Pesticide Risk Assessment and Management for Pollinators

Transcription

1 Pesticide Risk Assessment and Management for Pollinators Jeffrey Jenkins Department of Environmental and Molecular Toxicology Oregon State University

2 Colony Collapse Disorder 'Colony Collapse Disorder' first discovered in the US in 2006 Suggested causes fall within 5 broad categories: Pathogens (such as fungi, amoeba, bacteria, and viruses that infect honey bee brood and adults) Parasites (such as tracheal (internal) and Varroa (external) mites Varroa mites injure adult bees and brood by direct feeding and transmission of pathogenic viruses) Pesticides (such as miticides and antibiotics used inside the hive and pesticides used outside the hive) Malnutrition (lack of food sources, nectar diversity) Management Stressors (such as transportation stress, overcrowding, feeding practices, and genetic fitness of the queen source) The exact cause of increased colony losses remains unknown it is most likely a combination of stressors.

3 EPA Pesticide Risk Assessment and Management Under FIFRA/FQPA Quasi risk benefit balancing statutes Determine risks to human health and the environment: Toxicity to humans and wildlife Opportunities for exposure Registration/Re registration decision Mitigate risks with label restrictions/mandates Generally not site specific

4 EPA Pesticide Risk Assessment Risk = f (exposure, toxicity) Source: Purdue University Pesticides Program

5 Risk: Conceptual Framework Opportunities Pesticide Use for Pesticide Practices Exposure Human Wildlife Risk Human/wildlife Susceptibility and Behavior

6 Risk Assessment and Management

7 Pesticide Risk to Honey Bees As a general rule, insecticides are more toxic to honey bees than fungicides and herbicides. Most poisonings occur when insecticides are applied during the blooming period. Other exposure pathways include Pesticide drift onto adjoining crops/plants that are in bloom Contamination of flowering ground cover plants Pesticide residues on pollen and nectar transferred by foraging pollinators to the colony Pollinators drinking or touching contaminated water (dew, guttation water) Exposure to dust from seed treatments

8 Pesticide Risk to Honey Bees The U.S. EPA evaluates pesticide outdoor uses for toxicity to pollinators. Initial testing (Tier 1) determines Acute contact lethal dose to half the test population (LD50) Toxicity Category I, "highly toxic to bees" If LD50 <= 2 ug/bee Toxicity Category II, "toxic to bees" if LD50 >= 2 and < 11 ug/bee Toxicity Category III, no bee caution on label, if LD50 > 11 ug/bee Residual toxicity how long following application the pesticide is toxic to bees.

9 Pesticide Risk to Honey Bees Field Testing for Pollinators (Tier 2) may be required if the above tests indicate adverse effects on bees. Toxicity Categories I and II are "bee toxic pesticides" and the product label will have specific use instructions to reduce the risk to pollinators. Bee toxic pesticides with extended residual toxicity may require additional mitigation measures (application restrictions) to protect pollinators.

10

11

12 FIFRA/FQPA Federal State Partnerships designed to Achieve Safe and Beneficial Pesticide Use Risk characterization through sound science Cost effective requirements to insure safe use Clear understanding of label restrictions and use mandates Informed decision making at the frontline of pesticide use

13 Pesticide Benefit Risk Assessment Environmental fate: Persistence (how long does it last) Re distribution in the environment (where does it go) Maximum efficacy/minimum environmental impact: apply to target only effective pest control minimal impact on beneficials/non target sp. no movement from site degrades to non toxic products

14 Consistent exposure and effect assessment is possible if processes in the environmental system and in the organisms (biological system) are treated with the same modelling structure and tools R. P. Schwarzenbach et al., Science 313, (2006) 14 Published by AAAS

15 Chemical Fate Bioavailability Exposure air xxx Adapted from R. P. Schwarzenbach et al., Science 313, (2006)

16 Transfer of agrochemicals to the target R. Pontzen, Pflanzenschutz Nachrichten Bayer 59/2006, 1, p 63 72

17 Spray deposit of thiacloprid on a barley leaf (electron micrograph). R. Pontzen, Pflanzenschutz Nachrichten Bayer 59/2006, 1, p 63 72

18 Agrochemical Spray deposit on the leaf surface R. Pontzen, Pflanzenschutz Nachrichten Bayer 59/2006, 1, p 63 72

19 Pesticide partitioning between leaf surface deposit, moisture, and air water air air Aged Surface Deposit Chemical In water Chemical In air Aged Surface Deposit chemical In air K ow K h describes the relationship between pesticide concentration K h describes the relationship between pesticide concentration

20 Systemic Pesticides Systemic pesticides are soluble enough in water that they can be absorbed by a plant and moved around in its tissues. Systemic pesticides can be applied to the soil beneath a plant and transported in the xylem to reach pests that are otherwise hard to kill. When systemic pesticides are applied to the soil, beneficial insects, birds, pets, and people are much less likely to encounter the pesticide in the form of residues or spray drift.

