Changes in the digestive enzymes and hormones of gilthead seabream larvae (Sparus aurata, L. 1758) fed on Artemia nauplii enriched with free lysine

Variations in digestive enzymes and hormones during the larval development of gilthead seabream (Sparus aurata) fed on live prey (Artemia nauplii) enriched with free lysine were investigated for 16 days (from day 24 to day 40). Prior to initiation of the experiment, newly hatched larvae were transferred from incubators to fiber glass tanks (300 l) with black walls and fed the same diet until day 24. Each experiment was performed in triplicate. The amount of free lysine in the Artemia nauplii was increased by adding a 5.3 mM free amino acid solution to the culture water during a 16-h enrichment period. Larvae were sampled four times at four-day intervals, for 16 days. Larvae fed on the control group had lower growth than those fed on the lysine group at the end of the study but the difference was not significant (P > 0.05). The highest trypsin activity and lap/leu–ala peptidase ratios were observed in the control group (P < 0.05). Significant differences between bombesin activities of the treatment groups were not found in the fifth minute after the start of feeding (P > 0.05) but were significant in the fifteenth minute (P < 0.05). Significant differences between the CCK levels of the treatment groups were found (P < 0.05). In conclusion, three main ideas are presented in this study. First, Artemia nauplii can successfully be enriched with free lysine. Second, bombesin (GRP) and cholecystokinin (CCK) activity can be stimulated by free lysine. Third, the mechanisms controlling adaptation of the activity of the trypsin to the amount of dietary protein were not activated until day 40.     

Effect of high temperatures on survival and longevity of the predator Cryptolaemus montrouzieri Mulsant

The effect of high temperature on survival and longevity of Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) female adults was studied in the laboratory by daily exposure of the beetles to 35°C (mean r.h. 52%) combined with 1-, 2- and 3-h intervals of thermal treatment at 38, 40, 42 and 44°C (r.h. 46–48%). Fifty percent of females survived until the 12th–13th day of the thermal treatment at 38°C (depending on the exposure time), the 2nd–10th day at 40°C for 1–2 h exposure and the 4th–5th day at 42°C for 1 h exposure. Survival was 25–38% on the 1st–2nd day of the thermal treatment at 40, 42 and 44°C for 3, 2 and 1 h of exposure, respectively. Three hours of exposure of female C. montrouzieri at 42°C and 2 h exposure at 44°C were lethal for the beetles. Mean longevity of the predator was 33.13?±?1.22 days at 35°C and was significantly shorter as the temperature of the thermal treatments increased from 38^o to 44°C. These results suggest that daily temperature regimes of 35°C combined with 38–40°C for 1–3 h are marginal for the survival and longevity of the C. montrouzieri, whereas temperatures above 42°C are lethal even at short exposure. These results can partly justify the inability of C. montrouzieri to be permanently established in Pakistan environments and could contribute to a pre-evaluation assay of its potential adaptability in such environmental systems.     

Effects of abamectin on intracellular potassium ion activity and membrane potential in dipteran skeletal muscle

The effects of abamectin (AVMB₁) on intracellular potassium ion activity (aK_i) and resting membrane potential (E_m) of the skeletal muscle cells of final instar larvae of Phormia terraenovae (Diptera) were investigated using K⁺-selective micro-electrodes. Bathing the preparation in 10^? M AVMB₁(+ 1 ml litre^?1 dimethylsulfoxide) for 60 min caused a significant (31%) decrease in aK_i, whilst E_m depolarized on average by 19 mV (nearly 50% of the original control value). The difference E_K-E_m increased by 9 mV, although E_K (potassium equilibrium potential) remained more negative than E_m. These results could be due to a cationic effect of AVMB₁ possibly involving an increase in K⁺ and Na⁺ conductances of the muscle plasma membrane.     

Combined Application of Biochar and Biocontrol Agents Enhances Plant Growth and Activates Resistance Against Meloidogyne incognita in Tomato

Gesunde Pflanzen - Biochar (BC) is known to enhance plant growth and may activate plant resistance to various soil borne pathogens. In this experiment, the rice husk (RH) BC was combined with...     

Phytopathogenic fungi new for southern Anatolia,Turkey

Twenty-nine new records are reported from Turkey. The fungi species, including their macro-and microscopic features and distributions, are described. http://www.phytoparasitica.org posting July 14, 2004.     

Growth loss of Lebanon cedar (Cedrus libani) stands as related to periodic outbreaks of the cedar shoot moth (Dichelia cedricola)

An outbreak ofDichelia cedricola (Diakonoff) (Lep.: Tortricidae), the cedar shoot moth (CSM), began in spring 1998 and lasted 3 years. This was the first monitored outbreak of the CSM in Isparta, Turkey. Tree crowns recovered to near normal condition by the middle of each growing season (in early June) during the outbreak. Tree volume and volume element increments were examined throughout the outbreak cycle from 1954 to 2001. In the past, CSM activity in stands of Lebanon cedar (Cedrus libani A. Rich.) was assessed through radial increment analyses. Cedar tree ring chronologies were analyzed for evidence of the CSM. Tree-ring chronologies from nonhost cedar (nondefoliated sample trees) were used to estimate potential growth in the host cedar (defoliated sample trees) during current and past outbreaks; all trees selected were the same subspecies and varieties. Regional outbreaks of the CSM were identified by synchronous and sustained growth periods of the trees. In 2001, increment cores were collected from 17 host and 16 nonhost dominant or codominant trees and annual radial growth indices from 1954–2001 were calculated for each of two host and two nonhost sample plots. Growth functions were defined as the cumulative sum of radial, height, and volume increment, and were graphically compared between CSM host cedar and nonhost cedar trees. Tree ring evidence suggests that a large-scale outbreak occurred in 1955 (from 1955 to 1966) and a small outbreak occurred in 1985 (1985–1990) and in 1998 (1998-continued) in the study area. The average diameter growth reductions around 1955, 1985 and 1998 were 40%, 46% and 7% of potential, respectively. It was concluded that a narrow latewood band is significant indicator of defoliation by the CSM and the outbreaks appear to be associated with dry winter and spring weather prior to the autumn and winter in which wood feeding occurred. http://www.phytoparasitica.org posting Nov. 24, 2004.     

Potential of Azolla pinnata R. Br. green manure for boosting soil fertility and yield of terrestrial crops in Uganda: a case study of Eleusine coracana (L.) Gaertn

Journal of Crop Science and Biotechnology - Azolla fern has traditionally been used over centuries as a source of nutrients for rice grown in paddies with minimal attention on crops grown...