Met gezonde bijen naar de heide

Op 22 maart 2010 kwam een bont gezelschap van bijenhouders van ABTB, ANI en NBV bijeen in Hoenderloo. Het onderwerp die avond was de vraag: “Hoe combineer ik varroabestrijding met de heidedracht?” Hieronder het antwoord en wel in de vorm van de basisprincipes van varroa bestrijding plus een concrete methode om deze te combineren met de heidedracht

Varroabestrijding met bijenbroed als mijtenval (2)

Bij deze bestrijdingsmethode worden belegde darreraten uit een moergoede veger overgehangen naar het moerloze en later broedloze hoofdvolk. Hier worden de mijten die zich op de bijen bevinden gevangen. Nadat de laatste darreraat uit een hoofdvolk is verwijderd, wordt het bijenvolk met Perizine behandel

Adhesion of 2D MoS2_2 to Graphite and Metal Substrates Measured by a Blister Test

Using a blister test, we measured the work of separation between MoS$_2$ membranes from metal, semiconductor, and graphite substrates. We found a work of separation ranging from 0.11 +- 0.05 J/m^2 for chromium to 0.39 +- 0.1 J/m^2 for graphite substrates. In addition, we measured the work of adhesion of MoS$_2$ membranes over these substrates and observed a dramatic difference between the work of separation and adhesion which we attribute to adhesion hysteresis. Due to the prominent role that adhesive forces play in the fabrication and functionality of devices made from 2D materials, an experimental determination of the work of separation and adhesion as provided here will help guide their development

Impressie bijeenkomst Duitse bijeninstituten : Zonnige Arbeitstagung in Marburg

Ieder jaar gaan er ook vanuitNederland een aantal geïnteresseerdennaar het Duitse werkcongresvan bijenonderzoekers,steeds door een ander instituutgeorganiseerd. Johan Calis,Willem Boot en Tjeerd Blacquière,wetend dat de bijen thuis het algoed deden, konden een paardagen weg, om te snuffelen aande stand van het onderzoek inDuitsland

Model evaluation of methods for Varroa jacobsoni mite control based on trapping in honey bee brood

Biotechnical Varroa mite control methods are based on the principle that mites inside brood cells are trapped and can then easily be removed from a honey bee colony. Here, a validated trap-comb model based on work on invasion rates of mites into brood cells is used to estimate and compare effectiveness of different trap-comb methods. Trapping with worker brood is labour intensive because a large amount of brood is needed to trap a sufficient number of mites for effective control. In addition, trapping with worker brood requires subsequent treatment of the capped brood to selectively kill the mites, because beekeepers want to save the brood. Trapping with drone brood demands fewer brood cells for effective mite control, and destruction of drone brood with trapped mites is common practice. Moreover, preparation of trap-combs with drone brood can be integrated into swarm-prevention techniques and will take little extra time. © Inra/DIB/AGIB/Elsevier, Pari

New cut-off values for ferritin and soluble transferrin receptor for the assessment of iron deficiency in children in a high infection pressure area

Background: Due to the potential risk of iron supplementation in iron replete children, it is important to properly identify children who may require iron supplementation. However, assessment of the iron status has proven to be difficult, especially in children living in areas with high infection pressure (including malaria). Aims and Methods: Biochemical iron markers were compared to bone marrow iron findings in 381 Malawian children with severe anaemia. Results: Soluble transferrin receptor/log ferritin (TfR-F index), using a cut-off of 5.6, best predicted bone marrow iron stores deficiency (sensitivity 74%, specificity 73%, accuracy 73%). In order to improve the diagnostic accuracy of ferritin or sTfR as a stand-alone marker, the normal cut-off value needed to be increased by 810% and 83% respectively. Mean cell haemoglobin concentration (MCHC), using a cut-off of 32.1 g/dl, had a sensitivity of 67% and specificity of 64% for detecting iron stores deficiency. Conclusion: TfR-F index incorporated the high sensitivity of sTfR, a proxy for cellular iron need, and the high specificity of ferritin, a proxy for iron stores. In areas with a high infection pressure, the TfR-F index best predicted iron deficiency. However, in settings where diagnostic tests are limited, MCHC may be an acceptable alternative screening test

Invasion of Varroa jacobsoni into drone brood cells of the honey bee, Apis mellifera.

