9 ref. Sum. (En)

Biological control of aquatic weeds in less than five years old in Australia, but already exciting results have been achieved. Until early 1978, programmes were restricted to extending to Australia, work carried out by U.S.A. entomologists against Eichhornia crassipes (Mart.) Solms., water hyacinth, and Alternanthera philoxeroides (Mart.) Griseb, alligator weed. Insects originally from South America were imported from the U.S.A., quarantine tested for host specificity and freedom from disease, and liberated in Australia. Neochetina eichhorniae Warner and Sameodes albiguttalis (Warren) have been released against E. crassipes from October 1975 and October 1977 respectively. N. eichhorniae is reproducing steadily and has caused significant collapse of plants at some sites. S. albiguttalis has reproduced and spread very quickly but not caused collapse of plants as yet. Agasicles hygrophilla Selman and Vogt and Vogtia malloi Pastrana were released against A. philoxeroides from January 1977 and December 1977 respectively. A hygrophilla completely destroyed floating mats of weed 15 months after release but as predicted has not affected the weed in terrestrial situations. V. malloi is successfully established. Two recent developments are the initiation of a programme against Salvinia molesta D.S. Mitchell, salvinia, and the commencement of exploration in South America for agents specifically suited to attack floating weeds under Australian conditions