Lincoln, Neb. —For decades, University of Nebraska-Lincoln entomologists have maintained black light traps at locations across Nebraska to serve as an early warning for potentially damaging crop insect pests that may occur. Black light, or ultraviolet traps are attractive to several night flying insects, particularly moths. Several of these moth species produce plant feeding caterpillars which can damage many Nebraska crops.
Currently, black light traps are maintained at four locations; Haskell Ag Laboratory near Concord; Eastern Nebraska Research Extension, and Education Center, near Mead; the South Central Ag Laboratory near Clay Center; and the West Central Research, Extension and Education Center in North Platte.
These traps are monitored several times a week during the growing season. Information is reported online at https://entomology.unl.edu/fldcrops/lightrap and shared in newsletter articles and social media. UNL research and extension Entomologists who currently maintain these light traps and report data during the growing season include Tom Hunt (Concord), Justin McMechan (Ithaca), Bob Wright (Clay Center) and Julie Peterson (North Platte), with support from their technical staff.
Insect abundance varies across the state and fluctuates from year to year, both in its timing and magnitude, so monitoring current conditions can be useful to growers, crop consultants and others as they check fields during the growing season. Light trap data cannot predict insect abundance in individual fields but can be important to alert people to know what to watch for.
Light trap data are not only a valuable tool for our Nebraska Extension programming during the current year, but we have found that having historical black light trap records can be an important research tool as well. Several examples of this include:
Bt corn hybrids, which were engineered to be resistant to certain pests, were first commercialized in the US in 1996 and relatively rapidly adopted by growers because of their efficacy in reducing damage from European corn borer larvae tunneling in the corn stalk. As more acres of Bt corn hybrids were grown, Midwestern university entomologists who worked with corn and other crops noticed they were seeing reduced numbers of European corn borer moths in their black light traps and in commercial fields.
Entomologists from Nebraska and surrounding states shared their black light trap data from years before and after the introduction of Bt corn hybrids and were able to document that there was a significant relationship between the percentage of corn acres in an area planted to Bt corn hybrids and European corn borer moth catches in black light traps. As acres planted to Bt corn hybrids increased, the European corn borer populations decreased compared to their numbers before 1996. This relationship held up across multiple states in the midwestern U. S. and resulted in a paper being published in the prestigious journal, Science.
The western bean cutworm, a pest of corn and dry beans in Nebraska, has been difficult to study because it is difficult to rear in the lab. Information on degree-day requirements for insect development is a useful predictive tool to provide people localized recommendations on when to check fields for pest insects. Typically, degree day requirements are determined by rearing insects in the lab at different constant temperatures to determine what is their minimum temperature for development and how much heat (degree-days) is required for egg hatch or larval and pupal development. Fortunately, UNL entomologists have maintained black light traps at several locations for decades.
Using historic data from these traps, UNL researchers, in cooperation with entomologists from University of Minnesota, we were able to develop a statistical model to help predict western bean cutworm moth emergence. We now use this information to alert Nebraska growers when moth emergence has begun in different parts of Nebraska, based on temperature data available from Nebraska Climate Office weather stations across the state. The timing of moth emergence is a signal that it is a good time to begin to check fields for western bean cutworm egg-laying, so that if needed, timely insecticide applications can be made. This research was published in the Journal of Economic Entomology.
Most recently, a group of entomologists from North Carolina State University is leading an effort to analyze the distribution of corn earworms in the United States and predict how this might change under various climate change scenarios in the future. Nebraska entomologists have shared historical data on corn earworm moth captures from our black light trap network to this study. We recently submitted an article to Proceedings of the National Academy of Sciences based on this work.