American Entomologist (2009) 55, 234-243

Allan T. Showler (2009)
Roles of host plants in boll weevil range expansion beyond tropical Mesoamerica
American Entomologist 55 (4), 234-243
Abstract: New findings about the food habits of the boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), refine current theories about range expansion beyond its tropical Mesoamerican origin. The weevil co-evolved with perennial host plants including cotton, Gossypium hirsutum L., and patches of host plants were reached by flight, likely instigated by competition for limited resources. Boll weevils might have sought nectar, pollen, or both for energy to facilitate searching for patches of host plants. Range expansion was facilitated by shifts to new host plants, and in its dispersion north, the insect reached the subtropical Lower Rio Grande Valley of Texas, becoming established only when the citrus industry first boomed in the early 1890s. Commonly grown subtropical citrus species bear fruit containing sugars and other nutrients that can sustain active boll weevils over winter in spite of a 5-mo mandatory fall cotton plowdown. Feeding on citrus and cactus fruit, and possibly on nectars andpollens, makes nonreproductive host plants (used only for foraging) important for dispersal to and establishment at new latitudes. Once in south Texas, the pest moved rapidly through the Cotton Belt during warm seasons. To cope with cold temperate winters, the insect resorted to a poorly adapted dormancy response whereby mortality at study sites is often 100%. Extensive cotton monocultures support the buildup of large enough summer populations to increase the chance that a few survive and infest the spring crop. Establishment in temperate fringe areas (central Texas, southern Arizona, and California) and the pest's range expansion into subtropical northern Argentina are discussed in terms of associations with reproductive (plants that confer sufficient nutrients for boll weevil reproduction) and nonreproductive, indigenous, and exotic host plants.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Allan T. Showler

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Anthonomus grandis	Cotton (Gossypium)