June 13, 2007 | By: Laura Skillman
PRINCETON, Ky.

Insects can damage crops and pastures causing economic losses to farmers. That's why the University of Kentucky College of Agriculture is working on an early warning system to tell farmers when the risk is elevated or not elevated for a particular insect in a particular year. 

“We are giving them a way to estimate ahead of time what they are likely to face,” said Doug Johnson, UK extension entomologist. “This gives them time to decide what it is they are going to do -- if they have to make an (insecticide) application and what are they going to use. If the numbers are low, they probably look back every once in a while but are going to go on and do something else.”

Johnson and Patty Lucas, UK extension specialist for integrated pest management, are developing the Regional Multi-State Insect Trapping Network for use in issuing scouting alerts and predicting potential field crop insect damage.

It’s a fairly simple idea, but one that could be wide in scope, Johnson said. They are developing sets of data and trapping techniques that will allow them to make inferences about when and if insect populations will develop into economically important populations.

The network is focusing on six insects, all of which have a moth stage, which are trapped using pheromone bait. The number of moths captured is tallied on a weekly basis and graphs of these populations are made. The growth rate of these particular insects is completely dependent on the ambient temperature, so weather data is also a crucial piece of this system. If they know when the peak moth flight is, then they can estimate the peak caterpillar appearance using the temperature data. 

“We want to know when the caterpillars appear, because they are the ones that cause the damage,” Johnson said. “By knowing when the insect is captured and using a combination of historic temperature data, which is available on the ag weather site, and this year’s data, we can predict when the caterpillars will appear. That’s what we are looking for.”

All the information is based on data already available, except for when an insect will appear in our area and daily temperatures for the current year. By doing this over a number of years, they can build a database that shows curves of the population, so they know when to expect them. By applying the temperature models in a current year, you can estimate when the caterpillars will appear.

By comparing this data with problems that occur in the field, they will know when a population is large enough to be at a high risk or small enough to be at a low risk of damaging a crop. Johnson said this can occur only when there is a large database of information available for a localized area.

In Kentucky, they have 14 to 15 years of information from Princeton on armyworm, European corn borer, black cutworm and corn earworm, Lucas said. There is less data available on southwestern corn borer and fall armyworm. These are the six insects being monitored.

“We have a database here, but we don’t have one at Lexington,” Johnson said. “Other places have done similar things and what we are trying to do is get a series of databases in several different locations. We are doing it in Kentucky, but we are also working with the University of Tennessee who has two locations in that state. We’ve also submitted a position paper for possible funding to look at this in essentially the entire Mississippi River drainage area. This adds another factor, allowing states to look at curves from the more southern states and get an early warning about when the insect becomes active.”

The Kentucky Integrated Pest Management Web site, http://www.uky.edu/Ag
/IPM/ipm.htm, is the gateway to the trapping information and also links to the temperature models used to determine the development of each of these insects. 

Trapping information is graphed for each insect using three lines – the rolling five-year average minus outbreak years, a known outbreak year (if available) and the current year’s data. 

“So, if you are plotting the current year and it is way down on the graph, you know there’s not very much risk,” he said. “We cannot say in absolutes, but we can say there is more risk when you have numbers close to past problems.”

Johnson said this trapping and data system does not manage insect populations, but it gives farmers a tool to be able to judge the relative risk that they are experiencing with each of these insects in that particular year and when that risk is likely to occur. 

“We will never be able to say where it will occur. They will always have to go and look at their fields, but they can be more efficient because they will know the time frame in which they will have to look, and they’ll have an idea whether the insects are going to be easy or hard to find,” he said. “So, you can become more efficient in terms of time management. It will cut down on scouting time.”

Scouting fields is a key component to the overall success of the early warning system. The trapping network information will not tell a farmer whether to spray. They will need to use the number of caterpillars in the field and the size of the caterpillars in determining whether to spray. By using the trapping system and scouting their fields, a farmer can not only make the decision on whether to spray but can also make the insecticide application in a timely fashion to allow for an economic benefit. 

Determining when to spray is based on economic threshold levels that include number and size of the insect in a given area. These are available through the Kentucky IPM scouting manual and UK insecticide recommendations also have them.

UK received a competitive grant from the U.S. Department of Agriculture’s Cooperative State Research, Education and Extension Service through the Southern Region IPM Center for $23,838 to partially fund the project’s first year. A seventh insect, beet armyworm, a major vegetable crop pest, will be added to the monitoring system if the Mississippi River proposal comes to fruition.

Contact: 

Doug Johnson, 270-365-7541, ext. 214, Patty Lucas, 270-365-7541, ext. 218