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from ultraviolet breakdown or solar insoluation in the salt marshes of south Louisiana since the DWH spill (unpublished results).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).本研究旨在探究：在实验室环境下，与DWH漏油事件相关的风化油乳剂的直接与间接接触，是否会导致家蟋蟀（Acheta domesticus Linnaeus，直翅目：蟋蟀科）的死亡率升高。自DWH漏油事件发生以来，路易斯安那州南部盐沼的原位生物测定（in situ bioassays）中，家蟋蟀的死亡率被用于指示空气中油类、油类组分、潜在空气传播代谢物，以及紫外线降解或太阳辐照产生的化学组分的存在（未发表结果）。本研究针对实验室试验中的死亡原因展开探究，在恒定环境条件下开展了针对油乳剂直接与间接暴露的相关实验。本研究验证的假说包括：1. 直接接触DWH漏油事件产生的风化油，会提升家蟋蟀的死亡率；2. 仅通过暴露于油类蒸气的间接接触DWH风化油，也会提升家蟋蟀的死亡率。家蟋蟀在直接接触油类（50%和100%死亡率对应的时间均为p<0.0001）与间接接触油类（50%死亡率对应p=0.0053，100%死亡率对应p=0.0005）的暴露条件下，达到50%和100%死亡率的时间均显著缩短。与对照组相比，暴露于油类蒸气的家蟋蟀成虫寿命缩短、成熟时间延长，且寄生虫抗性发生改变。本研究设计实验以追踪实验室环境下油类蒸气与接触暴露对蟋蟀死亡率的影响，并记录了置信下限（lower confidence limit, LCL）与置信上限（upper confidence limit, UCL）处的相关数据。