The Research - Part 2
So how do entomologists even begin to collect information about a CRW population? There is a lot of preparation and planning that happens before any data is collected.
- First, a hypothesis (research question) needs to be identified.
- Second, there needs to be a population of CRW available to observe. This means planning must take place (i.e. location selected, trap crops planted) well before the desired data collection time.
- Next, observations are made and data collected. It is important to collect replicated data to have a realistic picture of what is occurring instead of just drawing conclusions from visual observation.
Figure 4: CRW adult beetle on corn silks. Credit: Tom Hlavarty, USDA ARS, Bugwood.org
Data collected depends on the original hypothesis. For example, if Dr. Meinke's hypothesis is: a higher percentage of CRW beetles will emerge from conventional corn where traditional soil insecticide applications were made than from Bt corn; then one of the pieces of data he could collect would be the number of beetles that emerge from each of these treatments. Then using statistical analysis to compare data collected from each treatment, results can be obtained and Dr. Meinke can make conclusions about his original hypothesis. Take a look at the following video to see how Dr. Meinke sets up and conducts his field research.
Does this process of collecting the CRW beetles account for all of the beetles in the population? No, but the beetles collected are a good representation of the genetic make-up of the population. There are enough beetles collected that allow accurate conclusions to be made about the possible impact of one or more technologies on beetle survival and physical condition (fitness). Figure 5 is an example of the type of data that Dr. Meinke collects from his field research on CRW. Notice there are two controls and one treatment in this experiment listed in figure 5. The Bt corn plants and control corn plants have similar background genetics but differ in the toxin present to kill CRW larvae. The control (no insecticide) is used as a reference and the control (+ soil insecticide) used as a comparison to the Bt corn treatment in the experiment.
Figure 5: Hypothetical dataset: Adult Emergence of CRW. This graph shows the life history parameters of CRW in these three different environments. Credit: Lance Meinke, University of Nebraska-Lincoln.
Looking at CRW emergence data can be helpful in making conclusions about CRW survival and temporal occurrence (refers to the time emergence occurred or patterns of emergence over the season), especially in different environments or when using different control methods.