination, which limit the spread of C. cyanus populations

Pre-dispersal seed mortality in Centaurea cyanus

Seed production is reduced by various kinds of pests, including those hosted by the fruit that impact seed ripening and viability indirectly, and those directly attacking the seeds before they are released. This results in pre-dispersal seed mortality, which may have strong effects on plant population dynamics. However, compensative evolution (or co-evolution) could select for fruits with adapted morphology. We wonder if pre-dispersal mortality could limit the population growth rate and contribute to the decline of Centaurea cyanus L. (also Cyanus segetum, Hill). The present study focused on the occurrence and abundance of seed-feeding insects of cornflower flower heads, and their relationships to capitula size, seed viability and germination. Larger capitula had lower proportion of healthy seeds. Although no visible damage was observed to the seeds of C. cyanus, the presence of cecidomye larvae inside the capitula correlated with seed loss. It seems that gall midges could have a significant impact on ovule fertilization, seed abortion and viability of fully developed seeds of cornflower. A higher rate of aborted seeds in presence of gall midge larvae could have resulted from fewer visits by pollinators, which may have been repelled, or from the deprivation of resources (by the larvae).The viability of the apparently healthy seeds is lower when the capitulum contains aborted seed and/or larvae. In conclusion, pre-dispersal mortality could select against the evolution of the species toward larger capitula, and have detrimental consequences on seed number, viability and germination, which limit the spread of C. cyanus populations

Does gall midge larvae cause pre-dispersal seed mortality and limit cornflower population growth?

International audienceMany kinds of pests can reduce seed production. Some directly attack seeds before they are released, and some are hosted by the fruit and impact seed ripening and viability indirectly. Pre-dispersal seed mortality may have strong effects on plant population dynamics and evolution. Our goals were to determine to what extent insect-mediated pre-dispersal seed mortality contributes to population-level declines of cornflower, Centaurea cyanus L. We recorded occurrence and abundance of seed-feeding insects on flower heads in twelve cornflower populations. We measured flower head size, number of disc florets, seed production, and seed viability and germination. Larger flower heads had proportionally fewer healthy seeds. Although we observed no visible damage to the C cyanus seed, the presence of gall midge (Cecidomyiidae) larvae inside the flower head correlated with four times fewer viable seeds. It seems that gall midges could have a significant impact on ovule fertilization, seed abortion and viability of fully developed cornflower seeds. The higher rate of aborted seeds in the presence of gall midge larvae could have been because the larvae extracted resources from the seeds, or because the larvae repelled pollinators. The viability of apparently healthy seeds was 40% lower in flower heads that contained larvae and/or aborted seed. Insect-mediated pre-dispersal mortality could select against evolution toward larger flower head, and have detrimental consequences on seed number, viability and germination, all of which could limit the spread of C cyanus populations

Case Report of Presumed (In)voluntary Capsaicin Intoxication Mimicking an Acute Abdomen

Background. The clinical features of a presumed capsaicin intoxication have not been reported so far. Case Presentation. A 27-year-old man took part in a qualifying for a competition in spicy food tolerance. During this qualifying, he swallowed 4 chili peppers type Bhut jolokia (about 1 million Scoville units) and other extremely spicy foods; the total amount of capsaicin ingested (roughly calculated retrospectively) accounted for at least 600 mg. After 2½ hours, the patient developed severe abdominal pain, which led to hospital admission. In contrast to the severe symptoms, clinical, laboratory, and imaging examinations (ultrasound and plain X-ray of the abdomen) did not reveal any significant abnormalities. Treatment with analgesics resulted in complete regression of the abdominal pain within 30 hours. Conclusions. The clinical picture in the view of pharmacological investigations on intestinal capsaicin infusions suggests that excessive doses of capsaicin can induce severe abdominal pain; the prolonged symptoms were probably due to the failure to vomit. Thus, a capsaicin intoxication must be considered in the differential diagnosis of an acute abdomen

Electrophysiology and Behavioral Assessment of the New Molecule SMe1EC2M3 as a Representative of the Future Class of Triple Reuptake Inhibitors

SMe1EC2M3 is a pyridoindole derivative related to the neuroleptic drug carbidine. Based on the structural similarities of SMe1EC2M3 and known serotonin (5-HT), norepinephrine, and dopamine reuptake inhibitors, we hypothesized that this compound may also have triple reuptake inhibition efficacy and an antidepressant-like effect. PreADMET and Dragon software was used for in silico prediction of pharmacokinetics and pharmacodynamics of SMe1EC2M3. Forced swim test was used to evaluate its antidepressant-like effects. Extracellular in vivo electrophysiology was used to assess 5-HT, norepinephrine, and dopamine reuptake inhibition efficacy of SMe1EC2M3. PreADMET predicted reasonable intestinal absorption, plasma protein binding, and blood-brain permeability for SMe1EC2M3. Dragon forecasted its efficiency as an antidepressant. Using behavioral measurements, it was found that SMe1EC2M3 decreased immobility time and increase swimming time during the forced swim test (FST). Electrophysiological investigations showed that SMe1EC2M3 dose-dependently suppressed the excitability of 5-HT neurons of the dorsal raphe nucleus (DRN), norepinephrine neurons of the locus coeruleus (LC), and dopamine neurons of the ventral tegmental area (VTA). The SMe1EC2M3-induced suppression of 5-HT, norepinephrine, and dopamine neurons was reversed by the antagonists of serotonin-1A (5-HT1A; WAY100135), &alpha;-2 adrenergic (&alpha;2, yohimbine), and dopamine-2 receptors (D2, haloperidol), respectively. We conclude that SMe1EC2M3 is prospective triple 5-HT, norepinephrine, and dopamine reuptake inhibitor with antidepressant-like properties, however future studies should be performed to complete the pharmacological profiling of this compound

Characterizing prevalence and ecological impact of non-native terrestrial isopods (Isopoda, Oniscidea) in tallgrass prairie

Isopods are terrestrial crustaceans whose role and impact in the tallgrass prairie ecosystem remains little explored despite being rather prevalent non-native inhabitants. To better understand this role, we conducted two related studies. The first was a rapid survey of isopods in experimental treatments at Konza Prairie LTER site to investigate the diversity and relative abundance of isopod species present. Of the four species known in Kansas thus far, all non-native, Armadillidium vulgare was the most abundantly found, accounting for 93% of individuals found. Armadillidium nasatum, Cylisticus convexus, and Porcellionides pruinosus were also found and we report the first record of Porcellio laevis in the State of Kansas. Survey results showed no evidence for a relationship between isopod abundance and fire frequency or grazing treatment. The second experiment was a food preference study to explore granivory in non-native isopods and characterize their seed predator behavior on native plants. Individual isopods were placed in Petri dishes with food options including leaf litter and seeds from one of 15 species; dishes were then incubated for 6-12 days and preference was assessed based on pre- and post-trial weights of the feed and individual isopod. Isopods showed a significant preference for leaves compared to seeds in nine of the 15 seed species evaluated; no evidence for leaf-vs.-seed preference was apparent in the remaining six seed species. However, in all cases, isopods did consume some amount of seeds even when leaf litter was present. Taken together, the relatively low abundance of non-native terrestrial isopods and their lack of apparent preference for native plant seeds suggest that isopods are unlikely to pose considerable threat to tallgrass prairie ecosystems. More extensive research, including a preference study with greater representation of seed species and a quantitative survey throughout the year, would be needed to further characterize the ecological role of isopods in the tallgrass prairie