Control ofAgrotis ypsilon (Hufn.) (Lep., Noctuidae) on some vegetable crops in Egypt using the microbial agentBacillus thuringiensis
The effective threshold rate of application of Dipel 2X was 250g/f. Incorporation of some chemical additives such as calcium sulphate (CaSO4) or calcium oxide (CaO) significantly potentiated the effectiveness of Dipel 2X on larval population. The addition of calcium carbonate (CaCO3) and zinc sulphate (ZnSO4) to Dipel 2X greatly reduced the larval population and led to a significant increase in the yield of some vegetable crops. Dipel 2X baits at 250g/f were almost as effective as the chemical insecticide Hostathion when used at 1.5l/f in controllingA. ypsilon larvae attacking vegetable crops.Control of the greasy cutwormAgrotis ypsilon population was better achieved when the biological control agent Dipel 2X was used as baits.ZusammenfassungDie Wirksamkeits-Schwelle desBac. thuringiensis-Präparats Dipel 2X betrug 250g/f(eddan). Eine Hinzugabe von CaSO4 oder CaO erhöhte die Wirkung von Dipel 2X auf die Raupen signifikant. Die Hinzugabe von CaCO3 und ZnSO4 zu Dipel 2X führte zu starker Reduzierung der Raupenpopulation und zu signifikanter Steigerung der Ernte bei einigen Gemüse-Arten. Dipel 2X-Köder in einer Dosierung von 250g/f waren fast so wirksam wie das chemische Insektizid Hostathion (1,5l/f). Die Bekämpfung der Raupen vonAgrotis ypsilon ist somit in biologischer Form mittels Gebrauchs von Dipel 2X-Ködern sehr gut möglich.
Novel biochemical avenues for enhancingBacillus thuringiensis endotoxin potency againstSpodoptera littoralis [Lep.: Noctuidae]
Simple biochemical means were used to enhance the endotoxin effect ofBacillus thuringiensis Berliner through optimization of conditions present in the insect gut required for release of intoxicating fragments from nonpoisonous intact endotoxin. This was achieved through the addition of either alkaline compounds naturally occurring in the insect midgut, general proteolytic activators or midly toxic compounds of inorganic (e.g. borax) and organic (e.g. tannic acid) nature along with endotoxin in the diet. A marked increase in the potency ofB.t. vars.entomocidus HD-635 andaizawai HD-133 againstSpodoptera littoralis (Boisduval) was obtained in the presence of 0.5% concentration of potassium carbonate. On the other hand, sodium carbonate was less effective at the tested concentrations. Among the tested proteolytic activators, the effect of magnesium ion was proportional to the concentration of the incorporated salt. Thus the potencies of δ-endotoxin preparations of HD-635 and HD-133 were increased 2–3 times after the addition of 1% concentration of magnesium chloride. A lesser effect was noted at 0.5%, whereas virtually the potency did not change at 0.25% concentration of the salt. Similar trends were noted with the incorporation of calcium chloride along with the endotoxin in the insect diet. The addition of sodium borate or tannic acid was highly effective in enhancing the potency of the tested sporeδ-endotoxin preparations with 2–4 fold increase.RésuméDes moyens biochimiques simples sont utilisés pour accroître l'action deBacillus thuringiensis Berliner par une optimisation des conditions dans le tube digestif de l'insecte, de façon à obtenir la formation de fractions toxiques à partir de l'endotoxine intacte non toxique. Ce processus a été réalisé par l'addition à l'endotoxine dans l'aliment, soit de composés alcalins naturellement présents dans l'intestin moyen, en général des activateurs de la protéolyse, soit de produits moyennement toxiques de nature minérale (borax) ou organique (acide tannique).Une augmentation nette de l'activité deB.t. var.entomocidus HD 635 HD 635 etaizawai HD 133, contreSpodoptera littoralis (Boisduval) a été notée en présence d'une concentration de 0,5% de carbonate de potassium. Par contre, le carbonate de sodium a été moins actif aux concentrations étudiées. Parmi les activateurs de protéolyse testés, l'ion magnésium a eu un effet proportionnel à la concentration. Le pouvoir toxique des préparations à base de δ-endotoxine de HD 635 et HD 133 a été accru de 2 à 3 fois avec l'addition de 1% de chlorure de magnésium. Un effet moindre a été enregistré avec 0,5% et il n'y a pas eu de modification de l'activité avec 0,25%.Des tendances analogues ont été notées avec du chlorure de calcium dans l'aliment. L'addition de borate de sodium ou d'acide tannique s'est révélée hautement efficace pour l'accroissement de 2 à 4 fois du pouvoir toxique des préparations de spores et d'endotoxine utilisées.
Brushite-collagen composites for bone regeneration.
Brushite-based biomaterials are of special interest in bone regeneration due to their biocompatibility and biodegradability; on the other hand, collagen is a well-known osteoconductive biomaterial. In the present study a new brushite-collagen composite biomaterial is reported. This new biomaterial was prepared by combining citric acid/collagen type I solutions with a brushite cement powder. The obtained biomaterial was a cement paste, with improved handling properties. The effect of collagen on the setting reaction of brushite cement was studied, and was found to speed up the cement setting reaction. The cement paste set into a hard ceramic material within 18.5+/-2.1min and had compressive strength similar to that of spongeous bone (48.9+/-5.9MPa in dry conditions and 12.7+/-1.5MPa in humid conditions). The combination of collagen with citric acid revealed an interesting synergistic effect on the compressive strength of the composite material. Moreover, this new biomaterial had excellent cohesion properties (ninefold better than brushite cement), and high cellular adhesion capacity (threefold higher than brushite cement). The composite biomaterial described in this study combines good handling properties, compressive strength, cohesion and cell adhesion capacity, along with the osteoconductive and biodegradable properties inherent in brushite and in collagen-based biomaterials.