No abstract

The main method used for the control of gastrointestinal nematodes in sheep production is the application of chemotherapeutic agents, which often lead to the selection of parasites resistant to given active principles. Biological control can be considered a promising alternative, contributing to an increase in the efficacy of verminous control. We determined the in vitro activity and in situ survival of the predatory fungi Arthrobotrys musiformis and Arthrobotrys conoides during passage through the gastrointestinal tract of sheep after oral administration of conidia in microencapsulated form and as a liquid in natura. Initial in vitro tests showed that both fungi were efficient in the predation of trichostrongylid L3 larvae present in the faeces of sheep naturally infected with gastrointestinal nematodes. The fungi presented high nematophagous activity, which was 99.3% for A. conoides and 73.7% for A. musiformis. A. conoides did not survive passage through the gastrointestinal tract under the conditions of the present experiment. On the other hand, A. musiformis was reisolated after administration in either microencapsulated or liquid form, suggesting that this species is a promising alternative for the control of nematodes in sheep since it survives without any protection (in natura).

Resumo: O estudo tem como objetivo avaliar a carga parasitária (helmintos) de bovinos da região de Jaboticabal, Estado de São Paulo. Para tanto, foram utilizados 42 bovinos naturalmente infectados, machos, mestiços (taurinos x zebuínos), com idade variando entre 8 e 14 meses. Os resultados necroscópicos revelaram a presença de 17 espécies de helmintos, com a seguinte prevalência e a média da intensidade de infecção: Haemonchus placei 97,62% (1961,81) ) and Cooperia (77,91%) were the most frequently observed helminths. Mixed infections were commonly observed, 71,43% of the animals were parasitized with three to five different species of helminths. Only 2,38% of the calves were parasitized with ten different species of helminths.

Este trabalho objetivou avaliar, in vitro e in vivo, o fungo predador Arthrobotrys musiformis, administrado via oral na forma de conídios microencapsulados em alginato ou in natura em meio líquido, após passagem pelo trato gastrintestinal de ovinos. No teste in vitro, avaliou-se a manutenção da atividade predatória, e no teste in vivo, a capacidade de controlar nematóides parasitos de ovinos naturalmente infectados, mantidos em pastagens. O resultado do teste in vitro confirmou a viabilidade de A. musiformis (95,5%), mesmo após a passagem pelo trato gastrintestinal. Na avaliação in vivo, não houve diferença estatística entre o número de ovos por grama de fezes dos grupos tratados e controle, provavelmente em razão da baixa lotação dos piquetes, da quantidade e periodicidade insuficientes de oferecimento de conídios aos ovinos, o que teria proporcionado dispersão e migração das larvas na pastagem. Contudo, os helmintos recuperados na necropsia dos animais traçadores mostraram que A. musiformis reduziu em 50,9% e 57,6% o número de Trichostrongylus colubriformis dos grupos tratados com conídios microencapsulados e in natura, respectivamente, e em 95% o número de L4 de Haemonchus do grupo tratado com conídios in natura. Embora os resultados não sejam conclusivos, A. musiformis mostrou-se promissor agente no biocontrole de nematóides parasitos gastrintestinais.

Resumo: O controle biológico é uma alternativa promissora no controle dos estágios pré-parasitários de helmintos, por meio da ação de fungos nematófagos. Abstract: Biological control is a promising alternative for the control of pre-parasitic stages through the action of nematophagous fungi's. The present study evaluated in vitro the patogenicity of both Arthrobotrys musiformis and A. conoides fungi on "infective larvae (or L3 state larvae)" of Haemonchus contortus, L3 larvae of Ancylostoma spp. and larvated eggs of the nematode Ascaridia galli. Nine groups were formed: six treated groups (G1A and G2A: L3 of H. contortus; G1B and G2B: L3 of Ancylostoma spp.; G1C and G2C: larvated eggs of A. galli, being that G1 with A. musiformis and G2 with A. conoides) and three untreated groups (G3A, G3B and G3C: larvae of H. contortus, Ancylostoma spp. and eggs of A. galli, respectively, without fungi). Each treatment had ten repetitions (ten Petri dishes with an average of 120 larvae of H. contortus and 200 larvae of Ancylostoma spp. and, approximately, 100 larvated A. galli eggs). The results showed A. musiformis plundered 66% and 94% of Ancylostoma spp. L3 larvae and H. contortus L3 larvae, respectively. While that A. conoides plundered 51,7% and 89,4% at the same larvae. The nematophagous fungi evaluated have not presented any predation type on A. galli larvated eggs. Afterwards, both are promising fungi as to their use for biological control of parasitic helminths of animal hosts.