Low Biodiversity Associated with Lower Crop Yields

Recent research suggests pesticide application may actually decrease crop yield through negative impacts on non-target flora and fauna. 

There are several ways that pesticides interact and impact the environment around agricultural fields, making this a very complex issue; but this issue nonetheless deserves to be highlighted, even if done so briefly.

Technology such as the Bacillus thuringiensis GMO trait has led to the reduction in the quantity of insecticide usage. However, toxicology studies on pyrethroids and neonicotinoids published by the German Federal Environmental Foundation, the British Ecological Society, and the University of Sussex, respectively, found that despite a decrease in quantity, insecticides have increased substantially in toxicity. 

Pyrethroids and neonicotinoids have popularly faced backlash due to an understated negative impact on honeybees, however their impacts on non-target insect species are broader than anticipated. 

According to a study by Cornell University, an estimated 0.1% of pesticides applied reach their target pests, therefore 99.9% remain in the environment.  

A combination of insecticides being applied as preventative measures, being designed to stay in the environment longer than in the past, and having increased toxicity creates a dilemma where their negative impacts begin to outweigh any positive pest control. 

Additionally, seed coatings were thought to be less harmful that spray insecticides, but were recently discovered to have greater negative impact than originally thought. 

All this becomes a major problem when non-target species are negatively impacted. Integrated pest management strategies that aim to reduce chemical usage through biological pest control end up failing because populations of beneficial insects drop. 

In soybean production, neonicotinoids were found to reduce yields by reducing populations of major beneficial insects needed for biological control of soybean pests. 

In cooler climates, slugs are a major soybean pest that are primarily controlled by various beetle species. A study published by the University of Sussex found that applying neonicotinoids to control other soybean pests reduced beneficial beetle populations. The reduction of beetles led to an increase in slug populations, which then reduced overall yield. 

While this is only one example, there are likely many more that research has yet to uncover. Neuro-toxic pesticides such as neonicotinoids are shown to decrease populations of beetle larvae, lacewings, predatory wasps, ladybugs, honeybees, and non-target Lepidoptera species. 

In the past 25 years, herbicide-resistant crops have led to a massive increase in the use of herbicides. 

Increase in herbicide usage has led to numerous impacts on local ecology, which end up negatively impacting agricultural fields. 

In a study published by the Canadian Journal of Plant Sciences, the edges of agricultural fields where herbicide was regularly applied saw a decrease in biodiversity and native plant species and an increase in weedy species.  

This negatively impacts insects that rely on these habitats and increases the spread of weed species into agricultural fields by proximity.

Additionally, many studies have raised alarm that risk assessments performed for herbicides do not include reproductive stages of non-target plant species. 

Furthermore, risk assessment trials often don’t consider interactions between different pesticides which create different, often more intense negative impacts than predicted in the laboratory. 

Prior to intensified herbicide usage, edges of farm fields used to be significantly biodiverse and served as a major habitat for threatened species such as monarch butterflies and milkweed species. 

Reduced biodiversity in these areas is theorized to have a significant impact on many bird and insect species which now struggle to survive.

This all creates a cycle of further intensified agrochemical usage because it becomes more difficult to attempt alternative pest management strategies with the loss of beneficial species and the increase in weeds. 

While it’s not easy, farmers can begin to break this cycle by protecting the edges of their fields. 

A major way that beneficial insect and plant species can be protected is by maintaining diverse hedgerows and woodland edges. 

Studies have indicated that farms with biodiverse edges see an overall decrease in pesticide usage because more beneficial insects can survive in the field and weedy plant populations are reduced. 

In order to do this, there must be a concentrated effort to reduce agrochemical drift during spray application, as well as a reduction in the frequency and quantity of agrochemicals applied to the field. Additionally, beneficial native plants can be planted around farm edges to create more diverse habitats.