The Insecticide Imidacloprid Causes Mortality of the Freshwater Amphipod Gammarus pulex by Interfering with Feeding Behavior

Abstract

If an organism does not feed, it dies of starvation. Even though some insecticides which are used to control pests in agriculture can interfere with feeding behavior of insects and other invertebrates, the link from chemical exposure via affected feeding activity to impaired life history traits, such as survival, has not received much attention in ecotoxicology. One of these insecticides is the neonicotinoid imidacloprid, a neurotoxic substance acting specifically on the insect nervous system. We show that imidacloprid has the potential to indirectly cause lethality in aquatic invertebrate populations at low, sublethal concentrations by impairing movements and thus feeding. We investigated feeding activity, lipid content, immobility, and survival of the aquatic arthropod Gammarus pulex under exposure to imidacloprid. We performed experiments with 14 and 21 days duration, both including two treatments with two high, one day pulses of imidacloprid and one treatment with a low, constant concentration. Feeding of G. pulex as well as lipid content were significantly reduced under exposure to the low, constant imidacloprid concentration (15 µg/L). Organisms were not able to move and feed – and this caused high mortality after 14 days of constant exposure. In contrast, feeding and lipid content were not affected by repeated imidacloprid pulses. In these treatments, animals were mostly immobilized during the chemical pulses but did recover relatively fast after transfer to clean water. We also performed a starvation experiment without exposure to imidacloprid which showed that starvation alone does not explain the mortality in the constant imidacloprid exposure. Using a multiple stressor toxicokinetic-toxicodynamic modeling approach, we showed that both starvation and other toxic effects of imidacloprid play a role for determining mortality in constant exposure to the insecticide.

Development and application of the adverse outcome pathway framework for understanding and predicting chronic toxicity: II. A focus on growth impairment in fish

“…Concentrations that affect locomotory behavior are often similar to those causing growth impairment in the longer-term (Little and Finger, 1990;Melvin and Wilson, 2013). Detrimental effects of chemicals on locomotory behavior have also been reported for various invertebrate species (Salanki, 2000;Tu et al, 2010;Hellou, 2011;Pekar, 2012;Oliveira et al, 2013;Pereira et al, 2013;Fong and Ford, 2014) and in some studies directly shown to coincide with reduction in food intake as well (Das and Khangarot, 2011;Agatz et al, 2012;Nyman et al, 2013). This suggests that the role in growth impairment of both KEs, impairment of locomotion and reduction in food intake, may be conserved in a broad spectra of taxa.…”

Feeding toxicity and impact of imidacloprid formulation and mixtures with six representative pesticides at residue concentrations on honey bee physiology (Apis mellifera)

“…Possibly as the consequence of feeding inhibition [61–62] from Advise, honey bee body weight was substantially reduced in bees fed with Advise-containing sugar solutions.…”

Nutrient–insecticide interactions decouple density‐dependent predation pressure in aquatic insects

“…This interpretation is supported by multiple reports indicating that imidacloprid immobilises a number of aquatic insects (e.g. Alexander et al ., ; Nyman et al ., ). Irrespective of the mechanism, such body size‐dependent differences could also explain the positive effects of imidacloprid on algal biomass that we found ( r = 0.32), if the loss of grazers releases periphyton from consumption.…”