Egg Hatching Inhibition Research Articles

In Vitro Activity of Pithecellobium Dulce and Lysiloma Acapulcensis on Exogenous Development Stages of Sheep Gastrointestinal Strongyles

An experiment was conducted to evaluate the effects of two lyophilised aqueous extracts of Lysiloma acapulcensis (LAE) and Phitecellobium dulce (PDE) tree leaves on in vitro assessment of hatching of eggs, larval development and migration of gastrointestinal nematodes of sheep using a general linear model. Treatments contained extracts from both species at concentrations of 0, 125, 250 and 500 µg/mL. Both albendazole and levamisole were used at a level of 1% as positive control. The extract of LAE, compared to PDE, showed better inhibition (P<0.05) of egg hatching. Different doses of both the LAE and PDE extracts showed a larvicidal effect (P<0.05) on all larvae exposed to different doses of the extracts. In the larval migration assay, a similar effect with levamisole at doses of 250 and 500 µg/mL occurred with the LAE extract. The extract of P. dulce had a lower larvicidal effect (P<0.05) than levamisole and L. acapulcensis extracts. Using aqueous extracts of both species of L. acapulcensis and P. dulce could be a promising alternative to synthetic anthelmintics as treatments of gastrointestinal nematodes of sheep in organic and conventional production systems under subtropical conditions.

POTENCIAL OVICIDA DE Origanum vulgare (Lamiaceae) EM NEMATÓDEOS GASTRINTESTINAIS DE BOVINOS

Due to anthelmintic resistance in nematodes, several research studies have been developed seeking control alternatives to these parasites. This study evaluated the in vitro action of Origanum vulgare on gastrointestinal nematode eggs of cattle. In order to evaluate the ability to inhibit egg hatch, different dried leaves extracts of this plant were tested, such as dye, hydroalcoholic and aqueous extracts at concentrations varying from 0.62 to 80 mg/mL. Each assay was accompanied by control containing levamisole hydrochloride (0.2 mg/mL), distilled water and 70o GL grain alcohol at the same concentration of the extracts. Test results showed that the different O. vulgare extracts inhibited egg hatch of cattle gastrointestinal nematodes at a percentage that varied from 8.8 to 100%; dye and hydroalcoholic extract were the most promising inhibitors. In view of this ovicidal property, O. vulgare may be an important source of viable antiparasitic compounds for nematodiosis control in ruminants. KEYWORDS: Haemonchus spp.; in vitro; oregano; phytotherapic.

Screening and in Vitro Evaluation of Native Pseudomonas Spp., against Nematode Pathogens and Soil Borne Fungal Pathogens

The objective of this study was to assess the efficacy of native Pseudomonas spp., against root-knot nematode, Meloidogyne incognita and other soil borne fungal pathogens such as Fusarium oxysporum f. sp. Lycopersici and Sclerotium rolfsii . The eggs and second stage juveniles (J2) of M. incognita were exposed to each isolates of Pseudomonas spp., by diluting the standard culture filtrate to fifty percent and to undiluted culture filtrate (100%). Four isolates of Pseudomonas spp. (CRS3, CRS6, and CRS8 and CRS10) significantly induced inhibition of egg hatching and mortality of M. incognita juveniles. The per cent mortality was proportional to the concentration of culture filtrate and the duration of exposure period. The highest percentage of inhibition of egg hatching was recorded for CRS3 while mortality of second stage juveniles was found in the case of CRS10 in undiluted culture filtrate. The CRS6 caused 48% inhibition of Sclerotium rolfsii while CRS8 caused 58% inhibition of Fusarium oxysporum f. sp. lycopersici. Since meloidogyne infection can predispose plants to plant pathogens, these isolates show promise for management of nematode and disease complex of vegetable crops.

