Impact of aquatic insect life stage and emergence strategy on sensitivity to esfenvalerate exposure

Abstract

We investigated the impact of aquatic insect life stage and emergence strategy on sensitivity to esfenvalerate, a synthetic pyrethroid insecticide, using field-collected Brachycentrus americanus Banks (Trichoptera: Brachycentridae) and Cinygmula reticulata McDunnough (Ephemeroptera: Heptageniidae) insects. Final-instar C. reticulata emergence was observed for one week following three environmentally relevant, 48-h esfenvalerate exposures (0.005, 0.01, and 0.015 g/L). Emergence was significantly depressed following exposure to esfenvalerate and resulted from an increase in nymph mortality during the emergence process. This experiment was duplicated for late-instar C. reticulata nymphs, which were similar in size to the final-instar nymphs but were not near emergence. Late-instar C. reticulata mayflies were approximately fivefold less sensitive to esfenvalerate exposures as gauged by one-week mortality rates. Brachycentrus americanus pupal mortality was significantly increased over that in controls following 48-h esfenvalerate exposures of 0.1 and 0.2 g/L. These response concentrations correlated closely with those for caseabandonment rates of fourth-instar B. americanus larvae (a sublethal effect of esfenvalerate exposure). Pupal mortality rates were approximately 16-fold higher than those observed in larvae. Adult female egg weight as a percentage of total body weight was significantly decreased following pupal esfenvalerate exposures of 0.05, 0.1, and 0.2 g/L. These findings suggest that exposure to esfenvalerate may impair hemimetabolous insect emergence behaviors and may decrease fecundity in holometabolous aquatic insects.

Pyrethroid Insecticides: Use, Environmental Fate, and Ecotoxicology

“…There is some evidence that a reduced emergence rate following pyrethroid exposure may be related to physical or physiological difficulties in exoskeleton shedding. Reductions in mayfly (Cinygmula reticulata) emergence following 48-hour esfenvalerate exposures of 0.005 to 0.015 µg/L were a result of increases in unsuccessful molting (Palmquist et al, 2008b). Affected insects appeared unable to shed nymphal exoskeletons, which led to death; a similar response was observed for B. americanus caddisfly emergence after 48-hour pupal exposures of 0.1 µg/L esfenvalerate and greater (Palmquist et al, 2008b).…”

“…One-hour exposures to esfenvalerate (0.01 to 0.1 µg/L) followed by low food availability reduced egg production in female Cloeon dipterum mayflies (Beketov & Liess, 2005). Similarly, 48-hour pupal exposures to 0.05 µg/L esfenvalerate and greater reduced the ratio of egg weight to total female body weight in B. americanus caddisflies (Palmquist et al, 2008b). Chronic exposure to fenvalerate concentrations of 0.005 µg/L increased Daphnia galeata mendotae longevity by an average of 14 days, but reduced brood size by approximately 5 individuals.…”

Rapid evolution of increased vulnerability to an insecticide at the expansion front in a poleward‐moving damselfly

“…A key finding was that esfenvalerate negatively affected body mass, fat content, and relative flight muscle mass, three traits known to shape flight performance in Coenagrion damselflies (Gyulav ari et al 2014;Therry et al 2014c). Delayed effects of esfenvalerate across metamorphosis have also been documented in the caddisfly Brachycentrus americanus where adults that had been exposed to esfenvalerate in the pupal stage invested less in egg mass (Palmquist et al 2008). The pesticide-induced reductions in the flight-related traits, especially flight muscle mass is a highly relevant trait for key functions such as flight ability (e.g., Therry et al 2014a), and therefore important for shaping foraging, predator evasion, mating success, and dispersal ability in damselflies (Stoks and Cordoba-Aguilar 2012).…”

Chronic toxicity of 6 neonicotinoid insecticides to Chironomus dilutus and Neocloeon triangulifer

“…Instead, we hypothesize that metamorphosis failure could be rooted in energetics, with mayflies lacking the energy needed to complete metamorphosis on a physiological level. Alternatively, the final molt from PEN stage to subimago may be more sensitive to toxicant stress compared with prior molts, as suggested by Palmquist et al (2008), who saw similar mortality events in late-instar mayflies after exposure to esfenvalerate. FIGURE 2: Chronic species sensitivity distribution (SSD) of chronic toxicity data (!5 d for algae, !6 d for Ceriodaphnia, !21 d for other invertebrates and fish) for imidacloprid constructed using data for Chironomus dilutus and Neocloeon triangulifer generated from the present study, and external literature data mined from the ECOTOX database.…”