Mitigation of malathion's acute toxicity by four submersed macrophyte species

Abstract

Some submersed macrophyte species rapidly sorb some insecticides from the water, potentially reducing exposure for aquatic species. The rates at which macrophytes remove insecticides, however, can differ widely among plant species. Furthermore, few studies have examined how much macrophytes actually influence insecticide toxicity to sensitive animals. The authors quantified the ability of several macrophyte species to mitigate insecticide toxicity by comparing the survival of the aquatic herbivore, Daphnia magna, following exposure to a factorial combination of 3 malathion concentrations (0 µg/L, 3 µg/L, and 24 µg/L) and 7 macrophyte treatments (no macrophytes, 4 different macrophyte monocultures, and 2 inert substrates: plastic plants and polypropylene rope). The authors also quantified the rate that different macrophytes reduced malathion's toxicity by exposing D. magna to water samples collected from each treatment after 2 h, 8 h, and 48 h of exposure. The results revealed that whereas 3 µg/L and 24 µg/L of malathion decimated D. magna in the no-macrophyte, plastic plant, and rope treatments, all 4 macrophyte species strongly mitigated these effects. When the authors compared the rate at which malathion's toxicity decreased, they found that all macrophytes negated malathion's toxicity within 2 h, whereas it took more than 8 h in the absence of macrophytes or in the presence of inert substrates. These results demonstrate that numerous macrophyte species can equally and strongly mitigate insecticide toxicity, whereas inert substrates cannot.

Response and recovery of the macrophytes Elodea canadensis and Myriophyllum spicatum following a pulse exposure to the herbicide iofensulfuron‐sodium in outdoor stream mesocosms

“…They may also function as ecological engineers, influencing the hydrological conditions by reducing the flow velocity and retaining sediment particles, for example [2,5,6]. The ecotoxicological value of aquatic macrophytes in lotic ecosystems can also be related to the mitigation of exposurerelated adverse effects through sorption and phytoremediation of plant protection products [7][8][9].…”

Submerged Macrophytes Mitigate Direct and Indirect Insecticide Effects in Freshwater Communities

“…range = 177 to 747 g dry weight/m 3 ; [ 41 ]) reduced malathion’s toxicity to Daphnia magna in a density-dependent manner, with the highest Elodea densities increasing the insecticide’s LC50 48-h value by six times. These effects appear to be generalizable across most macrophyte species [ 31 ] because mitigation is primarily driven by the elevated water pH caused by plant photosynthesis [ 14 ]. While wetlands often range from pH 5 to 8 [ 42 ], pH levels of 9 and above are not uncommon in dense macrophyte beds [ 43 , 44 ], particularly in the canopy near the surface [ 45 , 46 ].…”

“…In the few studies investigating the ecological effects of single and repeated insecticide perturbations, repeated- exposures have ecological effects that are longer lasting and many times larger in magnitude than single exposures [ 12 , 28 , 29 ]. While submerged macrophytes can mitigate single insecticide applications in microcosm studies [ 30 , 31 ], their ability to mitigate the effects of repeated exposures has never been examined. Clearly, considering different exposure regimes is critical for understanding the factors influencing realistic insecticide impacts in freshwater communities.…”

The possible protective effect of vitamin C on the kidney cortex of adult female albino rat after chronic exposure to malathion

“…The presence of low levels of OPCs in the diet over an extended period of time has a more serious impact on animal and human health. Immobilization of this enzyme results in an accumulation of excessive amounts of acetylcholine in nervous tissue and muscular motor plates, as well as in symptoms of endogenic poisoning by this neurohormone [5]. Malathion is known to induce excitotoxicity through its bioactivated analog, malaoxon.…”