1. Comparison of Two Stink Bug Scouting Techniques Under Field Conditions
Eric Blinka1, John Van Duyn1, Ames Herbert2, Sean Malone2, Jack Bacheler1, Philip Roberts3, Jeremy Greene4 and J.R. Bradley1
1North Carolina State University, 2Virginia Tech, 3University of Georgia, and 4Clemson University
Introduction
Introduction
Materials and Methods
Materials and Methods
Results & Discussion
Laboratory Study (cont.)
Bolls were reexamined for internal boll damage symptoms via dissection; time required per rep was also recorded.
Field Study
Eight field sites with stink bug infestations were selected in NC and VA.
Within each field, 10 sites were per-marked with flagged polls in a pattern that was consistent with a typical scouting pattern (Figure 4).
Field Study (cont.)
Investigators entered the field and proceeded to the first marked sampling area, where 10 bolls were pulled, examined, and the number of bolls with 4 or more external feeding lesions recorded.
Investigators proceeded to the next sampling area and repeated the procedure.
This process was continued until bolls had been collected and examined from all ten sites for a total of 100 bolls per field.
When investigator exited the field, ending time was recorded.
The procedure previously described for was repeated. However this time, 10 bolls per sampling area were pulled, dissected on-spot, and the numbers of bolls with internal damage recorded.
Starting time and ending time were recorded as before.
Data were subjected to Proc Corr and Proc GLM in SAS®.
External vs. Internal Pearson Correlation Coefficient (R2 value).
Lab = Field = 0.27
Figure 1. Adult brown stink bug (Euschistus servus) left, and adult green stink bug (Acrosternum hilare) right.
Stink bug pest status in cotton continues to increase due to reductions in broad spectrum insecticide use, the bugs ability to adapt, and the suitability of the agricultural environment.
Current scouting methods require quarter sized bolls to be dissected in order to observe internal damage (warts, stained lint, etc. Figure 2).
Stink bug feeding can result in an external circular, concaved lesion approximately 1/16 inch in diameter and other less obvious symptoms (Figure 3).
Figure 3. External stink bug feeding sign.
Objective
To evaluate the relationships between external and internal damage symptoms and the time requirement for boll examination based upon each of the two methods (lab and field).
Figure 5. Internal vs. External time under lab and field conditions. Field time includes the amount of time to travel from one sampling area to another.
Similar positive correlations between external vs. internal were noted under both lab and field conditions (R2 values).
Amount of time was significantly less for the external as compared to the internal method (Figure 5).
Data suggest that an external boll scouting method may be achievable.
The amount of time saved by external boll examination could be utilized to increase sampling efficiency or sample size.
Materials and Methods
Laboratory Study
One hundred bolls were collected from each of 11 fields in NC, SC, and GA and taken to the laboratory.
Bolls were collected as 10 reps per field and 10 bolls per rep.
The bolls were examined for external lesions and numbers recorded per rep; times for examining each rep were also recorded.
Figure 4. Example of a typical field scouting pattern used in field study.
External and internal boll damage examinations were done separately.
Investigators first recorded the start time at the field border, then proceeded through the sampling route.
ACKNOWLEDGEMENTS
We thank Cotton Incorporated for funding support of this project
Figure 2. Stink bug feeding wart (left) and damaged/stained lint (right).