The study of Indian shrimp larvae feeding by enriched rotifer with vitamin C and unsaturated fatty acid (epa, dha) and its effects on growth factors, survival rate and environmental stresses

In this experiment, the feeding of Indian white shrimp larvae by unenriched rotifers (treatment 1) and enriched with highly unsaturated fatty acid (treatment 2) and highly unsaturated fatty acid along with vitamin C (treatment 3) on the growth factors, survival and resistance against salinity and formalin stress tests were studied and their differences with control treatment including newly hatched Artemia nauplii is compared. In this the study four treatments in a completely randomized design with 3 replicates per treatment were used. Farming of shrimp larvae of Zoea II to postlarvae 5 was done in 20 liter plastic bucket. Present results indicated that growth factors and survival rate of stage Zoea II to postlarvae 1 in treatments 1, 2 and 3 improve rather than control in which this case was due to optimal size rotifer rather than Artemia nauplii. Also, treatments 2 and 3 feeding with oil liver cod emulsion enriched rotifer have the highest concentration of DHA (mg/g DW) and the ratio DHA/EPA in which due to have shown the highest growth factors and a significant difference (P<0.05) with treatments 1 and control. The highest survival at stage PL1 were observed in treatment 3 that was enriched with ascorbyl palmitate in which have to the synergistic properties of vitamin C rather than treatments 2, 1 and control and showed a significant difference (P<0.05). But in stage PL5 the highest amount of growth and survival rates were related to control treatment which showed a significant difference (P<0.05) with other treatments that control has higher size rather than treatments 1, 2 and 3. Also, among experiment treatments that the two treatments 2 and 3 due to enrichment had higher growth and survival rates compared with treatment 1 in which their differences have also been significant (P<0.05). In the case of stress tests, results indicated that the highest survival rate has been reported when specimens were offered a diet containing high levels of highly unsaturated fatty acids with vitamin C. So that in stage PL1 in the salinity stress tests 10 and 20 ppt the highest survival rate was observed in treatment 3. As for the second, treatment 2 showed a significant difference (P<0.05) with treatment 3. It is worth mentioning that treatment 3 showed a higher survival rate compared to treatment 2 due to the synergistic properties of vitamin C. The difference between these two treatments with treatment 1 and control was also significant. No significant difference was observed in formalin stress test 100 ppm in this stage between treatments 3 and 2 which shows the highest survival rate. But their difference with treatments 1 and control was significant (P<0.05). Also, in stage PL5 in the salinity stress tests 10 and 20 ppt the highest survival rate was observed in treatment 3 which showed no significant difference (P<0.05) with control treatment. While their difference in the amount of survival rate with treatment 1 and 2 was significant (P<0.05). In this stage, the highest observed survival rate in formalin stress test 100 ppm included treatments control, 3 and 2 among which there were no significant differences (P<0.05). While the difference between these three treatments with treatment 1 was significant.

Feeding, morphological changes and allometric growth during starvation in miiuy croaker larvae

We investigated the effects of the timing of first feeding (larvae in F0, F1, F2, F3 and S were first fed on day 3, 4, 5, 6 days after hatching (DAH) and unfed, respectively) on feeding, morphological changes, survival and growth in miiuy croaker larvae at 24A degrees C. The fed larvae initiated feeding on 3 DAH and reached point of no return (PNR) on 6 DAH. Larvae in F0 and F1 groups survived apparently better than F2 group at the end of the experiment on 36 DAH. High larval mortality occurred from 3 to 7 DAH in all feeding groups, accounting for 40% (F0, F1 and F2 groups) to 90% (F3 and S groups) of the total mortality. Larvae in F0 and F1 groups grew better than F2 group throughout the experiment. Eye diameter, body height, head height and mouth gape of the first feeding larvae were more sensitive to starvation than other morphometrics and could be used as indicators for evaluating their nutritional status. Results indicated that delayed first feeding over 1 day after yolk exhaustion could lead to poor larval survival and growth. To avoid starvation and obtain good growth in culturing, larvae feeding should be initiated within 1 day after yolk exhaustion at 24A degrees C.

