Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 19, 2002
Publication Date: August 1, 2002
Citation: Showler, A. 2002. Effects of kaolin particle film application on boll weevil (Coleoptera: Curculionidae) injury to cotton, and on selected nontarget arthropod populations. Journal of Economic Entomology. 95(4):754-762. Interpretive Summary: A white mineral, kaolin, when applied in a wettable powder formulation to cotton squares and whole plants in the laboratory, initially deterred boll weevil feeding and egg laying on squares to a significant extent. Kaolin's deterrent properties were overcome when untreated squares were in increasingly short supply. In a small plot study, kaolin application to cotton plants appeared to protect lint yield to a significant degree when compared to adjacent fields that were treated with early applications of commercial insecticide or left unsprayed. It was suggested that boll weevils can orient toward areas with cotton, based to some extent, upon color.
Technical Abstract: This study examined a non-insecticidal tactic for suppressing boll weevil, Anthonomus grandis Boheman, damage to cotton, Gossypium hirsutum L., squares. Kaolin, a reflective white mineral, applied to excised cotton squares, squares on cotton plants, or to the foliage, initially resulted in lower boll weevil injury to squares. Boll weevils fed and oviposited more on kaolin treated cotton when unused, untreated squares were increasingly in short supply. Field trials showed that boll weevils distinguish between cotton plots based on color differences caused by kaolin, and the ability to distinguish appears to influence levels of damage. Square damage in the plots treated with kaolin was reduced (P < 0.05), except when rain washed the kaolin off the foliage. Cotton lint yield differences were not detected within the small plots, but the kaolin small plot field yielded as much as 2.36 times (P < 0.05) more cotton lint than an adjacent untreated control field, and up to 1.39-fold (P < 0.05) more than another adjacent field sprayed twice with pre-emptive applications of azinphosmethyl when cotton squares were at the pinhead stage. The comparisons of lint yields in the small plots to the external untreated control and the pre-emptive azinphosmethyl treated external fields suggest that visual perception by the boll weevil might play a role in orientation toward areas that are more recognizable as sources of hosts, or toward areas that appear to offer greater quantities of host plants. Kaolin application also reduced Cicadellidae and Diptera populations (P < 0.05), but increased numbers of cotton aphids, Aphis gossypii Glover (P < 0.05).