of Quelea Control Operations

The degree of environmental contamination and environmental risk posed by air-to-air control operations with ULV formulations of fenthion against the Red-billed Quelea, Que-lea quelea, and possible reasons for the apparent lack of efficacy achieved during such control actions were investigated. Air-borne residues were monitored using high volume monitoring and pesticide deposition was studied after deliveries of microscopic pesticide droplets above roosting and breeding sites of quelea, when environmental contamination due to primary and secondary drift is likely. Fenthion persisted in environmental samples far longer (64 h in air, 46 days in soil) than reported previously and could be detected as far as 3 km from the spray site. Deposition results showed uneven target site coverage, which may explain the lack of efficacy during aerial control actions. Fenthion was also detected in non-target bird species, confirming the risk of primary and secondary poisoning. Additional observations after fuel-explosion operations against roosts of quelea indicated a high potential risk and mortality of non-target raptor species