Inhibitory effect of Tamarindus indica and Carica papaya on egg hatch larva mortality of Meloidogyne incognita

Essentially, the most effective control of plant parasitic nematodes involves the use of synthetic nematicide. However, apart from their very high cost, increased concern on the environment has necessitated a reduction in the amount of nematicides used for nematode control. In view of these, this research work was conducted to evaluate the effects of different concentrations of root extract of Tamarindus indica and Carica papaya at different concentrations S (100% concentration), “S/2” (50% concentration), “S/10” (10% concentration) and “S/100”(1% concentration) in the inhibition of egg hatch and mortality of larva of root-knot nematode, Meloidogyne incognita .The experiment was laid out in a completely randomised design and replicated four times. Combination of equal proportion of T. indica and C .papaya root extract indicated that all the concentrations inhibited egg hatch. The standard solution S of all the selected botanicals were more toxic and effective at (p ≤ 0.05) than the other concentrations. Similarly, combinations of root extracts of T. indica and C. papaya were the most effective of all the selected botanicals in the inhibition of egg hatch and larvae mortality, followed by T. indica root extracts and then C. papaya root extracts.

Effect of Castor Bean (&lt;i&gt;Ricinus communis&lt;/i&gt; L.) Aqueous Extracts on the Performance of Root-Knot Nematodes (&lt;i&gt;Meloideogyne&lt;/i&gt; spp.) on Tomato (&lt;i&gt;Solanum lycopersicum&lt;/i&gt; L.)

The increased concern for environmental and health hazards have called for a reduction in the use of synthetic nematicides for nematode control. Experiments were, therefore, conducted to ascertain the nematicidal potential of castor bean’s crude extract and its five lower concentrations with water as control. In the in vitro studies, crude castor bean aqueous extract and 10, 20, 30 and 40% different concentrations with 100 root-knot nematode eggs or juveniles in separate Petri dishes showed that all the different concentrations had toxic effects on eggs and juveniles of root-knot nematode. Egg hatch inhibition and juvenile mortality increased with increased concentration of the extracts. With an increase in exposure time, juvenile mortality increased. In potted plant studies, crude castor bean aqueous extracts and its lower concentrations of 20, 40 and 60% caused significant improvement in plant growth measures such as height and fresh shoot weight over the water blank control. The crude castor bean extract was nematotoxic to root -knot nematodes in vitro and in potted-tomato plants, but this was not demonstrated in field studies. Further work needs to be done before a firm recommendation can be madeKeywords: Control, juveniles, nematicides, phytochemicals, water

The efficacy of four common anthelmintic drugs and traditional Chinese medicinal plant extracts to control Dactylogyrus vastator (Monogenea)

Disease caused by Dactylogyrus vastator has resulted in considerable economic damage in aquaculture. To control this parasite effectively, the anthelmintic properties of several extracts obtained from Euphorbia fischeriana and four common anthelmintic drugs (trichlorfon, praziquantel, 40% phoxim and mebendazole) against adults and eggs of D. vastator were assessed in vitro and in vivo. Trichlorfon (0.5, 1 and 1.5mg/L), praziquantel (10 and 20mg/L), 40% phoxim (0.1, 0.2 and 0.4mg/L), mebendazole (0.02 and 0.04mg/L) and the ethyl acetate extract of E. fischeriana (10 and 20mg/L) were effective to kill the parasites in vitro, while the other extracts (petroleum ether, n-butanol and distilled water) of E. fischeriana had no significant effects. Praziquantel effectively killed adults with the efficacy of 80.3% at 20mg/L and inhibited egg hatching, while trichlorfon and the ethyl acetate extract of E. fischeriana effectively eliminated adult parasites with the efficacy of 87.3% and 80.1% at 2.5mg/L and 14mg/L, but had no effect on egg viability. 40% phoxim was highly effective in suppressing egg hatching, but mebendazole was not significantly effective on either adults or eggs. Overall, this study found that 40% phoxim and praziquantel could prevent horizontal infection via eggs in aquaculture facilities and that trichlorfon, praziquantel and the ethyl acetate extract of E. fischeriana could be effective against adult parasites. However, the effective dose of the ethyl acetate extract of E. fischeriana was very close to the toxic dose, a factor that likely limits its practical application in aquaculture.

