Non-Target Insects and Beneficial Species
Impact of Pesticides on Non-Target Insects and Beneficial Species
Non-target and beneficial species can be impacted by pesticides through direct or indirect routes, such as water contamination and runoff, pesticide residues, and by consuming food that has been sprayed.
- A 2014 study published in Chemosphere examined the effects of different pesticides on a common insect predator.
- Researchers found that exposure to some pesticides were lethal, while exposure to others led to a decrease in plant feeding time and reduced predation rates.
Chlaenius tricolor, beneficial beetle
- Soy beans were treated with the neonicotinoid thiamethoxam.
- The seed treatments had zero effect on pest slugs, and instead were bioaccumulated and then transferred through the slugs into their insect predators, impairing or killing >60%.
- This resulted in a loss of crop due to a decline in beneficial insect predators and an increase in pest slug population.
The European Academies' Science Advisory Council (EASAC) estimates global natural pest control to be worth $100 billion annually. Natural pest control is where insects consume pests so that chemicals are not necessary. It focuses on encouraging predatory insects to consume pests, which is a least-toxic approach that is undermined through chemical usage by destroying the balance that exists within a predator-prey relationship.
Non-target insects also act as a food source for animals that bring in a substantial amount of revenue. US citizens spend over $60 billion annually on hunting, fishing and observing wildlife, much of which is dependent on insects as a food source. Researchers have found that there is a steady decline in these insects due to pesticide exposure and an overall decline in biodiversity. It could be concluded then that, as beneficial insect populations decline, their ability to provide ecosystem services will also decline, impacting the available wildlife for hunting, fishing, and observing. The demand for these recreational activities will stay constant while the supply (availability) will decline, causing an increase in dollars spent by US citizens for each year.
What Can You Do?
- Learn about the Hazards and Alternatives to using lawn pesticides.
- Go Organic – Visit our Eating with a Conscience page to learn why eating organic foods is the right choice.
- Visit our Tools for Change page to learn how to organize your community against pesticide use.
- Sign up for Beyond Pesticides’ Action Alerts to stay up-to-date on the latest petitions and news.
Declining bee populations diminish pollination services, damaging plant and agricultural biodiversity. One of the causes of this decline is the use of pesticides. Pesticides with glyphosate as the main active ingredient are among the most used pesticides worldwide, being the most used in Brazil. This study determined the 24 and 48 h LD50 (median lethal dose) of the herbicide’s glyphosate-based formulation by ingestion, identified sublethal doses, and investigated its effects on the locomotion and behavior of Tetragonisca angustula workers. The LD50 found indicates that a glyphosate-based formulation is highly toxic to T. angustula. The doses applied, including concentrations found in nature, caused death, motor changes (decreased speed and tremors), excessive self-cleaning, and disorientation (return to light and stop). Although we did not test for pollination effects, we can infer from our results that this formulation can negatively affect the pollination activity of T. angustula. Evaluation of the toxicity and sublethal effects of pesticides on bees contributes to a better understanding of their harmful effects on hives and allows for the development of strategies to reduce these impacts.
[Prado, I.S., da Rocha, A.A., Silva, L.A. and Gonzalez, V.C., 2023. Ecotoxicology, 32(4), pp.513-524.]
The widespread use of glyphosate-based formulations to eliminate unwanted vegetation has increased concerns regarding their effects on non-target organisms, such as honey bees and their gut microbial communities. These effects have been associated with both glyphosate and co-formulants, but it is still unknown whether they translate to other bee species. In this study, we tested whether glyphosate, pure or in herbicide formulation, can affect the gut microbiota and survival rates of the eastern bumble bee, Bombus impatiens. We performed mark-recapture experiments with bumble bee workers from four different commercial colonies, which were exposed to field relevant concentrations of glyphosate or a glyphosate-based formulation (0.01 mM to 1 mM). After a 5-day period of exposure, we returned the bees to their original colonies, and they were sampled at days 0, 3 and 7 post-exposure to investigate changes in microbial community and microbiota resilience by 16S rRNA amplicon sequencing and quantitative PCR. We found that exposure to glyphosate, pure or in herbicide formulation, reduced the relative abundance of a beneficial bee gut bacterium, Snodgrassella, in bees from two of four colonies when compared to control bees at day 0 post-exposure, but this reduction became non-significant at days 3 and 7 post-exposure, suggesting microbiota resilience. We did not find significant changes in total bacteria between control and exposed bees. Moreover, we observed an overall trend in decreased survival rates in bumble bees exposed to 1 mM herbicide formulation during the 7-day post-exposure period, suggesting a potential negative effect of this formulation on bumble bees.
