The effects of the foliar fungicide pyrazophos on beneficial arthropods in barley fields

Abstract

The Game Conservancy, Fordingbridge, Hampshire. SP6 1 EF SUMMARY The insecticidal properties of the foliar fungicide pyrazophos were investigated in autumn-and spring-sown barley crops using several methods to estimate the density of non-target arthropods and by using manipulative experiments. In autumn-sown crops, pyrazophos significantly reduced densities of cereal aphid natural enemies relative to pre-treatment levels compared to areas of crop that were left unsprayed. These significant differences persisted in most groups for over 45 days after treatment. Groups most affected were aphid-specific predators, polyphagous predators, (Carabidae, Staphylinidae but not Araneae) and parasitoids. Insects known to be preferred food items of wild gamebird chicks and other non-target groups such as the Collembola were also significantly reduced in density on plots sprayed with pyrazophos, the effects again persisting for over 45 days. Densities of beneficial and non-target insects were also reduced in plots of spring barley sprayed with pyrazophos. However, the experimental design meant that levels of reductions were not significant for most arthropod groups.Removal of prey items (Drosophila pupae) placed in sprayed and unsprayed spring barley plots showed that the proportion predated was significantly lower on pyrazophos-treated plots compared to those remaining unsprayed, the difference persisting for at least 7 wk after treatment. Removal of cereal aphids from colonies introduced to sprayed and unsprayed plots was also significantly lower on plots treated with pyrazophos. Difficulties of data interpretation associated with experimental design are discussed together with the consequences of the use of broad-spectrum pesticides in I.P. M. programmes in cereals. 1987 Association of Applied Biologists

Temporal and spatial changes in aphid and parasitoid populations following applications of deltamethrin in winter wheat

“…Invertebrate data were transformed by the log-difference method (Sotherton et al, 1987): all data were transformed by log 10 (n+1) and then post-treatment values at each sample position were subtracted from the pre-treatment value to yield a log-difference. Invertebrate data were transformed by the log-difference method (Sotherton et al, 1987): all data were transformed by log 10 (n+1) and then post-treatment values at each sample position were subtracted from the pre-treatment value to yield a log-difference.…”

Ecological impacts of arable intensification in Europe

“…Moreby et al, 1994), although the effects differ between species, depending in part on their ecology (Grieg- Smith et al, 1995). Some fungicides have also been implicated in influencing invertebrate abundance (Sotherton et al, 1987;Reddersen et al, 1998).…”

The effects of foliar fungicides on beneficial arthropods in wheat fields

“…The extent of the spectrum of activity of pyrazophos against groups of beneficial arthropods, the extent of the insecticidal action of this compound and the duration of its effects on small plots closely resembled work carried out in the same seasons and on the same farms but in crops of barley (Sotherton, Moreby & Langley, 1987).…”