Predicted buffer zones to protect temporary pond invertebrates from ground-based insecticide applications against desert locusts

To estimate safe downwind distances (i.e. buffer zone widths) for temporary ponds from ULV-treatments with current locust insecticides, experimental t rials with two ground-based sprayers, the hand-held Micro-Ulva(R) and the v ehicle-mounted Ulva-Mast(R) X15 Mark I, were conducted with fenitrothion (S umithion(R) L50) as a model insecticide, Deposition profiles for each spray er were obtained for a single- and a five-track application. Water from gla ss containers exposed to the multiple-track treatments was used for laborat ory bioassays with the backswimmer Anisops sardeus (Hemiptera, Notonectidae ). Buffer zone widths were defined as the distance at which 48 h-mortality in the bioassays was 20% or less. The deposition profiles from the multiple -track applications were subsequently used to estimate buffer zone widths f or 11 insecticides currently used in desert locust control. It was conclude d that at moderate wind speeds (2-4 m/s), a buffer zone width of 200 m for the Micro-Ulva and 400 m for the Ulva-Mast will, in general, be safe enough to avoid side-effects from any of these insecticides on sensitive aquatic invertebrates in temporary ponds. (C) 2000 Elsevier Science Ltd. All rights reserved.