Effect of abamectin on citrus rust mite Phyllocoptruta oleivora and brown citrus rust mite Tegolophus australis and the scale natural enemies Aphytis lingnanensis and Chilocorus circumdatus on oranges

Abstract

The miticide abamectin (combined with 0.2% petroleum oil) controlled the rust mites Phyllocoptruta oleivora (Ashmead) and Tegolophus australis Keifer at 0.0018, 0.0027 and 0.0045 g a.i. L" (10, 15 and 25 mL of 1.8% emulsifiable concentrate per 100L respectively) for 20 weeks in a trial conducted on late Valencia oranges at Nambour, Queensland during January-June 1997. There were no significant differences in mite mortality between rates or methods of application (airblast or hand-sprayed). Fenbutatin oxide was also effective but P. oleivora reinfested the airblast treatments after 16 weeks. Neither miticide affected abundance of larvae, pupae or adults of the predatory ladybird Chilocorus circumdatus Gylenhall. Abamectin, at all three rates caused significant mortality of adults of the scale parasitoid Aphytis lingnanensis Compere when they were exposed to freshly sprayed leaves for 24 hours. Th ere was no significant residual effect one and two days after spraying. Fenbutatin oxide caused no mortality of A. lingnanensis.
Parasitoids which survived contact with fresh deposits of abamectin parasitized fewer oleander scale than those which were untreated or exposed to fenbutatin oxide. There was no significant residual effect on the percentage of scales parasitized by A. lingnanensis exposed one d ay after spraying.