Moving past neonicotinoids and honeybees: A systematic review of existing research on other insecticides and bees

Synthetic pesticides (e.g. herbicides, fungicides and insecticides) are used widely in agriculture to protect crops from pests, weeds and disease. However, their use also comes with a range of environmental concerns. One key concern is the effect of insecticides on non-target organisms such as bees, who provide pollination services for crops and wild plants. This systematic literature review quantifies the existing research on bees and insecticides broadly, and then focuses more specifically on non-neonicotinoid insecticides and non-honeybees. We find that articles on honeybees (Apis sp.) and insecticides account for 80% of all research, with all other bees combined making up 20%. Neonicotinoids were studied in 34% of articles across all bees and were the most widely studied insecticide class for non-honeybees overall, with almost three times as many studies than the second most studied class. Of non-neonicotinoid insecticide classes and non-honeybees, the most studied were pyrethroids and organophosphates followed by carbamates, and the most widely represented bee taxa were bumblebees (Bombus), followed by leaf-cutter bees (Megachile) and mason bees (Osmia). Research has taken place across several countries, with the highest numbers of articles from Brazil and the US, and with notable gaps from countries in Asia, Africa and Oceania. Mortality was the most studied effect type, while sub-lethal effects such as on behaviour were less studied. Few studies tested how the effect of insecticides were influenced by multiple pressures, such as climate change and co-occurring pesticides (cocktail effects). As anthropogenic pressures do not occur in isolation, we suggest that future research also addresses these knowledge gaps. Given the changing global patterns in insecticide use, and the increasing inclusion of both non-honeybees and sub-lethal effects in pesticide risk assessment, there is a need for expanding research beyond its current state to ensure a strong scientific evidence base for the development of risk assessment and associated policy.

Solitary bee behaviour and pollination service delivery is differentially impacted by neonicotinoid and pyrethroid insecticides

Solitary bees are important pollinators of crops and wild plants, and their decline poses a risk to the sustained provision of the services they provide. Although evidence suggests that exposure to insecticides can affect bees, most pesticide research and risk assessment has focussed on social bees and mortality while solitary species are understudied. The ability to forage is critical for solitary bee reproduction, also in how they deliver pollination services, and we know little about how insecticides can impact these behaviours. We exposed solitary red mason bees (Osmia bicornis) to field realistic levels of two widely used insecticides with differing modes of action (lambda-cyhalothrin (pyrethroid) and acetamiprid (neonicotinoid)), in a semi-field setting over multiple rounds of exposure. We then tested impacts on bee behaviour and pollination in apples, an important global insect-pollinated crop. Pollination by insecticide-treated bees reduced apple production by up to 86 % depending on the compound and the number of exposures, but the underlying mechanism behind this remains unclear and should be investigated further. Other measurements of pollination services including number of seeds per apple and stigma pollen deposition showed no relationship with pesticide treatment. Bee foraging behaviour was also affected by treatment where both insecticides appear to induce an excitatory effect which was constant for acetamiprid and eventually ceased for lambda-cyhalothrin after multiple exposures. This suggests that both neonicotinoid and non‑neonicotinoid insecticides can potentially affect behaviour and pollination services of solitary bees depending on how often they are exposed, which is particularly important given the changing usage patterns of these compound classes based on regulations around their use. This highlights the importance of moving insecticide risk assessment towards more field realistic scenarios and including sublethal effects on solitary and social bees, in addition to considering repeated exposures of bees to pesticides as is realistic in the field.

CropPol: a dynamic, open and global database on crop pollination

Seventy five percent of the world's food crops benefit from insect pollination. Hence, there has been increased interest in how global change drivers impact this critical ecosystem service. Because standardized data on crop pollination are rarely available, we are limited in our capacity to understand the variation in pollination benefits to crop yield, as well as to anticipate changes in this service, develop predictions, and inform management actions. Here, we present CropPol, a dynamic, open and global database on crop pollination. It contains measurements recorded from 202 crop studies, covering 3,394 field observations, 2,552 yield measurements (i.e. berry weight, number of fruits and kg per hectare, among others), and 47,752 insect records from 48 commercial crops distributed around the globe. CropPol comprises 32 of the 87 leading global crops and commodities that are pollinator dependent. Malus domestica is the most represented crop (32 studies), followed by Brassica napus (22 studies), Vaccinium corymbosum (13 studies), and Citrullus lanatus (12 studies). The most abundant pollinator guilds recorded are honey bees (34.22% counts), bumblebees (19.19%), flies other than Syrphidae and Bombyliidae (13.18%), other wild bees (13.13%), beetles (10.97%), Syrphidae (4.87%), and Bombyliidae (0.05%). Locations comprise 34 countries distributed among Europe (76 studies), Northern America (60), Latin America and the Caribbean (29), Asia (20), Oceania (10), and Africa (7). Sampling spans three decades and is concentrated on 2001-05 (21 studies), 2006-10 (40), 2011-15 (88), and 2016-20 (50). This is the most comprehensive open global data set on measurements of crop flower visitors, crop pollinators and pollination to date, and we encourage researchers to add more datasets to this database in the future. This data set is released for non-commercial use only. Credits should be given to this paper (i.e., proper citation), and the products generated with this database should be shared under the same license terms (CC BY-NC-SA). This article is protected by copyright. All rights reserved.