Back to Search Start Over

Monitoring cotton squares with opened and/or yellowed bracts to determine the need and efficency of chemical control against the cotton boll weevil

Authors :
T. A. Lima
C. A. D. Silva
J. C. Zanuncio
Source :
Brazilian Journal of Biology, Vol 84 (2024)
Publication Year :
2024
Publisher :
Instituto Internacional de Ecologia, 2024.

Abstract

Abstract The technique of terrestrial sampling of boll weevil (BW) populations is expensive and inefficient over large areas, but may be cheaper and more efficient without involving the manipulation of cotton squares. The aim of this study was to develop a technique to sampling cotton squares based on the observation of opened and/or yellowing bracts to determine the need and efficacy of chemical control of BW in cotton crops. The first experiment aimed to estimate the ratio between the number of cotton squares with opened and/or yellowed bracts and that of squares with BW oviposition punctures. The second experiment, aimed to determine the efficacy of chemical control for BW by sampling cotton squares with opened and/or yellowed bracts. The ratio between the number of opened and/or yellowed bracts and the number of cotton squares with oviposition punctures was 2:1. The level and efficiency of chemical control of BW, based on the percentage and sampling of cotton plants with opened and/or yellowed bracts, was 5% and did not differ from the one based on the observation of cotton plants with 10% cotton squares with oviposition punctures by BW females. The control level based on sampling cotton plants with open and/or yellowing bracts was 5%. The efficiency of chemical insecticides using this economic threshold against the BW did not differ from that based on sampling cotton plants with 10% of cotton squares with oviposition punctures by BW females. This indicates that the chemical control of cotton boll weevil can be carried out based on cotton squares with open and/or yellowed bracts.

Details

Language :
English
ISSN :
16784375 and 15196984
Volume :
84
Database :
Directory of Open Access Journals
Journal :
Brazilian Journal of Biology
Publication Type :
Academic Journal
Accession number :
edsdoj.81f3a9cff384beda7f015a024e3c573
Document Type :
article
Full Text :
https://doi.org/10.1590/1519-6984.282231