Feeding behaviour of Japanese flounder larvae under laboratory conditions

Tank-reared Japanese flounder larvae, Paralichthys olivaceus, had a major feeding peak in the morning and a secondary peak in the afternoon throughout the larval development, with light being the primary factor regulating their feeding activity. The larvae consumed rotifers in preference to Artemia for up to 10 days, after which the food preference shifted to Artemia. Feeding rates of the larvae prior to 10 days post-batch depended on prey density, but in the old larvae, feeding rates were independent of prey density. Maximum feeding rate occurred at 19 degrees C. The occurrence of the attack posture, after its onset at first feeding (2 days post-hatch), increased up to 25 days, began to decrease when the larvae prepared to settle down, then disappeared after settlement. The occurrence frequency of the attack posture was positively related to fish density, but inversely related to starvation duration, and occurred most frequently at 19 degrees C. This posture depended on prey density in larvae prior to 10 days post-hatch, but became independent of prey density as the larvae developed. It was obvious that, for flounder larvae, attack posture was a behavioural character closely related to feeding and subject to larval development and environmental factors. (C) 2000 The Fisheries Society of the British Isles.

The feeding activity of Colossoma macropomum larvae (tambaqui) in fishponds with water hyacinth (Eichhornia crassipes) fertilizer

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The feeding activity of Colossoma macropomum larvae (tambaqui) in fishponds with water hyacinth (Eichhornia crassipes) fertilizer

O objetivo deste trabalho foi avaliar a influência do aguapé como fertilizante orgânico no comportamento alimentar de larvas de tambaqui (Colossoma macropomum) em viveiros de larvicultura. O aguapé foi utilizado para produzir um fertilizante orgânico na proporção de 100 g.m-2. Dois grupos de 5.000 larvas foram transferidos para dois viveiros com e sem fertilizante de macrófita e criados durante um período de 43 dias. O viveiro contendo fertilizante de macrófita apresentou maior abundância de plâncton durante o período de estudo quando comparado ao viveiro controle (P <0,001). A estrutura da comunidade fitoplanctônica não apresentou diferença significativa daquela encontrada no trato digestivo (P > 0,05) e nos viveiros (com e sem fertilizante), evidenciando que as larvas de peixe não apresentaram preferência ou seletividade (P > 0,01) em relação às diferentes algas presentes no viveiro, somente em relação aos organismos zooplanctônicos (P < 0,05). A aplicação de fertilizante aumentou significativamente (P < 0,05) a abundância de fitoplâncton e zooplâncton nos viveiros estudados. O fertilizante de aguapé é fácil de ser obtido e é barato, assim poderá ser utilizado como uma nova alternativa para melhorar a produção dos viveiros de piscicultura.

Predator presence moves Helicoverpa armigera larvae to distraction

Displacement of herbivorous insects by the presence of predators on whole plants has rarely been studied. By semi-continuous observations of an externally feeding insect herbivore and a predator, we show how the mere presence of the predator, Geocoris lubra Kirkaldy (Hemiptera: Geocoridae), on a plant can have a strong influence on the movement and behaviors of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) larvae. The presence of predators, as opposed to mortality by predators, influenced the proportion of larvae feeding, resting and implementing avoidance activities. In addition, the proportion of time individual larvae allocated to feeding, resting and dropping off plants was affected when predators were present with and without contact between the two. Predators do more than just reduce numbers of herbivores; they influence feeding, displacement and subsequently the distribution of plant damage.

Ontogenetic development of digestive enzymes and effect of starvation in miiuy croaker Miichthys miiuy larvae

The ontogenetic development of the digestive enzymes amylase, lipase, trypsin, and alkaline phosphatase and the effect of starvation in miiuy croaker Miichthys miiuy larvae were studied. The activities of these enzymes were detected prior to exogenous feeding, but their developmental patterns differed remarkably. Trypsin activity continuously increased from 2 days after hatching (dah), peaked on 20 dah, and decreased to 25 dah at weaning. Alkaline phosphatase activity oscillated at low levels within a small range after the first feeding on 3 dah. In contrast, amylase and lipase activities followed the general developmental pattern that has been characterized in fish larvae, with a succession of increases or decreases. Amylase, lipase, and trypsin activities generally started to increase or decrease at transitions from endogenous to exogenous feeding or diet changes, suggesting that these enzymatic activities can be modulated by feeding modes. The activities of all the enzymes remained stable from 25 dah onwards, coinciding with the formation of gastric glands and pyloric caecum. These results imply that specific activities of these enzymes underwent changes due to morphological and physiological modifications or diet shift during larval development but that they became stable after the development of the digestive organs and associated glands was fully completed and the organs/glands functioned. Trypsin and alkaline phosphatase were more sensitive to starvation than amylase and lipase because delayed feeding up to 2 days after mouth opening was able to adversely affect their activities. Enzyme activities did not significantly differ among feeding groups during endogenous feeding; however, all activities were remarkably reduced when delayed feeding was within 3 days after mouth opening. Initiation of larvae feeding should occur within 2 days after mouth opening so that good growth and survival can be obtained in the culture.

