Cricket Oil Mortality Studies in the Lab

The objective was to determine if direct and indirect contact with weathered oil emulsions associated with the DWH oil spill caused increased mortality in the house cricket, Acheta domesticus Linnaeus (Orthoptera: Gryllidae) in the lab. The mortality of A. domesticus, in in situ bioassays is being used to indicate the presence of airborne oil, airborne oil constituents, possible airborne metabolites, and chemical constituents from ultraviolet breakdown or solar insoluation in the salt marshes of south Louisiana since the DWH spill (unpublished results). We investigated the cause of mortality in laboratory trials. We conducted experiments looking at both direct and indirect exposure to the oil emulsion under constant environmental conditions. The hypotheses tested were: Direct contact with weathered oil from the DWH spill will increase mortality in Acheta domesticus; and Indirect contact with weather oil from the DWH spill through exposure to only vapors will increase mortality in Acheta domesticus.The time for 50% and 100% mortality to occur in A. domesticus was significantly less when exposed to direct contact with oil (p < 0.0001 for both 50% and 100%) and indirect contact with oil (p = 0.0053, p = 0.0005 for 50% and 100%, respectively). House crickets exposed to oil vapors showed reduced adult life spans, longer time to maturation, and changes in resistance to parasites when compared with controls. Experiments were developed to track the affect of oil vapor and contact on the mortality rate of crickets in the lab. Data was taken at the lower confidence limit (LCL) and the upper confidence limit (UCL).