Philippine E-Journals

Responses of Paddy Earthworm, Sparganophilus sp., to Butachlor Herbicide

Jehru C. Magahud | Sheena Lourdes P. Dalumpines | Nonillon M. Aspe | Christopher C. Cabusora

 

Abstract:

Irrigated rice areas are habitats of earthworms that can be used as additional test species for assessing risks from contamination or pollution of toxic chemicals. Basic studies about responses of the potential test species to a toxic chemical can serve as basis for future research that will develop suitable test procedure for such species. Sparganophilus is a semi-aquatic fresh-water earthworm that commonly inhabit stream banks and rice paddies. Tis study presents the first record of Sparganophilus in the Philippines. Meanwhile, butachlor is a common active ingredient in herbicides used to control undesirable weeds in rice fields. Hence, this study tested the mortality, growth, and development of Sparganophilus sp. in soils mixed with increasing concentrations of butachlor at 0 – 948 mg/kg. Avoidance behavior was also tested at 0 – 474 mg/kg by allowing free migration of earthworms. Results showed that mortality of mature and immature worms increased with increasing concentrations of butachlor after seven and 14 days of exposure. Cast production of immature worms was lower in soil spiked with 758 mg/kg butachlor than in soil not spiked after seven days of exposure. Furthermore, avoidance behavior was observed after 21 and 45 hours of incubation and generally increased with increasing concentrations of butachlor. The study implies that mortality, cast production, and avoidance responses of Sparganophilus sp. are potential indicators for assessing butachlor contamination of soils.