Foraging behaviour of the egg parasitoid Uscana lariophaga : towards biological control of bruchid pests in stored cowpea in West Africa

Seed beetles cause considerable losses in traditionally stored cowpea ( Vigna unguiculata Walp.) under subsistence farming conditions in West Africa. The indigenous egg parasitoid Uscana lariophaga Steffan (Hymenoptera; Trichogrammatidae) is evaluated as a candidate for a conservation strategy of biological control against the major pest Callosobruchus maculatus Fab. (Coleoptera; Bruchidae). Different aspects of U. lariophaga 's searching efficiency, such as host habitat location, host cluster location, the functional response, egg laying capacity and egg load, host handling time, arrestment response, photo- and geotaxis, dispersal and walking behaviour, have been investigated and results are reported in this thesis. Uscana lariophaga uses odour of uninfested cowpea seeds and of C. maculatus eggs to locate host habitats and host clusters therein. Host clusters with many eggs are more frequently located than clusters with few eggs, probably through olfaction. The parasitoid demonstrates a Holling Type II functional response, and the maximum number of hosts parasitized is determined by her ovarial egg load. Due to a strong arrestment response within host clusters, and area restricted searching behaviour after an oviposition, U. lariophaga parasitizes more eggs in host clusters with an even or clumped distribution than in clusters with a low density random distribution. Uscana lariophaga is positive phototactic and negative geotactic, and can move through cowpea stock over several meters a day. Under optimal conditions, U. lariophaga can significantly reduce losses in stored cowpea by C. maculatus . Further progress towards biological control of cowpea storage pests is discussed

Kidney Dysfunction Increases Mortality and Incident Events after Young Stroke: The FUTURE Study.

BACKGROUND: In about 30% of young stroke patients, no cause can be identified. In elderly patients, kidney dysfunction has been suggested as a contributing risk factor for mortality as well as stroke. There are hypotheses that novel non-traditional risk factors, like chronic inflammation and oxidative stress, are involved in chronic kidney disease, affecting the cerebral microvasculature that would in turn lead to stroke. Our objective is to investigate the influence of kidney dysfunction on long-term mortality and incident vascular events after stroke in young adults aged 18 through 50 and if this relationship would be independent of other cardiovascular risk factors. METHODS: We prospectively included 460 young stroke patients with an ischemic stroke or transient ischemic attack admitted to our department between January 1, 1980 and November 1, 2010. Follow-up was done between 2014 and 2015. Estimated glomerular filtration rate (eGFR) was calculated from baseline creatinine levels and was divided in 3 subgroups: eGFR 120 ml/min/1.73 m2. Cox proportional hazard models were used to determine the effect of kidney dysfunction on mortality and incident vascular events, adjusting for cardiovascular risk factors. RESULTS: An eGFR <60 (HR 4.6; 95% CI 2.6-8.2) was associated with an increased risk of death and an increased risk of incident stroke (HR 4.1; 95% CI 1.9-9.0) independent of cardiovascular risk factors, but it was not associated with other vascular events. The point estimate for the 15-year cumulative mortality was 70% (95% CI 46-94) for patients with a low eGFR, 24% (95% CI 18-30) for patients with a normal eGFR and 30% (95% CI 12-48) for patients with a high eGFR. The point estimate for the 15-year cumulative risk of incident stroke was 45% (95% CI 16-74) for patients with a low eGFR, 13% (95% CI 9-17) for patients with a normal eGFR and 8% (95% CI 0-18) for patients with a high eGFR. CONCLUSIONS: Kidney dysfunction is related to long-term mortality and stroke recurrence, but not to incident cardiovascular disease, on average 11 years after young stroke. This warrants a more intensive follow-up of young stroke patients with signs of kidney dysfunction in the early phase. In addition, the clear association between kidney dysfunction and incident stroke seen in our young stroke population might be a first step in the recognition of kidney dysfunction as a new risk factor for the development of stroke at young age. Also, it can lead to new insights in the etiological differences between cardiovascular and cerebrovascular disease.This study was funded by the Dutch Epilepsy Fund (grant number 10-18)

Trigger factors for stroke in young adults: a case-crossover study

Background and ObjectivesCauses of stroke in young adults differ from those in the elderly individuals, and in a larger percentage,no cause can be determined. To gain more insight into the etiology of (cryptogenic) stroke in theyoung population, we investigated whether trigger factors, such as short-lasting exposure to toxins orinfection, may play a role.MethodsPatients aged 18–49 years with a first-ever ischemic stroke or intracerebral hemorrhage (ICH) in 17participating centers in the Netherlands completed a questionnaire about exposure to 9 potentialtrigger factors in hazard periods and on a regular yearly basis. A case-crossover design was used toassess relative risks (RRs) with 95% confidence intervals (95% CIs) by the Mantel-Haenszel case-crossover method, for any stroke (ischemic stroke and ICH combined) and for different etiologicsubgroups of ischemic stroke.ResultsOne thousand one hundred forty-six patients completed the questionnaire (1,043 patients withan ischemic stroke and 103 with an ICH, median age 44.0 years, 52.6% men). For any stroke, anincreased risk emerged within 1 hour of cola consumption (RR 2.0, 95% CI 1.5–2.8) and vigorousphysical exercise (RR 2.6, 95% CI 2.2–3.0), within 2 hours after sexual activity (RR 2.4, 95% CI1.6–3.5), within 4 hours after illicit drug use (RR 2.8, 95% CI 1.7–4.9), and within 24 hours afterfever or flu-like disease (RR 14.1, 95% CI 10.5–31.2; RR 13.9, 95% CI 8.9–21.9). Four triggerfactors increased the risk of other determined and cryptogenic ischemic stroke, 3 that of car-dioembolic stroke, 2 that of large vessel atherosclerosis and likely atherothrombotic strokecombined and stroke with multiple causes, and none that of stroke due to small vessel disease.DiscussionWe identified cola consumption, vigorous physical exercise, sexual activity, illicit drug use, fever, andflu-like disease as potential trigger factors for stroke in the young population and found differencesin the type and number of trigger factors associated with different etiologic subgroups of ischemicstroke. These findings might help in better understanding the pathophysiologic mechanisms of(cryptogenic) stroke in the young population.Paroxysmal Cerebral Disorder

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