Predatory Insects in Saskatchewan Farming Systems
Date
1999
Authors
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Publisher
ORCID
Type
Degree Level
Masters
Abstract
This study was designed to examine the effect of cropping systems and agrochemical input systems on the predatory insect fauna within four Saskatchewan farming systems. Two cropping systems, wheat-wheat-fallow and diversified grain-forage and two input systems, high level and organic, were
examined. Pitfall traps were used to collect the ground-dwelling predatory insects and sweep nets were used to collect the predatory insects present in the crop foliage. Eight fields were sampled three times during the summer (June/July/August) and the study was replicated over 3 years (1994 -1996).
A total of 2,076 ground-dwelling predators representing thirty eight genera and 1,704 foliar-dwelling predators representing eight different genera were collected over the duration of the study. The collection was dominated by five genera of ground-dwelling predators (Carabidae: Bembidion, Amara, Agonum, Harpalus, Pterostichus) and two genera of foliar predators (Anthocoridae: Orius; Nabidae: Nabis).
Abundance, richness (Menhinick index) and dominance (Berger-Parker index) of the predatory insect fauna were analysed using a split-plot analysis of variance model with years as the replicate, sample date as the main plot effect, and farm site as the sub-plot effect. Comparisons were made between the diversified grain-forage and wheat-wheat-fallow cropping systems (n= 4 farms)
and the organic and high input systems (n=4 farms) using linear contrasts.
The results showed that cropping system had the greatest influence on the abundance and diversity of the predatory insect fauna. The wheat-wheat-fallow system was found to have a significantly higher abundance and diversity of the ground-dwelling predators while the diversified grain-forage system had a higher abundance and diversity of foliar-dwelling predators. No clear
differences were observed between the two input systems.
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Degree
Master of Science (M.Sc.)
Department
Graduate Studies and Research
Program
Biology