Sublethal effect of organophosphorus pesticides on the gut flora of Litopenaeus vannamei (Boone, 1931), Whiteleg shrimp

Abstract

During the present study, the sublethal effects of two organophosphorus pesticides, chlorpyrifos (CPF) and dimethoate (DMT), on the gut flora of Litopenaeus vannamei (Boone, 1931), Whiteleg shrimp juveniles were studied for 21 days. Bacterial species such as Alteromonas sp., Bacillus sp., Demequina sp., Micrococcus sp., Pseudomonas sp., Pseudoalteromonas sp., Pseudoruegeria sp., Staphylococcus sp., Shewanella sp., and Vibrio sp. were reported from the guts of shrimps exposed to pesticides and in control groups. Bacteria such as Demequina flava, D. globuliformis and Pseudoruegeria sp. were isolated for the first time from the gut flora of L. vannamei. During the 21 Days of Exposure (DoE), a total of 17 different bacterial strains were identified from the control group; however, 10 and 12 strains were identified from the CPF- and DMT-treated groups, respectively. The bacterial diversity quantified by the Shannon diversity index (H') in CPF- and DMT-exposed shrimps was observed to decrease over the exposure period compared to the control. Pesticide exposure leads to a decrease in valuable microbes and an increase in harmful microbes in the gut microflora of shrimp. Therefore, this may result in reduced growth, weakened health, increased susceptibility to diseases, and a decrease in the production of high-quality shrimp.