Environmental Entomology (1999) 28, 979-982

A.G. Appel, W.J. Moar and M.J. Tanley (1999)
Water loss and mortality of adult cowpea weevils (Coleoptera: Bruchidae) exposed to desiccants and desiccating environments
Environmental Entomology 28 (6), 979-982
Abstract: Water relations and desiccation tolerance of adult cowpea weevils, Callosobruchus maculatus (F.), were examined in response to exposure to desiccants and desiccating environments. Cuticular permeability was similar for both sexes (~5.3 µg cm^-2 h^-1 torr^-1) and was comparable with other xerically adapted arthropods. At 30°C and 0% RH, percentage of initial mass lost as well as percentage of total body water lost increased curvilinearly with time of desiccation for both sexes. All desiccant and insecticide dust formulations were toxic to cowpea weevils. LT₅₀ values ranged from ~11 min for male beetles exposed to DeltaDust (0.05% [AI] deltamethrin) to ~597 min for female beetles exposed to pine ash. Continuous exposure to any of the formulations resulted in 100% mortality within 24 h. Exposure to any dust formulation resulted in increased water loss by adult cowpea weevils. Continuous exposure to Eaton's KIO system (diatomaceous earth) resulted in an 88.7% increase in cuticular permeability of male beetles; exposure to DriDie (silica gel) resulted in an 1,660% increase in cuticular permeability for female beetles. Pine ash increased cuticular permeability ~150% and ~320% for adult male and female beetles, respectively; similar to the effects of DeltaDust. Exposure to any of the dust formulations tested in this study resulted in significant increases in adult cowpea weevil cutaneous water loss and mortality.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): Arthur G. Appel, William J. Moar

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Callosobruchus maculatus	Stored legumes