Behavioural responses of workers towards worker-produced male larvae and queen-produced worker larvae in Acromyrmex subterraneus brunneus Forel, 1911 (Hym., Formicidae)

Leaf-cutting ant workers care for larvae with an elaborate behavioural repertoire to satisfy the needs of the offspring. In order to investigate worker discrimination ability in the leaf-cutting ant Acromyrmex subterraneus brunneus, we compared the behavioural responses of workers towards worker-produced male larvae and queen-produced worker larvae, including the following behavioural acts: licking the larval body, transporting larvae, feeding larvae with hyphae, scraping larval mouth parts, ingesting faecal fluid excreted by the larva, and inserting hyphae of the symbiontic fungus on the larval body. We verified that workers behaved differently depending on larval origin, i.e. licking the larval body, transporting larvae and inserting hyphae of the symbiontic fungus on the larval body. Observed differences denote the ability of workers in discriminating among larvae, probably because of their different individual needs.

Pest-damage relationships for Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) on vegetative soybean.

The response of vegetative soybean (Glycine max) to Helicoverpa armigera feeding was studied in irrigated field cages over three years in eastern Australia to determine the relationship between larval density and yield loss, and to develop economic injury levels. Rather than using artificial defoliation techniques, plants were infested with either eggs or larvae of H. armigera, and larvae allowed to feed until death or pupation. Larvae were counted and sized regularly and infestation intensity was calculated in Helicoverpa injury equivalent (HIE) units, where 1 HIE was the consumption of one larva from the start of the infestation period to pupation. In the two experiments where yield loss occurred, the upper threshold for zero yield loss was 7.51 ± 0.21 HIEs and 6.43 ± 1.08 HIEs respectively. In the third experiment, infestation intensity was lower and no loss of seed yield was detected up to 7.0 HIEs. The rate of yield loss/HIE beyond the zero yield loss threshold varied between Experiments 1 and 2 (-9.44 ± 0.80 g and -23.17 ± 3.18 g, respectively). H. armigera infestation also affected plant height and various yield components (including pod and seed numbers and seeds/pod) but did not affect seed size in any experiment. Leaf area loss of plants averaged 841 and 1025 cm2/larva in the two experiments compared to 214 and 302 cm2/larva for cohort larvae feeding on detached leaves at the same time, making clear that artificial defoliation techniques are unsuitable for determining H. armigera economic injury levels on vegetative soybean. Analysis of canopy leaf area and pod profiles indicated that leaf and pod loss occurred from the top of the plant downwards. However, there was an increase in pod numbers closer to the ground at higher pest densities as the plant attempted to compensate for damage. Defoliation at the damage threshold was 18.6 and 28.0% in Experiments 1 and 2, indicating that yield loss from H. armigera feeding occurred at much lower levels of defoliation than previously indicated by artificial defoliation studies. Based on these results, the economic injury level for H. armigera on vegetative soybean is approximately 7.3 HIEs/row-metre in 91 cm rows or 8.0 HIEs/m2.

Organic and conventional fertilizer effects on a tritrophic interaction: parasitism, performance and preference of Cotesia vestalis

Interest in sustainable farming methods that rely on alternatives to conventional synthetic fertilizers and pesticides is increasing. Sustainable farming methods often utilize natural populations of predatory and parasitic species to control populations of herbivores, which may be potential pest species. We investigated the effects of several types of fertilizer, including those typical of sustainable and conventional farming systems, on the interaction between a herbivore and parasitoid. The effects of fertilizer type on percentage parasitism, parasitoid performance, parasitoid attack behaviour and responses to plant volatiles were examined using a model Brassica system, consisting of Brassica oleracea var capitata, Plutella xylostella (Lepidoptera) larvae and Cotesia vestalis (parasitoid). Percentage parasitism was greatest for P. xylostella larvae feeding on plants that had received either a synthetic ammonium nitrate fertilizer or were unfertilized, in comparison to those receiving a composite fertilizer containing hoof and horn. Parasitism was intermediate on plants fertilized with an organically produced animal manure. Male parasitoid tibia length showed the same pattern as percentage parasitism, an indication that offspring performance was maximized on the treatments preferred by female parasitoids for oviposition. Percentage parasitism and parasitoid size were not correlated with foliar nitrogen concentration. The parasitoids did not discriminate between hosts feeding on plants in the four fertilizer treatments in parasitoid behaviour assays, but showed a preference for unfertilized plants in olfactometer experiments. The percentage parasitism and tibia length results provide support for the preference–performance hypothesis

