SAMPLING EFFICIENCY OF THE KEEP-IT-SIMPLE-SAMPLER FOR ADULT BOLL WEEVILS

Authors: Esquivel, Jesus; Spurgeon, Dale; Suh, Charles

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/5/2003
Publication Date: 6/1/2003
Citation: Esquivel, J.F., Spurgeon, D.W., Suh, C.P. 2003. Sampling efficiency of the keep-it-simple-sampler for adult boll weevils. National Cotton Council Beltwide Cotton Conference. p. 1572-1574.

Interpretive Summary: A modified leaf blower, the Keep-It-Simple-Sampler (KISS), had previously been used to sample sparse populations of adult boll weevils (one of the most serious insect pests that attack cotton) but detailed estimates of collection efficiency in different stages of cotton were not provided. Further, previous mark-release-recapture studies had not clearly documented whether marked weevils remained on the plants after release to be available for sampling with the KISS. We conducted two preliminary experiments to estimate weevil movement and sampling efficiency in pre-fruiting cotton, and to compare sampling efficiencies of the KISS in pre-fruiting cotton and two fruiting stages of cotton. In the first experiment, virtually all marked boll weevils remained on pre-fruiting plants after release, and a high percentage of these weevils remained on the plants after sampling with the KISS. Thus, a very low percentage of weevils was recovered, and high variability in percent recovery was observed. Similarly, low recovery rates and high variations in recovery were observed in all stages of cotton sampled in the second experiment. The high percentage of weevils remaining on plants after release, and the observed low and variable recovery rates suggest the KISS does not provide reliable estimates of sparse weevil populations. Despite this shortcoming, the KISS remains a labor-efficient tool for detecting sparse populations of adult boll weevils, especially considering the absence of practical alternatives.

Technical Abstract: Early-season boll weevil (Anthonomus grandis Boheman) populations are difficult to sample because their levels are typically low and labor requirements for precise estimates are prohibitive. Recent studies suggest a hand-held pneumatic sampler (Keep-It-Simple-Sampler; KISS) may offer a less laborious alternative to hand-sampling, but detailed estimates of KISS collection efficiency in different phenological stages of cotton (Gossypium hirsutum L.) are not available. We used mark-and-release techniques to obtain preliminary estimates of KISS collection efficiency for boll weevils in pre-fruiting, pinhead square, and third-grown square stages of cotton. Observations of weevils released in pre-fruiting cotton indicated a majority of weevils (97%) remained on the cotton plants between the time of release and sampling with the KISS. Overall, recovery of weevils by the KISS 20 min after release was about 11%. Further, about 13% of marked weevils were dislodged from the plant but not collected by the KISS. In comparisons of collection efficiency among plant phenologies, the mean percentages of marked weevils recovered from pre-fruiting (19%), pinhead (21%), and third-grown square (12%) stage plants were not statistically different. The KISS detected weevils in most samples and the overall estimated collection efficiency was 17±12%. The low and variable recovery rates we observed suggest the KISS does not provide precise estimates of low-level boll weevil populations. Despite this shortcoming, the KISS remains a labor-efficient tool for detecting low-level populations, especially in the absence of practical alternatives.