Resistance of 57 greenhouse-grown accessions of Lycopersicon esculentum and three cultivars to Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

The aim of this study was to evaluate resistance to Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) by antixenosis on 57 Lycopersicon esculentum Mill. accessions from the Horticultural Germplasm Bank (HGB) of Universidade Federal de Viçosa and by the three commercial cultivars (Santa Clara, Moneymaker and TOM-601) under greenhouse conditions. A randomized complete block design was used with three replications. Infestations with T. absoluta adults were performed weekly and the following characteristics were evaluated: number of small, large and total mines/leaf and % of leaves mined at days 60, 75 and 90 after planting. Low infestation occurred at days 60 and 75 but at day 90, infestation was sufficient to evaluate insect damage. Based on these data it was concluded that only accessions HGB-674 and HGB-1497 appeared to be the most promising. In addition, to determine possible chemical causes of resistance, hexane extracts were analyzed at day 90 by gas chromatography/mass spectrometry and the major peaks identified by a mass spectral database using similarity index. Nine hydrocarbons, viz., hexadecane, heptadecane, eicosane, tricosane, 2-methyltricosane, tetracosane, hexacosane, octacosane and triacontane were identified in the hexane extracts in many samples. Tricosane, tetracosane and hexacosane presented significant correlations with the leaves mined. Only tricosane presented a negative correlation with the number of small mines (r = −0.28), total number of mines (r = −0.27) and % of leaves mined (r = −0.22). However, tetracosane and hexacosane presented significant positive correlations (r = 0.25 and 0.24, respectively) with the % of leaves mined.     

Upscaling as ecological information transfer: a simple framework with application to Arctic ecosystem carbon exchange

Transferring ecological information across scale often involves spatial aggregation, which alters information content and may bias estimates if the scaling process is nonlinear. Here, a potential solution, the preservation of the information content of fine-scale measurements, is highlighted using modeled net ecosystem exchange (NEE) of an Arctic tundra landscape as an example. The variance of aggregated normalized difference vegetation index (NDVI), measured from an airborne platform, decreased linearly with log(scale), resulting in a linear relationship between log(scale) and the scale-wise modeled NEE estimate. Preserving three units of information, the mean, variance and skewness of fine-scale NDVI observations, resulted in upscaled NEE estimates that deviated less than 4% from the fine-scale estimate. Preserving only the mean and variance resulted in nearly 23% NEE bias, and preserving only the mean resulted in larger error and a change in sign from CO₂ sink to source. Compressing NDVI maps by 70–75% using wavelet thresholding with the Haar and Coiflet basis functions resulted in 13% NEE bias across the study domain. Applying unique scale-dependent transfer functions between NDVI and leaf area index (LAI) decreased, but did not remove, bias in modeled flux in a smaller expanse using handheld NDVI observations. Quantifying the parameters of statistical distributions to preserve ecological information reduces bias when upscaling and makes possible spatial data assimilation to further reduce errors in estimates of ecological processes across scale.     

Response of gladiolus (Gladiolus spp) plants after exposure corms to chitosan and hot water treatments

The state of Morelos, Mexico has gradually become an important producer of gladiolus. Some preconditioning treatments of corms are empirically done causing uneven emergence and low quality of flowers. In this investigation, before planting, gladiolus corms var. ‘Blanca Borrego’ were dipped in chitosan (chitosan reagent and commercial chitosan Biorend^®), in hot water at various temperatures and in treatments combined with Biorend^® at 1.5% and hot water. Results indicated that the most influenced variables were corm germination, number of flowers per spike, number of cormlets and vase life. Overall, the commercial product Biorend^® at 1.5% accelerated corm emergence in approximately 4 days, the number of flowers increased by 2–7 and the vase life extended for 3 days. The number of cormlets was also duplicated. Corms dipped in the commercial chitosan Biorend^® at 1.5% at different intervals of time were not greatly affected except for the emergence and number of cormlets. However, for this experiment there were significant effects on the number of leaves and flowers because of the interactions between chitosan and the immersion time. The temperature of 55 °C affected plant development because emergence was delayed by 6 days; and there were less number of leaves, flowers and cormlets. On the other hand, the incidence of Fusarium oxysporum in naturally infected corms was 0% at temperatures of 55 °C and 50 °C. Immersion times (0, 10, 15 and 20 min) in hot water at 50 °C did not show significant effects on plant development and vase life. Corms dipped in Biorend^® at 1.5% and hot water at 50 °C accelerated their emergence for about 1–7 days, the number of flowers increased by two, extended the storage life for 1–3 days and increased the number of cormlets. The integration of these two treatments -Biorend^® and hot water- might be a good option for increasing the gladiolus plant quality and vase life.     

