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Title: The conundrum of chemical boll weevil control in subtropical regions

item Showler, Allan

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 7/18/2011
Publication Date: 2/15/2012
Citation: Showler, A.T. 2012. The conundrum of chemical boll weevil control in subtropical regions. In: Perveen, F., editor. Insecticides - Pest Engineering. InTech: Rijeka, Croatia. p. 437-448.

Interpretive Summary: The boll weevil, a key pest of cotton, is an invasive pest from tropical Mexico. Attempts at achieving control using insecticides have largely been unsatisfactory and, in the subtropics, the eradication effort has not performed as well as in temperate cotton growing regions. In the subtropics, control and eradication have been problematic primarily because of long-held misunderstandings about the boll weevil’s biology and ecology such as what it can feed on, and where and how it overwinters. There are also weaknesses in boll weevil surveillance methods, which probably need to become more sensitive so that spray timing can be more effective, and insecticides are not conducive to long-term control. Possibilities for enhancing boll weevil control in the subtropics are discussed.

Technical Abstract: The boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), is a tropical Mesoamerican insect that invaded the United States in 1893, spreading across the Cotton Belt as the key pest of cotton and causing billions of dollars in yield losses and insecticide-based control efforts; infestations became so severe that winter “cotton-free” periods were instituted. Insecticide-based control tactics for crop protection purposes, however, have not been completely satisfactory, and, in subtropical regions, the eradication approach that was successful under temperate conditions has encountered obstacles. Weaknesses in routine crop protection and temperate eradication approaches in subtropical regions stem from erroneous assumptions about boll weevil ecology, which, in some aspects, differs fundamentally from that of temperate areas. Such assumptions include boll weevil overwinter behavior in the subtropics, breadth of the food sources that can sustain them through the relatively warm winters, and dogma that the tropical insect evolved a diapauses response to cold temperate winters. Weaknesses in surveillance tools can lead to suboptimal insecticide spray timing which, to be successful, must be coordinated with important phenological stages of the cotton plant. Still other issues involve reliance on short residual insecticides, protection from insecticides by development of immature within fruiting bodies, and nonadoption of emerging information relevant to subtropical conditions. Chemical-based and cultural possibilities for enhancing impacts of insecticides are discussed.