Effect of pesticides used in banana and pineapple plantations on aquatic ecosystems in Costa Rica

Abstract

Current knowledge on fate and effect of agricultural pesticides comes is mainly from temperate ecosystems. More studies are needed in tropical systems in order to assess contamination risks to nontarget endemic tropical species from the extensive use of pesticides e.g. in banana and pineapple plantations. In this study, acute laboratory toxicity tests with organophosphate pesticides ethoprophos and chlorpyrifos were conducted on two Costa Rican species, cladoceran and fish . Tests showed that chlorpyrifos was more toxic than ethoprophos to and and that was also more sensitive than to both pesticides. Additionally, bioassays were performed by exposing and to contaminated water collected from the field. Chemical analyses of field water revealed that fungicides were generally the most frequent pesticide group found, followed by insecticides/nematicides and herbicides. The bioassays and values obtained from the literature confirmed that was more sensitive to pesticide contamination than and that was more sensitive than , suggesting that the native cladoceran is a more suitable test species than its temperate counterpart. Species sensitivity distributions showed no significant difference in sensitivity between tropical and temperate fish and the arthropod species exposed to chlorpyrifos in this study. Choline esterase activity (ChE) was measured in in laboratory tests in order to assess the applicability of this biomarker. ChE inhibition in was observed in the laboratory at levels below the LC of both ethoprophos and chlorpyrifos, confirming that ChE is an efficient biomarker of exposure. Both indigenous Costa Rican species used in this study were found to be suitable standard tropical test species. Further studies are needed to investigate how protective the safe environmental concentrations, derived from LC of native tropical species, are for protecting tropical aquatic natural communities.