Malaysian herbs as feeding attractants and enhancers for the giant freshwater prawn (Macrobrachium rosenbergii) and the whiteleg shrimp (Litopenaeus vannamei)

Feeding attractiveness of 21 fresh herbs was examined for the giant freshwater prawn (Macrobrachium rosenbergii) and the whiteleg shrimp (Litopenaeus vannamei) at different growth stages in tanks. The feeding attractant and enhancement were assessed by behavioural observations of the test animals in response to pelleted feeds incorporated with the herbal extracts in different concentrations. For M. rosenbergii, peppermint (Mentha piperita) and dokudami (Houttuynia cordata) were the most attractive herbs at all stages, and garlic (Allium sativum) strongly attracting to the juveniles but only weekly to the adults, postlarvae and larvae. Peppermint significantly enhanced feeding of M. rosenbergii at all stages except for the larvae. Garlic was a significant feeding enhancer for M. rosenbergii juveniles and postlarvae. The inclusion of the herbal extract at high concentrations had a negative effect on the feeding. As far as L. vannamei is concerned, the red chilli (Capsicum annuum) was the best feeding attractant and ginger (Zingiber officinale) and peppermint were moderate attractants for adults and juveniles. While galangal (Alpinia galangal), ginger and yellow onion (Allium cepa sp.) enhanced feeding in L. vannamei adults, but red chilli, garlic and peppermint did not enhance feeding. Evidently, the strong feeding attractants were not necessarily effective feeding enhancers. The incorporation of several herb extracts at higher concentrations caused a negative effect on the feeding of the test animals. This could be due to the presence of feeding deterrents in the herb such as saponins which are known to lower food palatability in insect, decapod crustaceans and fishes. More long-term work is warranted to determine if inclusion of feeding enhancing herbs in artificial feed promotes growth performance of the shrimp.

Occurence and spreading of box tree moth (Cydalima perspectalis Walker 1859) on the North-East region of Great Hungarian Plain

Box tree moth shows (Cydalima perspectalis) rapid spread in Europe. In Hungary it appeared first near to the western border of the country in 2011. In the eastern part of Hungary the first specimen was caught in 2015 with blacklight trap. Here we summarize its distribution in northern part of the Alföld (Great Hungarian Plain) on the basis of blacklight, pheromone and feeding attractant traps. We publish five new distribution data from northern part (4 from Hungary, 1 from Transcarpathia) and two from southern part of the Alföld. Beyond that the flight of three generations was observed both in the year 2015 and 2016.

Weaning of Burbot, Lota lota (L.) from Live to Dry Feed Using NaCl as Dietary Attractant

Weaning of 150 days post hatch Lota lota from live feed (zooplankton) to formulated dry feed (FDF) was investigated. L. lota could not be forced from live feed to FDF. They refused FDF for periods up to 21 d. Body mass decreased for 20%, condition factor for 15%, and hepatosomatic index for 50%. In 21 days lasting co-feeding experiments with FDF and live feed L. lota selected exclusively the live feed organisms. NaCl in a concentration of 5% was a dietary feeding attractant for L. lota. When FDF was supplemented with 5% NaCl, L. lota could be abruptly weaned from live to dry feed. During a 21 d lasting experiment body mass increased for circa 40%, total length for 10%, condition factor for 5% and hepatosomatic index remained constant. These values were similar to live zooplankton feeding. However, increased mortality of > 20% was recorded for fish fed with the 5% NaCl containing FDF. To reduce mortality FDF was supplemented with zooplankton meal to upgrade its quality and extruded to optimize its density and sedimentation rate. With the adjusted FDF mortality rates were reduced to < 5%. Using the optimized dry feed easy and sustainable weaning protocols were developed where NaCl and zooplankton meal were gradually reduced to adapt fish to pure FDF.