The Effects of Vancouver City's Pesticide Spraying on Bees

     The Vancouver Park Board began it's annual pesticide spraying to remove the invasive Japanese beetle on April 3rd.  "April 3 2020 – The Vancouver Park Board is set to begin larvicide treatment to eradicate Japanese beetle larvae in more than 30 parks, boulevards, medians, and other city land beginning April 6."  This is the fourth year of treatment of an area that includes the West End, Downtown, Strathcona, Mount Pleasant, Fairview and Kitsilano neighbourhoods.  The spraying has been effective in reducing the population of this potentially devastating intruder.
  

     As stated the effects of the Japanese Beetle could be significant.  "Japanese beetle larvae feed on the roots of lawns and other plants.  Adults are heavy feeders, attacking the flowers, foliage, and fruit of more than 250 plant species, including roses, blueberries, and grapevines.  The damage they cause is significant compared to other pests like European chafer beetles." (from City of Vancouver)  Here is a mug shot of the deviant offender.

Japanese Beetle

     The pesticide they are using is the low impact, effective larvicide, Acelepryn which is produced by the agrichemical corporation Syngenta.  The active ingredient is the insecticide chlorantraniliprole.  The City claims there is no impact on anything other than the Japanese beetle ("will not impact people, pets, mammals, birds, bees, butterflies or other animals").  From the provincial government, "Why is Acelepryn being used for Japanese Beetle in B.C.?  Japanese beetle is a new invasive pest found for the first time in B.C. in the False Creek area of Vancouver in 2017. This pest is a significant threat to agriculture in B.C. An eradication program is underway to address this threat. One component of the eradication program is a larvicide treatment in areas where the beetle is known to be present. Acelepryn was selected because it has a very favourable health and environmental profile, is also very effective against Japanese beetle larvae, and does not impact mammals, birds, bees, butterflies or other animals."  
     I've heard these claims of bee friendly insecticides far too often in the past only to be proven later to have significant negative impacts.  I had to check it out.  Most of the studies I read agreed that Chlorantraniliprole had little or no effect on bees or other critters.  It was often stated that bees would not be interested in turf which it is usually applied to since there was usually no flowers and that if there were flowers in the turf that the grass should be mowed before to remove the flowers and irrigated soon after. I've been running the Vancouver seawall for many years and the part by David Lam Park since it was built after expo.  During my runs I observed the grass portion of the park covered in small flowers which were being heavily foraged upon by honey and bumble bees.  I observed them spraying on the flowers and foraging bees while I ran by.  In addition to this bumble bees nest in the ground and it's likely their nesting areas are being sprayed.  We have found over the years a problem with studies that observe the effects on bees is that they are usually not long term and do not observe the sublethal, accumulative effects (which over time become lethal).  Here are a few studies that shows a potential negative impact of  chlorantraniliprole on bee populations.

"BACKGROUND:

Pollinators such as the bumblebee, Bombus terrestris, fulfil a crucial role in agriculture. In this context, tests were conducted with the insecticide chlorantraniliprole (Coragen®) as a model compound active on the ryanodine receptor of insects.

RESULTS:

Chronic oral exposure via pollen induced lethargic behaviour in B. terrestris workers and their offspring (drones). Indeed, in nests exposed to 0.4 mg L(-1) , representing 1/100 of the concentration recommended for use in the field, workers and drones did not take their defensive position upon stimulation and they were less active than non-exposed insects. The different risk assessment tests used here demonstrated that contact and pollen exposure had no effect on bumblebee worker survival, whereas oral exposure via sugar water caused both acute (72 h LC50  = 13 mg L(-1) ) and chronic (7 week LC50  = 7 mg L(-1) ) toxicity. Severe sublethal effects on reproduction were recorded in nests orally exposed to pollen treated with chlorantraniliprole.

CONCLUSION:

The present study identified an important physiological endpoint of sublethal effects on reproduction, as this is associated with lethargic behaviour after oral intake. As such, this is a factor that should now be incorporated into future risk assessments. Secondly, it confirmed that the assessment of sublethal effects on behaviour is needed for adequate risk assessment of 'potentially deleterious' compounds with a neurogenic target, as is also pointed out in the recent European Food Safety Authority (EFSA) guidelines (from "Dietary chlorantraniliprole suppresses reproduction in worker bumblebees")."  
     Here is a study of the effects on honey bees (Honey bees long-lasting locomotor deficits after exposure to the diamide chlorantraniliprole are accompanied by brain and muscular calcium channels alterations).
     The point here is not to vilify Acelepryn as it is a much needed low impact larvacide (not no impact as stated by city sources) but to be clear and honest about the potential impact on other living things and to take the necessary steps to reduce that impact. All pesticides are toxic to some degree. The city field (Strathcona Park) adjacent to our apiary which at present houses both honey and blue mason bees is covered in clover, yarrow and other assorted small flowers much of the growing year. Similiar to David Lam Park the field was not mowed prior to spraying this year.  Also, in the past I have requested that the Parks Board cut the field adjacent to our apiary early in the morning to minimize the killing of bees foraging on the turf flowers but as of yet they continue to cut in the middle of the day when the fields are covered in bees. Maybe some day .....