Bio-control activity of Purpureocillium lilacinum strains in managing root-knot disease of tomato caused by Meloidogyne incognita

The potential of 24 indigenous isolates of Purpureocillium lilacinum (Paecilomyces lilacinus) (Thom) Samson collected from different agro-climatic zones of India was investigated against the root-knot nematode, Meloidogyne incognita. The studies were conducted in vitro (larvicidal, ovicidal and egg-parasitising capacity) and under naturally infested field conditions with selected strains. Repeated field trials were conducted with talc-based preparations of fungal strains at 10 kg ha−1, which were applied mixed in farm yard manure (FYM) at 1.5 t ha−1. Results (in vitro) showed that all tested isolates were capable to parasitise eggs, inhibit egg hatching and cause juvenile mortality of M. incognita at various levels. Based on the performance under in vitro studies, eight isolates (NDPL-01, ANDPL-02, SHGPL-03, HYBPL-04, AHDPL-05, PTNPL-06, SNGPL-07 and VNSPL-08) were re-tested to confirm the results. HYBDPL-04 was found causing highest mortality (80%), inhibition of egg hatching (90%) as well as parasitisation of M. incognita eggs (75%). Under field trials also, the best protection of root-knot disease of tomato (Lycopersicon esculentum L.), in terms of reduction of galls (61%) and reproductive factor (Pf/Pi (RF) = 0.2) was achieved through application of HYBDPL-04 + FYM compared to control and other tested isolates. It also enhanced marketable yield of tomato up to 43%. It is concluded that the HYBDPL-04 strain of P. lilacinum is highly effective for management of root-knot disease of tomato under naturally infested field conditions. It is the isolate which produced the maximum number of metabolites which were extracted through high pressure liquid chromatography.

Bio-efficacy of some leaf extracts on the inhibition of egg hatching and mortality of Meloidogyne incognita

Nematicidal activities of extracts from plants were assayed against Meloidogyne incognita in vitro. Leaves of six different plants were collected in and around Aligarh Muslim University Campus. Aqueous extracts of six plants were screened for egg hatchability and nematicidal activity against second stage juveniles of M. incognita in the plant pathology and nematology laboratory, AMU Aligarh. The nematode egg and juveniles were exposed 12, 24 and 48 h in (S, S/2, S/10, S/100) concentrations of plant extracts. The plant extracts of leaves of six plants species viz. Jatropha pandurifolia, Polyalthia longifolia, Wedelia chinensis, Nerium indicum, Duranta repens and Cassia fistula exhibited highly promising mortality of 99.00–72.00% after 48 h of exposure. Aqueous extracts of leaves of J. pandurifolia, P. longifolia, W. chinensis were recorded to be highly effective for inhibition of egg hatching and increasing juvenile mortality of M. incognita. There was a gradual decrease in egg hatching and increase in mortality rate of juveniles of M. incognita with increase in the concentration of leaf extract and exposure time.

English

In vitro experiments were conducted to determine the anthelmintic effects of crude aqueous extracts of the leaves of Carissa spinarum and Azadrichta indica, fruits ofPhytolacca dodecandra and stem bark of Acacia tortilis on eggs and adults ofHaemonchus contortus using egg hatch assay and mortality of adult parasite. Extracts of the leaves of C. spinarum and A. indica inhibited hatching of egg at concentration less than or equal to 1 mg/ml. Low egg hatch inhibition were observed for extracts of A. tortilis(100%) and P. dodecandra (99.4%) at the maximum concentration tested (2 mg/ml). Of the plants tested, extracts of C. spinarum and A. indica showed very good activity against the adult worms of H. contortus, mortality raised to the levels of 96.8 and 93.9%, respectively, at concentration of 4 mg/ml. P. dodecandra and A. tortilis produced mortality of 68.1 and 53.03% of adult H. contortus at 4 mg/ml concentration, respectively. Albendazole killed the parasites in a dose dependant manner and all the worms were dead at a concentration of 0.5 mg/kg within 24 h. The overall findings of the current study indicated that most of the plants have potential anthelmintic effect warranting further in vitro and in vivo evaluation. Key words: Anthelmintic, Haemonchus contortus, in vitro experiment, plant extracts.