Blood and haemoglobin meal as protein sources in diets for gilthead sea bream (Sparus aurata): effects on growth, nutritive efficiency and fillet sensory differences

Two parallel experiments were conducted to evaluate the effect of partial substitution of fish meal by two different animal protein sources, blood meal (B) and haemoglobin meal (H) at 0, 50 and 100 g kg⁻¹ of level inclusion in diets for gilthead sea bream, considering a long feeding period for juveniles (Trial 1) and a short feeding period (Trial 2) for on-growing fish. In Trial 1, 33 g juveniles were fed for 242 days and the fish fed with 5% and 10% of haemoglobin dietary inclusion obtained less growth, although feed efficiency, protein efficiency ratio and muscle composition were similar in all diets. In Trial 2, 179 g initial weight fish were fed for 164 days and growth of fish fed H10 showed the lowest growth, although nutrient efficiency and muscle composition were not affected significantly. The results of these experiments demonstrated that blood meal can substitute fish meal (up to 10%) with no effect on performance, but may lead to sensory differences compared with fish fed diet 0, while the inclusion of 5% blood meal had no effect on growth or sensory characteristics. Fish fed 10% haemoglobin inclusion had the poorest growth values.     

Enriching rotifers with “premium” microalgae. Isochrysis aff. galbana clone T-ISO

The effect of semi-continuous culture on the nutritional value of microalgae was tested in the rotifer Brachionus plicatilis in short-term enrichment experiments. Isochrysis aff. galbana clone T-ISO was cultured semi-continuously with renewal rates from 10 to 50% of the volume of the culture per day and used to feed the rotifers. After 24 h, dramatic differences in dry weight and protein, lipid and carbohydrate contents were observed in the rotifers depending on the renewal rate applied to the microalgal culture. Rotifers fed T-ISO cultured with low renewal rates showed low dry weight and organic content, whereas rotifers fed microalgae from nutrient-sufficient, high renewal rate cultures showed higher dry weight and increases up to 60% in protein, 35% in lipid and 100% in carbohydrate contents. Feed conversion rate (FCR) and organic FCR decreased with increasing renewal rates, indicating a more efficient assimilation of the microalgal biomass obtained at high growth rates. The fatty acid profile of rotifers reflected that of T-ISO, with maximum content of polyunsaturated fatty acids (PUFAs), n-3 fatty acids and docosahexaenoic acid (DHA) being found in the rotifers fed microalgae from the renewal rate of 40%. Results demonstrate that the biochemical composition of B. plicatilis is strongly modified through the use of semi-continuous cultures of microalgae in short-term enrichment processes. This technique provides an excellent tool to improve the nutritional value of the live feed used in fish larvae cultures.     

Trawling for cephalopods off the Portuguese coast—Fleet dynamics and landings composition

Fleet dynamics was addressed for three cephalopod taxa of commercial interest, the squid Loligo vulgaris, the octopuses Octopus vulgaris and Eledone cirrhosa, and the cuttlefish Sepia officinalis, for 48 trawlers of the fish trawling fleet. Landing profiles (LP) were identified based on the species composition of the landings using hierarchical cluster analysis. Four out of a total of 12 different LP were related to cephalopods and other species associated with them.The effects on the landing proportions of a number of variables, year, season and vessel, are analysed for each of the species studied using generalized linear models (GLM). The factor “vessel”, including an ensemble of technical characteristics as well as the abilities of individual skippers, explained most of the model deviance, strongly reinforcing the existence of a fleet component dedicated to catch cephalopods. However, time also explains much of the variation found in the data.Seasonal alternation between landings of octopodidae and cuttlefish was observed within a small group of old trawlers operating mainly off the south coast, following the abundance cycles of these species. For a larger group of more modern trawlers, operating off the western coast, inter-annual shift between octopus and squid was found, together with a well marked seasonal pattern between the catches of cephalopods and horse mackerel.Spatial patterns of activity were identified using vessel monitoring system (VMS) data available for trawlers in Portugal, demonstrating the existence of cephalopod targeting strategies in Portuguese fish trawling activities.     

