In vitro and in vivo effects of neem tree (Azadirachta indica A. Juss) products on larvae of the sheep nose bot fly (Oestrus ovis L. Díptera: Oestridae).

Two studies were carried out in order to test the effects of neem tree extracts (Azadirachta indica A. Juss) on sheep bot fly larvae (Oestrus ovis L. Diptera: Oestridae). First, aqueous extracts from neem seeds (ASNE) at 0, 5 y 10% (w/v) concentrations were tested on larval mortality in vitro. In a second study, the effect of oral administration with neem seed meal (0, 100 y 200mg/kg) and neem leaves (1% of diet) on number of larvae found at necropsy and larval development was evaluated in experimentally O. ovis-infected sheep. Results in Experiment 1 showed a significant (P<0.05) effect of ASNE on time to L1 mortality in a dosis-dependent manner. In Experiment 2, oral administration of seeds or leaves did not affect the number of larvae found at necropsy of the sheep, but interfered with larval development and there was a tendency to reduce larval weight at the end of the infection period (55d).

In vitro culture of Oestrus ovis (Linné 1761) first instar larvae: its application to antiparasitic drug screening.

A culture medium in which 1st instar larvae of Oestrus ovis can survive for up to 2 months has been developed with Dulbecco's Modified Eagle's Medium (DMEM) pH 7.7, penicillin 100 U/ml, streptomycin 100 micrograms ml-1, gentamicin 10 micrograms ml-1 and foetal calf serum (50%) added. Larvae were incubated in flat plastic tissue culture bottles (3 ml of medium) in a 5% CO2 atmosphere at 37 degrees C in darkness. Subsequently an antiparasitic in vitro screening test was developed with moxidectin and closantel. These drugs were not as effective in vitro as in vivo. This might be due to the fact that they cause damage to parasites and host immune responses, then contribute to their death.