Honey Bees as Environmental Biomonitors and Effects of Climate Change on Their Population

Introduction

The honey bees (Apis spp.) are well known for the ecosystem services they provide in the form of pollination. According to reports, about 84% of the species of cultivated plants along with 35% of agricultural crops depend on the activity of insect pollinators including honey bees (Klein et al., 2007). Additionally, the honey bees help to pollinate several species of entomophilous wild plants (Michener, 2000). Thus, they are equally important for the agricultural industry as well as for the conservation of biodiversity. The honey bees benefit from their mutualistic association with plants by obtaining nutrient-rich nectar and/or pollen from the flowers. In fact, the major source of protein for the bee colony is pollen which nourishes both the brood as well as the adult bees (Flores et al., 2019). Recently, some studies have reported severe decline in the population of honey bees (Reddy et al., 2012). This threatens the agricultural sector as well as the global biodiversity.

Investigations into the reasons for the vanishing population of honey bees reveal pollution, intensification of agriculture, introduction of new pesticides, habitat loss, fragmented landscapes, reduction of floral biodiversity and climate change as the major factors (Vasiliev and Greenwood, 2021). Additionally, invasion by predators, pathogens and parasites also cause destruction to their population (Abou-Shaara, 2016). Despite these findings, the issue of eroding population of honey bees has been neglected for long because honey bee colonies are resilient to stressors even though the individuals are sensitive to them enabling many of the negative impacts to go unnoticed (Cunningham et al., 2022). Interestingly, the honey bees can accumulate pollutants without collapsing. They do so by concentrating the pollutants in their products like honey, beeswax, stored pollen, etc. (Cunningham et al., 2022). As such, analysis of these bee products can help to gain qualitative and quantitative information about the environmental condition of the adjoining areas. Thus, the honey bees have emerged as excellent candidates for monitoring environmental quality (Cunningham et al., 2022).

Among all the factors affecting honey bees, it is expected that climate change will have serious repercussions in the future. Their sensitivity to climatic factors arise from their ectothermic nature. The existence of different honey bee ecotypes can aggravate the problems further because they may face challenges in adjusting themselves to the new climate regimes (Le Conte and Navajas, 2008). It may eventually lead to their colony collapse (Flores et al., 2019). Studies show that alterations in climatic conditions will have direct effects on their physiology, behaviour, development and distribution (Reddy et al., 2012). Additionally, the effects of climate change on plant phenology and their natural enemies (i.e. predators, parasites and pathogens) can also exert indirect effects on honey bee population (Reddy et al., 2012). Under such circumstances, the honey bees may not only be deprived of nutritional resources but also be exposed to new and emerging agents of infection (Reddy et al., 2012).

Despite these findings, the field lacks extensive research. Further studies in this sector can help the agricultural practitioners, the environmentalists and the policy makers plan conservation strategies for honey bees (Apis spp.). This will not only form a protective measure against the future food security but also an important tool for the conservation of biodiversity and maintenance of ecological balance. Based on this background, the current chapter tries to explore the diversity and importance of honey bees (Apis spp.) together with the means by which climate change can exert negative impacts on their population. Last but not the least, it also tries to suggest mitigation strategies for the emerging problems.