Individual study: Interactions in entomology: aphids, aphidophaga and ants in pecan orchards
Dutcher J.D., Estes P.M. & Dutcher M.J. (1999) Interactions in entomology: aphids, aphidophaga and ants in pecan orchards. Journal of Entomological Science, 34, 40-56
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Exclude ants that protect pests
A randomised, replicated, controlled study in 1993-1994 in four pecan Carya illinoinensis orchards in Alabama and Georgia, USA (Dutcher et al. 1999) found that beneficial insects were not affected by insecticide barriers to exclude ants in 1993. Ladybeetle (Coccinellidae) numbers were similar or showed inconsistent differences between trees with and without ant barriers in 1994, but at one site more were found in trees with (0.35-0.50 ladybeetles/bud) than without ant barriers (0.17-0.32 ladybeetles) in mid-May, when cover crops were also planted under trees. Barriers had no or inconsistent effects on aphids, for example fewer blackmargined aphids Monellia caryella occurred in trees with than without ant barriers on three sampling dates at one site, but the opposite was found on two other dates. Evidence from one of two sites showed that numbers of blackmargined aphids during the spring peak in 1994 were lowest when combining ant barrier treatments with cover crops and a foliage spray to attract natural enemies. Barriers successfully prevented red imported fire ant Solenopsis invicta from accessing pecan trees. Ant barriers were chlorpyrifos sprays (1 kg/ha) applied in spring in a 1 m-width band around tree trunks. Barriers were re-applied if ants were observed overcoming the barrier.