Submitted to: International Symposium on Biological Control of Arthropods
Publication Type: Proceedings
Publication Acceptance Date: December 2, 2008
Publication Date: February 8, 2009
Citation: Weber, D.C., R.S. Pfannenstiel, and J.G. Lundgren. 2008. Diel predation pattern assessment and exploitation of sentinel prey: New interpretations of community and individual behaviors. Pp. 485-494 in Proceedings of the Third International Symposium on Biological Control of Arthropods, Christchurch, New Zealand, 8-13 February 2009, edited by Peter G. Mason, David R. Gillespie & Charles Vincent. USDA Forest Service Publication FHTET-2008-06, Morgantown, WV, USA. Weber, D.C., R.S. Pfannenstiel, and J.G. Lundgren. 2008. Diel predation pattern assessment and exploitation of sentinel prey: New interpretations of community and individual behaviors. Pp. 485-494 in Proceedings of the Third International Symposium on Biological Control of Arthropods, Christchurch, New Zealand, 8-13 February 2009, edited by Peter G. Mason, David R. Gillespie & Charles Vincent. USDA Forest Service Publication FHTET-2008-06, Morgantown, WV, USA. Interpretive Summary: Insect predators are very important for the biological control of major insect pests. Many insect activities occur after dark, including insect predator consumption of insect pests. Because of the lack of study during the night time, important predators have been underestimated or missed completely. Round-the-clock observations are important to reveal what predators are most important in pest suppression in the field. A valuable technique is to place out pest life stages, such as eggs, to serve as sentinel prey, and visit these at all hours to record their disappearance and the predators responsible. We have employed sentinel prey in a variety of agricutural crops to determine the patterns of predation. Several groups are mostly or exclusively found after dark, such as hunting spiders, certain ants and cockroaches, and ground (carabid) beetles. With better knowledge of which predators are most important, agricultural practices can be designed to conserve and enhance these species, thereby making pest management using biological control more effective for the grower. This information should prove useful to researchers and pest managers in potatoes and related crops.
Technical Abstract: Little effort has been made to characterize the diel pattern of predation on insect pests in the field, particularly predatory events that occur nocturnally. Round-the-clock observations by the authors in systems such as potatoes, cotton, soybean, maize, and ley crops under varying cultural practices, and woodlands, with additional published studies, highlight several important considerations when working on predator communities. (1) Predator communities differ greatly between day and night. Depending on the system, cursorial spiders, carabid and other predatory beetles, cockroaches, ants, and earwigs, are important after dark. (2) Predators have distinct diel patterns of behavior, which do not conform simply to a nocturnal/diurnal dichotomy; circular statistics are important in diel analysis. (3) Diurnal appraisals are at best biased; predators causing significant mortality to target pests may be completely overlooked. (4) Sentinel (emplaced) prey are uniquely useful, provided they represent target pests and are stationed realistically. Predator taxa and diversity vary greatly with prey type, habitat, and position. (5) Combining direct observations with other methods (including DNA and protein-based molecular tools) strengthen predation assessments. (6) Disturbed habitats tend to host lower predator diversity and only during limited diel windows; cultural techniques which enhance complexity in agricultural habitats may expand the diel period for higher intensity and diversity of predation on pests. We conclude that nocturnal predation must be addressed explicitly to accurately characterize predator-prey systems, and that round-the-clock observation of sentinel prey is a key technique for assessing pest suppression as an ecosystem service.