Investigators: James C. Kriz, Stephen D. Danielson, Department of Entomology, and James Brandle, School of Natural Resources, University of Nebraska-Lincoln

Contact: Stephen D. Danileson (sdanielson1@unl.edu)

Project description: Alfalfa is associated with a large complement of insects. In Nebraska, the primary pest insects associated with alfalfa are various Aphididae, the alfalfa weevil (Curculionidae), potato leafhopper (Cicadellidae), and various grasshopper species (Orthoptera). The primary predatory insects associated with Nebraska alfalfa are the lady beetles (Coccinellidae), damsel bugs (Nabidae), and green lacewings (Chrysopidae).

There are many factors that may affect predatory insect abundance in alfalfa. This study examined the effects of surrounding landscape patch structure and the temporal distribution of predaceous Coccinellidae, Nabidae, and Chrysopidae abundance in alfalfa. The study found Hippodamia parenthesis Say, Coleomegilla maculata DeGeer, Hippodamia convergens Guerin-Meneville, Coccinella septempunctata L., Harmonia axyridis Pallas, and Cycloneda munda Say to be the most abundant coccinellid species. Nabis americoferus Carayon was the most abundant nabid species. Green lacewings, Chrysoperla sp., were also collected. Using patch structure analysis it was determined that H. parenthesis, C. maculata, Chrysoperla sp., and N. americoferus abundance was affected by landscape structure surrounding an alfalfa field. C. septempunctata and H. convergens did not exhibit a relationship with the surrounding landscape structure. The study found that the temporal distribution of predaceous insects in alfalfa varied between species. C. maculata, N. americoferus, and Chrysoperla sp., were more abundant in the early part of the growing season. The other species exhibited a relatively even distribution throughout the study each year.

Current trends aim to reduce the amount of pesticides applied to alfalfa. Conservation biological control is a less disruptive and environmentally safer alternative to pesticide use and classical biological control techniques. The data collected in this study can be used to further analyze the potential use of native species as conservation biological control agents.

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Kriz, James C. 2003. Predaceous insect abundance as affected by landscape structure and temporal distribution in alfalfa fields in east central Nebraska. M.S. Thesis. University of Nebraska-Lincoln.

Molina-Ochoa, J. J. E. Carpenter, E. A. Heinrichs, and J. E. Foster. 2003. Parasitoids and parasites of Spodoptera frugiperda in the Americas and Caribbean Basin: An inventory. Florida Entomologist 86(3): 254-289.

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