Insect Science (2014) 21, 477-485

Christina L. Mogren, William E. Walton and John T. Trumble (2014)
Tolerance to individual and joint effects of arsenic and Bacillus thuringiensis subsp. israelensis or Lysinibacillus sphaericus in Culex mosquitoes
Insect Science 21 (4), 477-485
Abstract: Arsenic contamination of global water supplies has come to the forefront in policy decisions in recent decades. However, the effects of arsenic on lower trophic levels of insects inhabiting contaminated ecosystems are not well understood. One approach to document both acute and sublethal effects of toxicants like arsenic is to assay them in combination with microbial pathogens to evaluate shifts in survival curves of the test organisms. Larvae of Culex quinquefasciatus and Culex tarsalis were reared in water containing 0 or 1000 μg/L of arsenate or arsenite. Fourth instars were then exposed to a range of doses of Bacillus thuringiensis subsp. israelensis (Bti) or Lysinibacillus sphaericus (Ls), with shifts in lethal concentrations determined. Arsenic accumulation in 4th instars was also quantified, and a relative growth index (RGI) calculated for the treatments and compared to controls. Larvae of both species accumulated between 4447 ± 169 ng As/g and 6983 ± 367 ng As/g, though RGI values indicated accumulation did not affect growth and development. In all cases, the LC50's and LC90's of Cx. quinquefasciatus exposed jointly with arsenic and Bti/Ls were higher than Cx. tarsalis. Cx. tarsalis reared in arsenite showed a significant reduction in their Bti LC90 values compared to the control, indicating a sublethal effect of Bti. When exposed jointly with Ls, arsenite was more toxic than arsenate in Cx. tarsalis. Overall, these results indicate tolerance of these Culex species to arsenic exposures, and why this may occur is discussed.
(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): William E. Walton, John T. Trumble

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
environment - cropping system/rotation
Research topic(s) for beneficials or antagonists:
resistance/tolerance/defence of host
environment/habitat manipulation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Culex quinquefasciatus
	Culex tarsalis
Lysinibacillus sphaericus (entomopathogen)
Bacillus thuringiensis var. israelensis (entomopathogen)