Case Study The effects of predator exclusion and caging on cereal aphids in winter wheat Chambers et al 1983

Field cages were used to exclude aphid specific predators from small areas of wheat during 1976, 1977 and 1979. The changes in numbers of aphids (Sitobion avenae) inside and outside the cages were determined and related to changes in the density of the predators and other factors.

The cages used to exclude the aphid specific predators were 1.8 m high, rectangular (3 X 1.5 m) cages consisting of a tubular metal frame covered with polyester netting (mesh size 1 X 0.3 mm, thread thickness 0.1 mm). The netting extended below the soil surface to a depth of about 30 cm. Access to the cage was possible via a vent held closed by 'Velcro' strip.

Table 6.7. The mean number (0.5 m~2) of predators (for the period in which they were active in the field) and the totals for each year. The ratio peak number/shoot is the ratio of the peak number of aphids per shoot in the cages relative to the open plots (after Chambers et al., 1983).
0 0

Post a comment