Time-lag in extinction dynamics in experimental populations: evidence for a genetic Allee effect?

1. Propagule pressure, i.e. the number of individuals introduced, is thought to be a major predictor of the establishment success of introduced populations in the field. Its influence in laboratory experimental systems has however been questioned. In fact, other factors involved in long-term population persistence, like habitat size, were usually found to explain most of the dynamics of experimental populations. 2. To better understand the respective influence of short- and long-term factors and their potential interaction on extinction dynamics in experimental systems, we investigated the influence of propagule pressure, habitat size and genetic background on the early dynamics of laboratory-based populations of a hymenopteran parasitoid. 3. The amount of demographic variance differed between establishment and persistence phase and was influenced by habitat size and genetic background (geographic strain), but independent of propagule pressure. In contrast, the probability of extinction within five generations depended on the genetic background and on the interaction between propagule pressure and habitat size. Vulnerability to extinction in small size habitats was increased when populations were founded with a small number of individuals, but this effect was delayed until the thir

Data from: Intraspecific variability in the parasitoid wasp Trichogramma chilonis: can we predict the outcome of hybridization?

In the framework of biological control, the selection of effective natural enemies determines the final pest control. Thus, the genetic improvement of biocontrol agents could enhance the efficiency of biocontrol programs. Although promising, this approach has rarely been applied in this field. At the intraspecific level, hybridization between divergent populations of agents is expected to promote hybrid vigor (heterosis), but it is not clear to what extent. An even more difficult task is the ability to predict the fitness of hybrids from the biological characteristics of their parents. We investigated these general questions by crossing seven populations of the parasitoid wasp Trichogramma chilonis (Hymenoptera: Trichogrammatidae). Our results show different levels of mating compatibilities among populations, including asymmetric or almost complete reproductive isolation. Hybrids’ performance (fitness of the F1 generation) ranges from inbreeding depression to heterosis. It was possible, to some extent, to predict hybrid fitness from pairwise genetic and phenotypic distances among parents, in accordance with the “dominance” hypothesis. This may provide general guidelines for the genetic improvement of biological control agents

Lutte Biologique classique et insectes phytophages

National audienc

EVA-2012-039-OA.R1_dataset2_Jmating

EVA-2012-039-OA.R1_dataset2_Jmatin

Impact of Age-Adjusted Insulin-Like Growth Factor 1 on Major Cardiovascular Events After Acute Myocardial Infarction: Results From the Fast-MI Registry

International audienceBackground: The GH/IGF-1 axis is being targeted for therapeutic development in diseases such as short stature, cancer, and metabolic disorders. The impact of IGF-1 in cardiovascular disease remains controversial. We therefore studied whether IGF-1 at admission for acute myocardial infarction (AMI) predicted death, recurrent AMI, and stroke over a 2-year follow-up. Methods: Using data from the French registry of Acute ST-elevation and non-ST-elevation Myocardial Infarction registry, we measured IGF-1 among all the 1005 patients with AMI who participated in the serum data bank. Because IGF-1 decreases with age, a standardized IGF-1 score was calculated as previously described [IGF-1 score = (log [IGF-1 (micrograms per liter)] + 0.00625 x age - 2.555)/0.104]. Impact of IGF-1 score (continuous and quartiles) on outcomes were compared using Cox proportional hazards regression models. Results: During follow-up, 190 patients died or had a recurrent AMI or stroke. Patients in the lowest quartile of IGF-1 were older and more frequently female and diabetic compared with patients in the other quartiles. After adjustment for known cardiovascular factors, an increase of five units of IGF-1 score was associated with a 30% decrease of the risk of events during follow-up (adjusted hazard ratio 0.70; 95% confidence interval 0.54-0.92; P = .0093). Similarly, the lowest quartile of IGF-1 was associated with an increased risk of events (adjusted hazard ratio 1.52, 95% confidence interval 1.11-2.08; compared with others quartiles, P = .010). Conclusions: Low IGF-1 score is associated with an increased risk of all-cause death, recurrent myocardial infarction, and stroke in AMI patients. Whether patients treated by IGF-1 axis inhibitors have a specific clinical course after AMI would be worth studying

Acute stent thrombosis after primary percutaneous coronary intervention:insights from the EUROMAX trial (European Ambulance Acute Coronary Syndrome Angiography)

AbstractObjectivesThis study sought to determine clinical, procedural, and treatment factors associated with acute stent thrombosis (AST) in the EUROMAX (European Ambulance Acute Coronary Syndrome Angiography) trial.BackgroundBivalirudin started during transport for primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction significantly reduced major bleeding compared with heparin with or without glycoprotein IIb/IIIa inhibitors (GPI), but it was associated with an increase in AST.MethodsWe compared patients with (n = 12) or without AST (n = 2,184) regarding baseline, clinical, and procedural characteristics and antithrombotic treatment strategies (choice of P2Y12 inhibitor, post–primary PCI bivalirudin infusion dose [0.25 mg/kg/h, or BIV-LOW] vs. [1.75 mg/kg/h, or BIV-PCI] vs. heparin ± GPI). Logistic regression was performed to identify independent correlates of AST.ResultsThe overall AST rate was 0.6% and was higher with bivalirudin than with heparin ± GPI (1.1% vs. 0.2%; p = 0.007). Median time to AST was 2.3 h (interquartile range: 1.9 to 2.8 h). Patients with AST had less hypertension (2 of 14 [14.0%] vs. 961 of 2,182 [44.0%]; p = 0.03), and more frequently received GPI (11 of 14 [78.6%] vs. 880 of 2,183 [40.3%]; p = 0.004). Multivariate analysis using Firth penalized maximum likelihood estimation found hypertension (odds ratio [OR]: 0.24, 95% confidence interval [CI]: 0.07 to 0.92; p = 0.037) and BIV-LOW (OR: 5.8, 95% CI: 1.5 to 22.2; p = 0.010) predictive of AST. Choice of P2Y12 inhibitor had no impact on AST. Compared with heparin ± GPI, AST rates were higher for BIV-LOW (11 of 670 [1.6%] vs. 2 of 947 [0.2%]; p = 0.008), but not different for BIV-PCI (1 of 244 [0.4%]; p = 0.588).ConclusionsIn this post-hoc analysis from EUROMAX, AST occurred very early and was not mitigated by the novel P2Y12 inhibitors. Prolonging the bivalirudin infusion at the PCI dose (but not at a lower dose) appeared to mitigate the risk of AST