The Environmental Risks of neonicotinoid pesticides: a review of the evidence post-2013

Abstract

Neonicotinoid pesticides were first introduced in the mid-1990s and since then their use has grown rapidly so that they have become the most widely used class of insecticides in the world, with the majority being used as seed coatings. Neonicotinoids are water-soluble, and so a small quantity applied to a seed will dissolve when in contact with water in the soil and be taken up by the roots of the developing plant. Once inside the plant it becomes systemic and is found in vascular tissues and foliage, providing protection against herbivorous insects. This prophylactic use of neonicotinoids has become extremely widespread on a wide range of arable crops across much of the developed world.However, only approximately 5% of the neonicotinoid active ingredient is taken up by crop plants and most instead disperses into the wider environment. Since the mid-2000s numerous studies have raised concerns that neonicotinoids may be having a negative effect on non-target organisms. In particular, neonicotinoids were associated with mass poisoning events of honeybees and were shown to have serious negative effects on honeybee and bumblebee fitness when consumed. In response to this growing body of evidence, the European Food Safety Authority (EFSA) was commissioned to produce risk assessments for the use of clothianidin, imidacloprid and thiamethoxam and their impact on bees. These risk assessments, published in January 2013, conclude that the use of these compounds on certain flowering crops poses a high risk to bees. On the basis of these findings, the European Union adopted a partial ban on these substances in May 2013 which came into force on 1 st December 2013.The purpose of this review is to collate and summarise scientific evidence published since 2013 that investigates the impact of neonicotinoids on non-target organisms and to bring it into one place to aid informed decision making. Due to international concern over the unintended impacts of neonicotinoids on wildlife, this topic has received a great deal of scientific attention in this three year period. As the restrictions were put in place because of the risk neonicotinoids pose to bees, much of the recent research work has naturally focussed on this group. Risks to beesBroadly, the EFSA risk assessments addressed risks of exposure to bees from neonicotinoids through various routes and the direct lethal and sublethal impact of neonicotinoid exposure. New scientific evidence is available in all of these areas, and it is possible to comment on the change in the scientific evidence since 2013 compared to the EFSA reports. This process is not meant to be a formal assessment of the risk posed by neonicotinoids in the manner of that conducted by EFSA.Instead it aims to summarise how the new evidence has changed our understanding of the likely risks to bees; is it lower, similar or greater than the risk perceived in 2013. With reference to the EFSA 2013 risk assessments baseline, advances in each considered area and their impact on the original assessment can be summarise...

Neonicotinoid insecticides negatively affect performance measures of non‐target terrestrial arthropods: a meta‐analysis

“…However, exposure concentrations across studies varied depending on prescribed application rates and/or doses (ppb to ppm) examined in the trials (Tran et al 2004. Without baseline data from field studies, it is difficult to compare results of lab studies and make conclusions on potential lethal and sublethal impacts of neonicotinoids beyond a select number of species (Wood and Goulson 2017). As semi-field and field studies are unable to control for environmental conditions (e.g., climate, exposure to multiple pesticides), discerning neonicotinoid effects on non-target arthropods may be difficult due to external pressures (Goulson 2013.…”

Osmia bicornis is rarely an adequate regulatory surrogate species. Comparing its acute sensitivity towards multiple insecticides with regulatory Apis mellifera endpoints

“…There are also fed contaminated 19 pollen and nectar as larvae. Furthermore, there is potential uptake of soil residues by 20 adults and larvae of soil-nesting species [10]. Moreover, consumption of non-nectar 21 fluids such as puddle water, guttation droplets or extrafloral nectar may also lead to 22 contamination [11,12].…”

“…http://dx.doi.org/10.1101/366237 doi: bioRxiv preprint first posted online Jul. 10 [21]. This protocol is a precursor of a standardised testing guideline.…”

“…24 To prevent adverse impact of pesticide applications on wild bee populations, toxic 25 effects of these substances on bee species need to be understood. However, the majority 26 of toxicity testing in laboratory and field setups has been performed using the honey 27 bee, a bred livestock species, whereas all other bee species are far less well-understood 28 in their sensitivity [10]. 29 Furthermore, the honey bee is the only pollinator species that is tested for its 30 reaction towards pesticides in the current risk assessment scheme after Regulation (EC) 31 1107/2009 [13].…”

“…Additionally, formulations of 72 four insecticides that are not frequently applied were included because of the following 73 reasons: Imidacloprid has been implicated as a major factor in bee decline [10].…”