Growth,absorption and assimilation efficiency by mature cuttlefish (<Emphasis Type="Italic">Sepia officinalis</Emphasis>) fed with alternative and artificial diets

The effects of feeding three natural frozen diets, grass shrimp (Palaemonetes sp.), crayfish (Procambarus clarkii) and fish (Sardina pilchardus) and two semi-humid artificial diets (based on fish powder) to mature cuttlefish, Sepia officinalis, were analysed. Growth and feeding rates (GR and FR, % BW day⁻¹), food conversions (FC, %), and total protein and lipid composition of the diets were determined. Digestive gland to body weight ratio and absorption efficiency were calculated for each diet. Cuttlefish fed shrimp and crayfish grew larger (1.5 and 1.1% BW day⁻¹, respectively) compared to the other diets. Shrimp promoted the highest FC, followed by crayfish, and sardine. The highest FR was obtained for cuttlefish fed crayfish (8.4% BW day⁻¹). Although both artificial diets were accepted, none produced growth. A positive correlation (r = 0.96) between cuttlefish ingestion rate and digestive gland weight was obtained. Some cannibalism occurred among cuttlefish fed the artificial diets during the last week of the experiment. According to the results obtained, P. clarkii could be used as an alternative prey to shrimp for rearing adult mature (>50 g) S. officinalis.     

Soybean molasses as an organic carbon source in the farming of Litopenaeus vannamei (Boone, 1931) in a biofloc system

Soybean molasses was evaluated as a partial replacement for sugarcane molasses as a carbon source for biofloc development in the superintensive culture of Pacific white shrimp (Litopenaeus vannamei). A 50‐day study was conducted with juvenile (3.2 g) shrimp stocked in 16 800 L tanks at a stocking density of 250 shrimp m^?3. Control of total ammonia concentration was performed by the addition of combined mixtures of soybean and sugarcane molasses to the culture water. Three different molasses treatments were evaluated using different soybean‐to‐sugarcane molasses ratios: 15–85%, 38–62% and 60–40% respectively. The control group was treated only with sugarcane molasses. Water quality, chlorophyll a concentration, heterotrophic bacterial load, Vibrio spp. concentration and zootechnical indexes were all evaluated. Total ammonia concentration was controlled by heterotrophic and chemotrophic pathways. Biofloc formation, as quantified by measuring the total suspended solids, was not altered. The Vibrio spp. concentration showed a significant reduction in treatments with soybean‐to‐sugarcane molasses ratios of 38–62% and 60–40%. All combined mixtures of soybean and sugarcane molasses could maintain water quality and productivity in the superintensive culture of L. vannamei using the biofloc system. Thus, the potential use of a residue from agroindustry as a carbon source in a biofloc culture is demonstrated.     

MODELING GROWTH AND ION CONCENTRATION OF LILIUM IN RESPONSE TO NITROGEN:POTASSIUM:CALCIUM MIXTURE SOLUTIONS

Nutrient solution composition plays an important role in root uptake rate due to interactions among nutrients and internal regulation. Studies to determine the optimum nutrient solution concentration are focused on individual ions, ignoring the adaptation mechanisms triggered by plants when growing in a varying external nutrient concentration. The objective of the present study was to determine the response in growth and tissue ion concentration of lilium cv. ‘Navona’ to nutrient mixtures of varying proportions of nitrogen (N), potassium (K⁺), and calcium (Ca²⁺) in solution using mixture experiments methodology in order to determine the optimum concentration. Bulbs of lilium were transplanted in plastic crates and drip-irrigated with the treatment solutions, which consisted of a mixture of N, K⁺, and Ca²⁺ whose total concentration was 340 mg L^?1 and minimum concentrations of each ion was 34 mg L^?1. Chlorophyll concentration (SPAD), shoot fresh weight (FW), leaf FW, and leaf area were measured 60 days after transplanting and ion analysis was performed on shoot tissues from selected treatments. Lilium exhibited a moderate demand for N and K⁺ (136–170 mg L^?1 N and 116–136 mg L^?1 K⁺) and a very low demand for Ca²⁺ (34–88 mg · L^?1). This low demand may be due to the remobilization of the nutrients stored in the bulbs. Integrating the predictions of the models estimated to produce >90% of maximum growth, the optimum nutrient solution should contain Ca²⁺ at a concentration between 34 and 126 mg · L^?1, K⁺ between 119 and 211 mg · L^?1, and N between 92 mg · L^?1 and 211 mg · L^?1. Increasing external N concentration affected internal N concentration but not internal K⁺ or Ca²⁺ concentrations, despite that the increase in external N was associated with a decrease in external K⁺ and Ca²⁺. Similar trends were observed for external K⁺ and Ca²⁺ concentration. In conclusion, lilium was able to maintain a relatively constant K⁺ and Ca²⁺ concentration regardless of the lower concentration in the nutrient solution when N was increased (similar response was observed for K⁺ and Ca²⁺) and it has a low Ca²⁺ demand and moderate N and K⁺ supply.