Effect of new ethyl and methyl carbamates on Rhipicephalus microplus larvae and adult ticks resistant to conventional ixodicides

The effects of six new synthetic carbamates on fully engorged females of four Rhipicephalus microplus strains (one reference strain susceptible to conventional ixodicides, two strains multiresistant to ixodicides and one tick field isolate) were compared. In addition, the effect of two other new synthetic carbamates was tested on larvae from the same strains. The first six tested carbamates reduced egg laying and inhibited egg hatching in the four studied strains (P<0.05). Compared with untreated females, the eggs produced by the treated engorged female ticks of all strains had a dark, dry, opaque appearance and were less adherent. The remaining two tested carbamates induced larval mortality in all of the evaluated strains. The three studied R. microplus strains displayed 50% resistance ratios (RR50) of less than 2 when compared to the susceptible reference strain. These results demonstrate that both carbamates with a larvicidal effect and carbamates that inhibit egg laying and embryo development are efficacious against tick strains that are resistant to commercial ixodicides, no cross resistance was observed.

In vitro effect of heather extracts on Trichostrongylus colubriformis eggs, larvae and adults

This study was carried out to evaluate the in vitro effects of different heather species on Trichostrongylus colubriformis eggs, larvae and adult worms, and obtain scientific evidence to attribute these effects to the action of their phenolic compounds and/or tannins. Total phenolic extracts of three heather species (Calluna vulgaris, Erica cinerea, and Erica umbellata) and an equal mixture of these three extracts were tested in vitro in the three development stages of T. colubriformis using an egg hatching assay (EHA), larval exsheathment inhibition assay (LEIA), and adult motility inhibition assay (AMIA). The egg hatching rate was measured after incubation with heather extracts for 48h at 25°C. Infective third-stage larvae (L3) were incubated for 3h at 25°C with heather extracts. The evolution of artificial exsheathment over time was measured with repeated observations at 20-min intervals for 60min. Adult worms were obtained from one donor goat and incubated with the extracts at 37°C for 5 days in 48-multiwell plates. Worm motility was measured at 0, 19, 24, 43, 48, 67, 72, 96 and 115h after the beginning of the experiment. The extracts were tested at concentrations of 75, 150, 300, 600 and 1200μg/ml. All extracts significantly (P<0.001) inhibited egg hatching and the effect was dose dependent. All extracts inhibited or delayed the exsheathment of T. colubriformis L3, and the effect was dose dependent for C. vulgaris. Incubation with heather extracts induced a reduction in adult worm motility compared to control, although significant (P<0.05) differences were only found at the highest concentrations. Additional studies showed that purified tannins of the same heather species disturbed T. colubriformis larval exsheathment. All these results confirm the anthelmintic properties of heather against T. colubriformis, and suggest that not only tannins but also some other phenolic compounds might be involved.

Ovicidal activity of three insect growth regulators against Aedes and Culex mosquitoes