Impact of chemical structure of flavanol monomers and condensed tannins on in vitro anthelmintic activity against bovine nematodes

Plants containing condensed tannins (CT) may have potential to control gastrointestinal nematodes (GIN) of cattle. The aim was to investigate the anthelmintic activities of four flavan-3-ols, two galloyl derivatives and 14 purified CT fractions, and to define which structural features of CT determine the anti-parasitic effects against the main cattle nematodes. We used in vitro tests targeting L1 larvae (feeding inhibition assay) and adults (motility assay) of Ostertagia ostertagi and Cooperia oncophora. In the larval feeding inhibition assay, O. ostertagi L1 were significantly more susceptible to all CT fractions than C. oncophora L1. The mean degree of polymerization of CT (i.e. average size) was the most important structural parameter: large CT reduced larval feeding more than small CT. The flavan-3-ols of prodelphinidin (PD)-type tannins had a stronger negative influence on parasite activity than the stereochemistry, i.e. cis- vs trans-configurations, or the presence of a gallate group. In contrast, for C. oncophora high reductions in the motility of larvae and adult worms were strongly related with a higher percentage of PDs within the CT fractions while there was no effect of size. Overall, the size and the percentage of PDs within CT seemed to be the most important parameters that influence anti-parasitic activity.

Comportamento alimentar do camarão de agua doce, Macrobrachium rosenbergii (De Man) (Crustacea, Palaemonidae) durante a fase larval: análise qualitativa

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Variation in the host preferences and responses of Ascia monuste orseis Godart (Lepidoptera: Pieridae) to cultivars of collard greens Brassica oleracea (L.) var. acephala

This work evaluated the preference of Ascia monuste orseis among 29 cultivars of collard greens through free- and no-choice assays using female adults (attractiveness and oviposition) and third-instar larvae (feeding preference), in both laboratory and greenhouse conditions. In free-choice tests with female adults, the L, V, Y, H, A, and Z cultivars produced oviposition non-preference in butterflies. Cultivars R, P, C, and D produced feeding non-preference in third-instar larvae of A. monuste orseis in free- and no-choice tests. Our findings may be useful for genetic improvement focusing on the development of B. oleracea var. acephala cultivars resistant to A. monuste orseis.

Suplementação de enzimas exógenas em dieta microparticulada para larvicultura do pacu

Este experimento foi realizado para avaliar os efeitos da suplementação de enzimas exógenas (pancreatina suína) em microdietas sobre o crescimento, a sobrevivência e as alterações morfológicas do trato digestório de larvas de pacu, Piaractus mesopotamicus. Foram testados oito programas alimentares: alimentação exclusiva com náuplios de Artemia (AV); alimentação exclusiva com dieta microparticulada com (DMP) ou sem (DM) suplementação enzimática; substituição, aos cinco dias, dos náuplios de Artemia por dietas inertes com (AV5DMP) ou sem (AV5DM) suplementação; e substituição dos náuplios aos dez dias por dietas com (AV10DMP) ou sem (AV10DM) suplementação. O experimento teve duração de 28 dias. Larvas que receberam o alimento vivo durante todo o período experimental apresentaram maiores médias de peso. O efeito negativo da supressão do alimento vivo sobre o crescimento das larvas foi verificado tanto na substituição aos cinco dias como aos dez dias. No entanto, nas avaliações biométricas subseqüentes, observaram-se efeitos positivos da suplementação enzimática; a partir do 20º dia de experimento, as larvas que receberam a dieta suplementada com enzima exógena apresentaram peso médio estatisticamente superior ao daquelas alimentadas com a dieta sem suplementação. As diferenças morfológicas mais evidentes proporcionadas pela suplementação enzimática foram observadas nas larvas que receberam substituição alimentar aos cinco dias. As diferenças foram relativas à quantidade de grânulos de zimogênio no pâncreas e às inclusões supranucleares no intestino. As larvas submetidas à transição alimentar aos dez dias de experimento já apresentavam diferenciação morfológica do sistema digestório mais avançada, assemelhando-se muito às larvas do tratamento com alimento vivo. Os resultados deste experimento indicam que a suplementação com pancreatina proporcionou efeitos positivos sobre o crescimento e a sobrevivência das larvas de pacu.

Estudo morfológico e histoquímico do tubo digestivo de eleuteroembriões e larvas de Leporinus obtusidens (Valenciennes, 1836)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)