New infectious diseases among bees threaten world’s economies

Sub: Sci

Sec: health

Context:

A study in Switzerland found 10-times higher viral loads (e.g., deformed wing virus, black queen virus) in wild pollinators when sharing floral resources with managed honey bees.

Details:

Habitat Loss exacerbates the overlap between wild and managed bees, increasing the risk of pathogen spillover.
Research has uncovered the transmission of pathogens between managed honey bees and wild pollinators, a process called pathogen spillover and spillback.
- Western honey bees are often viral reservoirs and can infect wild species when they share habitats.
- These emerging infectious diseases also threaten the wider pollinator community.

Significance of insect pollinators:

A significant chunk of the world’s agricultural productivity and nutritional security relies on small insect pollinators. Over 75% of food crops, fruits, and flowering plants depend on small insect pollinators like bees, wasps, beetles, flies, moths, and butterflies for successful yields.
Threats to pollinators such as pesticides, pollution, climate change, and infectious diseases pose a serious risk to global agricultural productivity and nutritional security.
Data Scarcity: Most research on bees focuses on managed western honey bees (Apis mellifera), with limited data from biodiversity-rich regions like the Indian subcontinent.
Wild bees often outperform western honey bees in pollination efficiency. Research emphasises the need to study wild bee health and populations.

Indian Context:

Native Bee Species: India has over 700 bee species, including four indigenous honey bees:
- Asiatic honey bee (Apis cerana indica)
- Giant rock bee (Apis dorsata)
- Dwarf honey bee (Apis florea)
- Stingless bee (Trigona species)
Western honey bees were introduced to India in 1983, increasing honey production but also raising concerns about disease transmission.
The Thai sacbrood virus has devastated up to 90% of Asiatic honey bee colonies in South India, with reemergence in 2021.

Migration and Competition:

Migration Impact: Managed honey bees often migrate along routes with rich floral resources, which can disrupt local bee populations and increase competition.
Decline in Native Populations: In regions like Kolhapur, Maharashtra, the introduction of western honey bees led to a decline in indigenous pollinators and honey production due to diseases.

Managed Honey Bees:

Primarily Apis mellifera (Western honey bee), kept in human-made hives
Used extensively in commercial agriculture for crop pollination
Live in large colonies (up to 60,000 bees)
Produce honey and wax for human use
More generalist pollinators, visiting many types of flowers
Face challenges like Colony Collapse Disorder, parasites (especially Varroa mites), and pesticide exposure
Require human management for disease control and feeding

Wild Bees:

Incredibly diverse group with over 20,000 known species worldwide
Include solitary bees, bumblebees, and other native species
Many are specialist pollinators adapted to specific plants
Often more efficient pollinators for certain crops (e.g., mason bees for orchards)
Various nesting habits (ground, wood, plant stems)
Most don’t produce honey for human harvest
Face threats from habitat loss, pesticides, and climate change

Key Environmental Considerations:

While managed honey bees are important for agriculture, they can compete with wild bees for resources
Wild bees provide crucial ecosystem services and are essential for native plant reproduction
Both groups need diverse flower resources and pesticide-free environments
Conservation efforts should focus on protecting both managed and wild bee habitats

Source: TH