Interspecific variations in the susceptibility of freshly and embryonated eggs of Aedes albopictus, Ae. aegypti, Ae. atropalpus and Culex pipiens were tested against three classes of insect growth regulators (IGRs) including ecdysone agonist (azadirachtin), chitin synthesis inhibitor (diflubenzuron) and juvenile hormone analog (pyriproxyfen) at 0.001, 0.01, 0.1 and 1.0ppm concentrations. Egg hatching inhibition was dose dependent, the highest being at 1.0ppm concentration for freshly laid eggs of Ae. albopictus (pyriproxyfen: 80.6%, azadirachtin: 42.9% and diflubenzuron: 35.8%). Aedes aegypti showed lower egg hatching inhibition when exposed to pyriproxyfen (47.3%), azadirachtin (15.7%) and diflubenzuron (25.5%). Freshly laid eggs of Cx. pipiens were most susceptible to diflubenzuron. Aedes atropalpus eggs were tolerant to all three classes of IGRs. Embryonated eggs of Ae. albopictus, Ae. aegypti, Ae. atropalpus and Cx. pipiens were resistant to pyriproxyfen, azadirachtin and diflubenzuron than freshly laid eggs. The median desiccation time (DT50) of Ae. atropalpus eggs was maximum (5.1h) as compared to Ae. aegypti (4.9h), Ae. albopictus (3.9h) or Cx. pipiens (1.7h) eggs. Insignificant relationship between the rates of desiccation and egg hatching inhibition suggests other factors than physical providing eggs the ability to tolerate exposures to various IGRs. Egg hatching inhibition was due to the alteration in embryonic development caused by IGRs. Changes in the egg shell morphology and abnormal egg hatching from the side of the egg wall instead of operculum, was observed at higher concentrations of diflubenzuron. Morphological and physiological variations in eggs may be the key factor to influence the ovicidal efficacy of IGRs. The present data provide a base line for the improvement of the ovicidal efficacy of the insecticide and its formulation.

The effect of purified condensed tannins of forage plants from Botswana on the free-living stages of gastrointestinal nematode parasites of livestock

The effect of condensed tannins (CT) extracted from forage plants from Botswana on the free-living stages of a number of species of gastrointestinal nematode parasites derived from infected sheep were investigated using in vitro assays. Fresh samples of five different plants (Viscum rotundifolium, Viscum verrucosum, Tapinanthus oleifolius, Grewia flava and Ipomoea sinensis) were collected over two summers (February 2009 and 2010). Fractionation of each crude extract on a Sephadex LH-20 column yielded low molecular weight phenolics and CT-containing fractions. The effect of each purified CT fraction on parasites was evaluated using either egg hatch, larval development or larval migration inhibition assays. Three gastrointestinal nematode species (Haemonchus contortus, Trichostrongylus colubriformis and Teladorsagia circumcincta) derived from infected sheep were evaluated in the study. CT from V. rotundifolium and I. sinensis fractions from samples collected in 2009 and 2010 did not inhibit larval development. However, CT isolated from V. verrucosum, T. oleifolius and G. flava collected in 2009 completely inhibited the development of all parasite species. These CT fractions were more potent in inhibiting larval development of H. contortus than fractions from the same plant species collected in 2010. However, a slight effect on larval migration was observed with some CT extracts. The results suggest that CT extracts of some forage plants from Botswana have anti-parasitic properties in vitro, and that further research is required to determine any in vivo efficacy from feeding the plants to goats in a field situation.

Nematicidal potential of Artemisia annua and its main metabolites

Nematotoxic effect of an aqueous extract of Artemisia annua and its components caffeic acid, chlorogenic acid (5-caffeoylquinic acid, 5-CQA), artemisinin and the related semi-synthetic artesunate, was investigated on the root-knot nematode Meloidogyne incognita and the potato cyst nematode Globodera rostochiensis and on the virus-vector dagger nematode Xiphinema index. Juveniles of M. incognita and G. rostochiensis and females of X. index were exposed to 500, 250 and 125 μ lm l −1 solutions of the A. annua aqueous extract, caffeic acid, chlorogenic acid and artesunate and to 50 μ lm l −1 solution of artemisinin for 2, 4, 8 and 24 h. Egg masses of M. incognita and cysts of G. rostochiensis were exposed for 24, 48, 96 h and 1 or 2 weeks only to the extract solutions. Aqueous extract was highly effective on G. rostochiensis juveniles, whereas M. incognita juveniles were affected only at long exposure times. Adversely, egg hatch inhibition was strong on M. incognita and poor or minimal onG. rostochiensis.FemalesofX.indexweresensitiveonlyto long exposures to the highest extract concentration. Both caffeic and chlorogenic acid did not affect juve- niles of M. incognita but were highly active on G. rostochiensis juveniles and X. index females even at the lowest concentration. Artesunate toxicity was almost zero on M. incognita and low on X. index females, but high on G. rostochiensis juveniles. Artemisinin solution waslethaltomorethan50%ofG.rostochiensisjuveniles within 24 h, but did not affect M. incognita juveniles and X. index females. Results suggest different roles of the tested compounds in the biocidal activity on each target nematode species. The extract of A. annua and its main phytochemicals seem to have a potential to be developed into new nematicidal formulates, though their activity should be validated in the soil.

