Reduction of wasp (Hymenoptera: Vespidae) populations by poison-baiting; experimental use of sodium monofluoroacetate (1080) in canned sardine

Abstract

Poison-baiting trials were carried out in Canterbury, Nelson, and Westland in 1986/87 to 1989/90 to reduce wasp (predominantly Vespula vulgaris) populations. Compound 1080 was mixed with canned sardine in aspic jelly for bait. Bait stations were put out in areas of 1.5–3 ha, at a density of about 40/ha. Wasps were pre-fed with non-toxic bait for at least 3 days before poisoning.Poison-baits containing 0.001% and 0.01% 1080 had no significant effect on wasp traffic at nest entrances, 0.1% 1080 reduced wasp traffic by 17%, 0.5% 1080 by 78%, and 1% 1080 by 89%. Reduction in wasp numbers after poisoning with 0.5% or 1% 1080 was rapid, up to 100% within 6 h. The level of reduction declined beyond 100 m from bait stations. After poisoning, wasp traffic at nests within 100 m of bait stations remained low for the rest of the season, but partially recovered at nests more than 100 m from baits. Wasp numbers visiting bait stations containing non-toxic baits increased to about 30% of pre-poison levels 4 weeks after poisoning. These wasps must have come from nests more than 100 m from bait stations.Although 1080 in sardine baits effectively reduced wasp populations in local areas, a concentration of 0.5–1.0% was required. The hazard to non-target species was reduced by the bait being confined in bait stations and exposed for less than 6h. However, 1080 is highly toxic to vertebrates, especially dogs, which imposes restrictions on its use. Alternative poisons that are less toxic than 1080 to non-target species need to be found.