Abstract: The present invention is directed to a flea feeding apparatus and method for obtaining in vivo feeding data for fleas feeding from a blood source. In particular, the present invention is directed to a flea feeding apparatus and method for obtaining in vivo flea feeding data for fleas feeding from blood sources such as, for example, a mammal or reptile. The flea feeding apparatus includes a containment system comprised of a subject-restraining apparatus and a removable housing that confine the fleas in proximity with the blood source in order to obtain in vivo flea feeding data. This invention allows a known quantity of fleas to feed on a test blood source undisturbed, followed by the recovery of all of the fleas for further observation and analysis, with minimal stress and manipulation of the blood source (test animal host).

Abstract: An active avermectin analogue which can be produced by directed biosynthesis is described. The compound, named 26-R-Avermectin B.sub.

Abstract: A novel strain of Trichostrongylus colubriformis has the unique characteristics of being significantly resistant to the effect of antihelmintic drugs, in particular the antihelmintic drugs ivermectin and thiabendazole. The novel strain of T. colubriformis was prepared by the serial passage of the helminth through sheep. Twenty passages of the helminth through sheep were adequate to impart resistance to oral therapy of 20 times that normally expected with ivermectin. The highly resistant parasite is useful to screen for antihelmintic agents with different modes of action than that of ivermectin or thiabendazole which represent two of the three major classes of modern, broad spectrum anthelmintics.