Manipulating carabid beetle abundance alters prey removal rates in corn fields

• Published in: BioControl (Dordrecht, Netherlands) Netherlands), 1999-01, Vol.43 (4), p.441-456
• Main Authors: Menalled, F.D. (Michigan State Univ., East Lansing, MI (USA). Dept. of Entomology), Lee, J.C, Landis, D.A
• Format: Article
• Language: English
• Subjects: Abundance; Agricultural land; Animal populations; Arthropods; AUXILIAIRE DE LUTTE BIOLOGIQUE; Beetles; BIOLOGICAL CONTROL; BIOLOGICAL CONTROL ORGANISMS; Boundaries; CARABIDAE; Coleoptera; CONTROL BIOLOGICO; CONTROL DE PLAGAS; DEPREDADORES; Egress; ENEMIGOS NATURALES; ENNEMI NATUREL; Field study; Field tests; Growing season; INSECTE NUISIBLE; Insecticides; INSECTOS DANINOS; Insects; Invertebrates; LUTTE ANTIRAVAGEUR; LUTTE BIOLOGIQUE; NATURAL ENEMIES; Onions; ORGANISMOS PARA CONTROL BIOLOGICO; PEST CONTROL; PEST INSECTS; Pest outbreaks; Pests; PREDATEUR; Predation; PREDATORS; Prey; Pupae; Vertebrates; ZEA MAYS
• ISSN: 1386-6141; 1573-8248
• DOI: 10.1023/A:1009946004251

Generalist natural enemies such as carabid beetles have the potential to maintain a variety of pests below outbreak levels in annual crops. To assess the relationship between carabid beetle abundance and field rates of prey removal, we created plots surrounded by different boundaries that selectively affected dispersal of edaphic arthropods, primarily carabids. Three treatments were established: (1) naturally occurring communities, (2) augmented communities using ingress boundaries, and (3) reduced communities using egress boundaries. Selective boundaries altered carabid communities with minimal habitat alteration and without use of insecticides. Three times during the growing season, a fixed number of onion fly pupae were placed in plots to evaluate the impact of carabid abundance on predation rates. A combination of vertebrate and invertebrate exclosures allowed us to evaluate prey removal by invertebrates alone. In comparison to the no boundary treatment, carabids increased 54.2% and decreased 83.1% in plots surrounded by ingress and egress boundaries respectively. Predation rates were positively correlated with carabid abundance (r2 = 0.70, p < 0.0001). Significantly more pupae were removed from exclosures allowing access to invertebrates alone than from total exclosures, suggesting that invertebrates represented an important group of predators. Laboratory trials tested the feeding potential of the four most abundant carabid species and showed that they readily consumed onion fly pupae, supporting our hypothesis that carabids were the main predators in field tests. This study corroborates and extends previous observations of the importance of carabid beetles as generalist predators of insect pests in agricultural fields.