Further insecticidal activities of essential oils from Lippia sidoides and Croton species against Aedes aegypti L.

This study assessed new insecticidal activities of essential oils from Lippia sidoides and Croton species (Croton zehntneri, Croton nepetaefolius, Croton argyrophylloides, and Croton sonderianus) against Aedes aegypti mosquito. In addition, the acute toxicity upon mice was determined. All essential oils showed inhibition of egg hatching, with IC50 values ranging from 66.4 to 143.2μg mL(-1), larvicidal activity with LC50 ranging from 25.5 to 94.6μg mL(-1), and pupicidal action with PC50 ranging from 276.8 to over 500μg mL(-1). Only L. sidoides, C. zehntneri, and C. argyrophylloides essential oils were able to inhibit the oviposition of female gravid mosquitoes with OD50 values of 35.3, 45.3, and 45.8μg mL(-1), respectively. Oral acute toxicity in mice showed that C. sonderianus and C. argyrophylloides oils are nontoxic (LD50 > 6,000mg.kg(-1)) while C. nepetaefolius, C. zehntneri, and L. sidoides oils are moderately toxic (LD50 3,840; 3,464, and 2,624mg.kg(-1), respectively). The results indicate that these oils are promising sources of bioactive compounds, showing low or no toxicity to mammals.

Trigonella foenum-graecum (fenugreek)-mediated suppression of Meloidogyne javanica in mungbean

Soil amendments with powdered seeds of &lt;i&gt;Trigonella foenum - graecum&lt;/i&gt; (fenugreek) caused soil suppressiveness against &lt;i&gt;Meloidogyne javanica&lt;/i&gt;. Decomposed seeds of fenugreek caused marked reduction in nematode population densities and subsequent root-knot development as compared to the aqueous extract of the seeds indicating that some indirect factors are involved in the suppression of root-knot nematode. Both decomposed seeds and aqueous extracts enhanced plant height and fresh weights of shoot whereas root growth remained uninfluenced. Changes in fungal communities associated with nematode control were studied by comparing population numbers of fungi in the soil and in internal root tissues (endorhiza) in non-amended and fenugreekamended soils. &lt;i&gt;Acremonium&lt;/i&gt; sp., &lt;i&gt;Chaetomium globosum, Fusarium solani, Macrophomina phaseolina&lt;/i&gt; and &lt;i&gt;Rhizoctonia solani&lt;/i&gt; were found to colonize inner root tissues of mungbean. &lt;i&gt;Acremonium&lt;/i&gt; sp., &lt;i&gt;C. globosum&lt;/i&gt; and &lt;i&gt;F.solani&lt;/i&gt; were isolated in a relatively higher frequency from roots growing in the amended soils while &lt;i&gt;M. phaseolina&lt;/i&gt; and &lt;i&gt;R. solani&lt;/i&gt; colonized greatly in roots growing in non-amended soil. Of the fungi isolated from soils, &lt;i&gt;Penicillium brefaldianum&lt;/i&gt; caused maximum juvenile mortality of &lt;i&gt;M.javanica&lt;/i&gt; whereas &lt;i&gt;F.solani&lt;/i&gt; caused greatest inhibition of egg hatch.

