Description
Avermectin B2a is produced by the strain of Streptomyces avermitilis. It stimulates nerve cells to release Y-aminobutyric acid (GABA), which blocks the transmission of signals from the central nervous system to the motor nerve. It is not resistant to bacteria and fungi, but has strong activity to nematode parasites such as ancylostoma and Pteria, as well as insects such as flies. Abamectin B1a has the highest activity. Ivermectin obtained by catalytic hydrogenation contains 22 23- dihydroabamectin B1a (above 80%) and 22 23 dioxabamectin B1b (below 20%). Less active than B1a but less toxic. Used as repellent (subcutaneous or oral) for cattle, sheep and pigs, it is also effective against human filariasis