[Motta, E.V. and Moran, N.A., 2023. Science of The Total Environment, 872, p.162102.]
Several previous studies have investigated changes in insect biodiversity, with some highlighting declines and others showing turnover in species composition without net declines. Although research has shown that biodiversity changes are driven primarily by land-use change and increasingly by climate change, the potential for interaction between these drivers and insect biodiversity on the global scale remains unclear. Here we show that the interaction between indices of historical climate warming and intensive agricultural land use is associated with reductions of almost 50% in the abundance and 27% in the number of species within insect assemblages relative to those in less-disturbed habitats with lower rates of historical climate warming. These patterns are particularly evident in the tropical realm, whereas some positive responses of biodiversity to climate change occur in non-tropical regions in natural habitats. A high availability of nearby natural habitat often mitigates reductions in insect abundance and richness associated with agricultural land use and substantial climate warming but only in low-intensity agricultural systems. In such systems, in which high levels (75% cover) of natural habitat are available, abundance and richness were reduced by 7% and 5%, respectively, compared with reductions of 63% and 61% in places where less natural habitat is present (25% cover). Our results show that insect biodiversity will probably benefit from mitigating climate change, preserving natural habitat within landscapes and reducing the intensity of agriculture.
[Outhwaite, C.L., McCann, P. and Newbold, T., Nature, pp.1-6.]
Critical gaps in understanding how species respond to environmental change limit our capacity to address conservation risks in a timely way. Here, we examine the direct and interactive effects of key global change drivers, including climate change, land use change, and pesticide use, on persistence of 104 odonate species between two time periods (1980–2002 and 2008–2018) within 100 × 100 km quadrats across the USA using phylogenetic mixed models. Non-target effects of pesticides interacted with higher maximum temperatures to contribute to odonate declines. Closely related species responded similarly to global change drivers, indicating a potential role of inherited traits in species’ persistence or decline. Species shifting their range to higher latitudes were more robust to negative impacts of global change drivers generally. Inherited traits related to dispersal abilities and establishment in new places may govern both species’ acclimation to global change and their abilities to expand their range limits, respectively. This work is among the first to assess effects of climate change, land use change, and land use intensification together on Odonata, a significant step that improves understanding of multispecies effects of global change on invertebrates, and further identifies conditions contributing to global insect loss.
[Sirois-Delisle, C. and Kerr, J.T., 2021. ]
Survey data show a large-scale decline in insects. This global decline is often linked to human actions in intensive agricultural areas. To investigate whether this decline has a causal relationship with neonicotinoid insecticides, we performed an outdoor experiment with representative surface water concentrations of the neonicotinoid thiacloprid. We exposed naturally formed aquatic communities to increasing neonicotinoid concentrations and monitored insect emergence during a 3-mo period. We show that increasing neonicotinoid concentrations strongly decreased the abundance and biomass of five major insect orders that together comprised >99% of the 55,574 collected insects as well as the diversity of the most species-rich freshwater family, thus showing a causal relation between insect decline and neonicotinoids.
[Barmentlo, S.H., Schrama, M., De Snoo, G.R., Van Bodegom, P.M., van Nieuwenhuijzen, A. and Vijver, M.G. Proceedings of the National Academy of Sciences, 118(44).]
