Bioactive molecules of plant species are promising alternatives for the chemical control of gastrointestinal nematodes in ruminants. Extracts of native and exotic seed species from Brazil's semi-arid region were tested in vitro in an egg hatch assay and the bioactivity of their proteins was investigated. Each seed species was subjected to three extractions with three types of solvents. All the seeds showed ovicidal activity, which varied according to the solvents. Higher ovicidal activity was found in the molecule fractions of low molecular weight (<12 kDa) for Albizia lebbeck, Ipomoea asarifolia, Jatropha curcas, Libidibia ferrea, Moringa oleifera and Ricinus communis (P<0.05, Bonferroni test). The two fractions of Crotalaria spectabilis showed the same ovicidal activity (P>0.05, Bonferroni test). Hemagglutinating activity was detected in the fractions of C. spectabilis and M. oleifera fractions, hemolysin activity in the A. lebbeck and M. oleifera fractions, serine protease inhibitory activity in the A. lebbeck, I. asarifolia, J. curcas, M. oleifera and R. communis fractions, cysteine protease inhibitor activity in the M. oleifera fraction, and no protein activity in the L. ferrea fraction. The results of this work reveal new plant species with a potential for use in controlling nematode parasites in goats, thus opening a new field of research involving plant protein molecules with ovicidal properties.Keywords: Goats, nematodes, egg hatch assay, lectin, protease inhibitors, hemolysin. ResumoMoléculas bioativas de espécies vegetais são alternativas promissoras ao controle químico dos nematoides gastrintestinais em ruminantes. Extratos de sementes de espécies nativas e exóticas do Semiárido Brasileiro foram testados in vitro em ensaio de eclosão de ovos e investigada a natureza proteica da bioatividade. Três extrações com três solventes foram feitas para cada semente estudada. Todas as sementes apresentaram atividade ovicida, variando com o solvente utilizado. Maior taxa de inibição da eclosão concentrou-se nas frações de moléculas de baixa massa molecular (<12 kDa) para Albizia lebbeck, Ipomoea asarifolia, Jatropha curcas, Libidibia ferrea, Moringa oleifera e Ricinus communis (P<0,05, teste de Bonferroni). Crotalaria spectabilis mostrou atividade nas duas frações, sem diferença entre elas (P>0,05, teste de Bonferroni). Observou-se atividade hemaglutinante nas frações de C. spectabilis e M. oleifera, de hemolisina em A. lebbeck e M. oleifera, de atividade inibidora de protease da serina em A. lebbeck, I. asarifolia, J. curcas, M. oleifera

The nematicidal effect of different organic materials was evaluated in order to develop a non-chemical alternative soil treatment for control of the free-living stages of small ruminant gastrointestinal nematodes. The selected organic materials were residues from the juice industry of acerola, cashew, grape, guava, papaya and pineapple, as well as castor residue from the biodiesel industry. LC90 results showed that pineapple residue was the most efficient inhibitor of larval development, followed by castor, grape, cashew, acerola, guava and papaya. Castor residue was also a good source of nitrogen and was used in a greenhouse experiment to prevent larval development in contaminated goat faeces that was deposited in pots containing the grasses Brachiaria brizantha (var. Paiaguás) or Megathyrsus maximus x M. infestum (var. Massai). Castor residue caused a significant (P < 0.05) reduction (85.04%) in Paiaguás grass contamination (L3.dry mass-1) and a reduction of 17.35% in Massai grass contamination (P > 0.05), with an increase in the biomass production of Massai (251.43%, P < 0.05) and Paiaguás (109.19%, P > 0.05) grasses. This strategy, called Econemat®, with good results in vitro shows to be promising on pasture increasing phytomass production.