21 Systemic Pesticides Guttation - loss of liquid water from uninjured leaf margins due to root pressure, may contain dissolved substances, only occurs in some plants (grasses, tomato).

22 The Neonicotinoids Name Company Products Imidacloprid Bayer CropScience Confidor, Admire, Gaucho, Advocate Thiamethoxam Syngenta Actara, Platinum, Cruiser Clothianidin Sumitomo Chemical Bayer CropScience Poncho, Dantosu, Dantop Acetamiprid Nippon Soda Mospilan, Assail, ChipcoTristar Thiochoprid Bayer CropScience Calypso Dinotefuran Mitsui Chemicals Starkle, Safari, Venom Sulfoxaflor Dow Agrosciences Transform, Closer Nitenpyram Sumitomo Chemical Capstar, Bestguard

23 Neonicotinoids Mode of action Derivatives of nicotine (first insecticide use France 1690) Mode of action disrupt the nervous system by binding to postsynaptic nicotinic acetylcholine receptors. Toxic effects: modified feeding behavior, paralysis, and subsequent death. At low doses neurobehavioral effects? nicotine Imidacloprid

24 Neonicotinoids application methods Application methods Seed treatments (dust, systemic in plant) Soil application (soil insects, systemic in plant) Foliar application (surface residues, systemic in plant)

25 Neonicotinoids environmental fate High water solubility Low volatility Long half life Systemic in plants

26 Imidacloprid Characteristics days 1 Environmental Fate of Imidacloprid, California Department of Pesticide Regulation 2006

27 Neonicotinoids and Pollinators Exposure pathways Seed treatment: dust Systemic: pollen, nectar, guttation water Foliar: foliar residues, pollen, nectar, guttation water Foraging behavior amplifies individual exposure and hive exposure.

28 Neonicotinoids and Pollinators While acute lethal effects are of concern Major concern is for sub lethal and chronic effects on fitness and survival. These outcomes that may not be adequately addressed by current risk assessment methods.

29 Neonicotinoids and Pollinators Sublethal effects of concern include: disorientation and difficulties in returning back to the hive (homing ability) reduced foraging and travel impaired memory and learning failure to communicate properly with nest mates

30 Neonicotinoids and Pollinators The feeding, communication, reproduction, hygiene and immune response systems of social insects are highly complex. Study results can be confused by a wide variety of biological and geographic factors affecting the treated colonies and the untreated control colonies.

31 Neonicotinoids and Pollinators Lab and Field Studies Discrepancy between clear lab results and inconclusive or negative field results. Few lab studies conducted at environmentally relevant pesticide levels and patterns of exposure. Field study levels and patterns of exposure are not well understood and/or confounded with other stressors (i.e., disease and parasites).

32 Field study methodological obstacles What floral resources are available? What levels of pesticide residues are in the pollen and nectar collected? Do the hives all display similar levels of disease and parasites which can affect hive health? Is there considerable mortality or abnormal behavior observed in the control hives?

33 Crop diversity in Zollner Creek Watershed, Willamette Valley Typical bee foraging range difficult to conduct field studies. Total Units: 893 Mt Angel

34 CSIRO bee tagging project

35 New Research on Honeybee Viral Infection January 21, 2014

36 Zombie Bees 1 Parasitic fly Apocephalus Borealis Inserts eggs in honeybees, bumblebees Bees fly around in a disoriented way, get attracted to light, and then fall down and wander around like zombies. When parasite eggs hatch bees die. 1

37 Conclusions Uncertainty in ecological risk assessment is uniquely large relative to other science based policy areas. EPA/USDA identified pollinator risks include pesticides, parasites, and poor forage Current understanding of the risks to pollinators associated with pesticide use is inadequate. Resources should be allocated to a better understanding of: Pesticide patterns of use. Pesticide distribution and fate at a scale relevant to pollinator exposure (bioavailability of systemic pesticides). Pollinator occurrence and behavior that determines exposure. Pesticide adverse effects on pollinator fitness and survival.

38