Semi-natural field borders are frequently used in midwestern U.S. sustainable agriculture. These habitats are meant to help diversify otherwise monocultural landscapes and provision them with ecosystem services, including biological control. Predatory and parasitic arthropods (i.e., potential natural enemies) often flourish in these habitats and may move into crops to help control pests. However, detailed information on the capacity of semi-natural field borders for providing overwintering refuge for these arthropods is poorly understood. In this study, we used soil emergence tents to characterize potential natural enemy communities (i.e., predacious beetles, wasps, spiders, and other arthropods) overwintering in cultivated organic crop fields and adjacent field borders. We found a greater abundance, species richness, and unique community composition of predatory and parasitic arthropods in field borders compared to arable crop fields, which were generally poorly suited as overwintering habitat. Furthermore, potential natural enemies tended to be positively associated with forb cover and negatively associated with grass cover, suggesting that grassy field borders with less forb cover are less well-suited as winter refugia. These results demonstrate that semi-natural habitats like field borders may act as a source for many natural enemies on a year-to-year basis and are important for conserving arthropod diversity in agricultural landscapes.
[Clem, C.S. and Harmon-Threatt, A.N. Journal of Insect Science, 21(3), p.2.]
Seed coating (‘seed treatment’) is the leading delivery method of neonicotinoid insecticides in major crops such as soybean, wheat, cotton and maize. However, this prophylactic use of neonicotinoids is widely discussed from the standpoint of environmental costs. Growing soybean plants from neonicotinoid-coated seeds in field, we demonstrate that soybean aphids (Aphis glycines) survived the treatment, and excreted honeydew containing neonicotinoids. Biochemical analyses demonstrated that honeydew excreted by the soybean aphid contained substantial concentrations of neonicotinoids even one month after sowing of the crop. Consuming this honeydew reduced the longevity of two biological control agents of the soybean aphid, the predatory midge Aphidoletes aphidimyza and the parasitic wasp Aphelinus certus. These results have important environmental and economic implications because honeydew is the main carbohydrate source for many beneficial insects in agricultural landscapes.
[Calvo-Agudo, M., Dregni, J., González-Cabrera, J., Dicke, M., Heimpel, G.E. and Tena, A. Environmental Pollution, 289, p.117813.]
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.
[Schläppi, D., Kettler, N., Straub, L., Glauser, G. and Neumann, P., 2020. Communications biology, 3(1), pp.1-9.]
Declining insect population sizes are provoking grave concern around the world as insects play essential roles in food production and ecosystems. Environmental contamination by intense insecticide usage is consistently proposed as a significant contributor, among other threats. Many studies have demonstrated impacts of low doses of insecticides on insect behavior, but have not elucidated links to insecticidal activity at the molecular and cellular levels. Here, the histological, physiological, and behavioral impacts of imidacloprid are investigated in Drosophila melanogaster, an experimental organism exposed to insecticides in the field. We show that oxidative stress is a key factor in the mode of action of this insecticide at low doses. Imidacloprid produces an enduring flux of Ca2+ into neurons and a rapid increase in levels of reactive oxygen species (ROS) in the larval brain. It affects mitochondrial function, energy levels, the lipid environment, and transcriptomic profiles. Use of RNAi to induce ROS production in the brain recapitulates insecticide-induced phenotypes in the metabolic tissues, indicating that a signal from neurons is responsible. Chronic low level exposures in adults lead to mitochondrial dysfunction, severe damage to glial cells, and impaired vision. The potent antioxidant, N-acetylcysteine amide (NACA), reduces the severity of a number of the imidacloprid-induced phenotypes, indicating a causal role for oxidative stress. Given that other insecticides are known to generate oxidative stress, this research has wider implications. The systemic impairment of several key biological functions, including vision, reported here would reduce the resilience of insects facing other environmental challenges.
[Martelli, F., Zhongyuan, Z., Wang, J., Wong, C.O., Karagas, N.E., Roessner, U., Rupasinghe, T., Venkatachalam, K., Perry, T., Bellen, H.J. and Batterham, P., 2020. Proceedings of the National Academy of Sciences, 117(41), pp.25840-25850.]