2.2. Sampling procedure
Arthropods were sampled weekly fromJune until the end of the
harvest. The 625 m2
area of each plot followed the standards for
such field assessments; many arthropods could move between
plots, thereby reducing impacts of the different treatments.
Therefore to reduce as much as possible any bias concerning plot
size; samples were only taken (both pitfall and yellowtraps placed)
in 10 10m area within the centre of each 625 m2
plot. In this way
there was a greater distance between traps of different replicates.
Two standard methods were used to sample arthropods:
1. Pitfall traps were used to assess soil dwelling arthropods (rove
beetles, ground beetles, spiders). Three traps/plot (a total of 96)
were used and operated for seven days.
2. Plant dwelling species were collected weekly with 30 20 cm
Pherocon® AM (trade mark name by Tr ec e Inc) yellow sticky
traps installed on plants (for rove beetles). Again, three traps/
plot (a total of 96), were used to collect insects from plants.
Traps were operated for seven days in each year from June to
September. In each seven-day interval, traps were changed and
species were identified in the laboratory.
3. In 2007 and 2008 weed species and their area coverage (%) were
estimated by visual survey of 3 1m2
areas within the centre of
each plot (for rove beetles and spiders)