Invasion of Varroa mites into drone brood cells of honey bees was studied in colonies without worker brood. The probability for a mite to invade was dependent on the brood/bees ratio, which is defined as the number of drone brood cells capped per kg of bees. When compared with invasion in colonies with exclusively worker cells, Varroa mites invaded drone cells 11.6 times more frequently. This suggests that the biased distribution of mites over drone and worker cells in colonies with both types of brood cells results predominantly from the higher rate of invasion into a drone cell per se, when compared to that into a worker cell per se. Since the rate of invasion is high in drone cells, a trapping method using drone combs may be very effective in controlling the Varroa mite. When no other brood is present, 462 drone cells are estimated to be sufficient to trap 95% of the mites in a colony of 1 kg of bees

Improved method for assessing iron stores in the bone marrow

Background: Bone marrow iron microscopy has been the "gold standard'' method of assessing iron deficiency. However, the commonly used method of grading marrow iron remains highly subjective. Aim: To improve the bone marrow grading method by developing a detailed protocol that assesses iron in fragments, in macrophages around fragments and in erythroblasts. Methods: A descriptive study of marrow aspirates of 303 children (aged 6-60 months) with severe anaemia and 22 controls (children undergoing elective surgery) was conducted at hospitals in southern Malawi (2002-04). Results: Using an intensive marrow iron grading method, 22% and 39% of cases and controls had deficient iron stores, and 40% and 46% had functional iron deficiency, respectively. Further evaluation of the iron status classification by the intensive method showed that functional iron deficiency was associated with significantly increased C-reactive protein concentrations (126.7 (85.6) mg/l), and iron stores deficiency with significantly increased soluble transferrin receptor concentrations (21.7 (12.5) mg/ml). Conclusions: Iron assessment can be greatly improved by a more intense marrow examination. This provides a useful iron status classification which is of particular importance in areas where there is a high rate of inflammatory conditions

Secondary metabolites of Phlomis viscosa and their biological activities

Further phytochemical studies on the aerial parts of Phlomis viscosa (Lamiaceae) led to the isolation of 24 compounds: 3 iridoid glycosides, 10 phenylethanoid glycosides, a megastigmane glycoside and a hydroquinone glycoside, as well as 2 lignan glucosides and 7 neolignan glucosides, 1 of which is new (17b). Compound 17b was obtained as a minor component of an inseparable mixture (2:1) of 2 neolignan glucosides (17a/b), and characterized as 3',4-O-dimethylcedrusin 9-O-b -glucopyranoside. Full NMR data of the known 8-O-4' neolignan glucoside, erythro-1-(4-O-b-glucopyranosyl-3-methoxyphenyl)- 2-{2-methoxyl-4-[1-(E)-propene-3-ol]-phenoxyl}-propane-1,3-diol (18) are also reported. All isolated compounds were screened for cell growth inhibition versus 3 tumor cell lines (MCF7, NCI-H460, and SF-268) and several phenylethanoid glycosides were found to possess weak antitumoral activity. The phenylethanoid glycosides were also evaluated for their free radical (DPPH) scavenging, antibacterial and antifungal activities. The free radical (DPPH) scavenging activities of verbascoside (4), isoacteoside (5), forsythoside B (10), myricoside (13) and samioside (14) were found to be comparable to that of dl-a -tocopherol. Compounds 4, 5, 10 and 14 (MIC: 500 m g/mL) as well as Leucosceptoside A (8) and 13 (MIC:1000 m g/mL) showed very weak activity against Gram (+) bacteria