A fundamental deterioration in nature

By Debapriya Mukherjee-September 1, 2020

Former Senior Scientist
Central Pollution Control Board, India

A widespread loss of pollinating animals in recent decades is a fundamental deterioration in nature. This loss will ultimately lead to a “catastrophic collapse of nature’s ecosystems”. Although the decline in pollinator population abundance and diversity has been registered worldwide but their critical role and invaluable advantages in biodiversity and ecosystem services are not getting due importance, may be, on account of poor environmental awareness among the people despite knowing that “animal pollination supply a major proportion of nutrients in the human diet”. In addition, fodder crops, plant-derived medicines such as aspirin and morphine, and fibres such as cotton are all animal-pollinated. Also many of the trees that are the lungs of the planet and absorb carbon from the atmosphere are animal pollinated.

Politicians all over the world strongly advocate importance of biodiversity but in reality this particular issue is not taken into consideration in the name of development though we all know that biodiversity improves human wellbeing through various ecosystem services, including material (e.g. food, fibers, timber), regulating (e.g. pest regulation, pollination, and nutrient cycling), and non-material (e.g. health, aesthetic, spiritual, education, or recreation) contributions. Pollination is regarded as a fundamental ecosystem service that provides direct commercial benefits to crop production and makes a key contribution to the dynamics and persistence of native plant species and communities. Pollination occurs when pollen grains are moved between two flowers of the same species, or within a single flower by wind or insects and animals. Successful pollination results in healthy fruit and fertile seeds, allowing the plants to reproduce. The extensive and critical world of crop pollinators is a $200 billion a year industry.

Pollinators are vital for global food security, with approximately 73% of the world’s cultivated crops are dependent on pollination, of which 56.5% are pollinated by bees, 19% by flies, 6.5% by bats, 5% by wasps, 5% by beetles, 4% by birds, and 4% by butterflies and moths. The 25,000 different bee species differ greatly in their size and habit requirements and consequently, deviate in the plants they visit and fertilize. Though honey bees are vital pollinators of many crops and fruit plants, flies are also important pollinators of more than 100 cultivated plants, including economically important crops like mango, cashew, tea, cacao, apple, onions, and strawberries. Today, flies are the third largest and most diverse animal groups in the world, comprising over 160,000 named species in approximately 150 families. However, substantial concern exists over their current and future conservation status. 

The global pollination services have drastically reduced with the losses of both wild and managed populations of insect pollinators. These declines have serious economic as well as conservation implications. Anthropogenic alterations in climates and habitats have resulted in reduction in the biodiversity of many pollinator families. Different factors, a-biotic and biotic, influence these parameters in the wild: predators, competitors, parasites, pathogens, and the availability of key resources. In particular, key threats to pollinators include agricultural intensification and land- use intensification (particularly habitat loss and pesticide use), urbanization, deforestation, industrial development (climate change and environmental pollution) and the spread of alien species (intensive farming). All these factors, singly and/or in combination may alter survival, behaviour and reproduction and in turn jeopardize the delivery of pollination services to crops and wild plants. In this piquant situation, there is a critical absence of robust large-scale, species-specific estimates of distribution change for pollinating insects, in particular bees and hoverflies, which are considered some of the most important pollinators. 

 Among them, one key pressure is exposure to chemicals through contact and consumption of contaminated nectar, pollen, water and guttation fluids, or via contact during foraging or nesting (e.g. in the air with contaminated dust particles, on crops and in soil with contaminated surfaces). This includes pesticide classes routinely applied to flowering crops. The new research highlights the complex web of pesticide residues entering the internal hive environment and colony food stream bees. In agricultural fields, honey bee populations are not exposed only to a single chemical compound because farmers often use more than one insecticide individually or in mixtures in a growing season.

Researchers reported that collecting pollen from returning honey bee foragers in apiaries across the many countries during the active beekeeping season revealed widespread and prolonged pollen contamination by multiple insecticides, herbicides and fungicides under the current agricultural pesticide application practices. As a result, managed and wild pollinators even in the rural areas are routinely exposed to multiple pesticides. Presence of various insecticides/pesticides in dead honey bee samples is the clear evident of honey bee mortality. Scientists also observed that neither the most common herbicide nor the most common fungicide affected worker bee mortality on their own. But when the bees were exposed to the fungicide in combination with the neonicotinoid clothianidin, it took half as much of the chemicals to kill as many bees. Thereby it is pertinent to mention that colonies performing pollination services are subject to increased pesticide exposure compared to honey-production.

Honey bee colonies have been proposed as terrestrial biomonitor because workers from the same colony typically forage up to 6 km away (with max distances reported as 13.5 km) from the hive encompassing over 100 km2, and return with accumulated contaminants to the hive. A single colony, therefore, can act as a terrestrial sentinel, expanding radially into the surrounding environment to collect food resources and acquiring contaminants including pesticide-laced pollen that is then stored in the colony as “beebread.” Most importantly these contaminants threaten bee queens in particular. The colonies without queen will not have eggs or future bees. 

In addition to bees, moths also play a vital role as overnight pollinators of a wide range of flowers and plants and its transport networks are larger and more complex than those of daytime pollinators like bees. Over the past decade, public anxiety about the role of our pollinators has focused squarely on bees but not on moths. There is a big misconception that all moths come and eat the clothes but that is not happened at all. Some moths happen to be visiting flowers and can be an important part of the pollination process. Many moths are transporting pollen originating from 47 different plant species, including several that are rarely visited by bees, hoverflies and butterflies. Moths complement the work of daytime pollinators and help keep plant populations diverse and abundant. They serve as a form of back-up for biodiversity, which in turn supports crop yields.But steep decline in numbers since the 1970s on account of changes in land use and the increasing use of pesticides has a knock-on effect for birds that feed on moths, such as the cuckoo. Its decline is kind of tied to moth declines. Bats will feed on moths as well, so there is ties to other creatures having declines in their own populations, because their food supply, the moths, are going down as well. 

In this context it is pertinent to mention that natural farming farming can facilitate the development of much-needed recommendations to mitigate problems associated with pesticide exposure, thus helping to reduce pollinator exposure risk. Many federal, state and local government agencies, non-government organizations and universities have launched extensive efforts to protect pollinators. Despite this effort , government must work closely with farmers, forest landowners and other private landowners to increase pollinator habitat in targeted areas nationwide by implementing conservation practices such as cover crops, wildflower and native plantings in buffers and areas not in production.

If we successfully protect pollinators, we can protect our ability to grow food. People must participate in making a change, through education, through action, through becoming a beekeeper, through gardening – all of those things are super important to this issue and really can make a difference.