Spinnen als Prädatoren von landwirtschaftlich schädlichen Blattläusen

Direct observations in grasslands and cereal fields near Zurich (Switzerland) have shown that aphids constitute an essentiel component in many spiders' prey. Spiders were observed to be predators of the agricultural harmful aphidsRhopalosiphum padi L.,Sitobion avenae F.,Metopolophium dirhodum Walck.,Hyalopterus pruni Geoffr.,Myzus persicae Sulz. andAphis fabae Scop.     

Anwendung von Photoeklektoren beim Studium der kambio- und xylophagen Coleopteren

Use of photoeclectors in studies of cambio- and xylophagous beetles infesting trees is an effective method that makes work in this field easier, quicker and much more precise. As beetles from different families (Scolytidae, Cerambycidae, Buprestidae a. s. o.) are often significantly attracted to day-light, we can successfully use this method for collecting them in high numbers. The paper presented deals with the effectiveness of photoeclectors in studies of some cambio- and xylophagous beetles as well as their predators and parasites carried out under laboratory conditions.     

The Efficacy of Inactivated Photobacterium damselae subsp. piscicida Combined with Levan/Alum as Vaccine against Photobacteriosis in Cobia,Rachycentron canadum

Photobacterium damselae subsp. piscicida (Phdp) is a major pathogen of cultured cobia (Rachycentron canadum), a primary target species for offshore cage culture in Taiwan. Serum antibody titers as well as efficiency and duration of protection against Phdp were evaluated following intraperitoneal administration of a candidate vaccine prepared with formalin‐inactivated whole cells in combination with levan/alum adjuvants. The results showed vaccinates delayed the disease onset and had significantly (P < 0.05) less mortality than control nonvaccinates during Days 21–105 postvaccination with highest relative percentage of survival (RPS) and antibody titer up to 81.4% and 1:614, respectively. There was a highly significant positive linear correlation between the RPS and antibody titer (R² = 0.841). Long‐lasting and significant protection against Phdp can be achieved with inactivated Phdp plus levan/alum, a potential cobia vaccine against photobacteriosis. Levan/alum complex may represent a promising adjuvant formula for the development of a Phdp vaccine.     

Effect of rearing temperatures on the growth and maturation of Arctic charr (Salvelinus alpinus) during juvenile and on‐growing periods

The effect of rearing temperature on the growth and maturation of Arctic charr (Salvelinus alpinus) was investigated. Arctic charr juveniles were reared for 6 months (phase I, October–April, size range 20–500 g) at constant temperatures of 9, 12 and 15 °C and according to two temperature‐step groups (T_step) i.e. fish transferred from 15 to 12 °C or from 12 to 9 °C. All the previous treatments were then reared either at 7 °C or at 12 °C for an additional 4 months (phase II, size range 300–1000 g) and then slaughtered in August 2008. The overall growth rate was the highest at a constant temperature of 15 °C for the first 6 months of the trial, with the fish in this group being 44% and 78% heavier than the fish reared at a constant temperature of 12 or 9 °C respectively. Arctic charr showed a negative response in terms of the growth rate when transferred from higher to lower temperatures, especially for groups previously reared at 15 °C. There was a trend for higher gonadosomatic index values at the end of the experiment for groups of fish that were exposed to higher rearing temperatures during the juvenile phase i.e. 4.18% (±0.79) and 7.29% (±0.89), for the temperature groups of 12 and 15 °C, respectively, compared with 2.49% (±0.74) for the 9 °C group. Our results suggest that for the production of fish >1000 g, moderate or low temperatures (here 9 °C) should be applied during the juvenile phase in order to reduce the negative effects arising from maturation. Farmers with access to heat sources should accordingly choose more moderate rearing temperatures during the juvenile stage, especially if the fish is to be moved down in the temperature regime during the on‐growing period.     

Erwiderung zum Aufsatze: Verkümmern und Verderben von Bruten forstschädlicher Insekten von Forstrat Alois Nechleba,in Heft 10, 1927.

Ohne Zusammenfassung     

Nonnenkontroll -und Vorbeugungsmethode nach Professor Forst.-Ing. Ant. Dyk.

Ohne Zusammenfassung Mit 3 Abbildungen.