Efficacy of tricaine methanesulphonate and clove oil as anaesthetics for juvenile cobia Rachycentron canadum

Six experiments were designed to determine the optimal anaesthetic dosage of tricaine methanesulphonate (TMS) and clove oil that could be used safely on juvenile cobia Rachycentron canadum of two sizes [G1=4.9±0.8 g; G2=13.9±3.1 g]. We documented the stage of anaesthesia and the acute toxicity as 96 h LC₅₀ (lethal concentration 50% population) at various exposure times of the two anaesthetics. At 10 min induction time, the TMS 96 h LC₅₀ was 93.9 mg L⁻¹ in G1 and 97.0 mg L⁻¹ in G2. Compared with clove oil, the 96 h LC₅₀ was 60.0 mg L⁻¹ in G1 and 69.8 mg L⁻¹ in G2. The difference between the two groups (G1, G2) did not influence anaesthesia safety ( P >0.05). Rachycentron canadum achieved stage 3 anaesthesia more rapidly at a lower clove oil concentration level (40 mg L⁻¹, 10 min) than TMS (60 mg L⁻¹, 10 min), but the recovery period of clove oil, was significantly longer. Clove oil was the most effective in reducing the short-term stress induced by routine biometry (20 mg L⁻¹, 10 min) and also by transporting (1 mg L⁻¹, 8 h). Whereas, for long-term exposure, 40 mg L⁻¹ TMS was found to be safe.     

Influence of temperature on the volatilization of triallate and terbutryn from two soils

The rate of volatilization of the formulated herbicides triallate and terbutryn was studied in a volatilization chamber under controlled laboratory conditions using two soils with sand and loam textures, respectively. The influence of the most relevant experimental variables was investigated by measuring the amount of volatilized herbicides after their incorporation to the soils. The effect of soil temperature was studied in the range from 5 °C to 25 °C. Initial soil water content was fixed at field capacity depending on the physical characteristics of each soil. The volatilized herbicide was trapped in C18 cartridges during different time intervals and analyzed by HPLC. The volatilization losses for triallate ranged from 7 to 58%, whereas the losses for terbutryn ranged from 1 to 6%. Sorption and volatilization resulted in two coupled effects of major importance in these experiments: the sorption process was favoured as temperature decreased, whereas volatilization increased as temperature increased. © 2000 Society of Chemical Industry     

Controlled Mass Rearing of Cochineal Insect (Hemiptera: Dactylopiidae) Using Two Laboratory-Scale Production Systems in Peru

The carmine cochineal (Dactylopius coccus Costa) has high economic value as it is a natural source of carminic acid, an organic chromophore used in a wide range of sectors including pharmaceutics, food, and cosmetics. High demand is fuelling the search for innovative production techniques in order to move away from dependence on the prickly pear, which carries a number of limitations. The aim of this study was to establish cochineal colonies and breed and mass-produce the insects using two laboratory-scale production systems. The first system (STC-01) comprised a prismatic acrylic box with three compartments; synthetic matrices were placed vertically inside the box to provide support and a source of nutrients for the cochineal, and the system was lit artificially during fixed daylight periods. The second system (STC-02) comprised an automated micro-tunnel allowing the insects to move towards the sunlight, containing synthetic matrices arranged horizontally. There was a significant difference in yield between the two systems in a cochineal total life cycle of 120 d (80–90 d harvest period in both cases), with STC-01 being superior and producing a maximum yield of 4.86 ± 0.68 g fresh weight per day per square metre compared with 3.20 ± 0.14 g fresh weight per day per square metre production yield in STC-02. We conclude that cochineal production under controlled artificial conditions is feasible and sustainable, removing the need for natural and biological support and overcoming the environmental limitations posed by traditional production methods.     

Linking fish ecomorphotypes to food categories and local-scale habitat uses along a Brazilian coastal stream

Fish ecomorphological analyses often deal with several traits simultaneously, making it challenging to interpret general patterns, and have not addressed the longitudinal component of streams in morphology-habitat relationships. We identified ecomorphotypes of fishes and correlated their morphological variation with food, structural/hydrological variables, and abundances to detect their links with diet and local-scale habitat categories. Eighteen morphometric traits were obtained from specimens collected by electrofishing in a coastal Atlantic stream in Brazil. To test for morphology-habitat associations, headwaters, middle, and mouth reaches were divided into shorter sampling sites, with the middle reach being classified into riffle, run, and pool mesohabitats. Multivariate analyses highlighted the morphological variations and associated the form categories of 18 fish species with food and habitat categories. It resulted in four combined trophic and habitat ecomorphotypes: (1) benthic AB/lithophilic, composed of smaller to longer loricariids, detritivores, of fast-water, and pebbly habitats; (2) benthic C/lithophilic of very fast-waters, algal and detritus scrapers, with longer intestines than the other benthic species, wider suctorial mouths, inhabitants of headwaters, and riffles habitats; (3) nektobenthic/lithophilic with streamlined bodies, invertebrate feeders, and dwellers of faster-water, cobbly habitats; and (4) nektonic/limnophilic composed mainly by characins, which had strong correlations with terrestrial insect consumption, and lentic/pool, sandy habitats. The morphology–environment correlations linked these ecomorphotypes to the broad habitat gradient arrayed in longitudinal and local scales. These results permit inferring the larger form patterns expected for local fish assemblages and emphasise the fish trait categorisation as a possible surrogate to reveal broader ecomorphological associations.     

Effects of Different Drying Processes on Oil Absorption and Microstructure of Tortilla Chips

Tortilla chips were slow dried after baking and then fried in fresh soybean oil. Control chips were not dried before frying. Final oil content of sun-dried tortilla chips was significantly (P < 0.05) lower than those receiving the control treatment. As a result of drying, the structure of the tortilla chips was tighter before frying but expanded significantly during frying. An attempt was made to produce tortilla chips with the same characteristics of the sun-dried chips using impinging hot-air drying techniques. Results indicated that tortilla chips drying rate was mostly affected by air temperature; texture was crispier at higher air temperatures; shrinkage of the piece was higher at lower convective heat transfer coefficient; and microstructure looked smoother at higher air temperature.