Long-term effects of neonicotinoid insecticides on ants

Abstract

The widespread prophylactic usage of neonicotinoid insecticides has a clear impact on non-target organisms. However, the possible effects of long-term exposure on soil-dwelling organisms are still poorly understood especially for social insects with long-living queens. Here, we show that effects of chronic exposure to the neonicotinoid thiamethoxam on black garden ant colonies, Lasius niger, become visible before the second overwintering. Queens and workers differed in the residue-ratio of thiamethoxam to its metabolite clothianidin, suggesting that queens may have a superior detoxification system. Even though thiamethoxam did not affect queen mortality, neonicotinoid-exposed colonies showed a reduced number of workers and larvae indicating a trade-off between detoxification and fertility. Since colony size is a key for fitness, our data suggest long-term impacts of neonicotinoids on these organisms. This should be accounted for in future environmental and ecological risk assessments of neonicotinoid applications to prevent irreparable damages to ecosystems.

Toxicity and Risk of Plant-Produced Alkaloids to Daphnia magna.

“…as alkaloids have been shown to affect the neurotransmission system (Wink, 2003), or by upregulating detoxification pathways, which is an energy demanding process (Schläppi et al, 2020). The delayed growth of mothers at the start of the study was also seen by Gottardi et al (2017), who exposed D. magna to the azole fungicide epoxiconazole and the pyrethroid insecticide α-cypermethrin for 42 days, both separately (25 mg/L epoxiconazole, or 20 ng/L α-cypermethrin) and as a mixture.…”

Toxicity and risk of plant-produced alkaloids to Daphnia magna

“…All data indicate that the low chronic exposures to sparteine deprive the mother of resources. This could be either by decreasing feeding rate, as alkaloids have been shown to affect the neurotransmission system [45], or by upregulating detoxification pathways, which is an energy demanding process [41].…”

Positive Correlation between Pesticide Consumption and Longevity in Solitary Bees: Are We Overlooking Fitness Trade-Offs?

“…Individuals were chronically exposed to their respective treatments for 10 consecutive days. Under the given conditions (i.e., indirect light exposure and constant room temperature) both chemicals are considered highly stable and reveal high persistence and degradation times [22,38,47]. Post-exposure the feeders were replaced with pesticide-free 50% sucrose-solutions (weight:weight (w:w)) and thereafter exchanged upon the sign of fungal contamination or at the latest every 10 days.…”

“…Hence, workers of any eusocial species will very likely differ in their responses compared to females of solitary species. Indeed, queens and workers of eusocial insects show differences in their ability to cope with neonicotinoids [37,38]. While ERA authorities acknowledged this critical point [39,40], the majority of published data still focus on Western honeybees, A. mellifera, and other bee species remain widely overlooked.…”