Evolutionary ecotoxicology of pesticide resistance: a case study in Daphnia

Abstract

Natural populations that are exposed to pesticides in their environment may at the same time be exposed to natural stressors like parasites and predators, which may interact with pesticide exposure. This may not only impact target pest species but also a wide variety of non-target species. This review reports on a joint research program in the water flea Daphnia magna, a non-target species often used as model organism in ecology and ecotoxicology. The focus is on different aspects that are of key importance to understand the evolutionary ecology of pesticide exposure: (1) the capacity of natural populations to genetically adapt to pesticide exposure (2) the added complexity of synergistic effects caused by simultaneous exposure to natural stressors, and (3) the potential interference of evolutionary costs of adaptation to pesticide exposure. Our results showed that natural populations were able to rapidly evolve resistance to the pesticide carbaryl but at the expense of fitness costs. Individuals selected for carbaryl resistance had higher survival rates when exposed to the pesticide but also a greater susceptibility to the challenge imposed by the bacterial endoparasite Pasteuria ramosa. The evolved resistance to carbaryl was in some cases only expressed in the absence of fish kairomones. Further, it became clear that the responses to both exposure to single and combined stressors was for several life history variables strongly dependent upon past exposure to carbaryl. This indicates that past exposures to pesticides are important and can not be neglected when evaluating responses to current stressors.

Chronic contamination decreases disease spread: aDaphnia–fungus–copper case study

“…This expansion might prove important because genetic variation among hosts or parasite genotypes in toxicological traits [38,39] could lead to diverse responses to contamination within and among populations. Furthermore, rapid evolution of hosts during epidemics [21] and/or to contamination [38,39] might change the predictions offered here-especially if tradeoffs exist between toxicological and epidemiological traits among host genotypes [38,39]. Second, we viewed contamination scenarios as distinct, yet constant, environments, which provided a useful qualitative prediction here.…”

Evolved pesticide tolerance influences susceptibility to parasites in amphibians

“…Additionally, the evolution of pesticide tolerance in pest species is estimated to cause >$1.5 billion in crop losses each year (Pimentel, 2005). Despite our increasing knowledge of evolved pesticide tolerance in pest species, few studies have explored whether pesticide tolerance has evolved in nontarget species that are inadvertently exposed to these chemicals (Brausch & Smith, 2009a,b; Jansen, Coors, Stoks, & De Meester, 2011). Pesticide application for pest control is typically localized; however, processes such as aerial drift, runoff, and movement through food webs can distribute pesticides across the landscape potentially shaping the evolutionary courses of natural populations (Gilliom, 2007; Stone, Gilliom, & Ryberg, 2014).…”

“…Theory suggests that the evolution of pesticide tolerance can be achieved via two mechanisms: selection for constitutive tolerance over multiple generations or by inducing tolerance within a single generation via phenotypic plasticity (Cothran et al., 2013; Hua et al., 2015; Jansen et al., 2011). The evolution of constitutive tolerance is more likely when populations are in close proximity to agriculture (<200 m) and consistently exposed to pesticides (Crispo, 2007; Declerck et al., 2006).…”

Evolved pesticide tolerance in amphibians: Predicting mechanisms based on pesticide novelty and mode of action

“…Consequently, non-target populations are increasingly exposed to a broad range of pesticides that vary in mode of action and frequency of use (Grube et al, 2011;Newman, 2010;Ritter, 2009). Given the complex chemical milieu that non-target populations frequently encounter in nature, there is a need to explore how pesticides influence evolutionary processes in these populations (Jansen et al, 2011).…”