Estimating and reducing the amount of Plains-wanderer (Pedionomus torquatus Gould) habitat sprayed with pesticides for locust control in the New South Wales Riverina

The potential effects of pesticides used to control locusts in the New South Wales Riverina on the endangered Plains-wanderer (Pedionomus torquatus) have been of concern since the early 1980s. We used geographical information systems (GIS) to determine the intersection of primary and secondary Plains-wanderer habitat areas with historical locust-control data and provide estimates of the area of Plains-wanderer habitat sprayed by the Australian Plague Locust Commission for control of locusts between 1977 and 2005. Peaks among these estimates, expressed as a percentage of the identified habitat occurring on nine 1:100 000 map sheets within the New South Wales Riverina study area, corresponded with years of peak locust control activity, although the proportion of habitat affected was less than expected. The maximum amount of habitat exposed to pesticides occurred in 1993-94, when ∼16% of primary and 12% of secondary Plains-wanderer habitat was sprayed. Locust-control protocols during 2004-05 were altered to reduce the amount of Plains-wanderer habitat sprayed with fenitrothion from 16% to 1.5%, and to increase the use of the biological control agent, Metarhizium anisopliae var. acridum (Green Guard®), over plains-wanderer habitat from 0% to 3.6%. The use of Green Guard® during future locust control within Plains-wanderer habitat in the Riverina has been recommended in the draft NSW Plains-wanderer recovery plan (New South Wales National Parks and Wildlife Service 2002).