Insecticide and tillage effects on pest and non-pest arthropods in corn agroecosystems

Effects of carbamate and organophosphate insecticides, tillage and previous cropping history on pest and non-target soil arthropods in corn are reported. Also, degradation patterns of organophosphate insecticide were quantified in plowed and no-tillage systems. Overall, tillage and cropping sequence had greater effects on arthropod communities than did insecticide treatments. Rootworm (Diabrotica sp.) damage was less in no-tillage than in plowed systems. There was no significant difference between insecticides in affecting rootworm damage. The organophosphate-treated corn had less black cutworm (Agrostis ipsilon) damage than did the carbamate-treated corn. Cryptostigmata mite density was highest in no-tillage systems. In contrast, non-cryptostigmata mite density was highest in fallow—plowed systems. The carbamate insecticide had a greater negative effect on overall mite density than did the organophosphate compound. With respect to soil macroarthropods, herbivore numbers were highest in plowed systems and lowest in no-tillage systems. Spider numbers were highest in the no-tillage systems. The organo-phosphate insecticide degraded more rapidly in the no-tillage compared to the plowed systems; however, this difference did not appear to affect arthropod numbers.