Effect of aqueous extracts of Baccharis trimera on development and hatching of Rhipicephalus microplus (Acaridae) eggs

This study evaluated the effects of aqueous extracts of Baccharis trimera (Less.) DC (Asteraceae), colloquially known as carqueja, on egg production, and hatching rate of larvae of Rhipicephalus microplus. Plant samples were collected in Montes Claros, north of Minas Gerais, Brazil. Adult female ticks were distributed into 24 homogeneous groups of 10. The in vitro test was performed by immersing each group in 10ml solutions of aqueous extracts at 50, 100, 150, or 200mg of fresh leaves ml−1. These concentrations were compared with distilled water as negative control and a commercial product as positive control and the tests were repeated four times. The carqueja extract at concentrations of 150 and 200mg of fresh leaves ml−1 showed 100% efficacy in inhibiting egg hatching and therefore could have potential as an acaricide.

Effect of new ethyl and methyl carbamates on biological parameters and reproduction of the cattle tick Rhipicephalus microplus

The effect of carbamates on engorged female Rhipicephalus microplus ticks and larvae was evaluated using the adult immersion test (AIT) and the larval packet test (LPT), respectively. Seventeen synthetic carbamates different from current commercial acaricides were synthesised at the National Autonomous University of Mexico. None of the carbamates had an effect on the percentage of females laying eggs. Six of the compounds inhibited egg laying up to 65.4% and inhibited egg hatching by up to 100% (p<0.05). Compared to untreated females, eggs produced by treated females had a dark, dry, opaque appearance and were less adherent. Carbamates LQM 934 and LQM 938 had an effect on larval mortality (p<0.05). Carbamate LQM 934 showed lethal concentrations (LC) of LC90=0.76% and LC99=0.87%, while LQM 938 showed concentrations of LC90=0.267% and LC99=0.305%. The compounds were distributed into three classes of acaricidal activity using the AIT or the LPT. These three classes were as follows: (1) compounds having no apparent effect; (2) compounds that inhibit egg laying and embryo development or (3) compounds that exhibit acaricidal activity to larval ticks.

In vitro ovicidal and larvicidal activity of Agave sisalana Perr. (sisal) on gastrointestinal nematodes of goats

This study describes the in vitro anthelmintic activity of aqueous extracts (AE), ethyl acetate extracts (EE), flavonoid fractions (FF) and saponin fractions (SF) obtained from sisal waste (Agave sisalana) against gastrointestinal nematodes of goats. The activity of these extracts was evaluated by performing inhibition of egg hatch (EHA) and larval migration (LMI) assays. The EC50 results of the EHA corresponded to 4.7, 0.1 and 0.05mg/mL for EE, EA and FF, respectively. The SF fraction showed no ovicidal activity. The percent efficacies that were observed for the LMI were 50.3, 33.2 and 64.1% for the AE, EE and SF, respectively. The FF fraction did not show activity against the larvae. The analysis of the FF fraction indicates the presence of a homoisoflavonoid. This report suggests that the A. sisalana has activity in vitro against gastrointestinal nematodes of goats. This effect is likely related to the presence of homoisoflavonoid and saponin compounds, which have different actions for specific stages of nematode development.

Seaweed extracts as a natural control against the monogenean ectoparasite, Neobenedenia sp., infecting farmed barramundi (Lates calcarifer)

Aqueous extracts from common tropical seaweeds were evaluated for their effect on the life cycle of the commercially important ectoparasite, Neobenedenia sp. (Platyhelminthes: Monogenea), through the survival of attached adult parasites, period of embryonic development, hatching success and oncomiracidia (larvae) infection success. There was no significant effect of any extract on the survival of adult parasites attached to fish hosts or infection success by oncomiracidia. However, the extracts of two seaweeds, Ulva sp. and Asparagopsis taxiformis, delayed embryonic development and inhibited egg hatching. The extract of A. taxiformis was most effective, inhibiting embryonic development of Neobenedenia sp. and reducing hatching success to 3% compared with 99% for the seawater control. Furthermore, of the 3% of eggs that hatched, time to first and last hatch was delayed (days 14 and 18) compared with the seawater control (days 5 and 7). Asparagopsis taxiformis shows the most potential for development as a natural treatment to manage monogenean infections in intensive aquaculture with the greatest impact at the embryo stage.