Meeting Abstract
Malathion is an organophosphate insecticide that is commonly used in agricultural, public health, and residential settings, with over 16.7 million pounds being sprayed per year in the United States. This chemical can be broken down into non-toxic and toxic compounds, including malaoxon. Malathion and malaoxon inhibit acetylcholinesterase in many organisms, leading to involuntary movement or paralysis. Because malathion can drift during application, concentrations high enough to cause mortality in invertebrates have been discovered far outside of the target area. This study compares the effects of malathion on two invertebrates, the invasive crab Hemigrapsus sanguineus and the native panopeid mud crab Eurypanopeus depressus. Crabs were exposed to three ranges of malathion exposure; control (0ppb), middle (32-64ppb), and high (100-256ppb) concentrations. The impact of the insecticide was then evaluated using a standardized assay of righting behavior; placing affected crabs on their backs and measuring how long it took them to turn over. When the righting times of the Hemigrapsus and Eurypanopeus crabs were compared, the results indicated that the native Eurypanopeus is more inhibited by the insecticide than Hemigrapsus.
