SINCE ITS INTRODUCTION 
in the early 1990s, imidacloprid
has been widely used in the United States for
management of insect pests on ornamentals, primarily
various homopterans and leaf beetles. It has
systemic activity when applied either to foliage or
soil, but is most commonly used in the latter application.
Persistence in shade trees and shrubs after
soil injections or soil drenches can be long, sometimes
extending for 2 seasons	

Sclar, D. C., Gerace, D., & Cranshaw, W. S. (1998). Observations of population increases and injury by spider mites (Acari: Tetranychidae) on ornamental plants treated with imidacloprid. Journal of economic entomology, 91(1), 250-255.

* * *

> Pesticide use is necessary for agriculture especially as we prepare to feed 9 billion people by the year 2050 (UN 5/12/24). Knowing how a pesticide translocates through a plant is useful to many, including botanists, APHIS (for the control of invasive species), entomologists, toxicologists, farmers, landscapers, and gardeners. The knowledge that IMI [imidacloprid] partitions to leaves mostly and less to flowers, that it distributes differently through plants depending on the species and that different injection methods cause different times in peak expression allows IMI to be used more efficiently to target insects.

> The results we found suggest that IMI is not a risk to honey bees through the pollen of red maples but the high concentration of IMI in red maple leaves may raise a different issue to honey bees. The concentrations of IMI at levels on the order of 103 ppb in leaves could be an exposure risk to honey bees if the concentrations were released from the leaves.

> The repercussions of these findings are that worries by beekeepers of IMI exposures to honey bees through pollen under environmental real-world conditions may be allayed somewhat. Several studies report IMI pollen levels at or below 100ppb in pollen.

> The effects of IMI on honey bees have been well studied. At the sub lethal range between 5 and 100ppb, the effects are sometimes significant and sometimes not significant as Blacquiere et al. (2012) discusses, suggesting that at those concentrations, the LOEC or NOEC [Lowest observed effect concentrations, No observed effect concentration] may have been reached. Future research dollars might be better spent on other topics like synergy effects within hives or IMI effects on susceptible aquatic species, than on defining further the LOEC values on honey bees.

Josephine Johnson (2012) The role of pesticides on honey bee health and hive maintenance with an emphasis on the neonicotinoid, imidacloprid. PhD Thesis

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