differed from intercrops (P = 0.04). In Exp. 2, weed species compositions
between soybean crops and intercrops (P = 0.009) and
between soybean and sunflower (P = 0.05) were significantly different.
Richness of total, annual and perennial weeds was similar
among treatments, but different among experiments, being higher
in Exp. 1 than in Exp. 2. Abundance of total, annual and perennial
weeds, expressed as percent ground-cover, was similar among
treatments and experiments, except for abundance of perennial
weeds which differed among experiments, being higher in Exp. 1
than Exp. 2 (Table 3).
3.3. Effect on insect assemblages
Insect morpho-species were 18 and 27 in Exp. 1 and Exp. 2,
respectively (Table A3 and A4). Feeding behavior of all insect
morpho-species was determined in Exp. 1, whereas only one
morpho-species could not be identified in Exp. 2. Insect assemblages
differed among cropping systems in both experiments (Exp.
1: P = 0.03; Exp. 2: P = 0.006). Insect assemblages were significantly
different between sunflower crops and intercrops (P = 0.003)in Exp.
1, and between soybean crops and intercrop (P = 0.01) and sun-
flower (P = 0.001) in Exp. 2.
Total richness of insect morpho-species was significantly higher
in soybean crops than in the other treatments. Regarding feeding
habits, richness of non-herbivore insects was significantly higher
in soybean crops than intercrops, whereas herbivore richness did
not differ among cropping treatments but differed among experiments,
being higher in Exp. 1 than in Exp. 2. Insect abundance was
significantly lower in sunflower sole crops than in soybean crops
and intercrops, in Exp 1 than in Exp. 2. Herbivore abundance did
not differ among treatments but it was significantly higher in Exp.
2 than in Exp. 1. Concerning non-herbivore insects, abundance was
higher in soybean than in the other treatments and similar between
experiments (Table 4)